First day's progress on documentation
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+% Complete documentation on the extended LaTeX markup used for Python
+% documentation is available in ``Documenting Python'', which is part
+% of the standard documentation for Python. It may be found online
+% at:
+%
+% http://www.python.org/doc/current/doc/doc.html
+
+\documentclass{manual}
+
+\title{Python compiler package}
+
+\author{Jeremy Hylton}
+
+% Please at least include a long-lived email address;
+% the rest is at your discretion.
+\authoraddress{
+ PythonLabs \\
+ Zope Corp. \\
+ Email: \email{jeremy@zope.com}
+}
+
+\date{August 15, 2001} % update before release!
+ % Use an explicit date so that reformatting
+ % doesn't cause a new date to be used. Setting
+ % the date to \today can be used during draft
+ % stages to make it easier to handle versions.
+
+\release{2.2} % release version; this is used to define the
+ % \version macro
+
+\makeindex % tell \index to actually write the .idx file
+\makemodindex % If this contains a lot of module sections.
+
+
+\begin{document}
+
+\maketitle
+
+% This makes the contents more accessible from the front page of the HTML.
+\ifhtml
+\chapter*{Front Matter\label{front}}
+\fi
+
+%\input{copyright}
+
+\begin{abstract}
+
+\noindent
+The Python compiler package is a tool for analyzing Python source code
+and generating Python bytecode. The compiler contains libraries to
+generate an abstract syntax tree from Python source code and to
+generate Python bytecode from the tree.
+
+\end{abstract}
+
+\tableofcontents
+
+\chapter{Introduction\label{Introduction}}
+
+XXX Need basic intro
+
+XXX what are the major advantages... the abstract syntax is much
+closer to the python source...
+
+\section{The basic interface}
+
+The top-level of the package defines four functions.
+
+\begin{funcdesc}{parse}{buf}
+Returns an abstract syntax tree for the Python source code in \var{buf}.
+The function raises SyntaxError if there is an error in the source
+code. The return value is a \class{compiler.ast.Module} instance that
+contains the tree.
+\end{funcdesc}
+
+\begin{funcdesc}{parseFile}{path}
+Return an abstract syntax tree for the Python source code in the file
+specified by \var{path}. It is equivalent to \code{parse(open(path))}.
+\end{funcdesc}
+
+\begin{funcdesc}{walk}{ast, visitor, \optional{verbose=None}}
+Do a pre-order walk over the abstract syntax tree \var{ast}. Call the
+appropriate method on the \var{visitor} instance for each node
+encountered.
+\end{funcdesc}
+
+\begin{funcdesc}{compile}{filename}
+Compile the file \var{filename} and generated \var{filename}.pyc.
+\end{funcdesc}
+
+The \module{compiler} package contains the following modules:
+\module{ast}, \module{consts}, \module{future}, \module{misc},
+\module{pyassem}, \module{pycodegen}, \module{symbols},
+\module{transformer}, and \module{visitor}.
+
+\section{Limitations}
+
+There are some problems with the error checking of the compiler
+package. The interpreter detects syntax errors in two distinct
+phases. One set of errors is detected by the interpreter's parser,
+the other set by the compiler. The compiler package relies on the
+interpreter's parser, so it get the first phases of error checking for
+free. It implements the second phase itself, and that implement is
+incomplete. For example, the compiler package does not raise an error
+if a name appears more than once in an argument list:
+\code{def f(x, x): ...}
+
+\chapter{Python Abstract Syntax}
+
+\section{Introduction}
+
+The \module{compiler.ast} module defines an abstract syntax for
+Python. In the abstract syntax tree, each node represents a syntactic
+construct. The root of the tree is \class{Module} object.
+
+The abstract syntax offers a higher level interface to parsed Python
+source code. The \module{parser} module and the compiler written in C
+for the Python interpreter use a concrete syntax tree. The concrete
+syntax is tied closely to the grammar description used for the Python
+parser. Instead of a single node for a construct, there are often
+several levels of nested nodes that are introduced by Python's
+precedence rules.
+
+The abstract syntax tree is created by the
+\module{compiler.transformer} module. The transformer relies on the
+builtin Python parser to generate a concrete syntax tree. It
+generates an abstract syntax tree from the concrete tree.
+
+The \module{transformer} module was created by Greg Stein and Bill
+Tutt for the Python-to-C compiler. The current version contains a
+number of modifications and improvements, but the basic form of the
+abstract syntax and of the transformer are due to Stein and Tutt.
+
+\section{AST Nodes}
+
+The \module{ast} module is generated from a text file that describes
+each node type and its elements. Each node type is represented as a
+class that inherits from the abstract base class \class{ast.Node} and
+defines a set of named attributes for child nodes.
+
+\begin{classdesc}{Node}{}
+
+ The \class{Node} instances are created automatically by the parser
+ generator. The recommended interface for specific \class{Node}
+ instances is to use the public attributes to access child nodes. A
+ public attribute may be bound to a single node or to a sequence of
+ nodes, depending on the \class{Node} type. For example, the
+ \member{bases} attribute of the \class{Class} node, is bound to a
+ list of base class nodes, and the \member{doc} attribute is bound to
+ a single node.
+
+ Each \class{Node} instance has a \member{lineno} attribute which may
+ be \code{None}. XXX Not sure what the rules are for which nodes
+ will have a useful lineno.
+
+ \begin{methoddesc}{getChildren}{}
+ Returns a flattened list of the child nodes and objects in the
+ order they occur. Specifically, the order of the nodes is the
+ order in which they appear in the Python grammar. Not all of the
+ children are \class{Node} instances. The names of functions and
+ classes, for example, are plain strings.
+ \end{methoddesc}
+
+ \begin{methoddesc}{getChildNodes}{}
+ Returns a flattened list of the child nodes in the order they
+ occur. This method is like \method{getChildNodes}, except that it
+ only returns those children that are \class{Node} instances.
+ \end{methoddesc}
+
+\end{classdesc}
+
+Two examples illustrate the general structure of \class{Node}
+classes. The while statement is defined by the following grammar
+production:
+
+\begin{verbatim}
+while_stmt: "while" expression ":" suite
+ ["else" ":" suite]
+\end{verbatim}
+
+The \class{While} node has three attributes: \member{test},
+\member{body}, and \member{else_}. (If the natural name for an
+attribute is also a Python reserved word, it can't be used as an
+attribute name. An underscore is appended to the word to make it
+legal, hence \code{else_} instead of \code{else}.)
+
+The if statement is more complicated because it can include several
+tests.
+
+\begin{verbatim}
+if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
+\end{verbatim}
+
+The \class{If} node only defines two attributes: \member{tests} and
+\member{else_}. The \member{tests} attribute is a sequence of test
+expression, consequent body pairs. There is one pair of each if/elif
+clause. The first element of the pair is the test expression. The
+second elements is a \class{Stmt} node that contains the code to
+execute if the test is true.
+
+The \method{getChildren()} method of \class{If} returns a flat list of
+child nodes. If there are three if/elif clauses and no else clause,
+then \method{getChildren()} will return a list of six elements: the
+first test expression, the first \class{Stmt}, the second text
+expression, etc.
+
+The following table lists each of the \class{Node} subclasses defined
+in \module{compiler.ast} and each of the public attributes available
+on their instances. The values of most of the attributes are
+themselves \class{Node} instances or sequences of instances. When the
+value is something other than an instance, the type is noted in the
+comment. The attributes are listed in the order in which they are
+returned by \method{getChildren} and \method{getChildNodes}.
+
+\input{asttable}
+
+\section{Assignment nodes}
+
+There is a collection of nodes used to represent assignments. Each
+assignment statement in the source code becomes a single
+\class{Assign} node in the AST. The \member{nodes} attribute is a
+list that contains a node for each assignment target. This is
+necessary because assignment can be chained, e.g. \code{a = b = 2}.
+Each \class{Node} in the list will be one of the following classes:
+\class{AssAttr}, \class{AssList}, \class{AssName}, or
+\class{AssTuple}.
+
+XXX Explain what the AssXXX nodes are for. Mention \code{a.b.c = 2}
+as an example. Explain what the flags are for.
+
+\chapter{Using Visitors to Walk ASTs}
+
+The visitor pattern is ... The \module{compiler} package uses a
+variant on the visitor pattern that takes advantage of Python's
+introspection features to elminiate the need for much of the visitor's
+infrastructure.
+
+The classes being visited do not need to be programmed to accept
+visitors. The visitor need only define visit methods for classes it
+is specifically interested in; a default visit method can handle the
+rest.
+
+XXX The magic \method{visit()} method for visitors.
+
+\begin{classdesc}{ASTVisitor}{}
+
+The \class{ASTVisitor} is responsible for walking over the tree in the
+correct order. A walk begins with a call to \method{preorder()}. For
+each node, it checks the \var{visitor} argument to \method{preorder{}}
+for a method named `visitNodeType,' where NodeType is the name of the
+node's class, e.g. for a \class{While} node a \method{visitWhile}
+would be called . If the method exists, it is called with the node as
+its first argument.
+
+The visitor method for a particular node type can control how child
+nodes are visited during the walk. The \class{ASTVisitor} modifies
+the visitor argument by adding a visit method to the visitor; this
+method can be used to visit a particular child node. If no visitor is
+found for a particular node type, the \method{default} method is
+called.
+
+XXX describe extra arguments
+
+\begin{methoddesc}{default}{node\optional{, *args}}
+\end{methoddesc}
+
+\begin{methoddesc}{dispatch}{node\optional{, *args}}
+\end{methoddesc}
+
+\begin{methoddesc}{preorder}{tree, visitor}
+\end{methoddesc}
+
+\end{classdesc}
+
+\begin{funcdesc}{walk}{tree, visitor\optional{, verbose=None}}
+\end{funcdesc}
+
+\chapter{Bytecode Generation}
+
+The code generator is a visit that emits bytecodes. Each visit method
+can call the \method{emit} method to emit a new bytecode. The basic
+code generator is specialized for modules, classes, and functions. An
+assembler converts that emitted instructions to the low-level bytecode
+format. It handles things like generator of constant lists of code
+objects and calculation of jump offsets.
+
+%
+% The ugly "%begin{latexonly}" pseudo-environments are really just to
+% keep LaTeX2HTML quiet during the \renewcommand{} macros; they're
+% not really valuable.
+%
+% If you don't want the Module Index, you can remove all of this up
+% until the second \input line.
+%
+%begin{latexonly}
+\renewcommand{\indexname}{Module Index}
+%end{latexonly}
+\input{mod\jobname.ind} % Module Index
+
+%begin{latexonly}
+\renewcommand{\indexname}{Index}
+%end{latexonly}
+\input{\jobname.ind} % Index
+
+\end{document}