# 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.#       func_type_input is a PEP 484 Python 2 function type comment# NB: compound_stmt in single_input is followed by extra NEWLINE!# NB: due to the way TYPE_COMMENT is tokenized it will always be followed by a NEWLINEsingle_input:NEWLINE|simple_stmt|compound_stmtNEWLINEfile_input:(NEWLINE|stmt)*ENDMARKEReval_input:testlistNEWLINE*ENDMARKERdecorator:'@'dotted_name['('[arglist]')']NEWLINEdecorators:decorator+decorated:decorators(classdef|funcdef|async_funcdef)async_funcdef:ASYNCfuncdeffuncdef:'def'NAMEparameters['->'test]':'[TYPE_COMMENT]func_body_suiteparameters:'('[typedargslist]')'# The following definition for typedarglist is equivalent to this set of rules:##     arguments = argument (',' [TYPE_COMMENT] argument)*#     argument = tfpdef ['=' test]#     kwargs = '**' tfpdef [','] [TYPE_COMMENT]#     args = '*' [tfpdef]#     kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT | [',' [TYPE_COMMENT] [kwargs]])#     args_kwonly_kwargs = args kwonly_kwargs | kwargs#     poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT | [',' [TYPE_COMMENT] [args_kwonly_kwargs]])#     typedargslist_no_posonly  = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs#     typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT] typedargslist_no_posonly]])|(typedargslist_no_posonly)"## It needs to be fully expanded to allow our LL(1) parser to work on it.typedargslist:((tfpdef['='test](','[TYPE_COMMENT]tfpdef['='test])*','[TYPE_COMMENT]'/'[','[[TYPE_COMMENT]tfpdef['='test](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['*'[tfpdef](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['**'tfpdef[','][TYPE_COMMENT]]])|'**'tfpdef[','][TYPE_COMMENT]]])|'*'[tfpdef](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['**'tfpdef[','][TYPE_COMMENT]]])|'**'tfpdef[','][TYPE_COMMENT]]])|(tfpdef['='test](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['*'[tfpdef](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['**'tfpdef[','][TYPE_COMMENT]]])|'**'tfpdef[','][TYPE_COMMENT]]])|'*'[tfpdef](','[TYPE_COMMENT]tfpdef['='test])*(TYPE_COMMENT|[','[TYPE_COMMENT]['**'tfpdef[','][TYPE_COMMENT]]])|'**'tfpdef[','][TYPE_COMMENT]))tfpdef:NAME[':'test]# The following definition for varargslist is equivalent to this set of rules:##     arguments = argument (',' argument )*#     argument = vfpdef ['=' test]#     kwargs = '**' vfpdef [',']#     args = '*' [vfpdef]#     kwonly_kwargs = (',' argument )* [',' [kwargs]]#     args_kwonly_kwargs = args kwonly_kwargs | kwargs#     poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]]#     vararglist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs#     varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] | (vararglist_no_posonly)## It needs to be fully expanded to allow our LL(1) parser to work on it.varargslist:vfpdef['='test](','vfpdef['='test])*',''/'[','[(vfpdef['='test](','vfpdef['='test])*[','['*'[vfpdef](','vfpdef['='test])*[','['**'vfpdef[',']]]|'**'vfpdef[',']]]|'*'[vfpdef](','vfpdef['='test])*[','['**'vfpdef[',']]]|'**'vfpdef[','])]]|(vfpdef['='test](','vfpdef['='test])*[','['*'[vfpdef](','vfpdef['='test])*[','['**'vfpdef[',']]]|'**'vfpdef[',']]]|'*'[vfpdef](','vfpdef['='test])*[','['**'vfpdef[',']]]|'**'vfpdef[','])vfpdef:NAMEstmt:simple_stmt|compound_stmtsimple_stmt:small_stmt(';'small_stmt)*[';']NEWLINEsmall_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))+[TYPE_COMMENT]])annassign:':'test['='(yield_expr|testlist_star_expr)]testlist_star_expr:(test|star_expr)(','(test|star_expr))*[',']augassign:('+='|'-='|'*='|'@='|'/='|'%='|'&='|'|='|'^='|'<<='|'>>='|'**='|'//=')# For normal and annotated assignments, additional restrictions enforced by the interpreterdel_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_star_expr]yield_stmt:yield_exprraise_stmt:'raise'[test['from'test]]import_stmt:import_name|import_fromimport_name:'import'dotted_as_names# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSISimport_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_stmtasync_stmt:ASYNC(funcdef|with_stmt|for_stmt)if_stmt:'if'namedexpr_test':'suite('elif'namedexpr_test':'suite)*['else'':'suite]while_stmt:'while'namedexpr_test':'suite['else'':'suite]for_stmt:'for'exprlist'in'testlist':'[TYPE_COMMENT]suite['else'':'suite]try_stmt:('try'':'suite((except_clause':'suite)+['else'':'suite]['finally'':'suite]|'finally'':'suite))with_stmt:'with'with_item(','with_item)*':'[TYPE_COMMENT]suitewith_item:test['as'expr]# NB compile.c makes sure that the default except clause is lastexcept_clause:'except'[test['as'NAME]]suite:simple_stmt|NEWLINEINDENTstmt+DEDENTnamedexpr_test:test[':='test]test:or_test['if'or_test'else'test]|lambdeftest_nocond:or_test|lambdef_nocondlambdef:'lambda'[varargslist]':'testlambdef_nocond:'lambda'[varargslist]':'test_nocondor_test:and_test('or'and_test)*and_test:not_test('and'not_test)*not_test:'not'not_test|comparisoncomparison:expr(comp_opexpr)*# <> 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:'*'exprexpr: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_expr['**'factor]atom_expr:[AWAIT]atomtrailer*atom:('('[yield_expr|testlist_comp]')'|'['[testlist_comp]']'|'{'[dictorsetmaker]'}'|NAME|NUMBER|STRING+|'...'|'None'|'True'|'False')testlist_comp:(namedexpr_test|star_expr)(comp_for|(','(namedexpr_test|star_expr))*[','])trailer:'('[arglist]')'|'['subscriptlist']'|'.'NAMEsubscriptlist: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]')']':'suitearglist: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|'**'test|'*'test)comp_iter:comp_for|comp_ifsync_comp_for:'for'exprlist'in'or_test[comp_iter]comp_for:[ASYNC]sync_comp_forcomp_if:'if'test_nocond[comp_iter]# not used in grammar, but may appear in "node" passed from Parser to Compilerencoding_decl:NAMEyield_expr:'yield'[yield_arg]yield_arg:'from'test|testlist_star_expr# the TYPE_COMMENT in suites is only parsed for funcdefs,# but can't go elsewhere due to ambiguityfunc_body_suite:simple_stmt|NEWLINE[TYPE_COMMENTNEWLINE]INDENTstmt+DEDENTfunc_type_input:func_typeNEWLINE*ENDMARKERfunc_type:'('[typelist]')''->'test# typelist is a modified typedargslist (see above)typelist:(test(','test)*[','['*'[test](','test)*[',''**'test]|'**'test]]|'*'[test](','test)*[',''**'test]|'**'test)