# Grammar for Python

# Note: Changing the grammar specified in this file will most likely

# require corresponding changes in the parser module

# (../Modules/parsermodule.c). If you can't make the changes to

# that module yourself, please co-ordinate the required changes

# with someone who can; ask around on python-dev for help. Fred

# Drake <fdrake@acm.org> will probably be listening there.

# NOTE WELL: You should also follow all the steps listed at

# https://docs.python.org/devguide/grammar.html

# Start symbols for the grammar:

# file_input is a module or sequence of commands read from an input file;

# single_input is a single interactive statement;

# eval_input is the input for the eval() functions.

# NB: compound_stmt in single_input is followed by extra NEWLINE!

file_input: (NEWLINE | stmt)* ENDMARKER

single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE

eval_input: testlist NEWLINE* ENDMARKER

decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE

decorators: decorator+

decorated: decorators (classdef | funcdef | async_funcdef)

# NOTE: Francisco Souza/Reinoud Elhorst, using ASYNC/'await' keywords instead of

# skipping python3.5+ compatibility, in favour of 3.7 solution

async_funcdef: 'async' funcdef

funcdef: 'def' NAME parameters ['->' test] ':' suite

parameters: '(' [typedargslist] ')'

typedargslist: (tfpdef ['=' test] (',' tfpdef ['=' test])* [',' [

'*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]

| '**' tfpdef [',']]]

| '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]

| '**' tfpdef [','])

tfpdef: NAME [':' test]

varargslist: (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [

'*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]

| '**' vfpdef [',']]]

| '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]

| '**' vfpdef [',']

)

vfpdef: NAME

stmt: simple_stmt | compound_stmt

simple_stmt: small_stmt (';' small_stmt)* [';'] 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) |

('=' (yield_expr|testlist_star_expr))*)

annassign: ':' test ['=' test]

testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']

augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |

'<<=' | '>>=' | '**=' | '//=')

# For normal and annotated assignments, additional restrictions enforced by the interpreter

del_stmt: 'del' exprlist

pass_stmt: 'pass'

flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt

break_stmt: 'break'

continue_stmt: 'continue'

return_stmt: 'return' [testlist]

yield_stmt: yield_expr

raise_stmt: 'raise' [test ['from' test]]

import_stmt: import_name | import_from

import_name: 'import' dotted_as_names

# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS

import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+)

'import' ('*' | '(' import_as_names ')' | import_as_names))

import_as_name: NAME ['as' NAME]

dotted_as_name: dotted_name ['as' NAME]

import_as_names: import_as_name (',' import_as_name)* [',']

dotted_as_names: dotted_as_name (',' dotted_as_name)*

dotted_name: NAME ('.' NAME)*

global_stmt: 'global' NAME (',' NAME)*

nonlocal_stmt: 'nonlocal' NAME (',' NAME)*

assert_stmt: 'assert' test [',' 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: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]

while_stmt: 'while' test ':' suite ['else' ':' suite]

for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite]

try_stmt: ('try' ':' suite

((except_clause ':' suite)+

['else' ':' suite]

['finally' ':' suite] |

'finally' ':' suite))

with_stmt: 'with' with_item (',' with_item)* ':' suite

with_item: test ['as' expr]

# NB compile.c makes sure that the default except clause is last

except_clause: 'except' [test ['as' NAME]]

# Edit by Francisco Souza/David Halter: The stmt is now optional. This reflects

# how Jedi allows classes and functions to be empty, which is beneficial for

# autocompletion.

suite: simple_stmt | NEWLINE INDENT stmt* DEDENT

test: or_test ['if' or_test 'else' test] | lambdef

test_nocond: or_test | lambdef_nocond

lambdef: 'lambda' [varargslist] ':' test

lambdef_nocond: 'lambda' [varargslist] ':' test_nocond

or_test: and_test ('or' and_test)*

and_test: not_test ('and' not_test)*

not_test: 'not' not_test | comparison

comparison: expr (comp_op expr)*

# <> isn't actually a valid comparison operator in Python. It's here for the

# sake of a __future__ import described in PEP 401 (which really works :-)

comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'

star_expr: '*' expr

expr: xor_expr ('|' xor_expr)*

xor_expr: and_expr ('^' and_expr)*

and_expr: shift_expr ('&' shift_expr)*

shift_expr: arith_expr (('<<'|'>>') arith_expr)*

arith_expr: term (('+'|'-') term)*

term: factor (('*'|'@'|'/'|'%'|'//') factor)*

factor: ('+'|'-'|'~') factor | power

power: atom_expr ['**' factor]

atom_expr: ['await'] atom trailer*

atom: ('(' [yield_expr|testlist_comp] ')' |

'[' [testlist_comp] ']' |

'{' [dictorsetmaker] '}' |

NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False')

testlist_comp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )

trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME

subscriptlist: subscript (',' subscript)* [',']

subscript: test | [test] ':' [test] [sliceop]

sliceop: ':' [test]

exprlist: (expr|star_expr) (',' (expr|star_expr))* [',']

testlist: test (',' test)* [',']

dictorsetmaker: ( ((test ':' test | '**' expr)

(comp_for | (',' (test ':' test | '**' expr))* [','])) |

((test | star_expr)

(comp_for | (',' (test | star_expr))* [','])) )

classdef: 'class' NAME ['(' [arglist] ')'] ':' suite

arglist: argument (',' argument)* [',']

# The reason that keywords are test nodes instead of NAME is that using NAME

# results in an ambiguity. ast.c makes sure it's a NAME.

# "test '=' test" is really "keyword '=' test", 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 'test' includes '*expr' in star_expr,

# we explicitly match '*' 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 '=' test |

'**' test |

'*' test )

comp_iter: comp_for | comp_if

comp_for: ['async'] 'for' exprlist 'in' or_test [comp_iter]

comp_if: 'if' test_nocond [comp_iter]

# not used in grammar, but may appear in "node" passed from Parser to Compiler

encoding_decl: NAME

yield_expr: 'yield' [yield_arg]

yield_arg: 'from' test | testlist