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 # TODO We don't need to wrap this type
68 FurParenthesizedExpression = collections.namedtuple(
69 'FurParenthesizedExpression',
75 FurInfixExpression = collections.namedtuple(
85 def _integer_literal_expression_parser(index, tokens):
86 failure = (False, index, None)
88 if tokens[index].type != 'integer_literal':
90 value = int(tokens[index].match)
93 return True, index, FurIntegerLiteralExpression(value=value)
95 def _string_literal_expression_parser(index, tokens):
96 if tokens[index].type == 'single_quoted_string_literal':
97 return (True, index + 1, FurStringLiteralExpression(value=tokens[index].match[1:-1]))
99 return (False, index, None)
101 def _symbol_expression_parser(index, tokens):
102 if tokens[index].type == 'symbol':
103 return (True, index + 1, FurSymbolExpression(value=tokens[index].match))
105 return (False, index, None)
107 def _parenthesized_expression_parser(index, tokens):
108 failure = (False, index, None)
110 if tokens[index].type == 'open_parenthese':
115 success, index, internal = _expression_parser(index, tokens)
119 if tokens[index].type == 'close_parenthese':
122 raise Exception('Expected ")" on line {}, found "{}"'.format(
127 return True, index, FurParenthesizedExpression(internal=internal)
129 def _negation_expression_parser(index, tokens):
130 failure = (False, index, None)
132 if tokens[index].match != '-':
135 success, index, value = _literal_level_expression_parser(index + 1, tokens)
140 return (True, index, FurNegationExpression(value=value))
142 def _literal_level_expression_parser(index, tokens):
144 _negation_expression_parser,
145 _function_call_expression_parser,
146 _parenthesized_expression_parser,
147 _integer_literal_expression_parser,
148 _string_literal_expression_parser,
149 _symbol_expression_parser,
152 def _left_recursive_infix_operator_parser(operator_token_matcher, operand_parser, order):
153 def result_parser(index, tokens):
154 failure = (False, index, None)
156 success, index, result = operand_parser(index, tokens)
161 while success and index < len(tokens) and operator_token_matcher(tokens[index]):
164 if index + 1 < len(tokens):
165 success, try_index, value = operand_parser(index + 1, tokens)
168 result = FurInfixExpression(
170 operator=tokens[index].match,
176 return True, index, result
180 def _multiplication_level_expression_parser(index, tokens):
181 return _left_recursive_infix_operator_parser(
182 lambda token: token.type == 'multiplication_level_operator',
183 _literal_level_expression_parser,
184 'multiplication_level',
187 def _addition_level_expression_parser(index, tokens):
188 return _left_recursive_infix_operator_parser(
189 lambda token: token.type == 'addition_level_operator',
190 _multiplication_level_expression_parser,
194 def _comparison_level_expression_parser(index, tokens):
195 return _left_recursive_infix_operator_parser(
196 lambda token: token.type == 'comparison_level_operator',
197 _addition_level_expression_parser,
201 def _and_level_expression_parser(index, tokens):
202 return _left_recursive_infix_operator_parser(
203 lambda token: token.type == 'symbol' and token.match == 'and',
204 _comparison_level_expression_parser,
208 def _or_level_expression_parser(index, tokens):
209 return _left_recursive_infix_operator_parser(
210 lambda token: token.type == 'symbol' and token.match == 'or',
211 _and_level_expression_parser,
215 def _comma_separated_list_parser(index, tokens):
216 failure = (False, index, None)
220 success, index, expression = _expression_parser(index, tokens)
223 expressions.append(expression)
227 while success and index < len(tokens) and tokens[index].type == 'comma':
230 if index + 1 < len(tokens):
231 success, try_index, expression = _expression_parser(index + 1, tokens)
234 expressions.append(expression)
237 return True, index, tuple(expressions)
240 FurFunctionCallExpression = collections.namedtuple(
241 'FurFunctionCallExpression',
248 FurExpressionStatement = collections.namedtuple(
249 'FurExpressionStatement',
255 FurAssignmentStatement = collections.namedtuple(
256 'FurAssignmentStatement',
263 FurProgram = collections.namedtuple(
270 def _function_call_expression_parser(index, tokens):
271 # TODO Use a FurSymbolExpression for the name
272 failure = (False, index, None)
274 success, index, function = _symbol_expression_parser(index, tokens)
279 if tokens[index].type != 'open_parenthese':
283 success, index, arguments = _comma_separated_list_parser(index, tokens)
288 if tokens[index].type != 'close_parenthese':
289 raise Exception('Expected ")", found "{}" on line {}'.format(
295 return True, index, FurFunctionCallExpression(function=function, arguments=arguments)
297 _expression_parser = _or_level_expression_parser
299 def _expression_statement_parser(index, tokens):
300 failure = (False, index, None)
302 success, index, expression = _expression_parser(index, tokens)
307 return (True, index, FurExpressionStatement(expression=expression))
309 def _assignment_statement_parser(index, tokens):
310 # TODO Use a FurSymbolExpression for the target? Maybe this is actually not a good idea
311 failure = (False, index, None)
313 if tokens[index].type != 'symbol':
315 target = tokens[index].match
318 if tokens[index].type != 'assignment_operator':
320 assignment_operator_index = index
322 success, index, expression = _expression_parser(index + 1, tokens)
326 'Expected expression after assignment operator on line {}'.format(
327 tokens[assignment_operator_index].line
331 return True, index, FurAssignmentStatement(target=target, expression=expression)
333 def _statement_parser(index, tokens):
334 _, index, _ = consume_newlines(index, tokens)
336 if index == len(tokens):
337 return (False, index, None)
340 _assignment_statement_parser,
341 _expression_statement_parser,
344 def _program_formatter(statement_list):
345 return FurProgram(statement_list=statement_list)
347 _program_parser = _zero_or_more_parser(_program_formatter, _statement_parser)
349 def _parse(parser, tokens):
350 success, index, result = parser(0, tokens)
352 if index < len(tokens):
353 raise Exception('Unable to parse token {}'.format(tokens[index]))
358 raise Exception('Unable to parse')
361 return _parse(_program_parser, tokens)
363 if __name__ == '__main__':
368 class FurStringLiteralExpressionParserTests(unittest.TestCase):
369 def test_parses_single_quoted_string_literal(self):
371 _string_literal_expression_parser(0, tokenization.tokenize("'Hello, world'")),
375 FurStringLiteralExpression(value='Hello, world'),
379 class FurFunctionCallExpressionParserTests(unittest.TestCase):
380 def test_parses_function_with_string_literal_argument(self):
382 _function_call_expression_parser(0, tokenization.tokenize("print('Hello, world')")),
386 FurFunctionCallExpression(
388 arguments=(FurStringLiteralExpression(value='Hello, world'),),