# PEG grammar for Python# ========================= START OF THE GRAMMAR =========================# General grammatical elements and rules:## * Strings with double quotes (") denote SOFT KEYWORDS# * Strings with single quotes (') denote KEYWORDS# * Upper case names (NAME) denote tokens in the Grammar/Tokens file# * Rule names starting with "invalid_" are used for specialized syntax errors#     - These rules are NOT used in the first pass of the parser.#     - Only if the first pass fails to parse, a second pass including the invalid#       rules will be executed.#     - If the parser fails in the second phase with a generic syntax error, the#       location of the generic failure of the first pass will be used (this avoids#       reporting incorrect locations due to the invalid rules).#     - The order of the alternatives involving invalid rules matter#       (like any rule in PEG).## Grammar Syntax (see PEP 617 for more information):## rule_name: expression#   Optionally, a type can be included right after the rule name, which#   specifies the return type of the C or Python function corresponding to the#   rule:# rule_name[return_type]: expression#   If the return type is omitted, then a void * is returned in C and an Any in#   Python.# e1 e2#   Match e1, then match e2.# e1 | e2#   Match e1 or e2.#   The first alternative can also appear on the line after the rule name for#   formatting purposes. In that case, a | must be used before the first#   alternative, like so:#       rule_name[return_type]:#            | first_alt#            | second_alt# ( e )#   Match e (allows also to use other operators in the group like '(e)*')# [ e ] or e?#   Optionally match e.# e*#   Match zero or more occurrences of e.# e+#   Match one or more occurrences of e.# s.e+#   Match one or more occurrences of e, separated by s. The generated parse tree#   does not include the separator. This is otherwise identical to (e (s e)*).# &e#   Succeed if e can be parsed, without consuming any input.# !e#   Fail if e can be parsed, without consuming any input.# ~#   Commit to the current alternative, even if it fails to parse.# &&e#   Eager parse e. The parser will not backtrack and will immediately#   fail with SyntaxError if e cannot be parsed.## STARTING RULES# ==============file:[statements] ENDMARKERinteractive:statement_newlineeval:expressions NEWLINE* ENDMARKERfunc_type: '('[type_expressions] ')' '->'expression NEWLINE* ENDMARKER# GENERAL STATEMENTS# ==================statements:statement+statement:compound_stmt|simple_stmtsstatement_newline:|compound_stmt NEWLINE|simple_stmts| NEWLINE| ENDMARKERsimple_stmts:|simple_stmt !';' NEWLINE# Not needed, there for speedup| ';'.simple_stmt+[';'] NEWLINE# NOTE: assignment MUST precede expression, else parsing a simple assignment# will throw a SyntaxError.simple_stmt:|assignment|type_alias|star_expressions|return_stmt|import_stmt|raise_stmt|'pass'|del_stmt|yield_stmt|assert_stmt|'break'|'continue'|global_stmt|nonlocal_stmtcompound_stmt:|function_def|if_stmt|class_def|with_stmt|for_stmt|try_stmt|while_stmt|match_stmt# SIMPLE STATEMENTS# =================# NOTE: annotated_rhs may start with 'yield'; yield_expr must start with 'yield'assignment:| NAME ':'expression['='annotated_rhs]|('('single_target ')'|single_subscript_attribute_target) ':'expression['='annotated_rhs]|(star_targets '=')+(yield_expr|star_expressions) !'='[TYPE_COMMENT]|single_targetaugassign ~(yield_expr|star_expressions)annotated_rhs:yield_expr|star_expressionsaugassign:| '+='| '-='| '*='| '@='| '/='| '%='| '&='| '|='| '^='| '<<='| '>>='| '**='| '//='return_stmt:|'return'[star_expressions]raise_stmt:|'raise'expression['from'expression]|'raise'global_stmt:'global' ','.NAME+nonlocal_stmt:'nonlocal' ','.NAME+del_stmt:|'del'del_targets &(';'| NEWLINE)yield_stmt:yield_exprassert_stmt:'assert'expression[','expression]import_stmt:|import_name|import_from# Import statements# -----------------import_name:'import'dotted_as_names# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSISimport_from:|'from'('.'| '...')*dotted_name'import'import_from_targets|'from'('.'| '...')+'import'import_from_targetsimport_from_targets:| '('import_from_as_names[','] ')'|import_from_as_names !','| '*'import_from_as_names:| ','.import_from_as_name+import_from_as_name:| NAME['as' NAME]dotted_as_names:| ','.dotted_as_name+dotted_as_name:|dotted_name['as' NAME]dotted_name:|dotted_name '.' NAME| NAME# COMPOUND STATEMENTS# ===================# Common elements# ---------------block:| NEWLINE INDENTstatements DEDENT|simple_stmtsdecorators:('@'named_expression NEWLINE)+# Class definitions# -----------------class_def:|decoratorsclass_def_raw|class_def_rawclass_def_raw:|'class' NAME[type_params]['('[arguments] ')'] ':'block# Function definitions# --------------------function_def:|decoratorsfunction_def_raw|function_def_rawfunction_def_raw:|'def' NAME[type_params] '('[params] ')'['->'expression] ':'[func_type_comment]block|'async''def' NAME[type_params] '('[params] ')'['->'expression] ':'[func_type_comment]block# Function parameters# -------------------params:|parametersparameters:|slash_no_defaultparam_no_default*param_with_default*[star_etc]|slash_with_defaultparam_with_default*[star_etc]|param_no_default+param_with_default*[star_etc]|param_with_default+[star_etc]|star_etc# Some duplication here because we can't write (',' | &')'),# which is because we don't support empty alternatives (yet).slash_no_default:|param_no_default+ '/' ','|param_no_default+ '/' &')'slash_with_default:|param_no_default*param_with_default+ '/' ','|param_no_default*param_with_default+ '/' &')'star_etc:| '*'param_no_defaultparam_maybe_default*[kwds]| '*'param_no_default_star_annotationparam_maybe_default*[kwds]| '*' ','param_maybe_default+[kwds]|kwdskwds:| '**'param_no_default# One parameter.  This *includes* a following comma and type comment.## There are three styles:# - No default# - With default# - Maybe with default## There are two alternative forms of each, to deal with type comments:# - Ends in a comma followed by an optional type comment# - No comma, optional type comment, must be followed by close paren# The latter form is for a final parameter without trailing comma.#param_no_default:|param ',' TYPE_COMMENT?|param TYPE_COMMENT? &')'param_no_default_star_annotation:|param_star_annotation ',' TYPE_COMMENT?|param_star_annotation TYPE_COMMENT? &')'param_with_default:|paramdefault ',' TYPE_COMMENT?|paramdefault TYPE_COMMENT? &')'param_maybe_default:|paramdefault? ',' TYPE_COMMENT?|paramdefault? TYPE_COMMENT? &')'param: NAMEannotation?param_star_annotation: NAMEstar_annotationannotation: ':'expressionstar_annotation: ':'star_expressiondefault: '='expression|invalid_default# If statement# ------------if_stmt:|'if'named_expression ':'blockelif_stmt|'if'named_expression ':'block[else_block]elif_stmt:|'elif'named_expression ':'blockelif_stmt|'elif'named_expression ':'block[else_block]else_block:|'else' ':'block# While statement# ---------------while_stmt:|'while'named_expression ':'block[else_block]# For statement# -------------for_stmt:|'for'star_targets'in' ~star_expressions ':'[TYPE_COMMENT]block[else_block]|'async''for'star_targets'in' ~star_expressions ':'[TYPE_COMMENT]block[else_block]# With statement# --------------with_stmt:|'with' '(' ','.with_item+ ','? ')' ':'[TYPE_COMMENT]block|'with' ','.with_item+ ':'[TYPE_COMMENT]block|'async''with' '(' ','.with_item+ ','? ')' ':'block|'async''with' ','.with_item+ ':'[TYPE_COMMENT]blockwith_item:|expression'as'star_target &(','| ')'| ':')|expression# Try statement# -------------try_stmt:|'try' ':'blockfinally_block|'try' ':'blockexcept_block+[else_block][finally_block]|'try' ':'blockexcept_star_block+[else_block][finally_block]# Except statement# ----------------except_block:|'except'expression['as' NAME] ':'block|'except' ':'blockexcept_star_block:|'except' '*'expression['as' NAME] ':'blockfinally_block:|'finally' ':'block# Match statement# ---------------match_stmt:|"match"subject_expr ':' NEWLINE INDENTcase_block+ DEDENTsubject_expr:|star_named_expression ','star_named_expressions?|named_expressioncase_block:|"case"patternsguard? ':'blockguard:'if'named_expressionpatterns:|open_sequence_pattern|patternpattern:|as_pattern|or_patternas_pattern:|or_pattern'as'pattern_capture_targetor_pattern:| '|'.closed_pattern+closed_pattern:|literal_pattern|capture_pattern|wildcard_pattern|value_pattern|group_pattern|sequence_pattern|mapping_pattern|class_pattern# Literal patterns are used for equality and identity constraintsliteral_pattern:|signed_number !('+'| '-')|complex_number|strings|'None'|'True'|'False'# Literal expressions are used to restrict permitted mapping pattern keysliteral_expr:|signed_number !('+'| '-')|complex_number|strings|'None'|'True'|'False'complex_number:|signed_real_number '+'imaginary_number|signed_real_number '-'imaginary_numbersigned_number:| NUMBER| '-' NUMBERsigned_real_number:|real_number| '-'real_numberreal_number:| NUMBERimaginary_number:| NUMBERcapture_pattern:|pattern_capture_targetpattern_capture_target:| !"_" NAME !('.'| '('| '=')wildcard_pattern:|"_"value_pattern:|attr !('.'| '('| '=')attr:|name_or_attr '.' NAMEname_or_attr:|attr| NAMEgroup_pattern:| '('pattern ')'sequence_pattern:| '['maybe_sequence_pattern? ']'| '('open_sequence_pattern? ')'open_sequence_pattern:|maybe_star_pattern ','maybe_sequence_pattern?maybe_sequence_pattern:| ','.maybe_star_pattern+ ','?maybe_star_pattern:|star_pattern|patternstar_pattern:| '*'pattern_capture_target| '*'wildcard_patternmapping_pattern:| '{' '}'| '{'double_star_pattern ','? '}'| '{'items_pattern ','double_star_pattern ','? '}'| '{'items_pattern ','? '}'items_pattern:| ','.key_value_pattern+key_value_pattern:|(literal_expr|attr) ':'patterndouble_star_pattern:| '**'pattern_capture_targetclass_pattern:|name_or_attr '(' ')'|name_or_attr '('positional_patterns ','? ')'|name_or_attr '('keyword_patterns ','? ')'|name_or_attr '('positional_patterns ','keyword_patterns ','? ')'positional_patterns:| ','.pattern+keyword_patterns:| ','.keyword_pattern+keyword_pattern:| NAME '='pattern# Type statement# ---------------type_alias:|"type" NAME[type_params] '='expression# Type parameter declaration# --------------------------type_params:| '['type_param_seq ']'type_param_seq: ','.type_param+[',']type_param:| NAME[type_param_bound][type_param_default]| '*' NAME[type_param_starred_default]| '**' NAME[type_param_default]type_param_bound: ':'expressiontype_param_default: '='expressiontype_param_starred_default: '='star_expression# EXPRESSIONS# -----------expressions:|expression(','expression)+[',']|expression ','|expressionexpression:|disjunction'if'disjunction'else'expression|disjunction|lambdefyield_expr:|'yield''from'expression|'yield'[star_expressions]star_expressions:|star_expression(','star_expression)+[',']|star_expression ','|star_expressionstar_expression:| '*'bitwise_or|expressionstar_named_expressions: ','.star_named_expression+[',']star_named_expression:| '*'bitwise_or|named_expressionassignment_expression:| NAME ':=' ~expressionnamed_expression:|assignment_expression|expression !':='disjunction:|conjunction('or'conjunction)+|conjunctionconjunction:|inversion('and'inversion)+|inversioninversion:|'not'inversion|comparison# Comparison operators# --------------------comparison:|bitwise_orcompare_op_bitwise_or_pair+|bitwise_orcompare_op_bitwise_or_pair:|eq_bitwise_or|noteq_bitwise_or|lte_bitwise_or|lt_bitwise_or|gte_bitwise_or|gt_bitwise_or|notin_bitwise_or|in_bitwise_or|isnot_bitwise_or|is_bitwise_oreq_bitwise_or: '=='bitwise_ornoteq_bitwise_or:|('!=')bitwise_orlte_bitwise_or: '<='bitwise_orlt_bitwise_or: '<'bitwise_orgte_bitwise_or: '>='bitwise_orgt_bitwise_or: '>'bitwise_ornotin_bitwise_or:'not''in'bitwise_orin_bitwise_or:'in'bitwise_orisnot_bitwise_or:'is''not'bitwise_oris_bitwise_or:'is'bitwise_or# Bitwise operators# -----------------bitwise_or:|bitwise_or '|'bitwise_xor|bitwise_xorbitwise_xor:|bitwise_xor '^'bitwise_and|bitwise_andbitwise_and:|bitwise_and '&'shift_expr|shift_exprshift_expr:|shift_expr '<<'sum|shift_expr '>>'sum|sum# Arithmetic operators# --------------------sum:|sum '+'term|sum '-'term|termterm:|term '*'factor|term '/'factor|term '//'factor|term '%'factor|term '@'factor|factorfactor:| '+'factor| '-'factor| '~'factor|powerpower:|await_primary '**'factor|await_primary# Primary elements# ----------------# Primary elements are things like "obj.something.something", "obj[something]", "obj(something)", "obj" ...await_primary:|'await'primary|primaryprimary:|primary '.' NAME|primarygenexp|primary '('[arguments] ')'|primary '['slices ']'|atomslices:|slice !','| ','.(slice|starred_expression)+[',']slice:|[expression] ':'[expression][':'[expression]]|named_expressionatom:| NAME|'True'|'False'|'None'|strings| NUMBER|(tuple|group|genexp)|(list|listcomp)|(dict|set|dictcomp|setcomp)| '...'group:| '('(yield_expr|named_expression) ')'# Lambda functions# ----------------lambdef:|'lambda'[lambda_params] ':'expressionlambda_params:|lambda_parameters# lambda_parameters etc. duplicates parameters but without annotations# or type comments, and if there's no comma after a parameter, we expect# a colon, not a close parenthesis.  (For more, see parameters above.)#lambda_parameters:|lambda_slash_no_defaultlambda_param_no_default*lambda_param_with_default*[lambda_star_etc]|lambda_slash_with_defaultlambda_param_with_default*[lambda_star_etc]|lambda_param_no_default+lambda_param_with_default*[lambda_star_etc]|lambda_param_with_default+[lambda_star_etc]|lambda_star_etclambda_slash_no_default:|lambda_param_no_default+ '/' ','|lambda_param_no_default+ '/' &':'lambda_slash_with_default:|lambda_param_no_default*lambda_param_with_default+ '/' ','|lambda_param_no_default*lambda_param_with_default+ '/' &':'lambda_star_etc:| '*'lambda_param_no_defaultlambda_param_maybe_default*[lambda_kwds]| '*' ','lambda_param_maybe_default+[lambda_kwds]|lambda_kwdslambda_kwds:| '**'lambda_param_no_defaultlambda_param_no_default:|lambda_param ','|lambda_param &':'lambda_param_with_default:|lambda_paramdefault ','|lambda_paramdefault &':'lambda_param_maybe_default:|lambda_paramdefault? ','|lambda_paramdefault? &':'lambda_param: NAME# LITERALS# ========fstring_middle:|fstring_replacement_field| FSTRING_MIDDLEfstring_replacement_field:| '{'annotated_rhs '='?[fstring_conversion][fstring_full_format_spec] '}'fstring_conversion:| "!" NAMEfstring_full_format_spec:| ':'fstring_format_spec*fstring_format_spec:| FSTRING_MIDDLE|fstring_replacement_fieldfstring:| FSTRING_STARTfstring_middle* FSTRING_ENDstring: STRINGstrings:(fstring|string)+list:| '['[star_named_expressions] ']'tuple:| '('[star_named_expression ','[star_named_expressions]] ')'set: '{'star_named_expressions '}'# Dicts# -----dict:| '{'[double_starred_kvpairs] '}'double_starred_kvpairs: ','.double_starred_kvpair+[',']double_starred_kvpair:| '**'bitwise_or|kvpairkvpair:expression ':'expression# Comprehensions & Generators# ---------------------------for_if_clauses:|for_if_clause+for_if_clause:|'async''for'star_targets'in' ~disjunction('if'disjunction)*|'for'star_targets'in' ~disjunction('if'disjunction)*listcomp:| '['named_expressionfor_if_clauses ']'setcomp:| '{'named_expressionfor_if_clauses '}'genexp:| '('(assignment_expression|expression !':=')for_if_clauses ')'dictcomp:| '{'kvpairfor_if_clauses '}'# FUNCTION CALL ARGUMENTS# =======================arguments:|args[','] &')'args:| ','.(starred_expression|(assignment_expression|expression !':=') !'=')+[','kwargs]|kwargskwargs:| ','.kwarg_or_starred+ ',' ','.kwarg_or_double_starred+| ','.kwarg_or_starred+| ','.kwarg_or_double_starred+starred_expression:| '*'expressionkwarg_or_starred:| NAME '='expression|starred_expressionkwarg_or_double_starred:| NAME '='expression| '**'expression# ASSIGNMENT TARGETS# ==================# Generic targets# ---------------# NOTE: star_targets may contain *bitwise_or, targets may not.star_targets:|star_target !','|star_target(','star_target)*[',']star_targets_list_seq: ','.star_target+[',']star_targets_tuple_seq:|star_target(','star_target)+[',']|star_target ','star_target:| '*'(!'*'star_target)|target_with_star_atomtarget_with_star_atom:|t_primary '.' NAME !t_lookahead|t_primary '['slices ']' !t_lookahead|star_atomstar_atom:| NAME| '('target_with_star_atom ')'| '('[star_targets_tuple_seq] ')'| '['[star_targets_list_seq] ']'single_target:|single_subscript_attribute_target| NAME| '('single_target ')'single_subscript_attribute_target:|t_primary '.' NAME !t_lookahead|t_primary '['slices ']' !t_lookaheadt_primary:|t_primary '.' NAME &t_lookahead|t_primary '['slices ']' &t_lookahead|t_primarygenexp &t_lookahead|t_primary '('[arguments] ')' &t_lookahead|atom &t_lookaheadt_lookahead: '('| '['| '.'# Targets for del statements# --------------------------del_targets: ','.del_target+[',']del_target:|t_primary '.' NAME !t_lookahead|t_primary '['slices ']' !t_lookahead|del_t_atomdel_t_atom:| NAME| '('del_target ')'| '('[del_targets] ')'| '['[del_targets] ']'# TYPING ELEMENTS# ---------------# type_expressions allow */** but ignore themtype_expressions:| ','.expression+ ',' '*'expression ',' '**'expression| ','.expression+ ',' '*'expression| ','.expression+ ',' '**'expression| '*'expression ',' '**'expression| '*'expression| '**'expression| ','.expression+func_type_comment:| NEWLINE TYPE_COMMENT &(NEWLINE INDENT)# Must be followed by indented block| TYPE_COMMENT# ========================= END OF THE GRAMMAR ===========================# ========================= START OF INVALID RULES =======================