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Make parser REs into module-level "constants".

This commit is contained in:
Simon Forman 2019-12-02 14:26:07 -08:00
parent 39a0e73fac
commit fdf0339e16
1 changed files with 17 additions and 8 deletions
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25
joy/parser.py
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@ -36,11 +36,20 @@ brackets. Terms must be separated by blanks, which can be omitted
around square brackets.
'''
#TODO: explain the details of float lits and strings.
from re import Scanner
from .utils.stack import list_to_stack
#TODO: explain the details of float lits and strings.
FLOAT = r'-?\d+\.\d*'
INT = r'-?\d+'
SYMBOL = r'[•\w!@$%^&*()_+<>?|\/;:`~,.=-]+'
BRACKETS = r'\[|\]'
STRING_DOUBLE_QUOTED = r'"(?:[^"\\]|\\.)*"'
STRING_SINGLE_QUOTED = r"'(?:[^'\\]|\\.)*'"
BLANKS = r'\s+'
class Symbol(str):
'''A string class that represents Joy function names.'''
__repr__ = str.__str__
@ -105,11 +114,11 @@ def _parse(tokens):
_scanner = Scanner([
(r'-?\d+\.\d*', lambda _, token: float(token)),
(r'-?\d+', lambda _, token: int(token)),
(r'[•\w!@$%^&*()_+<>?|\/;:`~,.=-]+', lambda _, token: Symbol(token)),
(r'\[|\]', lambda _, token: token),
(r'"(?:[^"\\]|\\.)*"', lambda _, token: token[1:-1].replace('\\"', '"')),
(r"'(?:[^'\\]|\\.)*'", lambda _, token: token[1:-1].replace("\\'", "'")),
(r'\s+', None),
(FLOAT, lambda _, token: float(token)),
(INT, lambda _, token: int(token)),
(SYMBOL, lambda _, token: Symbol(token)),
(BRACKETS, lambda _, token: token),
(STRING_DOUBLE_QUOTED, lambda _, token: token[1:-1].replace('\\"', '"')),
(STRING_SINGLE_QUOTED, lambda _, token: token[1:-1].replace("\\'", "'")),
(BLANKS, None),
])