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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") | |