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<div class="section" id="python-compiler-package">
<span id="compiler"></span><h1>33. Python compiler package<a class="headerlink" href="#python-compiler-package" title="Permalink to this headline">¶</a></h1>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 2.6: </span>The <a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a> package has been removed in Python 3.</p>
</div>
<p>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
<a class="reference internal" href="../glossary.html#term-bytecode"><span class="xref std std-term">bytecode</span></a> from the tree.</p>
<p>The <a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a> package is a Python source to bytecode translator written in
Python. It uses the built-in parser and standard <a class="reference internal" href="parser.html#module-parser" title="parser: Access parse trees for Python source code."><code class="xref py py-mod docutils literal notranslate"><span class="pre">parser</span></code></a> module to
generate a concrete syntax tree. This tree is used to generate an abstract
syntax tree (AST) and then Python bytecode.</p>
<p>The full functionality of the package duplicates the built-in compiler provided
with the Python interpreter. It is intended to match its behavior almost
exactly. Why implement another compiler that does the same thing? The package
is useful for a variety of purposes. It can be modified more easily than the
built-in compiler. The AST it generates is useful for analyzing Python source
code.</p>
<p>This chapter explains how the various components of the <a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a> package
work. It blends reference material with a tutorial.</p>
<div class="section" id="module-compiler">
<span id="the-basic-interface"></span><h2>33.1. The basic interface<a class="headerlink" href="#module-compiler" title="Permalink to this headline">¶</a></h2>
<p>The top-level of the package defines four functions. If you import
<a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a>, you will get these functions and a collection of modules
contained in the package.</p>
<dl class="function">
<dt id="compiler.parse">
<code class="descclassname">compiler.</code><code class="descname">parse</code><span class="sig-paren">(</span><em>buf</em><span class="sig-paren">)</span><a class="headerlink" href="#compiler.parse" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns an abstract syntax tree for the Python source code in <em>buf</em>. The
function raises <a class="reference internal" href="exceptions.html#exceptions.SyntaxError" title="exceptions.SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a> if there is an error in the source code. The
return value is a <code class="xref py py-class docutils literal notranslate"><span class="pre">compiler.ast.Module</span></code> instance that contains the tree.</p>
</dd></dl>
<dl class="function">
<dt id="compiler.parseFile">
<code class="descclassname">compiler.</code><code class="descname">parseFile</code><span class="sig-paren">(</span><em>path</em><span class="sig-paren">)</span><a class="headerlink" href="#compiler.parseFile" title="Permalink to this definition">¶</a></dt>
<dd><p>Return an abstract syntax tree for the Python source code in the file specified
by <em>path</em>. It is equivalent to <code class="docutils literal notranslate"><span class="pre">parse(open(path).read())</span></code>.</p>
</dd></dl>
<dl class="function">
<dt id="compiler.walk">
<code class="descclassname">compiler.</code><code class="descname">walk</code><span class="sig-paren">(</span><em>ast</em>, <em>visitor</em><span class="optional">[</span>, <em>verbose</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.walk" title="Permalink to this definition">¶</a></dt>
<dd><p>Do a pre-order walk over the abstract syntax tree <em>ast</em>. Call the appropriate
method on the <em>visitor</em> instance for each node encountered.</p>
</dd></dl>
<dl class="function">
<dt id="compiler.compile">
<code class="descclassname">compiler.</code><code class="descname">compile</code><span class="sig-paren">(</span><em>source</em>, <em>filename</em>, <em>mode</em>, <em>flags=None</em>, <em>dont_inherit=None</em><span class="sig-paren">)</span><a class="headerlink" href="#compiler.compile" title="Permalink to this definition">¶</a></dt>
<dd><p>Compile the string <em>source</em>, a Python module, statement or expression, into a
code object that can be executed by the exec statement or <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>. This
function is a replacement for the built-in <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate"><span class="pre">compile()</span></code></a> function.</p>
<p>The <em>filename</em> will be used for run-time error messages.</p>
<p>The <em>mode</em> must be ‘exec’ to compile a module, ‘single’ to compile a single
(interactive) statement, or ‘eval’ to compile an expression.</p>
<p>The <em>flags</em> and <em>dont_inherit</em> arguments affect future-related statements, but
are not supported yet.</p>
</dd></dl>
<dl class="function">
<dt id="compiler.compileFile">
<code class="descclassname">compiler.</code><code class="descname">compileFile</code><span class="sig-paren">(</span><em>source</em><span class="sig-paren">)</span><a class="headerlink" href="#compiler.compileFile" title="Permalink to this definition">¶</a></dt>
<dd><p>Compiles the file <em>source</em> and generates a .pyc file.</p>
</dd></dl>
<p>The <a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a> package contains the following modules: <a class="reference internal" href="ast.html#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ast</span></code></a>,
<code class="xref py py-mod docutils literal notranslate"><span class="pre">consts</span></code>, <code class="xref py py-mod docutils literal notranslate"><span class="pre">future</span></code>, <code class="xref py py-mod docutils literal notranslate"><span class="pre">misc</span></code>, <code class="xref py py-mod docutils literal notranslate"><span class="pre">pyassem</span></code>, <code class="xref py py-mod docutils literal notranslate"><span class="pre">pycodegen</span></code>,
<code class="xref py py-mod docutils literal notranslate"><span class="pre">symbols</span></code>, <code class="xref py py-mod docutils literal notranslate"><span class="pre">transformer</span></code>, and <code class="xref py py-mod docutils literal notranslate"><span class="pre">visitor</span></code>.</p>
</div>
<div class="section" id="limitations">
<h2>33.2. Limitations<a class="headerlink" href="#limitations" title="Permalink to this headline">¶</a></h2>
<p>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
implementation is incomplete. For example, the compiler package does not raise
an error if a name appears more than once in an argument list: <code class="docutils literal notranslate"><span class="pre">def</span> <span class="pre">f(x,</span> <span class="pre">x):</span>
<span class="pre">...</span></code></p>
<p>A future version of the compiler should fix these problems.</p>
</div>
<div class="section" id="python-abstract-syntax">
<h2>33.3. Python Abstract Syntax<a class="headerlink" href="#python-abstract-syntax" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="#module-compiler.ast" title="compiler.ast"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler.ast</span></code></a> module defines an abstract syntax for Python. In the
abstract syntax tree, each node represents a syntactic construct. The root of
the tree is <code class="xref py py-class docutils literal notranslate"><span class="pre">Module</span></code> object.</p>
<p>The abstract syntax offers a higher level interface to parsed Python source
code. The <a class="reference internal" href="parser.html#module-parser" title="parser: Access parse trees for Python source code."><code class="xref py py-mod docutils literal notranslate"><span class="pre">parser</span></code></a> 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.</p>
<p>The abstract syntax tree is created by the <code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler.transformer</span></code> module.
The transformer relies on the built-in Python parser to generate a concrete
syntax tree. It generates an abstract syntax tree from the concrete tree.</p>
<p id="index-0">The <code class="xref py py-mod docutils literal notranslate"><span class="pre">transformer</span></code> module was created by Greg Stein and Bill Tutt for an
experimental 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.</p>
<div class="section" id="module-compiler.ast">
<span id="ast-nodes"></span><h3>33.3.1. AST Nodes<a class="headerlink" href="#module-compiler.ast" title="Permalink to this headline">¶</a></h3>
<p>The <a class="reference internal" href="#module-compiler.ast" title="compiler.ast"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler.ast</span></code></a> 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 <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">compiler.ast.Node</span></code></a> and defines a
set of named attributes for child nodes.</p>
<dl class="class">
<dt id="compiler.ast.Node">
<em class="property">class </em><code class="descclassname">compiler.ast.</code><code class="descname">Node</code><a class="headerlink" href="#compiler.ast.Node" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> instances are created automatically by the parser generator.
The recommended interface for specific <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> 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 <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> type. For
example, the <code class="xref py py-attr docutils literal notranslate"><span class="pre">bases</span></code> attribute of the <code class="xref py py-class docutils literal notranslate"><span class="pre">Class</span></code> node, is bound to a
list of base class nodes, and the <code class="xref py py-attr docutils literal notranslate"><span class="pre">doc</span></code> attribute is bound to a single
node.</p>
<p>Each <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> instance has a <code class="xref py py-attr docutils literal notranslate"><span class="pre">lineno</span></code> attribute which may be
<code class="docutils literal notranslate"><span class="pre">None</span></code>. XXX Not sure what the rules are for which nodes will have a useful
lineno.</p>
<p>All <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> objects offer the following methods:</p>
<dl class="method">
<dt id="compiler.ast.Node.getChildren">
<code class="descname">getChildren</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.ast.Node.getChildren" title="Permalink to this definition">¶</a></dt>
<dd><p>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 <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a>
instances. The names of functions and classes, for example, are plain
strings.</p>
</dd></dl>
<dl class="method">
<dt id="compiler.ast.Node.getChildNodes">
<code class="descname">getChildNodes</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.ast.Node.getChildNodes" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns a flattened list of the child nodes in the order they occur. This
method is like <a class="reference internal" href="#compiler.ast.Node.getChildren" title="compiler.ast.Node.getChildren"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getChildren()</span></code></a>, except that it only returns those
children that are <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> instances.</p>
</dd></dl>
</dd></dl>
<p>Two examples illustrate the general structure of <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> classes. The
<a class="reference internal" href="../reference/compound_stmts.html#while"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">while</span></code></a> statement is defined by the following grammar production:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">while_stmt</span><span class="p">:</span> <span class="s2">"while"</span> <span class="n">expression</span> <span class="s2">":"</span> <span class="n">suite</span>
<span class="p">[</span><span class="s2">"else"</span> <span class="s2">":"</span> <span class="n">suite</span><span class="p">]</span>
</pre></div>
</div>
<p>The <code class="xref py py-class docutils literal notranslate"><span class="pre">While</span></code> node has three attributes: <a class="reference internal" href="test.html#module-test" title="test: Regression tests package containing the testing suite for Python."><code class="xref py py-attr docutils literal notranslate"><span class="pre">test</span></code></a>, <code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code>, and
<code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code>. (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 a legal identifier, hence <code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code> instead of
<a class="reference internal" href="../reference/compound_stmts.html#else"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">else</span></code></a>.)</p>
<p>The <a class="reference internal" href="../reference/compound_stmts.html#if"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">if</span></code></a> statement is more complicated because it can include several
tests.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">if_stmt</span><span class="p">:</span> <span class="s1">'if'</span> <span class="n">test</span> <span class="s1">':'</span> <span class="n">suite</span> <span class="p">(</span><span class="s1">'elif'</span> <span class="n">test</span> <span class="s1">':'</span> <span class="n">suite</span><span class="p">)</span><span class="o">*</span> <span class="p">[</span><span class="s1">'else'</span> <span class="s1">':'</span> <span class="n">suite</span><span class="p">]</span>
</pre></div>
</div>
<p>The <code class="xref py py-class docutils literal notranslate"><span class="pre">If</span></code> node only defines two attributes: <code class="xref py py-attr docutils literal notranslate"><span class="pre">tests</span></code> and
<code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code>. The <code class="xref py py-attr docutils literal notranslate"><span class="pre">tests</span></code> attribute is a sequence of test expression,
consequent body pairs. There is one pair for each <a class="reference internal" href="../reference/compound_stmts.html#if"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">if</span></code></a>/<a class="reference internal" href="../reference/compound_stmts.html#elif"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">elif</span></code></a>
clause. The first element of the pair is the test expression. The second
elements is a <code class="xref py py-class docutils literal notranslate"><span class="pre">Stmt</span></code> node that contains the code to execute if the test
is true.</p>
<p>The <code class="xref py py-meth docutils literal notranslate"><span class="pre">getChildren()</span></code> method of <code class="xref py py-class docutils literal notranslate"><span class="pre">If</span></code> returns a flat list of child
nodes. If there are three <a class="reference internal" href="../reference/compound_stmts.html#if"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">if</span></code></a>/<a class="reference internal" href="../reference/compound_stmts.html#elif"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">elif</span></code></a> clauses and no
<a class="reference internal" href="../reference/compound_stmts.html#else"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">else</span></code></a> clause, then <code class="xref py py-meth docutils literal notranslate"><span class="pre">getChildren()</span></code> will return a list of six
elements: the first test expression, the first <code class="xref py py-class docutils literal notranslate"><span class="pre">Stmt</span></code>, the second text
expression, etc.</p>
<p>The following table lists each of the <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> subclasses defined in
<a class="reference internal" href="#module-compiler.ast" title="compiler.ast"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler.ast</span></code></a> and each of the public attributes available on their
instances. The values of most of the attributes are themselves <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a>
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 <code class="xref py py-meth docutils literal notranslate"><span class="pre">getChildren()</span></code> and
<code class="xref py py-meth docutils literal notranslate"><span class="pre">getChildNodes()</span></code>.</p>
<table class="docutils align-center">
<colgroup>
<col style="width: 30%" />
<col style="width: 26%" />
<col style="width: 43%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Node type</p></th>
<th class="head"><p>Attribute</p></th>
<th class="head"><p>Value</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Add</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td><p>left operand</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td><p>right operand</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">And</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>list of operands</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">AssAttr</span></code></p></td>
<td></td>
<td><p><em>attribute as target of
assignment</em></p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td><p>expression on the left-hand
side of the dot</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">attrname</span></code></p></td>
<td><p>the attribute name, a string</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td><p>XXX</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">AssList</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>list of list elements being
assigned to</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">AssName</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">name</span></code></p></td>
<td><p>name being assigned to</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td><p>XXX</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">AssTuple</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>list of tuple elements being
assigned to</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Assert</span></code></p></td>
<td><p><a class="reference internal" href="test.html#module-test" title="test: Regression tests package containing the testing suite for Python."><code class="xref py py-attr docutils literal notranslate"><span class="pre">test</span></code></a></p></td>
<td><p>the expression to be tested</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">fail</span></code></p></td>
<td><p>the value of the
<a class="reference internal" href="exceptions.html#exceptions.AssertionError" title="exceptions.AssertionError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">AssertionError</span></code></a></p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Assign</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>a list of assignment targets,
one per equal sign</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td><p>the value being assigned</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">AugAssign</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">node</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">op</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Backquote</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Bitand</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Bitor</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Bitxor</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Break</span></code></p></td>
<td></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">CallFunc</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">node</span></code></p></td>
<td><p>expression for the callee</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">args</span></code></p></td>
<td><p>a list of arguments</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">star_args</span></code></p></td>
<td><p>the extended *-arg value</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">dstar_args</span></code></p></td>
<td><p>the extended **-arg value</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Class</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">name</span></code></p></td>
<td><p>the name of the class, a string</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">bases</span></code></p></td>
<td><p>a list of base classes</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">doc</span></code></p></td>
<td><p>doc string, a string or
<code class="docutils literal notranslate"><span class="pre">None</span></code></p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><a class="reference internal" href="code.html#module-code" title="code: Facilities to implement read-eval-print loops."><code class="xref py py-attr docutils literal notranslate"><span class="pre">code</span></code></a></p></td>
<td><p>the body of the class statement</p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Compare</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">ops</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Const</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">value</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Continue</span></code></p></td>
<td></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Decorators</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>List of function decorator
expressions</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Dict</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">items</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Discard</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Div</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><a class="reference internal" href="constants.html#Ellipsis" title="Ellipsis"><code class="xref py py-class docutils literal notranslate"><span class="pre">Ellipsis</span></code></a></p></td>
<td></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Expression</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">node</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Exec</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><a class="reference internal" href="functions.html#locals" title="locals"><code class="xref py py-attr docutils literal notranslate"><span class="pre">locals</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><a class="reference internal" href="functions.html#globals" title="globals"><code class="xref py py-attr docutils literal notranslate"><span class="pre">globals</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">FloorDiv</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">For</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">assign</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">list</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">From</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">modname</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">names</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Function</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">decorators</span></code></p></td>
<td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Decorators</span></code> or <code class="docutils literal notranslate"><span class="pre">None</span></code></p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">name</span></code></p></td>
<td><p>name used in def, a string</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">argnames</span></code></p></td>
<td><p>list of argument names, as
strings</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">defaults</span></code></p></td>
<td><p>list of default values</p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td><p>xxx</p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">doc</span></code></p></td>
<td><p>doc string, a string or
<code class="docutils literal notranslate"><span class="pre">None</span></code></p></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><a class="reference internal" href="code.html#module-code" title="code: Facilities to implement read-eval-print loops."><code class="xref py py-attr docutils literal notranslate"><span class="pre">code</span></code></a></p></td>
<td><p>the body of the function</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">GenExpr</span></code></p></td>
<td><p><a class="reference internal" href="code.html#module-code" title="code: Facilities to implement read-eval-print loops."><code class="xref py py-attr docutils literal notranslate"><span class="pre">code</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">GenExprFor</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">assign</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><a class="reference internal" href="functions.html#iter" title="iter"><code class="xref py py-attr docutils literal notranslate"><span class="pre">iter</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">ifs</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">GenExprIf</span></code></p></td>
<td><p><a class="reference internal" href="test.html#module-test" title="test: Regression tests package containing the testing suite for Python."><code class="xref py py-attr docutils literal notranslate"><span class="pre">test</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">GenExprInner</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">quals</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Getattr</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">attrname</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Global</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">names</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">If</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">tests</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Import</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">names</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Invert</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Keyword</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">name</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Lambda</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">argnames</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">defaults</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><a class="reference internal" href="code.html#module-code" title="code: Facilities to implement read-eval-print loops."><code class="xref py py-attr docutils literal notranslate"><span class="pre">code</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">LeftShift</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">List</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">ListComp</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">quals</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">ListCompFor</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">assign</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">list</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">ifs</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">ListCompIf</span></code></p></td>
<td><p><a class="reference internal" href="test.html#module-test" title="test: Regression tests package containing the testing suite for Python."><code class="xref py py-attr docutils literal notranslate"><span class="pre">test</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Mod</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Module</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">doc</span></code></p></td>
<td><p>doc string, a string or
<code class="docutils literal notranslate"><span class="pre">None</span></code></p></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">node</span></code></p></td>
<td><p>body of the module, a
<code class="xref py py-class docutils literal notranslate"><span class="pre">Stmt</span></code></p></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Mul</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Name</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">name</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Not</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Or</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Pass</span></code></p></td>
<td></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Power</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Print</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">dest</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Printnl</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">dest</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Raise</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr1</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr2</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr3</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Return</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">value</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">RightShift</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Slice</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">lower</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">upper</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Sliceobj</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td><p>list of statements</p></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Stmt</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Sub</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">left</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">right</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Subscript</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">subs</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">TryExcept</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">handlers</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">TryFinally</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">final</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Tuple</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">UnaryAdd</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">UnarySub</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">While</span></code></p></td>
<td><p><a class="reference internal" href="test.html#module-test" title="test: Regression tests package containing the testing suite for Python."><code class="xref py py-attr docutils literal notranslate"><span class="pre">test</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">else_</span></code></p></td>
<td></td>
</tr>
<tr class="row-odd"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">With</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td></td>
<td><p><a class="reference internal" href="functions.html#vars" title="vars"><code class="xref py py-attr docutils literal notranslate"><span class="pre">vars</span></code></a></p></td>
<td></td>
</tr>
<tr class="row-odd"><td></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">body</span></code></p></td>
<td></td>
</tr>
<tr class="row-even"><td><p><code class="xref py py-class docutils literal notranslate"><span class="pre">Yield</span></code></p></td>
<td><p><code class="xref py py-attr docutils literal notranslate"><span class="pre">value</span></code></p></td>
<td></td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="assignment-nodes">
<h3>33.3.2. Assignment nodes<a class="headerlink" href="#assignment-nodes" title="Permalink to this headline">¶</a></h3>
<p>There is a collection of nodes used to represent assignments. Each assignment
statement in the source code becomes a single <code class="xref py py-class docutils literal notranslate"><span class="pre">Assign</span></code> node in the AST.
The <code class="xref py py-attr docutils literal notranslate"><span class="pre">nodes</span></code> attribute is a list that contains a node for each assignment
target. This is necessary because assignment can be chained, e.g. <code class="docutils literal notranslate"><span class="pre">a</span> <span class="pre">=</span> <span class="pre">b</span> <span class="pre">=</span>
<span class="pre">2</span></code>. Each <a class="reference internal" href="#compiler.ast.Node" title="compiler.ast.Node"><code class="xref py py-class docutils literal notranslate"><span class="pre">Node</span></code></a> in the list will be one of the following classes:
<code class="xref py py-class docutils literal notranslate"><span class="pre">AssAttr</span></code>, <code class="xref py py-class docutils literal notranslate"><span class="pre">AssList</span></code>, <code class="xref py py-class docutils literal notranslate"><span class="pre">AssName</span></code>, or <code class="xref py py-class docutils literal notranslate"><span class="pre">AssTuple</span></code>.</p>
<p>Each target assignment node will describe the kind of object being assigned to:
<code class="xref py py-class docutils literal notranslate"><span class="pre">AssName</span></code> for a simple name, e.g. <code class="docutils literal notranslate"><span class="pre">a</span> <span class="pre">=</span> <span class="pre">1</span></code>. <code class="xref py py-class docutils literal notranslate"><span class="pre">AssAttr</span></code> for an
attribute assigned, e.g. <code class="docutils literal notranslate"><span class="pre">a.x</span> <span class="pre">=</span> <span class="pre">1</span></code>. <code class="xref py py-class docutils literal notranslate"><span class="pre">AssList</span></code> and <code class="xref py py-class docutils literal notranslate"><span class="pre">AssTuple</span></code> for
list and tuple expansion respectively, e.g. <code class="docutils literal notranslate"><span class="pre">a,</span> <span class="pre">b,</span> <span class="pre">c</span> <span class="pre">=</span> <span class="pre">a_tuple</span></code>.</p>
<p>The target assignment nodes also have a <code class="xref py py-attr docutils literal notranslate"><span class="pre">flags</span></code> attribute that indicates
whether the node is being used for assignment or in a delete statement. The
<code class="xref py py-class docutils literal notranslate"><span class="pre">AssName</span></code> is also used to represent a delete statement, e.g. <code class="xref py py-class docutils literal notranslate"><span class="pre">del</span>
<span class="pre">x</span></code>.</p>
<p>When an expression contains several attribute references, an assignment or
delete statement will contain only one <code class="xref py py-class docutils literal notranslate"><span class="pre">AssAttr</span></code> node – for the final
attribute reference. The other attribute references will be represented as
<code class="xref py py-class docutils literal notranslate"><span class="pre">Getattr</span></code> nodes in the <code class="xref py py-attr docutils literal notranslate"><span class="pre">expr</span></code> attribute of the <code class="xref py py-class docutils literal notranslate"><span class="pre">AssAttr</span></code>
instance.</p>
</div>
<div class="section" id="examples">
<h3>33.3.3. Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h3>
<p>This section shows several simple examples of ASTs for Python source code. The
examples demonstrate how to use the <code class="xref py py-func docutils literal notranslate"><span class="pre">parse()</span></code> function, what the repr of an
AST looks like, and how to access attributes of an AST node.</p>
<p>The first module defines a single function. Assume it is stored in
<code class="file docutils literal notranslate"><span class="pre">doublelib.py</span></code>.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="sd">"""This is an example module.</span>
<span class="sd">This is the docstring.</span>
<span class="sd">"""</span>
<span class="k">def</span> <span class="nf">double</span><span class="p">(</span><span class="n">x</span><span class="p">):</span>
<span class="s2">"Return twice the argument"</span>
<span class="k">return</span> <span class="n">x</span> <span class="o">*</span> <span class="mi">2</span>
</pre></div>
</div>
<p>In the interactive interpreter session below, I have reformatted the long AST
reprs for readability. The AST reprs use unqualified class names. If you want
to create an instance from a repr, you must import the class names from the
<a class="reference internal" href="#module-compiler.ast" title="compiler.ast"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler.ast</span></code></a> module.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">compiler</span>
<span class="gp">>>> </span><span class="n">mod</span> <span class="o">=</span> <span class="n">compiler</span><span class="o">.</span><span class="n">parseFile</span><span class="p">(</span><span class="s2">"doublelib.py"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">mod</span>
<span class="go">Module('This is an example module.\n\nThis is the docstring.\n',</span>
<span class="go"> Stmt([Function(None, 'double', ['x'], [], 0,</span>
<span class="go"> 'Return twice the argument',</span>
<span class="go"> Stmt([Return(Mul((Name('x'), Const(2))))]))]))</span>
<span class="gp">>>> </span><span class="kn">from</span> <span class="nn">compiler.ast</span> <span class="k">import</span> <span class="o">*</span>
<span class="gp">>>> </span><span class="n">Module</span><span class="p">(</span><span class="s1">'This is an example module.</span><span class="se">\n\n</span><span class="s1">This is the docstring.</span><span class="se">\n</span><span class="s1">'</span><span class="p">,</span>
<span class="gp">... </span> <span class="n">Stmt</span><span class="p">([</span><span class="n">Function</span><span class="p">(</span><span class="kc">None</span><span class="p">,</span> <span class="s1">'double'</span><span class="p">,</span> <span class="p">[</span><span class="s1">'x'</span><span class="p">],</span> <span class="p">[],</span> <span class="mi">0</span><span class="p">,</span>
<span class="gp">... </span> <span class="s1">'Return twice the argument'</span><span class="p">,</span>
<span class="gp">... </span> <span class="n">Stmt</span><span class="p">([</span><span class="n">Return</span><span class="p">(</span><span class="n">Mul</span><span class="p">((</span><span class="n">Name</span><span class="p">(</span><span class="s1">'x'</span><span class="p">),</span> <span class="n">Const</span><span class="p">(</span><span class="mi">2</span><span class="p">))))]))]))</span>
<span class="go">Module('This is an example module.\n\nThis is the docstring.\n',</span>
<span class="go"> Stmt([Function(None, 'double', ['x'], [], 0,</span>
<span class="go"> 'Return twice the argument',</span>
<span class="go"> Stmt([Return(Mul((Name('x'), Const(2))))]))]))</span>
<span class="gp">>>> </span><span class="n">mod</span><span class="o">.</span><span class="n">doc</span>
<span class="go">'This is an example module.\n\nThis is the docstring.\n'</span>
<span class="gp">>>> </span><span class="k">for</span> <span class="n">node</span> <span class="ow">in</span> <span class="n">mod</span><span class="o">.</span><span class="n">node</span><span class="o">.</span><span class="n">nodes</span><span class="p">:</span>
<span class="gp">... </span> <span class="nb">print</span> <span class="n">node</span>
<span class="gp">...</span>
<span class="go">Function(None, 'double', ['x'], [], 0, 'Return twice the argument',</span>
<span class="go"> Stmt([Return(Mul((Name('x'), Const(2))))]))</span>
<span class="gp">>>> </span><span class="n">func</span> <span class="o">=</span> <span class="n">mod</span><span class="o">.</span><span class="n">node</span><span class="o">.</span><span class="n">nodes</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="gp">>>> </span><span class="n">func</span><span class="o">.</span><span class="n">code</span>
<span class="go">Stmt([Return(Mul((Name('x'), Const(2))))])</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="module-compiler.visitor">
<span id="using-visitors-to-walk-asts"></span><h2>33.4. Using Visitors to Walk ASTs<a class="headerlink" href="#module-compiler.visitor" title="Permalink to this headline">¶</a></h2>
<p>The visitor pattern is … The <a class="reference internal" href="#module-compiler" title="compiler: Python code compiler written in Python. (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compiler</span></code></a> package uses a variant on the
visitor pattern that takes advantage of Python’s introspection features to
eliminate the need for much of the visitor’s infrastructure.</p>
<p>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.</p>
<p>XXX The magic <code class="xref py py-meth docutils literal notranslate"><span class="pre">visit()</span></code> method for visitors.</p>
<dl class="function">
<dt id="compiler.visitor.walk">
<code class="descclassname">compiler.visitor.</code><code class="descname">walk</code><span class="sig-paren">(</span><em>tree</em>, <em>visitor</em><span class="optional">[</span>, <em>verbose</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.visitor.walk" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="class">
<dt id="compiler.visitor.ASTVisitor">
<em class="property">class </em><code class="descclassname">compiler.visitor.</code><code class="descname">ASTVisitor</code><a class="headerlink" href="#compiler.visitor.ASTVisitor" title="Permalink to this definition">¶</a></dt>
<dd><p>The <a class="reference internal" href="#compiler.visitor.ASTVisitor" title="compiler.visitor.ASTVisitor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ASTVisitor</span></code></a> is responsible for walking over the tree in the correct
order. A walk begins with a call to <a class="reference internal" href="#compiler.visitor.ASTVisitor.preorder" title="compiler.visitor.ASTVisitor.preorder"><code class="xref py py-meth docutils literal notranslate"><span class="pre">preorder()</span></code></a>. For each node, it checks
the <em>visitor</em> argument to <a class="reference internal" href="#compiler.visitor.ASTVisitor.preorder" title="compiler.visitor.ASTVisitor.preorder"><code class="xref py py-meth docutils literal notranslate"><span class="pre">preorder()</span></code></a> for a method named ‘visitNodeType,’
where NodeType is the name of the node’s class, e.g. for a <code class="xref py py-class docutils literal notranslate"><span class="pre">While</span></code> node a
<code class="xref py py-meth docutils literal notranslate"><span class="pre">visitWhile()</span></code> would be called. If the method exists, it is called with the
node as its first argument.</p>
<p>The visitor method for a particular node type can control how child nodes are
visited during the walk. The <a class="reference internal" href="#compiler.visitor.ASTVisitor" title="compiler.visitor.ASTVisitor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ASTVisitor</span></code></a> 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
<a class="reference internal" href="#compiler.visitor.ASTVisitor.default" title="compiler.visitor.ASTVisitor.default"><code class="xref py py-meth docutils literal notranslate"><span class="pre">default()</span></code></a> method is called.</p>
<p><a class="reference internal" href="#compiler.visitor.ASTVisitor" title="compiler.visitor.ASTVisitor"><code class="xref py py-class docutils literal notranslate"><span class="pre">ASTVisitor</span></code></a> objects have the following methods:</p>
<p>XXX describe extra arguments</p>
<dl class="method">
<dt id="compiler.visitor.ASTVisitor.default">
<code class="descname">default</code><span class="sig-paren">(</span><em>node</em><span class="optional">[</span>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.visitor.ASTVisitor.default" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="method">
<dt id="compiler.visitor.ASTVisitor.dispatch">
<code class="descname">dispatch</code><span class="sig-paren">(</span><em>node</em><span class="optional">[</span>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#compiler.visitor.ASTVisitor.dispatch" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="method">
<dt id="compiler.visitor.ASTVisitor.preorder">
<code class="descname">preorder</code><span class="sig-paren">(</span><em>tree</em>, <em>visitor</em><span class="sig-paren">)</span><a class="headerlink" href="#compiler.visitor.ASTVisitor.preorder" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
</dd></dl>
</div>
<div class="section" id="bytecode-generation">
<h2>33.5. Bytecode Generation<a class="headerlink" href="#bytecode-generation" title="Permalink to this headline">¶</a></h2>
<p>The code generator is a visitor that emits bytecodes. Each visit method can
call the <code class="xref py py-meth docutils literal notranslate"><span class="pre">emit()</span></code> 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
generation of constant lists of code objects and calculation of jump offsets.</p>
</div>
</div>
</div>
</div>
</div>
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<h3><a href="../contents.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">33. Python compiler package</a><ul>
<li><a class="reference internal" href="#module-compiler">33.1. The basic interface</a></li>
<li><a class="reference internal" href="#limitations">33.2. Limitations</a></li>
<li><a class="reference internal" href="#python-abstract-syntax">33.3. Python Abstract Syntax</a><ul>
<li><a class="reference internal" href="#module-compiler.ast">33.3.1. AST Nodes</a></li>
<li><a class="reference internal" href="#assignment-nodes">33.3.2. Assignment nodes</a></li>
<li><a class="reference internal" href="#examples">33.3.3. Examples</a></li>
</ul>
</li>
<li><a class="reference internal" href="#module-compiler.visitor">33.4. Using Visitors to Walk ASTs</a></li>
<li><a class="reference internal" href="#bytecode-generation">33.5. Bytecode Generation</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
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<h4>Next topic</h4>
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