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<!DOCTYPE html>

<head>

<title>ast --- Abstract syntax trees — مستندات Python3.14.6</title><meta name="viewport" content="width=device-width, initial-scale=1.0">

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<ul>

<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">ast</code> --- Abstract syntax trees</a><ul>

<li><a class="reference internal" href="#abstract-grammar">Abstract grammar</a></li>

<li><a class="reference internal" href="#node-classes">Node classes</a><ul>

<li><a class="reference internal" href="#root-nodes">Root nodes</a></li>

<li><a class="reference internal" href="#literals">Literals</a></li>

<li><a class="reference internal" href="#variables">Variables</a></li>

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<li><a class="reference internal" href="#subscripting">Subscripting</a></li>

<li><a class="reference internal" href="#comprehensions">Comprehensions</a></li>

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<li><a class="reference internal" href="#type-annotations">Type annotations</a></li>

<li><a class="reference internal" href="#type-parameters">Type parameters</a></li>

<li><a class="reference internal" href="#function-and-class-definitions">Function and class definitions</a></li>

<li><a class="reference internal" href="#async-and-await">Async and await</a></li>

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<li><a class="reference internal" href="#ast-helpers"><code class="xref py py-mod docutils literal notranslate">ast</code> helpers</a></li>

<li><a class="reference internal" href="#compiler-flags">Compiler flags</a></li>

<li><a class="reference internal" href="#command-line-usage">Command-line usage</a></li>

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<h1><code class="xref py py-mod docutils literal notranslate">ast</code> --- Abstract syntax trees<a class="headerlink" href="#module-ast" title="Link to this heading">¶</a></h1>

Source code: <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/ast.py">Lib/ast.py</a>

The <code class="xref py py-mod docutils literal notranslate">ast</code> module helps Python applications to process trees of the Python

abstract syntax grammar. The abstract syntax itself might change with each

Python release; this module helps to find out programmatically what the current

grammar looks like.

An abstract syntax tree can be generated by passing <a class="reference internal" href="#ast.PyCF_ONLY_AST" title="ast.PyCF_ONLY_AST"><code class="xref py py-data docutils literal notranslate">ast.PyCF_ONLY_AST</code></a> as

a flag to the <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> built-in function, or using the <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">parse()</code></a>

helper provided in this module. The result will be a tree of objects whose

classes all inherit from <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a>. An abstract syntax tree can be

compiled into a Python code object using the built-in <code class="xref py py-func docutils literal notranslate">compile()</code> function.

<h2>Abstract grammar<a class="headerlink" href="#abstract-grammar" title="Link to this heading">¶</a></h2>

The abstract grammar is currently defined as follows:

<div class="highlight-asdl notranslate"><div class="highlight"><pre>-- ASDL's 4 builtin types are:

-- identifier, int, string, constant

module Python

{

mod = Module(stmt* body, type_ignore* type_ignores)

| Interactive(stmt* body)

| Expression(expr body)

| FunctionType(expr* argtypes, expr returns)

stmt = FunctionDef(identifier name, arguments args,

stmt* body, expr* decorator_list, expr? returns,

string? type_comment, type_param* type_params)

| AsyncFunctionDef(identifier name, arguments args,

| ClassDef(identifier name,

expr* bases,

keyword* keywords,

stmt* body,

expr* decorator_list,

type_param* type_params)

| Return(expr? value)

| Delete(expr* targets)

| Assign(expr* targets, expr value, string? type_comment)

| TypeAlias(expr name, type_param* type_params, expr value)

| AugAssign(expr target, operator op, expr value)

-- 'simple' indicates that we annotate simple name without parens

| AnnAssign(expr target, expr annotation, expr? value, int simple)

-- use 'orelse' because else is a keyword in target languages

| For(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)

| AsyncFor(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)

| While(expr test, stmt* body, stmt* orelse)

| If(expr test, stmt* body, stmt* orelse)

| With(withitem* items, stmt* body, string? type_comment)

| AsyncWith(withitem* items, stmt* body, string? type_comment)

| Match(expr subject, match_case* cases)

| Raise(expr? exc, expr? cause)

| Try(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)

| TryStar(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)

| Assert(expr test, expr? msg)

| Import(alias* names)

| ImportFrom(identifier? module, alias* names, int? level)

| Global(identifier* names)

| Nonlocal(identifier* names)

| Expr(expr value)

| Pass | Break | Continue

-- col_offset is the byte offset in the utf8 string the parser uses

attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

-- BoolOp() can use left & right?

expr = BoolOp(boolop op, expr* values)

| NamedExpr(expr target, expr value)

| BinOp(expr left, operator op, expr right)

| UnaryOp(unaryop op, expr operand)

| Lambda(arguments args, expr body)

| IfExp(expr test, expr body, expr orelse)

| Dict(expr?* keys, expr* values)

| Set(expr* elts)

| ListComp(expr elt, comprehension* generators)

| SetComp(expr elt, comprehension* generators)

| DictComp(expr key, expr value, comprehension* generators)

| GeneratorExp(expr elt, comprehension* generators)

-- the grammar constrains where yield expressions can occur

| Await(expr value)

| Yield(expr? value)

| YieldFrom(expr value)

-- need sequences for compare to distinguish between

-- x < 4 < 3 and (x < 4) < 3

| Compare(expr left, cmpop* ops, expr* comparators)

| Call(expr func, expr* args, keyword* keywords)

| FormattedValue(expr value, int conversion, expr? format_spec)

| Interpolation(expr value, constant str, int conversion, expr? format_spec)

| JoinedStr(expr* values)

| TemplateStr(expr* values)

| Constant(constant value, string? kind)

-- the following expression can appear in assignment context

| Attribute(expr value, identifier attr, expr_context ctx)

| Subscript(expr value, expr slice, expr_context ctx)

| Starred(expr value, expr_context ctx)

| Name(identifier id, expr_context ctx)

| List(expr* elts, expr_context ctx)

| Tuple(expr* elts, expr_context ctx)

-- can appear only in Subscript

| Slice(expr? lower, expr? upper, expr? step)

-- col_offset is the byte offset in the utf8 string the parser uses

expr_context = Load | Store | Del

boolop = And | Or

operator = Add | Sub | Mult | MatMult | Div | Mod | Pow | LShift

unaryop = Invert | Not | UAdd | USub

cmpop = Eq | NotEq | Lt | LtE | Gt | GtE | Is | IsNot | In | NotIn

comprehension = (expr target, expr iter, expr* ifs, int is_async)

excepthandler = ExceptHandler(expr? type, identifier? name, stmt* body)

arguments = (arg* posonlyargs, arg* args, arg? vararg, arg* kwonlyargs,

expr?* kw_defaults, arg? kwarg, expr* defaults)

arg = (identifier arg, expr? annotation, string? type_comment)

-- keyword arguments supplied to call (NULL identifier for **kwargs)

keyword = (identifier? arg, expr value)

-- import name with optional 'as' alias.

alias = (identifier name, identifier? asname)

withitem = (expr context_expr, expr? optional_vars)

match_case = (pattern pattern, expr? guard, stmt* body)

pattern = MatchValue(expr value)

| MatchSingleton(constant value)

| MatchSequence(pattern* patterns)

| MatchMapping(expr* keys, pattern* patterns, identifier? rest)

| MatchClass(expr cls, pattern* patterns, identifier* kwd_attrs, pattern* kwd_patterns)

| MatchStar(identifier? name)

-- The optional "rest" MatchMapping parameter handles capturing extra mapping keys

| MatchAs(pattern? pattern, identifier? name)

| MatchOr(pattern* patterns)

attributes (int lineno, int col_offset, int end_lineno, int end_col_offset)

type_ignore = TypeIgnore(int lineno, string tag)

type_param = TypeVar(identifier name, expr? bound, expr? default_value)

| ParamSpec(identifier name, expr? default_value)

| TypeVarTuple(identifier name, expr? default_value)

attributes (int lineno, int col_offset, int end_lineno, int end_col_offset)

}

</pre></div>

</div>

</section>

<h2>Node classes<a class="headerlink" href="#node-classes" title="Link to this heading">¶</a></h2>

<dd>This is the base of all AST node classes. The actual node classes are

derived from the <code class="file docutils literal notranslate">Parser/Python.asdl</code> file, which is reproduced

<a class="reference internal" href="#abstract-grammar">above</a>. They are defined in the <code class="xref py py-mod docutils literal notranslate">_ast</code> C

module and re-exported in <code class="xref py py-mod docutils literal notranslate">ast</code>.

There is one class defined for each left-hand side symbol in the abstract

grammar (for example, <code class="xref py py-class docutils literal notranslate">ast.stmt</code> or <code class="xref py py-class docutils literal notranslate">ast.expr</code>). In addition,

there is one class defined for each constructor on the right-hand side; these

classes inherit from the classes for the left-hand side trees. For example,

<a class="reference internal" href="#ast.BinOp" title="ast.BinOp"><code class="xref py py-class docutils literal notranslate">ast.BinOp</code></a> inherits from <code class="xref py py-class docutils literal notranslate">ast.expr</code>. For production rules

with alternatives (aka "sums"), the left-hand side class is abstract: only

instances of specific constructor nodes are ever created.

_fields<a class="headerlink" href="#ast.AST._fields" title="Link to this definition">¶</a></dt>

<dd>Each concrete class has an attribute <code class="xref py py-attr docutils literal notranslate">_fields</code> which gives the names

of all child nodes.

Each instance of a concrete class has one attribute for each child node,

of the type as defined in the grammar. For example, <a class="reference internal" href="#ast.BinOp" title="ast.BinOp"><code class="xref py py-class docutils literal notranslate">ast.BinOp</code></a>

instances have an attribute <code class="xref py py-attr docutils literal notranslate">left</code> of type <code class="xref py py-class docutils literal notranslate">ast.expr</code>.

If these attributes are marked as optional in the grammar (using a

question mark), the value might be <code class="docutils literal notranslate">None</code>. If the attributes can have

zero-or-more values (marked with an asterisk), the values are represented

as Python lists. All possible attributes must be present and have valid

values when compiling an AST with <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>.

</dd></dl>

_field_types<a class="headerlink" href="#ast.AST._field_types" title="Link to this definition">¶</a></dt>

<dd>The <code class="xref py py-attr docutils literal notranslate">_field_types</code> attribute on each concrete class is a dictionary

mapping field names (as also listed in <a class="reference internal" href="#ast.AST._fields" title="ast.AST._fields"><code class="xref py py-attr docutils literal notranslate">_fields</code></a>) to their types.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> ast.TypeVar._field_types

{'name': <class 'str'>, 'bound': ast.expr | None, 'default_value': ast.expr | None}

</pre></div>

</div>

Added in version 3.13.

</div>

</dd></dl>

lineno<a class="headerlink" href="#ast.AST.lineno" title="Link to this definition">¶</a></dt>

col_offset<a class="headerlink" href="#ast.AST.col_offset" title="Link to this definition">¶</a></dt>

end_lineno<a class="headerlink" href="#ast.AST.end_lineno" title="Link to this definition">¶</a></dt>

end_col_offset<a class="headerlink" href="#ast.AST.end_col_offset" title="Link to this definition">¶</a></dt>

<dd>Instances of <code class="xref py py-class docutils literal notranslate">ast.expr</code> and <code class="xref py py-class docutils literal notranslate">ast.stmt</code> subclasses have

<a class="reference internal" href="#ast.AST.lineno" title="ast.AST.lineno"><code class="xref py py-attr docutils literal notranslate">lineno</code></a>, <a class="reference internal" href="#ast.AST.col_offset" title="ast.AST.col_offset"><code class="xref py py-attr docutils literal notranslate">col_offset</code></a>, <a class="reference internal" href="#ast.AST.end_lineno" title="ast.AST.end_lineno"><code class="xref py py-attr docutils literal notranslate">end_lineno</code></a>, and

<a class="reference internal" href="#ast.AST.end_col_offset" title="ast.AST.end_col_offset"><code class="xref py py-attr docutils literal notranslate">end_col_offset</code></a> attributes. The <code class="xref py py-attr docutils literal notranslate">lineno</code> and <code class="xref py py-attr docutils literal notranslate">end_lineno</code>

are the first and last line numbers of source text span (1-indexed so the

first line is line 1) and the <code class="xref py py-attr docutils literal notranslate">col_offset</code> and <code class="xref py py-attr docutils literal notranslate">end_col_offset</code>

are the corresponding UTF-8 byte offsets of the first and last tokens that

generated the node. The UTF-8 offset is recorded because the parser uses

UTF-8 internally.

Note that the end positions are not required by the compiler and are

therefore optional. The end offset is after the last symbol, for example

one can get the source segment of a one-line expression node using

<code class="docutils literal notranslate">source_line[node.col_offset : node.end_col_offset]</code>.

</dd></dl>

The constructor of a class <code class="xref py py-class docutils literal notranslate">ast.T</code> parses its arguments as follows:

<li>If there are positional arguments, there must be as many as there are items

in <code class="xref py py-attr docutils literal notranslate">T._fields</code>; they will be assigned as attributes of these names.</li>

<li>If there are keyword arguments, they will set the attributes of the same

names to the given values.</li>

</ul>

For example, to create and populate an <a class="reference internal" href="#ast.UnaryOp" title="ast.UnaryOp"><code class="xref py py-class docutils literal notranslate">ast.UnaryOp</code></a> node, you could

use

<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = ast.UnaryOp(ast.USub(), ast.Constant(5, lineno=0, col_offset=0),

lineno=0, col_offset=0)

</pre></div>

</div>

If a field that is optional in the grammar is omitted from the constructor,

it defaults to <code class="docutils literal notranslate">None</code>. If a list field is omitted, it defaults to the empty

list. If a field of type <code class="xref py py-class docutils literal notranslate">ast.expr_context</code> is omitted, it defaults to

<a class="reference internal" href="#ast.Load" title="ast.Load"><code class="xref py py-class docutils literal notranslate">Load()</code></a>. If any other field is omitted, a <a class="reference internal" href="exceptions.html#DeprecationWarning" title="DeprecationWarning"><code class="xref py py-exc docutils literal notranslate">DeprecationWarning</code></a> is raised

and the AST node will not have this field. In Python 3.15, this condition will

raise an error.

</dd></dl>

تغییر داده شده در نسخه 3.8: Class <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">ast.Constant</code></a> is now used for all constants.

</div>

تغییر داده شده در نسخه 3.9: Simple indices are represented by their value, extended slices are

represented as tuples.

</div>

تغییر داده شده در نسخه 3.13: AST node constructors were changed to provide sensible defaults for omitted

fields: optional fields now default to <code class="docutils literal notranslate">None</code>, list fields default to an

empty list, and fields of type <code class="xref py py-class docutils literal notranslate">ast.expr_context</code> default to

nodes (accessing them raised <a class="reference internal" href="exceptions.html#AttributeError" title="AttributeError"><code class="xref py py-exc docutils literal notranslate">AttributeError</code></a>).

</div>

تغییر داده شده در نسخه 3.14: The <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate">__repr__()</code></a> output of <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">AST</code></a> nodes includes

the values of the node fields.

</div>

منسوخ شده از نسخه‌ی 3.8، در نسخه‌ی 3.14 حذف شده است.: Previous versions of Python provided the AST classes <code class="xref py py-class docutils literal notranslate">ast.Num</code>,

<code class="xref py py-class docutils literal notranslate">ast.Str</code>, <code class="xref py py-class docutils literal notranslate">ast.Bytes</code>, <code class="xref py py-class docutils literal notranslate">ast.NameConstant</code> and

<code class="xref py py-class docutils literal notranslate">ast.Ellipsis</code>, which were deprecated in Python 3.8. These classes

were removed in Python 3.14, and their functionality has been replaced with

<a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">ast.Constant</code></a>.

</div>

منسوخ شده از نسخه 3.9: Old classes <code class="xref py py-class docutils literal notranslate">ast.Index</code> and <code class="xref py py-class docutils literal notranslate">ast.ExtSlice</code> are still

available, but they will be removed in future Python releases.

In the meantime, instantiating them will return an instance of

a different class.

</div>

منسوخ شده از نسخه‌ی 3.13, در نسخه‌ی 3.15 حذف خواهد شد.: Previous versions of Python allowed the creation of AST nodes that were missing

required fields. Similarly, AST node constructors allowed arbitrary keyword

arguments that were set as attributes of the AST node, even if they did not

match any of the fields of the AST node. This behavior is deprecated and will

be removed in Python 3.15.

</div>

توجه

The descriptions of the specific node classes displayed here

were initially adapted from the fantastic <a class="reference external" href="https://greentreesnakes.readthedocs.io/en/latest/">Green Tree

Snakes</a> project and

all its contributors.

</div>

<h3>Root nodes<a class="headerlink" href="#root-nodes" title="Link to this heading">¶</a></h3>

<dd>A Python module, as with <a class="reference internal" href="../reference/toplevel_components.html#file-input">file input</a>.

Node type generated by <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> in the default <code class="docutils literal notranslate">"exec"</code> mode.

<code class="docutils literal notranslate">body</code> is a <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate">list</code></a> of the module's <a class="reference internal" href="#ast-statements">Statements</a>.

<code class="docutils literal notranslate">type_ignores</code> is a <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate">list</code></a> of the module's type ignore comments;

see <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> for more details.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('x = 1'), indent=4))

Module(

body=[

Assign(

targets=[

Name(id='x', ctx=Store())],

value=Constant(value=1))])

</pre></div>

</div>

</dd></dl>

<dd>A single Python <a class="reference internal" href="../reference/toplevel_components.html#expression-input">expression input</a>.

Node type generated by <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> when mode is <code class="docutils literal notranslate">"eval"</code>.

<code class="docutils literal notranslate">body</code> is a single node,

one of the <a class="reference internal" href="#ast-expressions">expression types</a>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('123', mode='eval'), indent=4))

Expression(

body=Constant(value=123))

</pre></div>

</div>

</dd></dl>

<dd>A single <a class="reference internal" href="../reference/toplevel_components.html#interactive">interactive input</a>, like in <a class="reference internal" href="../tutorial/appendix.html#tut-interac">حالت تعاملی</a>.

Node type generated by <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> when mode is <code class="docutils literal notranslate">"single"</code>.

<code class="docutils literal notranslate">body</code> is a <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate">list</code></a> of <a class="reference internal" href="#ast-statements">statement nodes</a>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('x = 1; y = 2', mode='single'), indent=4))

Interactive(

body=[

Assign(

targets=[

Name(id='x', ctx=Store())],

value=Constant(value=1)),

Assign(

targets=[

Name(id='y', ctx=Store())],

value=Constant(value=2))])

</pre></div>

</div>

</dd></dl>

<dd>A representation of an old-style type comments for functions,

as Python versions prior to 3.5 didn't support <a class="pep reference external" href="https://peps.python.org/pep-0484/">PEP 484</a> annotations.

Node type generated by <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> when mode is <code class="docutils literal notranslate">"func_type"</code>.

Such type comments would look like this:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>def sum_two_number(a, b):

# type: (int, int) -> int

return a + b

</pre></div>

</div>

<code class="docutils literal notranslate">argtypes</code> is a <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate">list</code></a> of <a class="reference internal" href="#ast-expressions">expression nodes</a>.

<code class="docutils literal notranslate">returns</code> is a single <a class="reference internal" href="#ast-expressions">expression node</a>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('(int, str) -> List[int]', mode='func_type'), indent=4))

FunctionType(

argtypes=[

Name(id='int', ctx=Load()),

Name(id='str', ctx=Load())],

returns=Subscript(

value=Name(id='List', ctx=Load()),

slice=Name(id='int', ctx=Load()),

ctx=Load()))

</pre></div>

</div>

Added in version 3.8.

</div>

</dd></dl>

</section>

<h3>Literals<a class="headerlink" href="#literals" title="Link to this heading">¶</a></h3>

<dd>A constant value. The <code class="docutils literal notranslate">value</code> attribute of the <code class="docutils literal notranslate">Constant</code> literal contains the

Python object it represents. The values represented can be instances of <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a>,

<a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a>, <a class="reference internal" href="functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate">int</code></a>, <a class="reference internal" href="functions.html#float" title="float"><code class="xref py py-class docutils literal notranslate">float</code></a>, <a class="reference internal" href="functions.html#complex" title="complex"><code class="xref py py-class docutils literal notranslate">complex</code></a>, and <a class="reference internal" href="functions.html#bool" title="bool"><code class="xref py py-class docutils literal notranslate">bool</code></a>,

and the constants <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-data docutils literal notranslate">None</code></a> and <a class="reference internal" href="constants.html#Ellipsis" title="Ellipsis"><code class="xref py py-data docutils literal notranslate">Ellipsis</code></a>.

The <code class="docutils literal notranslate">kind</code> attribute is an optional string. For string literals with a

<code class="docutils literal notranslate">u</code> prefix, <code class="docutils literal notranslate">kind</code> is set to <code class="docutils literal notranslate">'u'</code>. For all other

constants, <code class="docutils literal notranslate">kind</code> is <code class="docutils literal notranslate">None</code>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('123', mode='eval'), indent=4))

Expression(

body=Constant(value=123))

>>> print(ast.dump(ast.parse("u'hello'", mode='eval'), indent=4))

Expression(

body=Constant(value='hello', kind='u'))

</pre></div>

</div>

</dd></dl>

class ast.FormattedValue(value, conversion, format_spec)<a class="headerlink" href="#ast.FormattedValue" title="Link to this definition">¶</a></dt>

<dd>Node representing a single formatting field in an f-string. If the string

contains a single formatting field and nothing else the node can be

isolated otherwise it appears in <a class="reference internal" href="#ast.JoinedStr" title="ast.JoinedStr"><code class="xref py py-class docutils literal notranslate">JoinedStr</code></a>.

<li><code class="docutils literal notranslate">value</code> is any expression node (such as a literal, a variable, or a

function call).</li>

<li><code class="docutils literal notranslate">conversion</code> is an integer:

<ul>

<li>-1: no formatting</li>

<li>97 (<code class="docutils literal notranslate">ord('a')</code>): <code class="docutils literal notranslate">!a</code> <a class="reference internal" href="functions.html#ascii" title="ascii"><code class="xref py py-func docutils literal notranslate">ASCII</code></a> formatting</li>

<li>114 (<code class="docutils literal notranslate">ord('r')</code>): <code class="docutils literal notranslate">!r</code> <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate">repr()</code></a> formatting</li>

<li>115 (<code class="docutils literal notranslate">ord('s')</code>): <code class="docutils literal notranslate">!s</code> <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate">string</code></a> formatting</li>

</ul>

</li>

<li><code class="docutils literal notranslate">format_spec</code> is a <a class="reference internal" href="#ast.JoinedStr" title="ast.JoinedStr"><code class="xref py py-class docutils literal notranslate">JoinedStr</code></a> node representing the formatting

of the value, or <code class="docutils literal notranslate">None</code> if no format was specified. Both

<code class="docutils literal notranslate">conversion</code> and <code class="docutils literal notranslate">format_spec</code> can be set at the same time.</li>

</ul>

</dd></dl>

<dd>An f-string, comprising a series of <a class="reference internal" href="#ast.FormattedValue" title="ast.FormattedValue"><code class="xref py py-class docutils literal notranslate">FormattedValue</code></a> and <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a>

nodes.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('f"sin({a}) is {sin(a):.3}"', mode='eval'), indent=4))

Expression(

body=JoinedStr(

values=[

Constant(value='sin('),

FormattedValue(

value=Name(id='a', ctx=Load()),

conversion=-1),

Constant(value=') is '),

FormattedValue(

value=Call(

func=Name(id='sin', ctx=Load()),

args=[

Name(id='a', ctx=Load())]),

conversion=-1,

format_spec=JoinedStr(

values=[

Constant(value='.3')]))]))

</pre></div>

</div>

</dd></dl>

class ast.TemplateStr(values, <abbr title="Positional-only parameter separator (PEP 570)">/</abbr>)<a class="headerlink" href="#ast.TemplateStr" title="Link to this definition">¶</a></dt>

Added in version 3.14.

</div>

Node representing a template string literal, comprising a series of

<a class="reference internal" href="#ast.Interpolation" title="ast.Interpolation"><code class="xref py py-class docutils literal notranslate">Interpolation</code></a> and <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a> nodes.

These nodes may be any order, and do not need to be interleaved.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> expr = ast.parse('t"{name} finished {place:ordinal}"', mode='eval')

Expression(

body=TemplateStr(

values=[

Interpolation(

value=Name(id='name', ctx=Load()),

str='name',

conversion=-1),

Constant(value=' finished '),

Interpolation(

value=Name(id='place', ctx=Load()),

str='place',

conversion=-1,

format_spec=JoinedStr(

values=[

Constant(value='ordinal')]))]))

</pre></div>

</div>

</dd></dl>

class ast.Interpolation(value, str, conversion, format_spec=None)<a class="headerlink" href="#ast.Interpolation" title="Link to this definition">¶</a></dt>

Added in version 3.14.

</div>

Node representing a single interpolation field in a template string literal.

<ul>

<li><code class="docutils literal notranslate">value</code> is any expression node (such as a literal, a variable, or a

function call).

This has the same meaning as <code class="docutils literal notranslate">FormattedValue.value</code>.</li>

<li><code class="docutils literal notranslate">str</code> is a constant containing the text of the interpolation expression.

If <code class="docutils literal notranslate">str</code> is set to <code class="docutils literal notranslate">None</code>, then <code class="docutils literal notranslate">value</code> is used to generate code

when calling <a class="reference internal" href="#ast.unparse" title="ast.unparse"><code class="xref py py-func docutils literal notranslate">ast.unparse()</code></a>. This no longer guarantees that the

generated code is identical to the original and is intended for code

generation.

</li>

<li><code class="docutils literal notranslate">conversion</code> is an integer:

<li>-1: no conversion</li>

</ul>

This has the same meaning as <code class="docutils literal notranslate">FormattedValue.conversion</code>.

</li>

of the value, or <code class="docutils literal notranslate">None</code> if no format was specified. Both

This has the same meaning as <code class="docutils literal notranslate">FormattedValue.format_spec</code>.</li>

</ul>

</dd></dl>

<dd>A list or tuple. <code class="docutils literal notranslate">elts</code> holds a list of nodes representing the elements.

<code class="docutils literal notranslate">ctx</code> is <a class="reference internal" href="#ast.Store" title="ast.Store"><code class="xref py py-class docutils literal notranslate">Store</code></a> if the container is an assignment target (i.e.

<code class="docutils literal notranslate">(x,y)=something</code>), and <a class="reference internal" href="#ast.Load" title="ast.Load"><code class="xref py py-class docutils literal notranslate">Load</code></a> otherwise.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('[1, 2, 3]', mode='eval'), indent=4))

Expression(

body=List(

elts=[

Constant(value=1),

Constant(value=2),

Constant(value=3)],

ctx=Load()))

>>> print(ast.dump(ast.parse('(1, 2, 3)', mode='eval'), indent=4))

Expression(

body=Tuple(

elts=[

Constant(value=1),

Constant(value=2),

Constant(value=3)],

ctx=Load()))

</pre></div>

</div>

</dd></dl>

<dd>A set. <code class="docutils literal notranslate">elts</code> holds a list of nodes representing the set's elements.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('{1, 2, 3}', mode='eval'), indent=4))

Expression(

body=Set(

elts=[

Constant(value=1),

Constant(value=2),

Constant(value=3)]))

</pre></div>

</div>

</dd></dl>

<dd>A dictionary. <code class="docutils literal notranslate">keys</code> and <code class="docutils literal notranslate">values</code> hold lists of nodes representing the

keys and the values respectively, in matching order (what would be returned

when calling <code class="code docutils literal notranslate">dictionary.keys()</code> and <code class="code docutils literal notranslate">dictionary.values()</code>).

When doing dictionary unpacking using dictionary literals the expression to be

expanded goes in the <code class="docutils literal notranslate">values</code> list, with a <code class="docutils literal notranslate">None</code> at the corresponding

position in <code class="docutils literal notranslate">keys</code>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('{"a":1, **d}', mode='eval'), indent=4))

Expression(

body=Dict(

keys=[

Constant(value='a'),

None],

values=[

Constant(value=1),

Name(id='d', ctx=Load())]))

</pre></div>

</div>

</dd></dl>

</section>

<h3>Variables<a class="headerlink" href="#variables" title="Link to this heading">¶</a></h3>

<dd>A variable name. <code class="docutils literal notranslate">id</code> holds the name as a string, and <code class="docutils literal notranslate">ctx</code> is one of

the following types.

</dd></dl>

<dd>Variable references can be used to load the value of a variable, to assign

a new value to it, or to delete it. Variable references are given a context

to distinguish these cases.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('a'), indent=4))

Module(

body=[

Expr(

value=Name(id='a', ctx=Load()))])

>>> print(ast.dump(ast.parse('a = 1'), indent=4))

Module(

body=[

Assign(

targets=[

Name(id='a', ctx=Store())],

value=Constant(value=1))])

>>> print(ast.dump(ast.parse('del a'), indent=4))

Module(

body=[

Delete(

targets=[

Name(id='a', ctx=Del())])])

</pre></div>

</div>

</dd></dl>

<dd>A <code class="docutils literal notranslate">*var</code> variable reference. <code class="docutils literal notranslate">value</code> holds the variable, typically a

node with <code class="docutils literal notranslate">*args</code>.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('a, *b = it'), indent=4))

Module(

body=[

Assign(

targets=[

Tuple(

elts=[

Name(id='a', ctx=Store()),

Starred(

value=Name(id='b', ctx=Store()),

ctx=Store())],

value=Name(id='it', ctx=Load()))])

</pre></div>

</div>

</dd></dl>

</section>

<h3>Expressions<a class="headerlink" href="#expressions" title="Link to this heading">¶</a></h3>

<dd>When an expression, such as a function call, appears as a statement by itself

with its return value not used or stored, it is wrapped in this container.

<code class="docutils literal notranslate">value</code> holds one of the other nodes in this section, a <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a>, a

<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, a <a class="reference internal" href="#ast.Lambda" title="ast.Lambda"><code class="xref py py-class docutils literal notranslate">Lambda</code></a>, a <a class="reference internal" href="#ast.Yield" title="ast.Yield"><code class="xref py py-class docutils literal notranslate">Yield</code></a> or <a class="reference internal" href="#ast.YieldFrom" title="ast.YieldFrom"><code class="xref py py-class docutils literal notranslate">YieldFrom</code></a> node.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('-a'), indent=4))

Module(

body=[

Expr(

value=UnaryOp(

op=USub(),

operand=Name(id='a', ctx=Load())))])

</pre></div>

</div>

</dd></dl>

<dd>A unary operation. <code class="docutils literal notranslate">op</code> is the operator, and <code class="docutils literal notranslate">operand</code> any expression

node.

</dd></dl>

<dd>Unary operator tokens. <code class="xref py py-class docutils literal notranslate">Not</code> is the <code class="docutils literal notranslate">not</code> keyword, <code class="xref py py-class docutils literal notranslate">Invert</code>

is the <code class="docutils literal notranslate">~</code> operator.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('not x', mode='eval'), indent=4))

Expression(

body=UnaryOp(

op=Not(),

operand=Name(id='x', ctx=Load())))

</pre></div>

</div>

</dd></dl>

class ast.BinOp(left, op, right)<a class="headerlink" href="#ast.BinOp" title="Link to this definition">¶</a></dt>

<dd>A binary operation (like addition or division). <code class="docutils literal notranslate">op</code> is the operator, and

<code class="docutils literal notranslate">left</code> and <code class="docutils literal notranslate">right</code> are any expression nodes.

<div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> print(ast.dump(ast.parse('x + y', mode='eval'), indent=4))

Expression(

body=BinOp(

left=Name(id='x', ctx=Load()),

op=Add(),

right=Name(id='y', ctx=Load())))

</pre></div>

</div>

</dd></dl>

<dd>Binary operator tokens.

</dd></dl>

<dd>A boolean operation, 'or' or 'and'. <code class="docutils literal notranslate">op</code> is <a class="reference internal" href="#ast.Or" title="ast.Or"><code class="xref py py-class docutils literal notranslate">Or</code></a> or <a class="reference internal" href="#ast.And" title="ast.And"><code class="xref py py-class docutils literal notranslate">And</code></a>.

<code class="docutils literal notranslate">values</code> are the values involved. Consecutive operations with the same

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