3 # NOTE WELL: You should also follow all the steps listed at
4 # https://docs.python.org/devguide/grammar.html
6 # Start symbols for the grammar:
7 # single_input is a single interactive statement;
8 # file_input is a module or sequence of commands read from an input file;
9 # eval_input is the input for the eval() functions.
10 # NB: compound_stmt in single_input is followed by extra NEWLINE!
11 single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
12 file_input: stmt* ENDMARKER
13 eval_input: testlist NEWLINE* ENDMARKER
14 decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
15 decorators: decorator+
16 decorated: decorators (classdef | funcdef | async_funcdef)
18 async_funcdef: 'async' funcdef
19 funcdef: 'def' NAME parameters ['->' test] ':' suite
21 parameters: '(' [typedargslist] ')'
22 typedargslist: (tfpdef ['=' test] (',' tfpdef ['=' test])* [',' [
23 '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
25 | '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
27 tfpdef: NAME [':' test]
28 varargslist: (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
29 '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
31 | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
36 stmt: simple_stmt | compound_stmt | NEWLINE
37 simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
38 small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
39 import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
40 expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
41 ('=' (yield_expr|testlist_star_expr))*)
42 annassign: ':' test ['=' test]
43 testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
44 augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |
45 '<<=' | '>>=' | '**=' | '//=')
46 # For normal and annotated assignments, additional restrictions enforced by the interpreter
47 del_stmt: 'del' exprlist
49 flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
51 continue_stmt: 'continue'
52 return_stmt: 'return' [testlist]
53 yield_stmt: yield_expr
54 raise_stmt: 'raise' [test ['from' test]]
55 import_stmt: import_name | import_from
56 import_name: 'import' dotted_as_names
57 # note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
58 import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+)
59 'import' ('*' | '(' import_as_names ')' | import_as_names))
60 import_as_name: NAME ['as' NAME]
61 dotted_as_name: dotted_name ['as' NAME]
62 import_as_names: import_as_name (',' import_as_name)* [',']
63 dotted_as_names: dotted_as_name (',' dotted_as_name)*
64 dotted_name: NAME ('.' NAME)*
65 global_stmt: 'global' NAME (',' NAME)*
66 nonlocal_stmt: 'nonlocal' NAME (',' NAME)*
67 assert_stmt: 'assert' test [',' test]
69 compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt
70 async_stmt: 'async' (funcdef | with_stmt | for_stmt)
71 if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
72 while_stmt: 'while' test ':' suite ['else' ':' suite]
73 for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite]
74 try_stmt: ('try' ':' suite
75 ((except_clause ':' suite)+
77 ['finally' ':' suite] |
79 with_stmt: 'with' with_item (',' with_item)* ':' suite
80 with_item: test ['as' expr]
81 # NB compile.c makes sure that the default except clause is last
82 except_clause: 'except' [test ['as' NAME]]
83 suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
85 test: or_test ['if' or_test 'else' test] | lambdef
86 test_nocond: or_test | lambdef_nocond
87 lambdef: 'lambda' [varargslist] ':' test
88 lambdef_nocond: 'lambda' [varargslist] ':' test_nocond
89 or_test: and_test ('or' and_test)*
90 and_test: not_test ('and' not_test)*
91 not_test: 'not' not_test | comparison
92 comparison: expr (comp_op expr)*
93 # <> isn't actually a valid comparison operator in Python. It's here for the
94 # sake of a __future__ import described in PEP 401 (which really works :-)
95 comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
97 expr: xor_expr ('|' xor_expr)*
98 xor_expr: and_expr ('^' and_expr)*
99 and_expr: shift_expr ('&' shift_expr)*
100 shift_expr: arith_expr (('<<'|'>>') arith_expr)*
101 arith_expr: term (('+'|'-') term)*
102 term: factor (('*'|'@'|'/'|'%'|'//') factor)*
103 factor: ('+'|'-'|'~') factor | power
104 power: atom_expr ['**' factor]
105 atom_expr: ['await'] atom trailer*
106 atom: ('(' [yield_expr|testlist_comp] ')' |
107 '[' [testlist_comp] ']' |
108 '{' [dictorsetmaker] '}' |
109 NAME | NUMBER | strings | '...' | 'None' | 'True' | 'False')
110 testlist_comp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )
111 trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
112 subscriptlist: subscript (',' subscript)* [',']
113 subscript: test | [test] ':' [test] [sliceop]
115 exprlist: (expr|star_expr) (',' (expr|star_expr))* [',']
116 testlist: test (',' test)* [',']
117 dictorsetmaker: ( ((test ':' test | '**' expr)
118 (comp_for | (',' (test ':' test | '**' expr))* [','])) |
120 (comp_for | (',' (test | star_expr))* [','])) )
122 classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
124 arglist: argument (',' argument)* [',']
126 # The reason that keywords are test nodes instead of NAME is that using NAME
127 # results in an ambiguity. ast.c makes sure it's a NAME.
128 # "test '=' test" is really "keyword '=' test", but we have no such token.
129 # These need to be in a single rule to avoid grammar that is ambiguous
130 # to our LL(1) parser. Even though 'test' includes '*expr' in star_expr,
131 # we explicitly match '*' here, too, to give it proper precedence.
132 # Illegal combinations and orderings are blocked in ast.c:
133 # multiple (test comp_for) arguments are blocked; keyword unpackings
134 # that precede iterable unpackings are blocked; etc.
135 argument: ( test [comp_for] |
140 comp_iter: comp_for | comp_if
141 sync_comp_for: 'for' exprlist 'in' or_test [comp_iter]
142 comp_for: ['async'] sync_comp_for
143 comp_if: 'if' test_nocond [comp_iter]
145 # not used in grammar, but may appear in "node" passed from Parser to Compiler
148 yield_expr: 'yield' [yield_arg]
149 yield_arg: 'from' test | testlist
151 strings: (STRING | fstring)+
152 fstring: FSTRING_START fstring_content* FSTRING_END
153 fstring_content: FSTRING_STRING | fstring_expr
154 fstring_conversion: '!' NAME
155 fstring_expr: '{' (testlist_comp | yield_expr) [ fstring_conversion ] [ fstring_format_spec ] '}'
156 fstring_format_spec: ':' fstring_content*