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192 lines
8 KiB
Text
192 lines
8 KiB
Text
# 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 | async_funcdef)
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async_funcdef: 'async' 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 (annassign | augassign (yield_expr|testlist) |
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('=' (yield_expr|testlist_star_expr))*)
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annassign: ':' test ['=' test]
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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 and annotated 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 | async_stmt
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async_stmt: 'async' (funcdef | with_stmt | for_stmt)
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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: ['await'] 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) ( old_comp_for | (',' (test|star_expr))* [','] )
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testlist_gexp: (test|star_expr) ( old_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: ['async'] 'for' exprlist 'in' or_test [comp_iter]
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comp_if: 'if' old_test [comp_iter]
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# As noted above, testlist_safe extends the syntax allowed in list
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# comprehensions and generators. We can't use it indiscriminately in all
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# derivations using a comp_for-like pattern because the testlist_safe derivation
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# contains comma which clashes with trailing comma in arglist.
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#
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# This was an issue because the parser would not follow the correct derivation
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# when parsing syntactically valid Python code. Since testlist_safe was created
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# specifically to handle list comprehensions and generator expressions enclosed
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# with parentheses, it's safe to only use it in those. That avoids the issue; we
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# can parse code like set(x for x in [],).
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#
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# The syntax supported by this set of rules is not a valid Python 3 syntax,
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# hence the prefix "old".
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#
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# See https://bugs.python.org/issue27494
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old_comp_iter: old_comp_for | old_comp_if
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old_comp_for: ['async'] 'for' exprlist 'in' testlist_safe [old_comp_iter]
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old_comp_if: 'if' old_test [old_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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