3 def consume_newlines(index, tokens):
4 while index < len(tokens) and tokens[index].type == 'newline':
7 return True, index, None
9 def _or_parser(*parsers):
10 def result_parser(index, tokens):
11 failure = (False, index, None)
13 for parser in parsers:
14 success, index, value = parser(index, tokens)
17 return (success, index, value)
23 def _zero_or_more_parser(formatter, parser):
24 def result_parser(index, tokens):
27 while index < len(tokens):
28 success, index, value = parser(index, tokens)
35 return (True, index, formatter(values))
39 FurIntegerLiteralExpression = collections.namedtuple(
40 'FurIntegerLiteralExpression',
46 FurStringLiteralExpression = collections.namedtuple(
47 'FurStringLiteralExpression',
53 FurSymbolExpression = collections.namedtuple(
54 'FurSymbolExpression',
60 FurNegationExpression = collections.namedtuple(
61 'FurNegationExpression',
67 FurInfixExpression = collections.namedtuple(
77 FurListLiteralExpression = collections.namedtuple(
78 'FurListLiteralExpression',
80 'item_expression_list',
84 FurIfExpression = collections.namedtuple(
87 'condition_expression',
89 'else_statement_list',
93 def _integer_literal_expression_parser(index, tokens):
94 failure = (False, index, None)
96 if tokens[index].type != 'integer_literal':
98 value = int(tokens[index].match)
101 return True, index, FurIntegerLiteralExpression(integer=value)
103 def _string_literal_expression_parser(index, tokens):
104 if tokens[index].type == 'single_quoted_string_literal':
105 return (True, index + 1, FurStringLiteralExpression(string=tokens[index].match[1:-1]))
107 return (False, index, None)
109 def _symbol_expression_parser(index, tokens):
110 if tokens[index].type == 'symbol':
111 return (True, index + 1, FurSymbolExpression(symbol=tokens[index].match))
113 return (False, index, None)
115 def _wrapped_parser(open_token, close_token, internal_parser):
116 def result_parser(index, tokens):
117 failure = (False, index, None)
119 if tokens[index].type == open_token:
124 success, index, internal = internal_parser(index, tokens)
128 if tokens[index].type == close_token:
131 # TODO Put the actual expected character in the error message
132 raise Exception('Expected closing token on line {}, found "{}"'.format(
137 return True, index, internal
141 def _bracket_wrapped_parser(internal_parser):
142 return _wrapped_parser('open_bracket', 'close_bracket', internal_parser)
144 def _parenthese_wrapped_parser(internal_parser):
145 return _wrapped_parser('open_parenthese', 'close_parenthese', internal_parser)
147 def _parenthesized_expression_parser(index, tokens):
148 return _parenthese_wrapped_parser(_expression_parser)(index, tokens)
150 def _list_literal_expression_parser(index, tokens):
151 failure = (False, index, None)
153 success, index, item_expression_list = _bracket_wrapped_parser(_comma_separated_expression_list_parser)(index, tokens)
156 return success, index, FurListLiteralExpression(
157 item_expression_list=item_expression_list,
162 def _negation_expression_parser(index, tokens):
163 failure = (False, index, None)
165 if tokens[index].match != '-':
168 success, index, value = _literal_level_expression_parser(index + 1, tokens)
173 return (True, index, FurNegationExpression(value=value))
175 def _literal_level_expression_parser(index, tokens):
177 _negation_expression_parser,
178 _list_item_expression_parser,
179 _function_call_expression_parser,
180 _parenthesized_expression_parser,
181 _integer_literal_expression_parser,
182 _string_literal_expression_parser,
183 _list_literal_expression_parser,
184 _symbol_expression_parser,
187 def _left_recursive_infix_operator_parser(operator_token_matcher, operand_parser, order):
188 def result_parser(index, tokens):
189 failure = (False, index, None)
191 success, index, result = operand_parser(index, tokens)
196 while success and index < len(tokens) and operator_token_matcher(tokens[index]):
199 if index + 1 < len(tokens):
200 success, try_index, value = operand_parser(index + 1, tokens)
203 result = FurInfixExpression(
205 operator=tokens[index].match,
211 return True, index, result
215 def _multiplication_level_expression_parser(index, tokens):
216 return _left_recursive_infix_operator_parser(
217 lambda token: token.type == 'multiplication_level_operator',
218 _literal_level_expression_parser,
219 'multiplication_level',
222 def _addition_level_expression_parser(index, tokens):
223 return _left_recursive_infix_operator_parser(
224 lambda token: token.type == 'addition_level_operator',
225 _multiplication_level_expression_parser,
229 def _comparison_level_expression_parser(index, tokens):
230 return _left_recursive_infix_operator_parser(
231 lambda token: token.type == 'comparison_level_operator',
232 _addition_level_expression_parser,
236 def _and_level_expression_parser(index, tokens):
237 return _left_recursive_infix_operator_parser(
238 lambda token: token.type == 'symbol' and token.match == 'and',
239 _comparison_level_expression_parser,
243 def _or_level_expression_parser(index, tokens):
244 return _left_recursive_infix_operator_parser(
245 lambda token: token.type == 'symbol' and token.match == 'or',
246 _and_level_expression_parser,
250 def _comma_separated_list_parser(subparser):
251 def result_parser(index, tokens):
256 _, index, _ = consume_newlines(index, tokens)
258 success, index, item = subparser(index, tokens)
263 return (True, start_index, ())
265 while success and index < len(tokens) and tokens[index].type == 'comma':
269 _, index, _ = consume_newlines(index, tokens)
271 if index < len(tokens):
272 success, try_index, item = subparser(index, tokens)
278 return True, index, tuple(items)
282 def _comma_separated_expression_list_parser(index, tokens):
283 return _comma_separated_list_parser(_expression_parser)(index, tokens)
285 FurListItemExpression = collections.namedtuple(
286 'FurListItemExpression',
293 FurFunctionCallExpression = collections.namedtuple(
294 'FurFunctionCallExpression',
301 FurExpressionStatement = collections.namedtuple(
302 'FurExpressionStatement',
308 FurAssignmentStatement = collections.namedtuple(
309 'FurAssignmentStatement',
316 FurFunctionDefinitionStatement = collections.namedtuple(
317 'FurFunctionDefinitionStatement',
320 'argument_name_list',
325 FurProgram = collections.namedtuple(
332 def _list_item_expression_parser(index, tokens):
333 failure = (False, index, None)
335 # We have to be careful what expressions we add here. Otherwise expressions
336 # like "a + b[0]" become ambiguous to the parser.
337 success, index, list_expression = _or_parser(
338 _symbol_expression_parser,
339 _parenthesized_expression_parser,
345 success, index, index_expression = _bracket_wrapped_parser(_expression_parser)(
353 while success and index < len(tokens):
354 # "list_expression" is actually the full list item expression if the next parse attempt doesn't succeed
355 # We can't give this a better name without a bunch of checks, however.
356 list_expression = FurListItemExpression(
357 list_expression=list_expression,
358 index_expression=index_expression,
361 success, index, index_expression = _bracket_wrapped_parser(_expression_parser)(
366 return True, index, list_expression
368 def _function_call_expression_parser(index, tokens):
369 failure = (False, index, None)
371 # We have to be careful what expressions we add here. Otherwise expressions
372 # like "a + b()" become ambiguous to the parser.
373 success, index, function = _or_parser(
374 _symbol_expression_parser,
375 _parenthesized_expression_parser,
381 success, index, arguments = _parenthese_wrapped_parser(_comma_separated_expression_list_parser)(
389 while success and index < len(tokens):
390 # "function" is actually the full function call if the next parse attempt doesn't succeed
391 # We can't give this a better name without a bunch of checks, however.
392 function = FurFunctionCallExpression(
397 success, index, arguments = _parenthese_wrapped_parser(_comma_separated_expression_list_parser)(
402 return True, index, function
404 def _if_expression_parser(index, tokens):
405 failure = (False, index, None)
407 if tokens[index].match == 'if':
412 success, index, condition_expression = _or_level_expression_parser(index, tokens)
415 raise Exception('Expected condition after "if" on line {}'.format(tokens[index].line))
417 if tokens[index].match == 'do':
420 raise Exception('Expected "do" after "if" on line {}'.format(tokens[index].line))
423 success, index, if_statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
424 _, index, _ = consume_newlines(index, tokens)
426 if tokens[index].match == 'else':
428 success, index, else_statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
429 _, index, _ = consume_newlines(index, tokens)
431 else_statement_list = ()
433 if tokens[index].match == 'end':
436 raise Exception('Expected "end" after "if" on line {}'.format(tokens[index].line))
442 condition_expression=condition_expression,
443 if_statement_list=if_statement_list,
444 else_statement_list=else_statement_list,
451 _expression_parser = _or_parser(
452 _or_level_expression_parser,
453 _if_expression_parser, # This should always be at the top level
456 def _expression_statement_parser(index, tokens):
457 failure = (False, index, None)
459 success, index, expression = _expression_parser(index, tokens)
464 return (True, index, FurExpressionStatement(expression=expression))
466 BUILTINS = {'print', 'pow'}
468 def _assignment_statement_parser(index, tokens):
469 failure = (False, index, None)
471 if tokens[index].type == 'symbol':
472 target = tokens[index].match
473 target_assignment_line = tokens[index].line
480 if tokens[index].type == 'assignment_operator':
481 if target in BUILTINS:
483 'Trying to assign to builtin "{}" on line {}'.format(target, target_assignment_line),
485 assignment_operator_index = index
489 success, index, expression = _expression_parser(index + 1, tokens)
493 'Expected expression after assignment operator on line {}'.format(
494 tokens[assignment_operator_index].line
498 return True, index, FurAssignmentStatement(target=target, expression=expression)
500 def _function_definition_statement_parser(index, tokens):
501 failure = (False, index, None)
503 if tokens[index].type == 'keyword' and tokens[index].match == 'def':
508 if tokens[index].type == 'symbol':
509 name = tokens[index].match
512 raise Exception('Expected function name, found "{}" on line {}'.format(
517 if tokens[index].type == 'open_parenthese':
520 raise Exception('Expected "(", found "{}" on line {}'.format(
525 success, index, argument_name_list = _comma_separated_list_parser(_symbol_expression_parser)(
530 if tokens[index].type == 'close_parenthese':
533 raise Exception('Expected ")", found "{}" on line {}'.format(
538 if tokens[index].match == 'do':
543 success, index, statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
545 _, index, _ = consume_newlines(index, tokens)
547 if tokens[index].type == 'keyword' and tokens[index].match == 'end':
552 return True, index, FurFunctionDefinitionStatement(
554 argument_name_list=tuple(an.symbol for an in argument_name_list),
555 statement_list=statement_list,
558 def _statement_parser(index, tokens):
559 _, index, _ = consume_newlines(index, tokens)
561 if index == len(tokens):
562 return (False, index, None)
565 _assignment_statement_parser,
566 _expression_statement_parser,
567 _function_definition_statement_parser,
570 def _program_formatter(statement_list):
571 return FurProgram(statement_list=statement_list)
573 _program_parser = _zero_or_more_parser(_program_formatter, _statement_parser)
575 def _parse(parser, tokens):
576 success, index, result = parser(0, tokens)
578 if index < len(tokens):
579 raise Exception('Unable to parse token {}'.format(tokens[index]))
584 raise Exception('Unable to parse')
587 return _parse(_program_parser, tokens)
589 if __name__ == '__main__':
594 class FurStringLiteralExpressionParserTests(unittest.TestCase):
595 def test_parses_single_quoted_string_literal(self):
597 _string_literal_expression_parser(0, tokenization.tokenize("'Hello, world'")),
601 FurStringLiteralExpression(string='Hello, world'),
605 class FurFunctionCallExpressionParserTests(unittest.TestCase):
606 def test_parses_function_with_string_literal_argument(self):
608 _function_call_expression_parser(0, tokenization.tokenize("print('Hello, world')")),
612 FurFunctionCallExpression(
614 arguments=(FurStringLiteralExpression(string='Hello, world'),),