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 <div class="section" id="full-grammar-specification">
<h1>10. Full Grammar specification<a class="headerlink" href="#full-grammar-specification" title="Permalink to this headline">¶</a></h1>
This is the full Python grammar, as it is read by the parser generator and used
to parse Python source files:
<div class="highlight-python3 notranslate"><div class="highlight"><pre># Grammar for Python

# NOTE WELL: You should also follow all the steps listed at
# https://devguide.python.org/grammar/

# Start symbols for the grammar:
# single_input is a single interactive statement;
# file_input is a module or sequence of commands read from an input file;
# eval_input is the input for the eval() functions.
# NB: compound_stmt in single_input is followed by extra NEWLINE!
single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
file_input: (NEWLINE | stmt)* ENDMARKER
eval_input: testlist NEWLINE* ENDMARKER

decorator: &#39;@&#39; dotted_name [ &#39;(&#39; [arglist] &#39;)&#39; ] NEWLINE
decorators: decorator+
decorated: decorators (classdef | funcdef | async_funcdef)

async_funcdef: ASYNC funcdef
funcdef: &#39;def&#39; NAME parameters [&#39;-&gt;&#39; test] &#39;:&#39; suite

parameters: &#39;(&#39; [typedargslist] &#39;)&#39;
typedargslist: (tfpdef [&#39;=&#39; test] (&#39;,&#39; tfpdef [&#39;=&#39; test])* [&#39;,&#39; [
 &#39;*&#39; [tfpdef] (&#39;,&#39; tfpdef [&#39;=&#39; test])* [&#39;,&#39; [&#39;**&#39; tfpdef [&#39;,&#39;]]]
 | &#39;**&#39; tfpdef [&#39;,&#39;]]]
 | &#39;*&#39; [tfpdef] (&#39;,&#39; tfpdef [&#39;=&#39; test])* [&#39;,&#39; [&#39;**&#39; tfpdef [&#39;,&#39;]]]
 | &#39;**&#39; tfpdef [&#39;,&#39;])
tfpdef: NAME [&#39;:&#39; test]
varargslist: (vfpdef [&#39;=&#39; test] (&#39;,&#39; vfpdef [&#39;=&#39; test])* [&#39;,&#39; [
 &#39;*&#39; [vfpdef] (&#39;,&#39; vfpdef [&#39;=&#39; test])* [&#39;,&#39; [&#39;**&#39; vfpdef [&#39;,&#39;]]]
 | &#39;**&#39; vfpdef [&#39;,&#39;]]]
 | &#39;*&#39; [vfpdef] (&#39;,&#39; vfpdef [&#39;=&#39; test])* [&#39;,&#39; [&#39;**&#39; vfpdef [&#39;,&#39;]]]
 | &#39;**&#39; vfpdef [&#39;,&#39;]
)
vfpdef: NAME

stmt: simple_stmt | compound_stmt
simple_stmt: small_stmt (&#39;;&#39; small_stmt)* [&#39;;&#39;] NEWLINE
small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
 import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
 (&#39;=&#39; (yield_expr|testlist_star_expr))*)
annassign: &#39;:&#39; test [&#39;=&#39; test]
testlist_star_expr: (test|star_expr) (&#39;,&#39; (test|star_expr))* [&#39;,&#39;]
augassign: (&#39;+=&#39; | &#39;-=&#39; | &#39;*=&#39; | &#39;@=&#39; | &#39;/=&#39; | &#39;%=&#39; | &#39;&amp;=&#39; | &#39;|=&#39; | &#39;^=&#39; |
 &#39;&lt;&lt;=&#39; | &#39;&gt;&gt;=&#39; | &#39;**=&#39; | &#39;//=&#39;)
# For normal and annotated assignments, additional restrictions enforced by the interpreter
del_stmt: &#39;del&#39; exprlist
pass_stmt: &#39;pass&#39;
flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
break_stmt: &#39;break&#39;
continue_stmt: &#39;continue&#39;
return_stmt: &#39;return&#39; [testlist]
yield_stmt: yield_expr
raise_stmt: &#39;raise&#39; [test [&#39;from&#39; test]]
import_stmt: import_name | import_from
import_name: &#39;import&#39; dotted_as_names
# note below: the (&#39;.&#39; | &#39;...&#39;) is necessary because &#39;...&#39; is tokenized as ELLIPSIS
import_from: (&#39;from&#39; ((&#39;.&#39; | &#39;...&#39;)* dotted_name | (&#39;.&#39; | &#39;...&#39;)+)
 &#39;import&#39; (&#39;*&#39; | &#39;(&#39; import_as_names &#39;)&#39; | import_as_names))
import_as_name: NAME [&#39;as&#39; NAME]
dotted_as_name: dotted_name [&#39;as&#39; NAME]
import_as_names: import_as_name (&#39;,&#39; import_as_name)* [&#39;,&#39;]
dotted_as_names: dotted_as_name (&#39;,&#39; dotted_as_name)*
dotted_name: NAME (&#39;.&#39; NAME)*
global_stmt: &#39;global&#39; NAME (&#39;,&#39; NAME)*
nonlocal_stmt: &#39;nonlocal&#39; NAME (&#39;,&#39; NAME)*
assert_stmt: &#39;assert&#39; test [&#39;,&#39; test]

compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt
async_stmt: ASYNC (funcdef | with_stmt | for_stmt)
if_stmt: &#39;if&#39; test &#39;:&#39; suite (&#39;elif&#39; test &#39;:&#39; suite)* [&#39;else&#39; &#39;:&#39; suite]
while_stmt: &#39;while&#39; test &#39;:&#39; suite [&#39;else&#39; &#39;:&#39; suite]
for_stmt: &#39;for&#39; exprlist &#39;in&#39; testlist &#39;:&#39; suite [&#39;else&#39; &#39;:&#39; suite]
try_stmt: (&#39;try&#39; &#39;:&#39; suite
 ((except_clause &#39;:&#39; suite)+
 [&#39;else&#39; &#39;:&#39; suite]
 [&#39;finally&#39; &#39;:&#39; suite] |
 &#39;finally&#39; &#39;:&#39; suite))
with_stmt: &#39;with&#39; with_item (&#39;,&#39; with_item)* &#39;:&#39; suite
with_item: test [&#39;as&#39; expr]
# NB compile.c makes sure that the default except clause is last
except_clause: &#39;except&#39; [test [&#39;as&#39; NAME]]
suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT

test: or_test [&#39;if&#39; or_test &#39;else&#39; test] | lambdef
test_nocond: or_test | lambdef_nocond
lambdef: &#39;lambda&#39; [varargslist] &#39;:&#39; test
lambdef_nocond: &#39;lambda&#39; [varargslist] &#39;:&#39; test_nocond
or_test: and_test (&#39;or&#39; and_test)*
and_test: not_test (&#39;and&#39; not_test)*
not_test: &#39;not&#39; not_test | comparison
comparison: expr (comp_op expr)*
# &lt;&gt; isn&#39;t actually a valid comparison operator in Python. It&#39;s here for the
# sake of a __future__ import described in PEP 401 (which really works :-)
comp_op: &#39;&lt;&#39;|&#39;&gt;&#39;|&#39;==&#39;|&#39;&gt;=&#39;|&#39;&lt;=&#39;|&#39;&lt;&gt;&#39;|&#39;!=&#39;|&#39;in&#39;|&#39;not&#39; &#39;in&#39;|&#39;is&#39;|&#39;is&#39; &#39;not&#39;
star_expr: &#39;*&#39; expr
expr: xor_expr (&#39;|&#39; xor_expr)*
xor_expr: and_expr (&#39;^&#39; and_expr)*
and_expr: shift_expr (&#39;&amp;&#39; shift_expr)*
shift_expr: arith_expr ((&#39;&lt;&lt;&#39;|&#39;&gt;&gt;&#39;) arith_expr)*
arith_expr: term ((&#39;+&#39;|&#39;-&#39;) term)*
term: factor ((&#39;*&#39;|&#39;@&#39;|&#39;/&#39;|&#39;%&#39;|&#39;//&#39;) factor)*
factor: (&#39;+&#39;|&#39;-&#39;|&#39;~&#39;) factor | power
power: atom_expr [&#39;**&#39; factor]
atom_expr: [AWAIT] atom trailer*
atom: (&#39;(&#39; [yield_expr|testlist_comp] &#39;)&#39; |
 &#39;[&#39; [testlist_comp] &#39;]&#39; |
 &#39;{&#39; [dictorsetmaker] &#39;}&#39; |
 NAME | NUMBER | STRING+ | &#39;...&#39; | &#39;None&#39; | &#39;True&#39; | &#39;False&#39;)
testlist_comp: (test|star_expr) ( comp_for | (&#39;,&#39; (test|star_expr))* [&#39;,&#39;] )
trailer: &#39;(&#39; [arglist] &#39;)&#39; | &#39;[&#39; subscriptlist &#39;]&#39; | &#39;.&#39; NAME
subscriptlist: subscript (&#39;,&#39; subscript)* [&#39;,&#39;]
subscript: test | [test] &#39;:&#39; [test] [sliceop]
sliceop: &#39;:&#39; [test]
exprlist: (expr|star_expr) (&#39;,&#39; (expr|star_expr))* [&#39;,&#39;]
testlist: test (&#39;,&#39; test)* [&#39;,&#39;]
dictorsetmaker: ( ((test &#39;:&#39; test | &#39;**&#39; expr)
 (comp_for | (&#39;,&#39; (test &#39;:&#39; test | &#39;**&#39; expr))* [&#39;,&#39;])) |
 ((test | star_expr)
 (comp_for | (&#39;,&#39; (test | star_expr))* [&#39;,&#39;])) )

classdef: &#39;class&#39; NAME [&#39;(&#39; [arglist] &#39;)&#39;] &#39;:&#39; suite

arglist: argument (&#39;,&#39; argument)* [&#39;,&#39;]

# The reason that keywords are test nodes instead of NAME is that using NAME
# results in an ambiguity. ast.c makes sure it&#39;s a NAME.
# &quot;test &#39;=&#39; test&quot; is really &quot;keyword &#39;=&#39; test&quot;, but we have no such token.
# These need to be in a single rule to avoid grammar that is ambiguous
# to our LL(1) parser. Even though &#39;test&#39; includes &#39;*expr&#39; in star_expr,
# we explicitly match &#39;*&#39; here, too, to give it proper precedence.
# Illegal combinations and orderings are blocked in ast.c:
# multiple (test comp_for) arguments are blocked; keyword unpackings
# that precede iterable unpackings are blocked; etc.
argument: ( test [comp_for] |
 test &#39;=&#39; test |
 &#39;**&#39; test |
 &#39;*&#39; test )

comp_iter: comp_for | comp_if
comp_for: [ASYNC] &#39;for&#39; exprlist &#39;in&#39; or_test [comp_iter]
comp_if: &#39;if&#39; test_nocond [comp_iter]

# not used in grammar, but may appear in &quot;node&quot; passed from Parser to Compiler
encoding_decl: NAME

yield_expr: &#39;yield&#39; [yield_arg]
yield_arg: &#39;from&#39; test | testlist
</pre></div>
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