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import os
import tempfile
import sympy
from sympy.testing.pytest import raises
from sympy.parsing.latex.lark import LarkLaTeXParser, TransformToSymPyExpr, parse_latex_lark
from sympy.external import import_module
lark = import_module("lark")
# disable tests if lark is not present
disabled = lark is None
grammar_file = os.path.join(os.path.dirname(__file__), "../latex/lark/grammar/latex.lark")
modification1 = """
%override DIV_SYMBOL: DIV
%override MUL_SYMBOL: MUL | CMD_TIMES
"""
modification2 = r"""
%override number: /\d+(,\d*)?/
"""
def init_custom_parser(modification, transformer=None):
with open(grammar_file, encoding="utf-8") as f:
latex_grammar = f.read()
latex_grammar += modification
with tempfile.NamedTemporaryFile() as f:
f.write(bytes(latex_grammar, encoding="utf8"))
parser = LarkLaTeXParser(grammar_file=f.name, transformer=transformer)
return parser
def test_custom1():
# Removes the parser's ability to understand \cdot and \div.
parser = init_custom_parser(modification1)
with raises(lark.exceptions.UnexpectedCharacters):
parser.doparse(r"a \cdot b")
parser.doparse(r"x \div y")
class CustomTransformer(TransformToSymPyExpr):
def number(self, tokens):
if "," in tokens[0]:
# The Float constructor expects a dot as the decimal separator
return sympy.core.numbers.Float(tokens[0].replace(",", "."))
else:
return sympy.core.numbers.Integer(tokens[0])
def test_custom2():
# Makes the parser parse commas as the decimal separator instead of dots
parser = init_custom_parser(modification2, CustomTransformer)
with raises(lark.exceptions.UnexpectedCharacters):
# Asserting that the default parser cannot parse numbers which have commas as
# the decimal separator
parse_latex_lark("100,1")
parse_latex_lark("0,009")
parser.doparse("100,1")
parser.doparse("0,009")
parser.doparse("2,71828")
parser.doparse("3,14159")
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