diff options
Diffstat (limited to 'Doc/lib/libparser.tex')
| -rw-r--r-- | Doc/lib/libparser.tex | 50 |
1 files changed, 25 insertions, 25 deletions
diff --git a/Doc/lib/libparser.tex b/Doc/lib/libparser.tex index 4b838c5..47b5bd4 100644 --- a/Doc/lib/libparser.tex +++ b/Doc/lib/libparser.tex @@ -89,7 +89,7 @@ to convert AST objects to other representations such as parse trees and compiled code objects, but there are also functions which serve to query the type of parse tree represented by an AST object. -\renewcommand{\indexsubitem}{(in module parser)} +\setindexsubitem{(in module parser)} \subsection{Creating AST Objects} @@ -289,30 +289,30 @@ bytecode generation, the simplest operation is to do nothing. For this purpose, using the \module{parser} module to produce an intermediate data structure is equivelent to the code -\bcode\begin{verbatim} +\begin{verbatim} >>> code = compile('a + 5', 'eval') >>> a = 5 >>> eval(code) 10 -\end{verbatim}\ecode +\end{verbatim} % The equivelent operation using the \module{parser} module is somewhat longer, and allows the intermediate internal parse tree to be retained as an AST object: -\bcode\begin{verbatim} +\begin{verbatim} >>> import parser >>> ast = parser.expr('a + 5') >>> code = parser.compileast(ast) >>> a = 5 >>> eval(code) 10 -\end{verbatim}\ecode +\end{verbatim} % An application which needs both AST and code objects can package this code into readily available functions: -\bcode\begin{verbatim} +\begin{verbatim} import parser def load_suite(source_string): @@ -324,7 +324,7 @@ def load_expression(source_string): ast = parser.expr(source_string) code = parser.compileast(ast) return ast, code -\end{verbatim}\ecode +\end{verbatim} % \subsubsection{Information Discovery} @@ -367,16 +367,16 @@ Consider the simplest case of interest when searching for docstrings: a module consisting of a docstring and nothing else. (See file \file{docstring.py}.) -\bcode\begin{verbatim} +\begin{verbatim} """Some documentation. """ -\end{verbatim}\ecode +\end{verbatim} % Using the interpreter to take a look at the parse tree, we find a bewildering mass of numbers and parentheses, with the documentation buried deep in nested tuples. -\bcode\begin{verbatim} +\begin{verbatim} >>> import parser >>> import pprint >>> ast = parser.suite(open('docstring.py').read()) @@ -404,7 +404,7 @@ buried deep in nested tuples. (4, ''))), (4, ''), (0, '')) -\end{verbatim}\ecode +\end{verbatim} % The numbers at the first element of each node in the tree are the node types; they map directly to terminal and non-terminal symbols in the @@ -444,7 +444,7 @@ form, allowing a simple variable representation to be the pattern matching, returning a boolean and a dictionary of variable name to value mappings. (See file \file{example.py}.) -\bcode\begin{verbatim} +\begin{verbatim} from types import ListType, TupleType def match(pattern, data, vars=None): @@ -462,13 +462,13 @@ def match(pattern, data, vars=None): if not same: break return same, vars -\end{verbatim}\ecode +\end{verbatim} % Using this simple representation for syntactic variables and the symbolic node types, the pattern for the candidate docstring subtrees becomes fairly readable. (See file \file{example.py}.) -\bcode\begin{verbatim} +\begin{verbatim} import symbol import token @@ -495,18 +495,18 @@ DOCSTRING_STMT_PATTERN = ( )))))))))))))))), (token.NEWLINE, '') )) -\end{verbatim}\ecode +\end{verbatim} % Using the \function{match()} function with this pattern, extracting the module docstring from the parse tree created previously is easy: -\bcode\begin{verbatim} +\begin{verbatim} >>> found, vars = match(DOCSTRING_STMT_PATTERN, tup[1]) >>> found 1 >>> vars {'docstring': '"""Some documentation.\012"""'} -\end{verbatim}\ecode +\end{verbatim} % Once specific data can be extracted from a location where it is expected, the question of where information can be expected @@ -569,7 +569,7 @@ grammar, but the method which recursively creates new information objects requires further examination. Here is the relevant part of the \class{SuiteInfoBase} definition from \file{example.py}: -\bcode\begin{verbatim} +\begin{verbatim} class SuiteInfoBase: _docstring = '' _name = '' @@ -599,7 +599,7 @@ class SuiteInfoBase: elif cstmt[0] == symbol.classdef: name = cstmt[2][1] self._class_info[name] = ClassInfo(cstmt) -\end{verbatim}\ecode +\end{verbatim} % After initializing some internal state, the constructor calls the \method{_extract_info()} method. This method performs the bulk of the @@ -620,13 +620,13 @@ def square(x): "Square an argument."; return x ** 2 while the long form uses an indented block and allows nested definitions: -\bcode\begin{verbatim} +\begin{verbatim} def make_power(exp): "Make a function that raises an argument to the exponent `exp'." def raiser(x, y=exp): return x ** y return raiser -\end{verbatim}\ecode +\end{verbatim} % When the short form is used, the code block may contain a docstring as the first, and possibly only, \constant{small_stmt} element. The @@ -662,7 +662,7 @@ the real extraction algorithm remains common to all forms of code blocks. A high-level function can be used to extract the complete set of information from a source file. (See file \file{example.py}.) -\bcode\begin{verbatim} +\begin{verbatim} def get_docs(fileName): source = open(fileName).read() import os @@ -671,7 +671,7 @@ def get_docs(fileName): ast = parser.suite(source) tup = parser.ast2tuple(ast) return ModuleInfo(tup, basename) -\end{verbatim}\ecode +\end{verbatim} % This provides an easy-to-use interface to the documentation of a module. If information is required which is not extracted by the code @@ -703,7 +703,7 @@ to may change between Python versions. This module also provides one additional data object: -\renewcommand{\indexsubitem}{(in module symbol)} +\setindexsubitem{(in module symbol)} \begin{datadesc}{sym_name} @@ -731,7 +731,7 @@ versions. This module also provides one data object and some functions. The functions mirror definitions in the Python C header files. -\renewcommand{\indexsubitem}{(in module token)} +\setindexsubitem{(in module token)} \begin{datadesc}{tok_name} |