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Added match stmt support to python.lark #1016

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Mar 6, 2022
Merged

Added match stmt support to python.lark #1016

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e939a4f
Added match stmt support to python.lark
MegaIng Oct 9, 2021
e20b5ae
Cleanup match pattern
MegaIng Oct 9, 2021
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7 changes: 3 additions & 4 deletions examples/advanced/python_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -48,9 +48,9 @@ def _read(fn, *args):
def _get_lib_path():
if os.name == 'nt':
if 'PyPy' in sys.version:
return os.path.join(sys.prefix, 'lib-python', sys.winver)
return os.path.join(sys.base_prefix, 'lib-python', sys.winver)
else:
return os.path.join(sys.prefix, 'Lib')
return os.path.join(sys.base_prefix, 'Lib')
else:
return [x for x in sys.path if x.endswith('%s.%s' % sys.version_info[:2])][0]

Expand Down Expand Up @@ -84,5 +84,4 @@ def test_earley_equals_lalr():
if __name__ == '__main__':
test_python_lib()
# test_earley_equals_lalr()
# python_parser3.parse(_read(sys.argv[1]) + '\n')

# python_parser3.parse(_read(sys.argv[1]) + '\n')
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Suggested change
# python_parser3.parse(_read(sys.argv[1]) + '\n')
# python_parser3.parse(_read(sys.argv[1]) + '\n')

87 changes: 69 additions & 18 deletions lark/grammars/python.lark
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Expand Up @@ -20,7 +20,7 @@ decorators: decorator+
decorated: decorators (classdef | funcdef | async_funcdef)

async_funcdef: "async" funcdef
funcdef: "def" NAME "(" [parameters] ")" ["->" test] ":" suite
funcdef: "def" name "(" [parameters] ")" ["->" test] ":" suite

parameters: paramvalue ("," paramvalue)* ["," SLASH] ["," [starparams | kwparams]]
| starparams
Expand All @@ -31,17 +31,17 @@ starparams: "*" typedparam? ("," paramvalue)* ["," kwparams]
kwparams: "**" typedparam ","?

?paramvalue: typedparam ("=" test)?
?typedparam: NAME (":" test)?
?typedparam: name (":" test)?


lambdef: "lambda" [lambda_params] ":" test
lambdef_nocond: "lambda" [lambda_params] ":" test_nocond
lambda_params: lambda_paramvalue ("," lambda_paramvalue)* ["," [lambda_starparams | lambda_kwparams]]
| lambda_starparams
| lambda_kwparams
?lambda_paramvalue: NAME ("=" test)?
lambda_starparams: "*" [NAME] ("," lambda_paramvalue)* ["," [lambda_kwparams]]
lambda_kwparams: "**" NAME ","?
?lambda_paramvalue: name ("=" test)?
lambda_starparams: "*" [name] ("," lambda_paramvalue)* ["," [lambda_kwparams]]
lambda_kwparams: "**" name ","?


?stmt: simple_stmt | compound_stmt
Expand Down Expand Up @@ -72,16 +72,17 @@ import_name: "import" dotted_as_names
// note below: the ("." | "...") is necessary because "..." is tokenized as ELLIPSIS
import_from: "from" (dots? dotted_name | dots) "import" ("*" | "(" import_as_names ")" | import_as_names)
!dots: "."+
import_as_name: NAME ["as" NAME]
dotted_as_name: dotted_name ["as" NAME]
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)*
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_stmt
?compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | match_stmt
| with_stmt | funcdef | classdef | decorated | async_stmt
async_stmt: "async" (funcdef | with_stmt | for_stmt)
if_stmt: "if" test ":" suite elifs ["else" ":" suite]
elifs: elif_*
Expand All @@ -92,12 +93,61 @@ try_stmt: "try" ":" suite except_clauses ["else" ":" suite] [finally]
| "try" ":" suite finally -> try_finally
finally: "finally" ":" suite
except_clauses: except_clause+
except_clause: "except" [test ["as" NAME]] ":" suite
except_clause: "except" [test ["as" name]] ":" suite
// NB compile.c makes sure that the default except clause is last


with_stmt: "with" with_items ":" suite
with_items: with_item ("," with_item)*
with_item: test ["as" expr]
// NB compile.c makes sure that the default except clause is last
with_item: test ["as" name]

match_stmt: "match" test ":" _NEWLINE _INDENT case+ _DEDENT

case: "case" pattern ["if" test] ":" suite

?pattern: sequence_item_pattern "," _sequence_pattern -> sequence_pattern
| as_pattern
?as_pattern: or_pattern ("as" NAME)?
?or_pattern: closed_pattern ("|" closed_pattern)*
?closed_pattern: literal_pattern
| NAME -> capture_pattern
| "_" -> any_pattern
| attr_pattern
| "(" as_pattern ")"
| "[" _sequence_pattern "]" -> sequence_pattern
| "(" (sequence_item_pattern "," _sequence_pattern)? ")" -> sequence_pattern
| "{" (mapping_item_pattern ("," mapping_item_pattern)* ","?)?"}" -> mapping_pattern
| "{" (mapping_item_pattern ("," mapping_item_pattern)* ",")? "**" NAME ","? "}" -> mapping_star_pattern
| class_pattern

literal_pattern: inner_literal_pattern

?inner_literal_pattern: "None" -> const_none
| "True" -> const_true
| "False" -> const_false
| STRING -> string
| number

attr_pattern: NAME ("." NAME)+ -> value

name_or_attr_pattern: NAME ("." NAME)* -> value

mapping_item_pattern: (literal_pattern|attr_pattern) ":" as_pattern

_sequence_pattern: (sequence_item_pattern ("," sequence_item_pattern)* ","?)?
?sequence_item_pattern: as_pattern
| "*" NAME -> star_pattern

class_pattern: name_or_attr_pattern "(" [arguments_pattern ","?] ")"
arguments_pattern: pos_arg_pattern ["," keyws_arg_pattern]
| keyws_arg_pattern -> no_pos_arguments

pos_arg_pattern: as_pattern ("," as_pattern)*
keyws_arg_pattern: keyw_arg_pattern ("," keyw_arg_pattern)*
keyw_arg_pattern: NAME "=" as_pattern



suite: simple_stmt | _NEWLINE _INDENT stmt+ _DEDENT

?test: or_test ("if" or_test "else" test)?
Expand Down Expand Up @@ -134,7 +184,7 @@ AWAIT: "await"

?atom_expr: atom_expr "(" [arguments] ")" -> funccall
| atom_expr "[" subscriptlist "]" -> getitem
| atom_expr "." NAME -> getattr
| atom_expr "." name -> getattr
| atom

?atom: "(" yield_expr ")"
Expand All @@ -146,7 +196,7 @@ AWAIT: "await"
| "{" comprehension{key_value} "}" -> dict_comprehension
| "{" _set_exprlist "}" -> set
| "{" comprehension{test} "}" -> set_comprehension
| NAME -> var
| name -> var
| number
| string_concat
| "(" test ")"
Expand Down Expand Up @@ -179,7 +229,7 @@ key_value: test ":" test

_set_exprlist: test_or_star_expr ("," test_or_star_expr)* [","]

classdef: "class" NAME ["(" [arguments] ")"] ":" suite
classdef: "class" name ["(" [arguments] ")"] ":" suite



Expand All @@ -202,7 +252,7 @@ ASYNC: "async"
?comp_if: "if" test_nocond

// not used in grammar, but may appear in "node" passed from Parser to Compiler
encoding_decl: NAME
encoding_decl: name

yield_expr: "yield" [testlist]
| "yield" "from" test -> yield_from
Expand All @@ -222,6 +272,7 @@ _NEWLINE: ( /\r?\n[\t ]*/ | COMMENT )+

// Python terminals

!name: NAME | "match" | "case"
NAME: /[a-zA-Z_]\w*/
COMMENT: /#[^\n]*/

Expand Down