# Grammar for 2to3. This grammar supports Python 2.x and 3.x.

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

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# require corresponding changes in the parser module

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

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

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

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

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# NOTE WELL: You should also follow all the steps listed in PEP 306,

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# "How to Change Python's Grammar"

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# Commands for Kees Blom's railroad program

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#diagram:token NAME

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#diagram:token NUMBER

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#diagram:token STRING

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#diagram:token NEWLINE

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#diagram:token ENDMARKER

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#diagram:token INDENT

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#diagram:output\input python.bla

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#diagram:token DEDENT

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#diagram:output\textwidth 20.04cm\oddsidemargin 0.0cm\evensidemargin 0.0cm

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#diagram:rules

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# Start symbols for the grammar:

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

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# single_input is a single interactive statement;

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

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

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file_input: (NEWLINE | stmt)* ENDMARKER

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single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE

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eval_input: testlist NEWLINE* ENDMARKER

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

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decorators: decorator+

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decorated: decorators (classdef | funcdef)

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

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parameters: '(' [typedargslist] ')'

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

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

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

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tname: NAME [':' test]

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tfpdef: tname | '(' tfplist ')'

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tfplist: tfpdef (',' tfpdef)* [',']

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

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

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

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vname: NAME

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vfpdef: vname | '(' vfplist ')'

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vfplist: vfpdef (',' vfpdef)* [',']

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stmt: simple_stmt | compound_stmt

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

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small_stmt: (expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt |

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import_stmt | global_stmt | exec_stmt | assert_stmt)

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expr_stmt: testlist_star_expr (augassign (yield_expr|testlist) |

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

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

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

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

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# For normal assignments, additional restrictions enforced by the interpreter

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print_stmt: 'print' ( [ test (',' test)* [','] ] |

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'>>' test [ (',' test)+ [','] ] )

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del_stmt: 'del' exprlist

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pass_stmt: 'pass'

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flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt

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break_stmt: 'break'

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continue_stmt: 'continue'

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return_stmt: 'return' [testlist]

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yield_stmt: yield_expr

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

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import_stmt: import_name | import_from

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import_name: 'import' dotted_as_names

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

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

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import_as_name: NAME ['as' NAME]

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dotted_as_name: dotted_name ['as' NAME]

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

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dotted_as_names: dotted_as_name (',' dotted_as_name)*

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dotted_name: NAME ('.' NAME)*

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

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exec_stmt: 'exec' expr ['in' test [',' test]]

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assert_stmt: 'assert' test [',' test]

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compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated

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if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]

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

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

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try_stmt: ('try' ':' suite

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((except_clause ':' suite)+

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['else' ':' suite]

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['finally' ':' suite] |

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'finally' ':' suite))

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

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with_item: test ['as' expr]

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with_var: 'as' expr

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

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except_clause: 'except' [test [(',' | 'as') test]]

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suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT

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# Backward compatibility cruft to support:

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# [ x for x in lambda: True, lambda: False if x() ]

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# even while also allowing:

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# lambda x: 5 if x else 2

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# (But not a mix of the two)

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testlist_safe: old_test [(',' old_test)+ [',']]

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old_test: or_test | old_lambdef

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old_lambdef: 'lambda' [varargslist] ':' old_test

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

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or_test: and_test ('or' and_test)*

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and_test: not_test ('and' not_test)*

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not_test: 'not' not_test | comparison

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comparison: expr (comp_op expr)*

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

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star_expr: '*' expr

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expr: xor_expr ('|' xor_expr)*

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xor_expr: and_expr ('^' and_expr)*

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and_expr: shift_expr ('&' shift_expr)*

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

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

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

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

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power: atom trailer* ['**' factor]

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

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'[' [listmaker] ']' |

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'{' [dictsetmaker] '}' |

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'`' testlist1 '`' |

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NAME | NUMBER | STRING+ | '.' '.' '.')

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

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

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

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

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

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

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sliceop: ':' [test]

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

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

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

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

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((test | star_expr)

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

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

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

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# "test '=' test" is really "keyword '=' test", but we have no such token.

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# These need to be in a single rule to avoid grammar that is ambiguous

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# to our LL(1) parser. Even though 'test' includes '*expr' in star_expr,

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# we explicitly match '*' here, too, to give it proper precedence.

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# Illegal combinations and orderings are blocked in ast.c:

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# multiple (test comp_for) arguments are blocked; keyword unpackings

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# that precede iterable unpackings are blocked; etc.

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argument: ( test [comp_for] |

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test '=' test |

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'**' expr |

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star_expr )

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comp_iter: comp_for | comp_if

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comp_for: 'for' exprlist 'in' testlist_safe [comp_iter]

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comp_if: 'if' old_test [comp_iter]

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testlist1: test (',' test)*

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

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encoding_decl: NAME

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yield_expr: 'yield' [yield_arg]

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yield_arg: 'from' test | testlist

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