3 def _or_parser(*parsers):
4 def result_parser(index, tokens):
5 failure = (False, index, None)
8 success, index, value = parser(index, tokens)
11 return (success, index, value)
17 def _zero_or_more_parser(formatter, parser):
18 def result_parser(index, tokens):
21 while index < len(tokens):
22 success, index, value = parser(index, tokens)
29 return (True, index, formatter(values))
33 FurIntegerLiteralExpression = collections.namedtuple(
34 'FurIntegerLiteralExpression',
40 FurStringLiteralExpression = collections.namedtuple(
41 'FurStringLiteralExpression',
47 FurSymbolExpression = collections.namedtuple(
48 'FurSymbolExpression',
54 FurNegationExpression = collections.namedtuple(
55 'FurNegationExpression',
61 FurParenthesizedExpression = collections.namedtuple(
62 'FurParenthesizedExpression',
68 FurAdditionExpression = collections.namedtuple(
69 'FurAdditionExpression',
76 FurSubtractionExpression = collections.namedtuple(
77 'FurSubtractionExpression',
84 FurMultiplicationExpression = collections.namedtuple(
85 'FurMultiplicationExpression',
92 FurIntegerDivisionExpression = collections.namedtuple(
93 'FurIntegerDivisionExpression',
100 FurModularDivisionExpression = collections.namedtuple(
101 'FurModularDivisionExpression',
108 FurEqualityExpression = collections.namedtuple(
109 'FurEqualityExpression',
116 FurInequalityExpression = collections.namedtuple(
117 'FurInequalityExpression',
124 FurLessThanOrEqualExpression = collections.namedtuple(
125 'FurLessThanOrEqualExpression',
132 FurGreaterThanOrEqualExpression = collections.namedtuple(
133 'FurGreaterThanOrEqualExpression',
140 FurLessThanExpression = collections.namedtuple(
141 'FurLessThanExpression',
148 FurGreaterThanExpression = collections.namedtuple(
149 'FurGreaterThanExpression',
156 def _integer_literal_expression_parser(index, tokens):
157 failure = (False, index, None)
159 if tokens[index].type != 'integer_literal':
161 value = int(tokens[index].match)
164 return True, index, FurIntegerLiteralExpression(value=value)
166 def _string_literal_expression_parser(index, tokens):
167 if tokens[index].type == 'single_quoted_string_literal':
168 return (True, index + 1, FurStringLiteralExpression(value=tokens[index].match[1:-1]))
170 return (False, index, None)
172 def _symbol_expression_parser(index, tokens):
173 if tokens[index].type == 'symbol':
174 return (True, index + 1, FurSymbolExpression(value=tokens[index].match))
176 return (False, index, None)
178 def _parenthesized_expression_parser(index, tokens):
179 failure = (False, index, None)
181 if tokens[index].type == 'open_parenthese':
186 success, index, internal = _expression_parser(index, tokens)
190 if tokens[index].type == 'close_parenthese':
193 raise Exception('Expected ")" on line {}, found "{}"'.format(
198 return True, index, FurParenthesizedExpression(internal=internal)
200 def _negation_expression_parser(index, tokens):
201 failure = (False, index, None)
203 if tokens[index].match != '-':
206 success, index, value = _literal_level_expression_parser(index + 1, tokens)
211 return (True, index, FurNegationExpression(value=value))
213 def _literal_level_expression_parser(index, tokens):
215 _negation_expression_parser,
216 _function_call_expression_parser,
217 _parenthesized_expression_parser,
218 _integer_literal_expression_parser,
219 _string_literal_expression_parser,
220 _symbol_expression_parser,
223 def _left_recursive_infix_operator_parser(token_type, operand_parser, operator_to_expression_type_mapping):
224 def result_parser(index, tokens):
225 failure = (False, index, None)
227 success, index, result = operand_parser(index, tokens)
232 while success and index < len(tokens) and tokens[index].type == token_type:
235 if index + 1 < len(tokens):
236 success, try_index, value = operand_parser(index + 1, tokens)
239 result = operator_to_expression_type_mapping[tokens[index].match](left=result, right=value)
242 return True, index, result
246 def _multiplication_level_expression_parser(index, tokens):
247 return _left_recursive_infix_operator_parser(
248 'multiplication_level_operator',
249 _literal_level_expression_parser,
251 '*': FurMultiplicationExpression,
252 '//': FurIntegerDivisionExpression,
253 '%': FurModularDivisionExpression,
257 def _addition_level_expression_parser(index, tokens):
258 return _left_recursive_infix_operator_parser(
259 'addition_level_operator',
260 _multiplication_level_expression_parser,
262 '+': FurAdditionExpression,
263 '-': FurSubtractionExpression,
267 def _equality_level_expression_parser(index, tokens):
268 return _left_recursive_infix_operator_parser(
269 'equality_level_operator',
270 _addition_level_expression_parser,
272 '==': FurEqualityExpression,
273 '!=': FurInequalityExpression,
274 '>=': FurGreaterThanOrEqualExpression,
275 '<=': FurLessThanOrEqualExpression,
276 '>': FurGreaterThanExpression,
277 '<': FurLessThanExpression,
281 def _comma_separated_list_parser(index, tokens):
282 failure = (False, index, None)
286 success, index, expression = _expression_parser(index, tokens)
289 expressions.append(expression)
293 while success and index < len(tokens) and tokens[index].type == 'comma':
296 if index + 1 < len(tokens):
297 success, try_index, expression = _expression_parser(index + 1, tokens)
300 expressions.append(expression)
303 return True, index, tuple(expressions)
306 FurFunctionCallExpression = collections.namedtuple(
307 'FurFunctionCallExpression',
314 FurAssignmentStatement = collections.namedtuple(
315 'FurAssignmentStatement',
322 FurProgram = collections.namedtuple(
329 def _function_call_expression_parser(index, tokens):
330 # TODO Use a FurSymbolExpression for the name
331 failure = (False, index, None)
333 success, index, function = _symbol_expression_parser(index, tokens)
338 if tokens[index].type != 'open_parenthese':
342 success, index, arguments = _comma_separated_list_parser(index, tokens)
347 if tokens[index].type != 'close_parenthese':
348 raise Exception('Expected ")", found "{}" on line {}'.format(
354 return True, index, FurFunctionCallExpression(function=function, arguments=arguments)
356 _expression_parser = _equality_level_expression_parser
358 def _assignment_statement_parser(index, tokens):
359 # TODO Use a FurSymbolExpression for the target? Maybe this is actually not a good idea
360 failure = (False, index, None)
362 if tokens[index].type != 'symbol':
364 target = tokens[index].match
367 if tokens[index].type != 'assignment_operator':
369 assignment_operator_index = index
371 success, index, expression = _expression_parser(index + 1, tokens)
375 'Expected expression after assignment operator on line {}'.format(
376 tokens[assignment_operator_index].line
380 return True, index, FurAssignmentStatement(target=target, expression=expression)
382 def _statement_parser(index, tokens):
383 # TODO It would be good to include newlines in the parsing of this because it removes the ambiguity between "function(argument)" (one statement) and "function\n(argument)" (two statements)
385 _assignment_statement_parser,
389 def _program_formatter(statement_list):
390 return FurProgram(statement_list=statement_list)
392 _program_parser = _zero_or_more_parser(_program_formatter, _statement_parser)
394 def _parse(parser, tokens):
395 success, index, result = parser(0, tokens)
397 if index < len(tokens):
398 raise Exception('Unable to parse token {}'.format(tokens[index]))
403 raise Exception('Unable to parse')
406 return _parse(_program_parser, tokens)
408 if __name__ == '__main__':
413 class FurStringLiteralExpressionParserTests(unittest.TestCase):
414 def test_parses_single_quoted_string_literal(self):
416 _string_literal_expression_parser(0, tokenization.tokenize("'Hello, world'")),
420 FurStringLiteralExpression(value='Hello, world'),
424 class FurFunctionCallExpressionParserTests(unittest.TestCase):
425 def test_parses_function_with_string_literal_argument(self):
427 _function_call_expression_parser(0, tokenization.tokenize("print('Hello, world')")),
431 FurFunctionCallExpression(
433 arguments=(FurStringLiteralExpression(value='Hello, world'),),