cpython-lru_cache-weakref: Doc/lib/libparser.tex annotate

annotate Doc/lib/libparser.tex @ 17581:c1937faabb23 2.1

Added support for optional explanation parameter to the \versionadded macro. Refactored do_cmd_versionadded() and do_cmd_versionchanged() to do most of the work in a helper function, with the do_cmd_*() wrappers just supplying a portion of the replacement text.

author	Fred Drake <fdrake@acm.org>
date	Wed, 18 Apr 2001 17:29:14 +0000
parents	c7c404b35f33
children	e5c3ca7b5099

rev	line source
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	1 \section{\module{parser} ---
e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	2 Access Python parse trees}
e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	3
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	4 % Copyright 1995 Virginia Polytechnic Institute and State University
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	5 % and Fred L. Drake, Jr. This copyright notice must be distributed on
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	6 % all copies, but this document otherwise may be distributed as part
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	7 % of the Python distribution. No fee may be charged for this document
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	8 % in any representation, either on paper or electronically. This
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	9 % restriction does not affect other elements in a distributed package
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	10 % in any way.
10245 bdbfe0ec970f Use more current approach to recording authors. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	11
8716 760dcf197048 Adjusted to use the new module synopsis support macros. Fred Drake <fdrake@acm.org> parents: 8040 diff changeset	12 \declaremodule{builtin}{parser}
10245 bdbfe0ec970f Use more current approach to recording authors. Fred Drake <fdrake@acm.org> parents: 8918 diff changeset	13 \modulesynopsis{Access parse trees for Python source code.}
8918 acfffe14628e New section header style. Fred Drake <fdrake@acm.org> parents: 8716 diff changeset	14 \moduleauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
acfffe14628e New section header style. Fred Drake <fdrake@acm.org> parents: 8716 diff changeset	15 \sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
8716 760dcf197048 Adjusted to use the new module synopsis support macros. Fred Drake <fdrake@acm.org> parents: 8040 diff changeset	16
760dcf197048 Adjusted to use the new module synopsis support macros. Fred Drake <fdrake@acm.org> parents: 8040 diff changeset	17
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	18 \index{parsing!Python source code}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	19
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	20 The \module{parser} module provides an interface to Python's internal
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	21 parser and byte-code compiler. The primary purpose for this interface
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	22 is to allow Python code to edit the parse tree of a Python expression
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	23 and create executable code from this. This is better than trying
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	24 to parse and modify an arbitrary Python code fragment as a string
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	25 because parsing is performed in a manner identical to the code
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	26 forming the application. It is also faster.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	27
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	28 There are a few things to note about this module which are important
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	29 to making use of the data structures created. This is not a tutorial
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	30 on editing the parse trees for Python code, but some examples of using
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	31 the \module{parser} module are presented.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	32
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	33 Most importantly, a good understanding of the Python grammar processed
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	34 by the internal parser is required. For full information on the
11463 17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	35 language syntax, refer to the \citetitle[../ref/ref.html]{Python
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	36 Language Reference}. The parser itself is created from a grammar
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	37 specification defined in the file \file{Grammar/Grammar} in the
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	38 standard Python distribution. The parse trees stored in the AST
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	39 objects created by this module are the actual output from the internal
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	40 parser when created by the \function{expr()} or \function{suite()}
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	41 functions, described below. The AST objects created by
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	42 \function{sequence2ast()} faithfully simulate those structures. Be
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	43 aware that the values of the sequences which are considered
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	44 ``correct'' will vary from one version of Python to another as the
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	45 formal grammar for the language is revised. However, transporting
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	46 code from one Python version to another as source text will always
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	47 allow correct parse trees to be created in the target version, with
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	48 the only restriction being that migrating to an older version of the
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	49 interpreter will not support more recent language constructs. The
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	50 parse trees are not typically compatible from one version to another,
17e12305973e Use \citetitle and \programopt as appropriate. Fred Drake <fdrake@acm.org> parents: 11265 diff changeset	51 whereas source code has always been forward-compatible.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	52
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	53 Each element of the sequences returned by \function{ast2list()} or
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	54 \function{ast2tuple()} has a simple form. Sequences representing
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	55 non-terminal elements in the grammar always have a length greater than
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	56 one. The first element is an integer which identifies a production in
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	57 the grammar. These integers are given symbolic names in the C header
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	58 file \file{Include/graminit.h} and the Python module
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10245 diff changeset	59 \refmodule{symbol}. Each additional element of the sequence represents
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	60 a component of the production as recognized in the input string: these
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	61 are always sequences which have the same form as the parent. An
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	62 important aspect of this structure which should be noted is that
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	63 keywords used to identify the parent node type, such as the keyword
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	64 \keyword{if} in an \constant{if_stmt}, are included in the node tree without
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	65 any special treatment. For example, the \keyword{if} keyword is
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	66 represented by the tuple \code{(1, 'if')}, where \code{1} is the
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	67 numeric value associated with all \constant{NAME} tokens, including
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	68 variable and function names defined by the user. In an alternate form
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	69 returned when line number information is requested, the same token
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	70 might be represented as \code{(1, 'if', 12)}, where the \code{12}
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	71 represents the line number at which the terminal symbol was found.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	72
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	73 Terminal elements are represented in much the same way, but without
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	74 any child elements and the addition of the source text which was
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	75 identified. The example of the \keyword{if} keyword above is
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	76 representative. The various types of terminal symbols are defined in
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	77 the C header file \file{Include/token.h} and the Python module
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10245 diff changeset	78 \refmodule{token}.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	79
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	80 The AST objects are not required to support the functionality of this
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	81 module, but are provided for three purposes: to allow an application
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	82 to amortize the cost of processing complex parse trees, to provide a
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	83 parse tree representation which conserves memory space when compared
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	84 to the Python list or tuple representation, and to ease the creation
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	85 of additional modules in C which manipulate parse trees. A simple
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	86 ``wrapper'' class may be created in Python to hide the use of AST
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	87 objects.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	88
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	89 The \module{parser} module defines functions for a few distinct
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	90 purposes. The most important purposes are to create AST objects and
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	91 to convert AST objects to other representations such as parse trees
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	92 and compiled code objects, but there are also functions which serve to
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	93 query the type of parse tree represented by an AST object.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	94
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	95
10845 5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	96 \begin{seealso}
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	97 \seemodule{symbol}{Useful constants representing internal nodes of
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	98 the parse tree.}
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	99 \seemodule{token}{Useful constants representing leaf nodes of the
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	100 parse tree and functions for testing node values.}
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	101 \end{seealso}
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	102
5ef4b3ca5564 Move the "See also:" section so it appears are part of the top HTML Fred Drake <fdrake@acm.org> parents: 10703 diff changeset	103
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	104 \subsection{Creating AST Objects \label{Creating ASTs}}
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	105
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	106 AST objects may be created from source code or from a parse tree.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	107 When creating an AST object from source, different functions are used
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	108 to create the \code{'eval'} and \code{'exec'} forms.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	109
11265 8336188a3c10 Name the parameter to expr() and suite() "source" instead of "string". Fred Drake <fdrake@acm.org> parents: 11160 diff changeset	110 \begin{funcdesc}{expr}{source}
8336188a3c10 Name the parameter to expr() and suite() "source" instead of "string". Fred Drake <fdrake@acm.org> parents: 11160 diff changeset	111 The \function{expr()} function parses the parameter \var{source}
12640 3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	112 as if it were an input to \samp{compile(\var{source}, 'file.py',
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	113 'eval')}. If the parse succeeds, an AST object is created to hold the
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	114 internal parse tree representation, otherwise an appropriate exception
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	115 is thrown.
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	116 \end{funcdesc}
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	117
11265 8336188a3c10 Name the parameter to expr() and suite() "source" instead of "string". Fred Drake <fdrake@acm.org> parents: 11160 diff changeset	118 \begin{funcdesc}{suite}{source}
8336188a3c10 Name the parameter to expr() and suite() "source" instead of "string". Fred Drake <fdrake@acm.org> parents: 11160 diff changeset	119 The \function{suite()} function parses the parameter \var{source}
12640 3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	120 as if it were an input to \samp{compile(\var{source}, 'file.py',
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	121 'exec')}. If the parse succeeds, an AST object is created to hold the
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	122 internal parse tree representation, otherwise an appropriate exception
3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	123 is thrown.
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	124 \end{funcdesc}
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	125
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	126 \begin{funcdesc}{sequence2ast}{sequence}
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	127 This function accepts a parse tree represented as a sequence and
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	128 builds an internal representation if possible. If it can validate
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	129 that the tree conforms to the Python grammar and all nodes are valid
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	130 node types in the host version of Python, an AST object is created
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	131 from the internal representation and returned to the called. If there
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	132 is a problem creating the internal representation, or if the tree
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	133 cannot be validated, a \exception{ParserError} exception is thrown. An AST
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	134 object created this way should not be assumed to compile correctly;
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	135 normal exceptions thrown by compilation may still be initiated when
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	136 the AST object is passed to \function{compileast()}. This may indicate
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	137 problems not related to syntax (such as a \exception{MemoryError}
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	138 exception), but may also be due to constructs such as the result of
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	139 parsing \code{del f(0)}, which escapes the Python parser but is
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	140 checked by the bytecode compiler.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	141
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	142 Sequences representing terminal tokens may be represented as either
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	143 two-element lists of the form \code{(1, 'name')} or as three-element
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	144 lists of the form \code{(1, 'name', 56)}. If the third element is
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	145 present, it is assumed to be a valid line number. The line number
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	146 may be specified for any subset of the terminal symbols in the input
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	147 tree.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	148 \end{funcdesc}
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	149
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	150 \begin{funcdesc}{tuple2ast}{sequence}
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	151 This is the same function as \function{sequence2ast()}. This entry point
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	152 is maintained for backward compatibility.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	153 \end{funcdesc}
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	154
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	155
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	156 \subsection{Converting AST Objects \label{Converting ASTs}}
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	157
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	158 AST objects, regardless of the input used to create them, may be
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	159 converted to parse trees represented as list- or tuple- trees, or may
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	160 be compiled into executable code objects. Parse trees may be
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	161 extracted with or without line numbering information.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	162
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	163 \begin{funcdesc}{ast2list}{ast\optional{, line_info}}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	164 This function accepts an AST object from the caller in
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	165 \var{ast} and returns a Python list representing the
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	166 equivalent parse tree. The resulting list representation can be used
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	167 for inspection or the creation of a new parse tree in list form. This
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	168 function does not fail so long as memory is available to build the
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	169 list representation. If the parse tree will only be used for
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	170 inspection, \function{ast2tuple()} should be used instead to reduce memory
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	171 consumption and fragmentation. When the list representation is
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	172 required, this function is significantly faster than retrieving a
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	173 tuple representation and converting that to nested lists.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	174
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	175 If \var{line_info} is true, line number information will be
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	176 included for all terminal tokens as a third element of the list
4591 8cdd94a3d02d (libparser.tex): Added note that the line number for a terminal token Fred Drake <fdrake@acm.org> parents: 4286 diff changeset	177 representing the token. Note that the line number provided specifies
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	178 the line on which the token \emph{ends}. This information is
4591 8cdd94a3d02d (libparser.tex): Added note that the line number for a terminal token Fred Drake <fdrake@acm.org> parents: 4286 diff changeset	179 omitted if the flag is false or omitted.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	180 \end{funcdesc}
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	181
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	182 \begin{funcdesc}{ast2tuple}{ast\optional{, line_info}}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	183 This function accepts an AST object from the caller in
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	184 \var{ast} and returns a Python tuple representing the
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	185 equivalent parse tree. Other than returning a tuple instead of a
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	186 list, this function is identical to \function{ast2list()}.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	187
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	188 If \var{line_info} is true, line number information will be
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	189 included for all terminal tokens as a third element of the list
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	190 representing the token. This information is omitted if the flag is
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	191 false or omitted.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	192 \end{funcdesc}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	193
7712 0cbc9df882b6 Change "\," to just "," in function signatures. This is easier to maintain, Fred Drake <fdrake@acm.org> parents: 7607 diff changeset	194 \begin{funcdesc}{compileast}{ast\optional{, filename\code{ = '<ast>'}}}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	195 The Python byte compiler can be invoked on an AST object to produce
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	196 code objects which can be used as part of an \keyword{exec} statement or
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	197 a call to the built-in \function{eval()}\bifuncindex{eval} function.
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	198 This function provides the interface to the compiler, passing the
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	199 internal parse tree from \var{ast} to the parser, using the
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	200 source file name specified by the \var{filename} parameter.
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	201 The default value supplied for \var{filename} indicates that
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	202 the source was an AST object.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	203
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	204 Compiling an AST object may result in exceptions related to
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	205 compilation; an example would be a \exception{SyntaxError} caused by the
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	206 parse tree for \code{del f(0)}: this statement is considered legal
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	207 within the formal grammar for Python but is not a legal language
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	208 construct. The \exception{SyntaxError} raised for this condition is
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	209 actually generated by the Python byte-compiler normally, which is why
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	210 it can be raised at this point by the \module{parser} module. Most
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	211 causes of compilation failure can be diagnosed programmatically by
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	212 inspection of the parse tree.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	213 \end{funcdesc}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	214
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	215
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	216 \subsection{Queries on AST Objects \label{Querying ASTs}}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	217
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	218 Two functions are provided which allow an application to determine if
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	219 an AST was created as an expression or a suite. Neither of these
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	220 functions can be used to determine if an AST was created from source
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	221 code via \function{expr()} or \function{suite()} or from a parse tree
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	222 via \function{sequence2ast()}.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	223
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	224 \begin{funcdesc}{isexpr}{ast}
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	225 When \var{ast} represents an \code{'eval'} form, this function
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	226 returns true, otherwise it returns false. This is useful, since code
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	227 objects normally cannot be queried for this information using existing
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	228 built-in functions. Note that the code objects created by
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	229 \function{compileast()} cannot be queried like this either, and are
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	230 identical to those created by the built-in
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	231 \function{compile()}\bifuncindex{compile} function.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	232 \end{funcdesc}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	233
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	234
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	235 \begin{funcdesc}{issuite}{ast}
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	236 This function mirrors \function{isexpr()} in that it reports whether an
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	237 AST object represents an \code{'exec'} form, commonly known as a
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	238 ``suite.'' It is not safe to assume that this function is equivalent
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	239 to \samp{not isexpr(\var{ast})}, as additional syntactic fragments may
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	240 be supported in the future.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	241 \end{funcdesc}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	242
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	243
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	244 \subsection{Exceptions and Error Handling \label{AST Errors}}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	245
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	246 The parser module defines a single exception, but may also pass other
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	247 built-in exceptions from other portions of the Python runtime
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	248 environment. See each function for information about the exceptions
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	249 it can raise.
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	250
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	251 \begin{excdesc}{ParserError}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	252 Exception raised when a failure occurs within the parser module. This
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	253 is generally produced for validation failures rather than the built in
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	254 \exception{SyntaxError} thrown during normal parsing.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	255 The exception argument is either a string describing the reason of the
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	256 failure or a tuple containing a sequence causing the failure from a parse
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	257 tree passed to \function{sequence2ast()} and an explanatory string. Calls to
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	258 \function{sequence2ast()} need to be able to handle either type of exception,
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	259 while calls to other functions in the module will only need to be
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	260 aware of the simple string values.
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	261 \end{excdesc}
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	262
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	263 Note that the functions \function{compileast()}, \function{expr()}, and
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	264 \function{suite()} may throw exceptions which are normally thrown by the
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	265 parsing and compilation process. These include the built in
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	266 exceptions \exception{MemoryError}, \exception{OverflowError},
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	267 \exception{SyntaxError}, and \exception{SystemError}. In these cases, these
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	268 exceptions carry all the meaning normally associated with them. Refer
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	269 to the descriptions of each function for detailed information.
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	270
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	271
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	272 \subsection{AST Objects \label{AST Objects}}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	273
7879 427a9b1c9abd Move a short paragraph outside the description of ASTType. Fred Drake <fdrake@acm.org> parents: 7877 diff changeset	274 Ordered and equality comparisons are supported between AST objects.
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10245 diff changeset	275 Pickling of AST objects (using the \refmodule{pickle} module) is also
8035 6c594988572a Add a note that pickling is supported. Fred Drake <fdrake@acm.org> parents: 7933 diff changeset	276 supported.
7879 427a9b1c9abd Move a short paragraph outside the description of ASTType. Fred Drake <fdrake@acm.org> parents: 7877 diff changeset	277
7607 00ad309bd508 Nits. Fred Drake <fdrake@acm.org> parents: 7457 diff changeset	278 \begin{datadesc}{ASTType}
00ad309bd508 Nits. Fred Drake <fdrake@acm.org> parents: 7457 diff changeset	279 The type of the objects returned by \function{expr()},
00ad309bd508 Nits. Fred Drake <fdrake@acm.org> parents: 7457 diff changeset	280 \function{suite()} and \function{sequence2ast()}.
00ad309bd508 Nits. Fred Drake <fdrake@acm.org> parents: 7457 diff changeset	281 \end{datadesc}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	282
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	283
8040 df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	284 AST objects have the following methods:
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	285
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	286
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	287 \begin{methoddesc}[AST]{compile}{\optional{filename}}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	288 Same as \code{compileast(\var{ast}, \var{filename})}.
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	289 \end{methoddesc}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	290
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	291 \begin{methoddesc}[AST]{isexpr}{}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	292 Same as \code{isexpr(\var{ast})}.
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	293 \end{methoddesc}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	294
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	295 \begin{methoddesc}[AST]{issuite}{}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	296 Same as \code{issuite(\var{ast})}.
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	297 \end{methoddesc}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	298
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	299 \begin{methoddesc}[AST]{tolist}{\optional{line_info}}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	300 Same as \code{ast2list(\var{ast}, \var{line_info})}.
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	301 \end{methoddesc}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	302
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	303 \begin{methoddesc}[AST]{totuple}{\optional{line_info}}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	304 Same as \code{ast2tuple(\var{ast}, \var{line_info})}.
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	305 \end{methoddesc}
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	306
df0fa5dc599a No more threats, just list the new methods under "AST Objects". Fred Drake <fdrake@acm.org> parents: 8035 diff changeset	307
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	308 \subsection{Examples \label{AST Examples}}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	309
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	310 The parser modules allows operations to be performed on the parse tree
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	311 of Python source code before the bytecode is generated, and provides
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	312 for inspection of the parse tree for information gathering purposes.
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	313 Two examples are presented. The simple example demonstrates emulation
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	314 of the \function{compile()}\bifuncindex{compile} built-in function and
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	315 the complex example shows the use of a parse tree for information
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	316 discovery.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	317
7879 427a9b1c9abd Move a short paragraph outside the description of ASTType. Fred Drake <fdrake@acm.org> parents: 7877 diff changeset	318 \subsubsection{Emulation of \function{compile()}}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	319
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	320 While many useful operations may take place between parsing and
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	321 bytecode generation, the simplest operation is to do nothing. For
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	322 this purpose, using the \module{parser} module to produce an
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	323 intermediate data structure is equivalent to the code
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	324
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	325 \begin{verbatim}
12640 3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	326 >>> code = compile('a + 5', 'file.py', 'eval')
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	327 >>> a = 5
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	328 >>> eval(code)
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	329 10
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	330 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	331
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	332 The equivalent operation using the \module{parser} module is somewhat
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	333 longer, and allows the intermediate internal parse tree to be retained
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	334 as an AST object:
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	335
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	336 \begin{verbatim}
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	337 >>> import parser
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	338 >>> ast = parser.expr('a + 5')
12640 3f06f4765ba4 Fix references to the built-in compile() that don't include the Fred Drake <fdrake@acm.org> parents: 12223 diff changeset	339 >>> code = ast.compile('file.py')
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	340 >>> a = 5
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	341 >>> eval(code)
21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	342 10
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	343 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	344
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	345 An application which needs both AST and code objects can package this
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	346 code into readily available functions:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	347
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	348 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	349 import parser
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	350
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	351 def load_suite(source_string):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	352 ast = parser.suite(source_string)
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	353 return ast, ast.compile()
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	354
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	355 def load_expression(source_string):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	356 ast = parser.expr(source_string)
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	357 return ast, ast.compile()
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	358 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	359
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	360 \subsubsection{Information Discovery}
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	361
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	362 Some applications benefit from direct access to the parse tree. The
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	363 remainder of this section demonstrates how the parse tree provides
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	364 access to module documentation defined in
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	365 docstrings\index{string!documentation}\index{docstrings} without
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	366 requiring that the code being examined be loaded into a running
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	367 interpreter via \keyword{import}. This can be very useful for
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	368 performing analyses of untrusted code.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	369
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	370 Generally, the example will demonstrate how the parse tree may be
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	371 traversed to distill interesting information. Two functions and a set
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	372 of classes are developed which provide programmatic access to high
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	373 level function and class definitions provided by a module. The
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	374 classes extract information from the parse tree and provide access to
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	375 the information at a useful semantic level, one function provides a
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	376 simple low-level pattern matching capability, and the other function
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	377 defines a high-level interface to the classes by handling file
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	378 operations on behalf of the caller. All source files mentioned here
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	379 which are not part of the Python installation are located in the
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	380 \file{Demo/parser/} directory of the distribution.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	381
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	382 The dynamic nature of Python allows the programmer a great deal of
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	383 flexibility, but most modules need only a limited measure of this when
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	384 defining classes, functions, and methods. In this example, the only
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	385 definitions that will be considered are those which are defined in the
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	386 top level of their context, e.g., a function defined by a \keyword{def}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	387 statement at column zero of a module, but not a function defined
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	388 within a branch of an \keyword{if} ... \keyword{else} construct, though
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	389 there are some good reasons for doing so in some situations. Nesting
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	390 of definitions will be handled by the code developed in the example.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	391
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	392 To construct the upper-level extraction methods, we need to know what
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	393 the parse tree structure looks like and how much of it we actually
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	394 need to be concerned about. Python uses a moderately deep parse tree
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	395 so there are a large number of intermediate nodes. It is important to
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	396 read and understand the formal grammar used by Python. This is
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	397 specified in the file \file{Grammar/Grammar} in the distribution.
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	398 Consider the simplest case of interest when searching for docstrings:
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	399 a module consisting of a docstring and nothing else. (See file
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	400 \file{docstring.py}.)
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	401
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	402 \begin{verbatim}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	403 """Some documentation.
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	404 """
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	405 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	406
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	407 Using the interpreter to take a look at the parse tree, we find a
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	408 bewildering mass of numbers and parentheses, with the documentation
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	409 buried deep in nested tuples.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	410
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	411 \begin{verbatim}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	412 >>> import parser
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	413 >>> import pprint
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	414 >>> ast = parser.suite(open('docstring.py').read())
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	415 >>> tup = ast.totuple()
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	416 >>> pprint.pprint(tup)
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	417 (257,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	418 (264,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	419 (265,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	420 (266,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	421 (267,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	422 (307,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	423 (287,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	424 (288,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	425 (289,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	426 (290,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	427 (292,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	428 (293,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	429 (294,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	430 (295,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	431 (296,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	432 (297,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	433 (298,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	434 (299,
16226 c7c404b35f33 Show '\011', '\012', and '\015' as '\t', '\n', '\r' in strings. Ka-Ping Yee <ping@zesty.ca> parents: 13625 diff changeset	435 (300, (3, '"""Some documentation.\n"""'))))))))))))))))),
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	436 (4, ''))),
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	437 (4, ''),
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	438 (0, ''))
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	439 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	440
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	441 The numbers at the first element of each node in the tree are the node
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	442 types; they map directly to terminal and non-terminal symbols in the
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	443 grammar. Unfortunately, they are represented as integers in the
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	444 internal representation, and the Python structures generated do not
10703 e4e800a78d8d Make internal module references hyperlinks wherever it makes sense. Fred Drake <fdrake@acm.org> parents: 10245 diff changeset	445 change that. However, the \refmodule{symbol} and \refmodule{token} modules
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	446 provide symbolic names for the node types and dictionaries which map
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	447 from the integers to the symbolic names for the node types.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	448
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	449 In the output presented above, the outermost tuple contains four
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	450 elements: the integer \code{257} and three additional tuples. Node
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	451 type \code{257} has the symbolic name \constant{file_input}. Each of
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	452 these inner tuples contains an integer as the first element; these
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	453 integers, \code{264}, \code{4}, and \code{0}, represent the node types
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	454 \constant{stmt}, \constant{NEWLINE}, and \constant{ENDMARKER},
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	455 respectively.
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	456 Note that these values may change depending on the version of Python
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	457 you are using; consult \file{symbol.py} and \file{token.py} for
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	458 details of the mapping. It should be fairly clear that the outermost
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	459 node is related primarily to the input source rather than the contents
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	460 of the file, and may be disregarded for the moment. The \constant{stmt}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	461 node is much more interesting. In particular, all docstrings are
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	462 found in subtrees which are formed exactly as this node is formed,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	463 with the only difference being the string itself. The association
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	464 between the docstring in a similar tree and the defined entity (class,
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	465 function, or module) which it describes is given by the position of
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	466 the docstring subtree within the tree defining the described
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	467 structure.
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	468
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	469 By replacing the actual docstring with something to signify a variable
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	470 component of the tree, we allow a simple pattern matching approach to
12223 e82e82b3b9ad Merged changes from the 1.5.2p2 release. Fred Drake <fdrake@acm.org> parents: 11463 diff changeset	471 check any given subtree for equivalence to the general pattern for
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	472 docstrings. Since the example demonstrates information extraction, we
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	473 can safely require that the tree be in tuple form rather than list
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	474 form, allowing a simple variable representation to be
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	475 \code{['variable_name']}. A simple recursive function can implement
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	476 the pattern matching, returning a boolean and a dictionary of variable
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	477 name to value mappings. (See file \file{example.py}.)
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	478
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	479 \begin{verbatim}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	480 from types import ListType, TupleType
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	481
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	482 def match(pattern, data, vars=None):
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	483 if vars is None:
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	484 vars = {}
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	485 if type(pattern) is ListType:
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	486 vars[pattern[0]] = data
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	487 return 1, vars
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	488 if type(pattern) is not TupleType:
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	489 return (pattern == data), vars
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	490 if len(data) != len(pattern):
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	491 return 0, vars
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	492 for pattern, data in map(None, pattern, data):
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	493 same, vars = match(pattern, data, vars)
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	494 if not same:
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	495 break
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	496 return same, vars
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	497 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	498
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	499 Using this simple representation for syntactic variables and the symbolic
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	500 node types, the pattern for the candidate docstring subtrees becomes
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	501 fairly readable. (See file \file{example.py}.)
3198 21cd50a4a3f7 Fred Drake's parser module Guido van Rossum <guido@python.org> parents: diff changeset	502
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	503 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	504 import symbol
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	505 import token
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	506
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	507 DOCSTRING_STMT_PATTERN = (
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	508 symbol.stmt,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	509 (symbol.simple_stmt,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	510 (symbol.small_stmt,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	511 (symbol.expr_stmt,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	512 (symbol.testlist,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	513 (symbol.test,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	514 (symbol.and_test,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	515 (symbol.not_test,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	516 (symbol.comparison,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	517 (symbol.expr,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	518 (symbol.xor_expr,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	519 (symbol.and_expr,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	520 (symbol.shift_expr,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	521 (symbol.arith_expr,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	522 (symbol.term,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	523 (symbol.factor,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	524 (symbol.power,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	525 (symbol.atom,
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	526 (token.STRING, ['docstring'])
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	527 )))))))))))))))),
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	528 (token.NEWLINE, '')
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	529 ))
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	530 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	531
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	532 Using the \function{match()} function with this pattern, extracting the
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	533 module docstring from the parse tree created previously is easy:
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	534
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	535 \begin{verbatim}
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	536 >>> found, vars = match(DOCSTRING_STMT_PATTERN, tup[1])
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	537 >>> found
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	538 1
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	539 >>> vars
16226 c7c404b35f33 Show '\011', '\012', and '\015' as '\t', '\n', '\r' in strings. Ka-Ping Yee <ping@zesty.ca> parents: 13625 diff changeset	540 {'docstring': '"""Some documentation.\n"""'}
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	541 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	542
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	543 Once specific data can be extracted from a location where it is
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	544 expected, the question of where information can be expected
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	545 needs to be answered. When dealing with docstrings, the answer is
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	546 fairly simple: the docstring is the first \constant{stmt} node in a code
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	547 block (\constant{file_input} or \constant{suite} node types). A module
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	548 consists of a single \constant{file_input} node, and class and function
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	549 definitions each contain exactly one \constant{suite} node. Classes and
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	550 functions are readily identified as subtrees of code block nodes which
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	551 start with \code{(stmt, (compound_stmt, (classdef, ...} or
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	552 \code{(stmt, (compound_stmt, (funcdef, ...}. Note that these subtrees
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	553 cannot be matched by \function{match()} since it does not support multiple
4084 7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	554 sibling nodes to match without regard to number. A more elaborate
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	555 matching function could be used to overcome this limitation, but this
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	556 is sufficient for the example.
7f83e24d1d86 New batch from Fred Guido van Rossum <guido@python.org> parents: 3759 diff changeset	557
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	558 Given the ability to determine whether a statement might be a
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	559 docstring and extract the actual string from the statement, some work
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	560 needs to be performed to walk the parse tree for an entire module and
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	561 extract information about the names defined in each context of the
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	562 module and associate any docstrings with the names. The code to
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	563 perform this work is not complicated, but bears some explanation.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	564
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	565 The public interface to the classes is straightforward and should
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	566 probably be somewhat more flexible. Each ``major'' block of the
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	567 module is described by an object providing several methods for inquiry
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	568 and a constructor which accepts at least the subtree of the complete
7363 f4a4723b9553 Separate the parse, symbol, and token documentation into separate files. Fred Drake <fdrake@acm.org> parents: 7277 diff changeset	569 parse tree which it represents. The \class{ModuleInfo} constructor
f4a4723b9553 Separate the parse, symbol, and token documentation into separate files. Fred Drake <fdrake@acm.org> parents: 7277 diff changeset	570 accepts an optional \var{name} parameter since it cannot
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	571 otherwise determine the name of the module.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	572
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	573 The public classes include \class{ClassInfo}, \class{FunctionInfo},
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	574 and \class{ModuleInfo}. All objects provide the
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	575 methods \method{get_name()}, \method{get_docstring()},
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	576 \method{get_class_names()}, and \method{get_class_info()}. The
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	577 \class{ClassInfo} objects support \method{get_method_names()} and
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	578 \method{get_method_info()} while the other classes provide
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	579 \method{get_function_names()} and \method{get_function_info()}.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	580
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	581 Within each of the forms of code block that the public classes
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	582 represent, most of the required information is in the same form and is
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	583 accessed in the same way, with classes having the distinction that
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	584 functions defined at the top level are referred to as ``methods.''
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	585 Since the difference in nomenclature reflects a real semantic
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	586 distinction from functions defined outside of a class, the
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	587 implementation needs to maintain the distinction.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	588 Hence, most of the functionality of the public classes can be
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	589 implemented in a common base class, \class{SuiteInfoBase}, with the
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	590 accessors for function and method information provided elsewhere.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	591 Note that there is only one class which represents function and method
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	592 information; this parallels the use of the \keyword{def} statement to
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	593 define both types of elements.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	594
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	595 Most of the accessor functions are declared in \class{SuiteInfoBase}
13625 fdfd1049f36e Rob W. W. Hooft's spelling fixes for the Library Reference. I hope Thomas Wouters <thomas@python.org> parents: 12640 diff changeset	596 and do not need to be overridden by subclasses. More importantly, the
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	597 extraction of most information from a parse tree is handled through a
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	598 method called by the \class{SuiteInfoBase} constructor. The example
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	599 code for most of the classes is clear when read alongside the formal
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	600 grammar, but the method which recursively creates new information
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	601 objects requires further examination. Here is the relevant part of
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	602 the \class{SuiteInfoBase} definition from \file{example.py}:
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	603
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	604 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	605 class SuiteInfoBase:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	606 _docstring = ''
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	607 _name = ''
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	608
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	609 def __init__(self, tree = None):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	610 self._class_info = {}
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	611 self._function_info = {}
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	612 if tree:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	613 self._extract_info(tree)
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	614
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	615 def _extract_info(self, tree):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	616 # extract docstring
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	617 if len(tree) == 2:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	618 found, vars = match(DOCSTRING_STMT_PATTERN[1], tree[1])
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	619 else:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	620 found, vars = match(DOCSTRING_STMT_PATTERN, tree[3])
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	621 if found:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	622 self._docstring = eval(vars['docstring'])
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	623 # discover inner definitions
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	624 for node in tree[1:]:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	625 found, vars = match(COMPOUND_STMT_PATTERN, node)
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	626 if found:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	627 cstmt = vars['compound']
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	628 if cstmt[0] == symbol.funcdef:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	629 name = cstmt[2][1]
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	630 self._function_info[name] = FunctionInfo(cstmt)
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	631 elif cstmt[0] == symbol.classdef:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	632 name = cstmt[2][1]
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	633 self._class_info[name] = ClassInfo(cstmt)
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	634 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	635
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	636 After initializing some internal state, the constructor calls the
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	637 \method{_extract_info()} method. This method performs the bulk of the
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	638 information extraction which takes place in the entire example. The
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	639 extraction has two distinct phases: the location of the docstring for
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	640 the parse tree passed in, and the discovery of additional definitions
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	641 within the code block represented by the parse tree.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	642
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	643 The initial \keyword{if} test determines whether the nested suite is of
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	644 the ``short form'' or the ``long form.'' The short form is used when
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	645 the code block is on the same line as the definition of the code
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	646 block, as in
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	647
7050 90edcb38fb00 Added \label{} to allow module references. Fred Drake <fdrake@acm.org> parents: 6648 diff changeset	648 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	649 def square(x): "Square an argument."; return x ** 2
7050 90edcb38fb00 Added \label{} to allow module references. Fred Drake <fdrake@acm.org> parents: 6648 diff changeset	650 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	651
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	652 while the long form uses an indented block and allows nested
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	653 definitions:
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	654
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	655 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	656 def make_power(exp):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	657 "Make a function that raises an argument to the exponent `exp'."
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	658 def raiser(x, y=exp):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	659 return x ** y
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	660 return raiser
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	661 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	662
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	663 When the short form is used, the code block may contain a docstring as
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	664 the first, and possibly only, \constant{small_stmt} element. The
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	665 extraction of such a docstring is slightly different and requires only
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	666 a portion of the complete pattern used in the more common case. As
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	667 implemented, the docstring will only be found if there is only
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	668 one \constant{small_stmt} node in the \constant{simple_stmt} node.
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	669 Since most functions and methods which use the short form do not
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	670 provide a docstring, this may be considered sufficient. The
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	671 extraction of the docstring proceeds using the \function{match()} function
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	672 as described above, and the value of the docstring is stored as an
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	673 attribute of the \class{SuiteInfoBase} object.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	674
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	675 After docstring extraction, a simple definition discovery
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	676 algorithm operates on the \constant{stmt} nodes of the
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	677 \constant{suite} node. The special case of the short form is not
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	678 tested; since there are no \constant{stmt} nodes in the short form,
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	679 the algorithm will silently skip the single \constant{simple_stmt}
9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	680 node and correctly not discover any nested definitions.
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	681
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	682 Each statement in the code block is categorized as
db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	683 a class definition, function or method definition, or
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	684 something else. For the definition statements, the name of the
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	685 element defined is extracted and a representation object
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	686 appropriate to the definition is created with the defining subtree
13625 fdfd1049f36e Rob W. W. Hooft's spelling fixes for the Library Reference. I hope Thomas Wouters <thomas@python.org> parents: 12640 diff changeset	687 passed as an argument to the constructor. The representation objects
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	688 are stored in instance variables and may be retrieved by name using
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	689 the appropriate accessor methods.
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	690
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	691 The public classes provide any accessors required which are more
7223 9dde07a593d8 Add some index entries; switch to logical markup. Fred Drake <fdrake@acm.org> parents: 7050 diff changeset	692 specific than those provided by the \class{SuiteInfoBase} class, but
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	693 the real extraction algorithm remains common to all forms of code
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	694 blocks. A high-level function can be used to extract the complete set
4286 db35d2b93eba (libparser.tex): Revised parser module documentation; improved logical Fred Drake <fdrake@acm.org> parents: 4132 diff changeset	695 of information from a source file. (See file \file{example.py}.)
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	696
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	697 \begin{verbatim}
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	698 def get_docs(fileName):
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	699 import os
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	700 import parser
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	701
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	702 source = open(fileName).read()
0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	703 basename = os.path.basename(os.path.splitext(fileName)[0])
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	704 ast = parser.suite(source)
11160 0baff135c4b4 Markup nits. Fred Drake <fdrake@acm.org> parents: 10845 diff changeset	705 return ModuleInfo(ast.totuple(), basename)
7277 bf4e790bd61a Remove all \bcode / \ecode cruft; this is no longer needed. See previous Fred Drake <fdrake@acm.org> parents: 7223 diff changeset	706 \end{verbatim}
7809 e580afa1c833 Minor nits. Fred Drake <fdrake@acm.org> parents: 7712 diff changeset	707
4132 c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	708 This provides an easy-to-use interface to the documentation of a
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	709 module. If information is required which is not extracted by the code
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	710 of this example, the code may be extended at clearly defined points to
c18d52e06238 Final set of changes by Fred before 1.4beta3 Guido van Rossum <guido@python.org> parents: 4084 diff changeset	711 provide additional capabilities.

Mercurial > cpython-lru_cache-weakref

annotate Doc/lib/libparser.tex @ 17581:c1937faabb23 2.1