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# Grammar for Python
# Change log:
# 19-May-93:
# Add access statement
# 18-May-93:
# Abolish old class header syntax
# 06-Apr-92:
# Use only '*' for varargs list
# 31-Mar-92:
# Tighten syntax for try statements
# 27-Feb-92:
# Allow NEWLINE* after eval input
# 16-Jan-92:
# Added '*' as alternative for '+' in varargs syntax
# (Not sure which alternative is better yet.)
# 11-Jan-92:
# Variable length argument list syntax added: def f(a, b, +rest): ...
# 8-Jan-92:
# Allow only '==' for equality testing
# Changes since version 8:
# Trailing commas in formal parameter lists are allowed
# Changes since version 7:
# New syntax to specify base classes (but old syntax retained for now)
# 'global' statement (valid only in functions but not enforced here)
# Changes since version 6:
# Add logical operators '|', '^', '&' and '~'
# Add shift operators '<<' and '>>'
# Changes since version 5:
# Comparison operators '<=' '>' '<>' are now 1 token
# Also support '!=' and '==' as alternatives for '<>' and '='
# Changes compared to version 4:
# Blank lines and lines only containing a comment are now eaten
# by the lexer, so the NEWLINE* things in suite are gone
# (but the 2nd NEWLINE terminating single_input stays!)
# Semicolons can separate small statements
# 'continue' statement
# Dictionary constructors: {key:value, key:value, ...}
# More tests instead of exprs
# Changes compared to version 3:
# Removed 'dir' statement.
# Function call argument is a testlist instead of exprlist.
# Changes compared to version 2:
# The syntax of Boolean operations is changed to use more
# conventional priorities: or < and < not.
# Changes compared to version 1:
# modules and scripts are unified;
# 'quit' is gone (use ^D);
# empty_stmt is gone, replaced by explicit NEWLINE where appropriate;
# 'import' and 'def' aren't special any more;
# added 'from' NAME option on import clause, and '*' to import all;
# added class definition.
# 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;
# expr_input is the input for the input() function;
# eval_input is the input for the eval() function.
# NB: compound_stmt in single_input is followed by extra NEWLINE!
single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
file_input: (NEWLINE | stmt)* ENDMARKER
expr_input: testlist NEWLINE
eval_input: testlist NEWLINE* ENDMARKER
funcdef: 'def' NAME parameters ':' suite
parameters: '(' [varargslist] ')'
varargslist: (fpdef ',')* '*' NAME | fpdef (',' fpdef)* [',']
fpdef: NAME | '(' fplist ')'
fplist: fpdef (',' fpdef)* [',']
stmt: simple_stmt | compound_stmt
simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
small_stmt: expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt | import_stmt | global_stmt | access_stmt
expr_stmt: (exprlist '=')* exprlist
# For assignments, additional restrictions enforced by the interpreter
print_stmt: 'print' (test ',')* [test]
del_stmt: 'del' exprlist
pass_stmt: 'pass'
flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt
break_stmt: 'break'
continue_stmt: 'continue'
return_stmt: 'return' [testlist]
raise_stmt: 'raise' test [',' test]
import_stmt: 'import' NAME (',' NAME)* | 'from' NAME 'import' ('*' | NAME (',' NAME)*)
global_stmt: 'global' NAME (',' NAME)*
access_stmt: 'access' NAME (',' NAME)* ':' accesstype (',' accesstype)*
accesstype: NAME+
# accesstype should be ('public' | 'protected' | 'private') ['read'] ['write']
# but can't be because that would create undesirable reserved words!
compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef
if_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)+ | 'try' ':' suite 'finally' ':' suite
# NB compile.c makes sure that the default except clause is last
except_clause: 'except' [test [',' test]]
suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
test: and_test ('or' and_test)*
and_test: not_test ('and' not_test)*
not_test: 'not' not_test | comparison
comparison: 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 | atom trailer*
atom: '(' [testlist] ')' | '[' [testlist] ']' | '{' [dictmaker] '}' | '`' testlist '`' | NAME | NUMBER | STRING
trailer: '(' [testlist] ')' | '[' subscript ']' | '.' NAME
subscript: test | [test] ':' [test]
exprlist: expr (',' expr)* [',']
testlist: test (',' test)* [',']
dictmaker: test ':' test (',' test ':' test)* [',']
classdef: class NAME ['(' testlist ')'] ':' suite
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