# 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 in PEP 306,# "How to Change Python's Grammar" # Commands for Kees Blom's railroad program#diagram:token NAME#diagram:token NUMBER#diagram:token STRING#diagram:token NEWLINE#diagram:token ENDMARKER#diagram:token INDENT#diagram:output\input python.bla#diagram:token DEDENT#diagram:output\textwidth 20.04cm\oddsidemargin  0.0cm\evensidemargin 0.0cm#diagram:rules # 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() and input() functions.# NB: compound_stmt in single_input is followed by extra NEWLINE!single_input: NEWLINE | simple_stmt | compound_stmt NEWLINEfile_input: (NEWLINE | stmt)* ENDMARKEReval_input: testlist NEWLINE* ENDMARKER decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINEdecorators: decorator+funcdef: [decorators] 'def' NAME parameters ':' suiteparameters: '(' [varargslist] ')'varargslist: ((fpdef ['=' test] ',')*              ('*' NAME [',' '**' NAME] | '**' NAME) |              fpdef ['=' test] (',' fpdef ['=' test])* [','])fpdef: NAME | '(' fplist ')'fplist: fpdef (',' fpdef)* [','] stmt: simple_stmt | compound_stmtsimple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINEsmall_stmt: (expr_stmt | print_stmt  | del_stmt | pass_stmt | flow_stmt |             import_stmt | global_stmt | exec_stmt | assert_stmt)expr_stmt: testlist (augassign (yield_expr|testlist) |                     ('=' (yield_expr|testlist))*)augassign: ('+=' | '-=' | '*=' | '/=' | '%=' | '&=' | '|=' | '^=' |            '<<=' | '>>=' | '**=' | '//=')# For normal assignments, additional restrictions enforced by the interpreterprint_stmt: 'print' ( [ test (',' test)* [','] ] |                      '>>' test [ (',' test)+ [','] ] )del_stmt: 'del' exprlistpass_stmt: 'pass'flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmtbreak_stmt: 'break'continue_stmt: 'continue'return_stmt: 'return' [testlist]yield_stmt: yield_exprraise_stmt: 'raise' [test [',' test [',' test]]]import_stmt: import_name | import_fromimport_name: 'import' dotted_as_namesimport_from: ('from' ('.'* dotted_name | '.'+)              'import' ('*' | '(' import_as_names ')' | import_as_names))import_as_name: NAME [('as' | NAME) NAME]dotted_as_name: dotted_name [('as' | NAME) 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)*exec_stmt: 'exec' expr ['in' test [',' test]]assert_stmt: 'assert' test [',' test] compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdefif_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' test [ with_var ] ':' suitewith_var: ('as' | NAME) expr# NB compile.c makes sure that the default except clause is lastexcept_clause: 'except' [test [',' test]]suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT # Backward compatibility cruft to support:# [ x for x in lambda: True, lambda: False if x() ]# even while also allowing:# lambda x: 5 if x else 2# (But not a mix of the two)testlist_safe: old_test [(',' old_test)+ [',']]old_test: or_test | old_lambdefold_lambdef: 'lambda' [varargslist] ':' old_test test: or_test ['if' or_test 'else' test] | lambdefor_test: and_test ('or' and_test)*and_test: not_test ('and' not_test)*not_test: 'not' not_test | comparisoncomparison: expr (comp_op expr)*comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'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 | powerpower: atom trailer* ['**' factor]atom: ('(' [yield_expr|testlist_gexp] ')' |       '[' [listmaker] ']' |       '{' [dictmaker] '}' |       '`' testlist1 '`' |       NAME | NUMBER | STRING+)listmaker: test ( list_for | (',' test)* [','] )testlist_gexp: test ( gen_for | (',' test)* [','] )lambdef: 'lambda' [varargslist] ':' testtrailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAMEsubscriptlist: subscript (',' subscript)* [',']subscript: '.' '.' '.' | test | [test] ':' [test] [sliceop]sliceop: ':' [test]exprlist: expr (',' expr)* [',']testlist: test (',' test)* [',']dictmaker: test ':' test (',' test ':' test)* [','] classdef: 'class' NAME ['(' [testlist] ')'] ':' suite arglist: (argument ',')* (argument [',']| '*' test [',' '**' test] | '**' test)argument: test [gen_for] | test '=' test  # Really [keyword '='] test list_iter: list_for | list_iflist_for: 'for' exprlist 'in' testlist_safe [list_iter]list_if: 'if' old_test [list_iter] gen_iter: gen_for | gen_ifgen_for: 'for' exprlist 'in' or_test [gen_iter]gen_if: 'if' old_test [gen_iter] testlist1: test (',' test)* # not used in grammar, but may appear in "node" passed from Parser to Compilerencoding_decl: NAME yield_expr: 'yield' [testlist]