import collections
+def consume_newlines(index, tokens):
+ while index < len(tokens) and tokens[index].type == 'newline':
+ index += 1
+
+ return True, index, None
+
def _or_parser(*parsers):
def result_parser(index, tokens):
failure = (False, index, None)
return result_parser
+NodeMetadata = collections.namedtuple(
+ 'NodeMetadata',
+ [
+ 'index',
+ 'line',
+ ],
+)
+
FurIntegerLiteralExpression = collections.namedtuple(
'FurIntegerLiteralExpression',
[
- 'value',
+ 'integer',
],
)
FurStringLiteralExpression = collections.namedtuple(
'FurStringLiteralExpression',
+ [
+ 'string',
+ ],
+)
+
+FurSymbolExpression = collections.namedtuple(
+ 'FurSymbolExpression',
+ [
+ 'symbol',
+ ],
+)
+
+FurNegationExpression = collections.namedtuple(
+ 'FurNegationExpression',
[
'value',
],
)
-FurAdditionExpression = collections.namedtuple(
- 'FurAdditionExpression',
+FurInfixExpression = collections.namedtuple(
+ 'FurInfixExpression',
[
+ 'metadata',
+ 'order',
+ 'operator',
'left',
'right',
],
)
-FurSubtractionExpression = collections.namedtuple(
- 'FurSubtractionExpression',
+FurListLiteralExpression = collections.namedtuple(
+ 'FurListLiteralExpression',
[
- 'left',
- 'right',
+ 'item_expression_list',
],
)
-FurMultiplicationExpression = collections.namedtuple(
- 'FurMultiplicationExpression',
+FurIfExpression = collections.namedtuple(
+ 'FurIfExpression',
[
- 'left',
- 'right',
+ 'condition_expression',
+ 'if_statement_list',
+ 'else_statement_list',
],
)
-FurIntegerDivisionExpression = collections.namedtuple(
- 'FurIntegerDivisionExpression',
+FurSymbolExpressionPair = collections.namedtuple(
+ 'FurSymbolExpressionPair',
[
- 'left',
- 'right',
+ 'symbol',
+ 'expression',
],
)
-FurModularDivisionExpression = collections.namedtuple(
- 'FurModularDivisionExpression',
+FurStructureLiteralExpression = collections.namedtuple(
+ 'FurStructureLiteralExpression',
[
- 'left',
- 'right',
+ 'fields',
],
)
value = int(tokens[index].match)
index += 1
- return True, index, FurIntegerLiteralExpression(value=value)
+ return True, index, FurIntegerLiteralExpression(integer=value)
def _string_literal_expression_parser(index, tokens):
+ if tokens[index].type == 'double_quoted_string_literal':
+ return (True, index + 1, FurStringLiteralExpression(string=tokens[index].match[1:-1]))
+
+ if tokens[index].type == 'single_quoted_string_literal':
+ return (True, index + 1, FurStringLiteralExpression(string=tokens[index].match[1:-1]))
+
+ return (False, index, None)
+
+def _symbol_expression_parser(index, tokens):
+ if tokens[index].type == 'symbol':
+ return (True, index + 1, FurSymbolExpression(symbol=tokens[index].match))
+
+ return (False, index, None)
+
+def _wrapped_parser(open_token, close_token, internal_parser):
+ def result_parser(index, tokens):
+ failure = (False, index, None)
+
+ if tokens[index].type == open_token:
+ index += 1
+ else:
+ return failure
+
+ success, index, internal = internal_parser(index, tokens)
+ if not success:
+ return failure
+
+ if tokens[index].type == close_token:
+ index += 1
+ else:
+ # TODO Put the actual expected character in the error message
+ raise Exception('Expected closing token on line {}, found "{}"'.format(
+ tokens[index].line,
+ tokens[index].match,
+ ))
+
+ return True, index, internal
+
+ return result_parser
+
+def _bracket_wrapped_parser(internal_parser):
+ return _wrapped_parser('open_bracket', 'close_bracket', internal_parser)
+
+def _parenthese_wrapped_parser(internal_parser):
+ return _wrapped_parser('open_parenthese', 'close_parenthese', internal_parser)
+
+def _parenthesized_expression_parser(index, tokens):
+ return _parenthese_wrapped_parser(_expression_parser)(index, tokens)
+
+def symbol_expression_pair_parser(index, tokens):
failure = (False, index, None)
- if tokens[index].type != 'single_quoted_string_literal':
+ if tokens[index].type == 'symbol':
+ symbol = tokens[index].match
+ index += 1
+ else:
return failure
- value = tokens[index].match[1:-1]
- index += 1
- return True, index, FurStringLiteralExpression(value=value)
+ if tokens[index].type == 'colon':
+ index += 1
+ else:
+ return failure
+
+ success, index, expression = _expression_parser(index, tokens)
+
+ if not success:
+ raise Exception()
+
+ return (
+ True,
+ index,
+ FurSymbolExpressionPair(
+ symbol=symbol,
+ expression=expression,
+ ),
+ )
+
+def _structure_literal_parser(index, tokens):
+ success, index, result = _parenthese_wrapped_parser(_comma_separated_list_parser(symbol_expression_pair_parser))(index, tokens)
+ return (
+ success,
+ index,
+ FurStructureLiteralExpression(
+ fields=result,
+ ),
+ )
+
+def _list_literal_expression_parser(index, tokens):
+ failure = (False, index, None)
+
+ success, index, item_expression_list = _bracket_wrapped_parser(_comma_separated_expression_list_parser)(index, tokens)
+
+ if success:
+ return success, index, FurListLiteralExpression(
+ item_expression_list=item_expression_list,
+ )
+ else:
+ return failure
def _literal_level_expression_parser(index, tokens):
return _or_parser(
+ _list_item_expression_parser,
+ _function_call_expression_parser,
+ _parenthesized_expression_parser,
_integer_literal_expression_parser,
_string_literal_expression_parser,
+ _list_literal_expression_parser,
+ _symbol_expression_parser,
+ _structure_literal_parser,
)(index, tokens)
-def _multiplication_level_expression_parser(index, tokens):
+def _dot_expression_parser(index, tokens):
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'period',
+ _literal_level_expression_parser,
+ 'dot_level',
+ )(index, tokens)
+
+def _negation_expression_parser(index, tokens):
failure = (False, index, None)
- success, index, result = _literal_level_expression_parser(index, tokens)
+ if tokens[index].match != '-':
+ return failure
+
+ success, index, value = _dot_expression_parser(index + 1, tokens)
if not success:
return failure
- while success and index < len(tokens) and tokens[index].type == 'multiplication_level_operator':
- success = False
+ return (True, index, FurNegationExpression(value=value))
- if index + 1 < len(tokens):
- success, try_index, value = _literal_level_expression_parser(index + 1, tokens)
+def _negation_level_expression_parser(index, tokens):
+ return _or_parser(
+ _dot_expression_parser,
+ _negation_expression_parser,
+ )(index, tokens)
- if success:
- result = {
- '*': FurMultiplicationExpression,
- '//': FurIntegerDivisionExpression,
- '%': FurModularDivisionExpression,
- }[tokens[index].match](left=result, right=value)
- index = try_index
+def _left_recursive_infix_operator_parser(operator_token_matcher, operand_parser, order):
+ def result_parser(index, tokens):
+ failure = (False, index, None)
+
+ success, index, result = operand_parser(index, tokens)
+
+ if not success:
+ return failure
+
+ while success and index < len(tokens) and operator_token_matcher(tokens[index]):
+ success = False
+
+ if index + 1 < len(tokens):
+ success, try_index, value = operand_parser(index + 1, tokens)
+
+ if success:
+ result = FurInfixExpression(
+ metadata=NodeMetadata(
+ index=tokens[index].index,
+ line=tokens[index].line,
+ ),
+ order=order,
+ operator=tokens[index].match,
+ left=result,
+ right=value,
+ )
+ index = try_index
+
+ return True, index, result
+
+ return result_parser
- return True, index, result
+def _multiplication_level_expression_parser(index, tokens):
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'multiplication_level_operator',
+ _negation_level_expression_parser,
+ 'multiplication_level',
+ )(index, tokens)
def _addition_level_expression_parser(index, tokens):
- failure = (False, index, None)
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'addition_level_operator',
+ _multiplication_level_expression_parser,
+ 'addition_level',
+ )(index, tokens)
- success, index, result = _multiplication_level_expression_parser(index, tokens)
+def _comparison_level_expression_parser(index, tokens):
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'comparison_level_operator',
+ _addition_level_expression_parser,
+ 'comparison_level',
+ )(index, tokens)
- if not success:
- return failure
+def _and_level_expression_parser(index, tokens):
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'symbol' and token.match == 'and',
+ _comparison_level_expression_parser,
+ 'and_level',
+ )(index, tokens)
+
+def _or_level_expression_parser(index, tokens):
+ return _left_recursive_infix_operator_parser(
+ lambda token: token.type == 'symbol' and token.match == 'or',
+ _and_level_expression_parser,
+ 'or_level',
+ )(index, tokens)
+
+def _comma_separated_list_parser(subparser):
+ def result_parser(index, tokens):
+ start_index = index
+
+ items = []
- while success and index < len(tokens) and tokens[index].type == 'addition_level_operator':
- success = False
+ _, index, _ = consume_newlines(index, tokens)
- if index + 1 < len(tokens):
- success, try_index, value = _multiplication_level_expression_parser(index + 1, tokens)
+ success, index, item = subparser(index, tokens)
if success:
- result = {
- '+': FurAdditionExpression,
- '-': FurSubtractionExpression,
- }[tokens[index].match](left=result, right=value)
- index = try_index
+ items.append(item)
+ else:
+ return (True, start_index, ())
+
+ while success and index < len(tokens) and tokens[index].type == 'comma':
+ index += 1
+ success = False
+
+ _, index, _ = consume_newlines(index, tokens)
+
+ if index < len(tokens):
+ success, try_index, item = subparser(index, tokens)
+
+ if success:
+ items.append(item)
+ index = try_index
- return True, index, result
+ return True, index, tuple(items)
-FunctionCall = collections.namedtuple(
- 'FunctionCall',
+ return result_parser
+
+def _comma_separated_expression_list_parser(index, tokens):
+ return _comma_separated_list_parser(_expression_parser)(index, tokens)
+
+FurListItemExpression = collections.namedtuple(
+ 'FurListItemExpression',
[
- 'name',
+ 'list_expression',
+ 'index_expression',
+ ],
+)
+
+FurFunctionCallExpression = collections.namedtuple(
+ 'FurFunctionCallExpression',
+ [
+ 'function',
'arguments',
],
)
+FurExpressionStatement = collections.namedtuple(
+ 'FurExpressionStatement',
+ [
+ 'expression',
+ ],
+)
+
+FurAssignmentStatement = collections.namedtuple(
+ 'FurAssignmentStatement',
+ [
+ 'target',
+ 'expression',
+ ],
+)
+
+FurFunctionDefinitionStatement = collections.namedtuple(
+ 'FurFunctionDefinitionStatement',
+ [
+ 'name',
+ 'argument_name_list',
+ 'statement_list',
+ ],
+)
+
FurProgram = collections.namedtuple(
'FurProgram',
[
],
)
-def _function_call_parser(index, tokens):
+def _list_item_expression_parser(index, tokens):
failure = (False, index, None)
- if tokens[index].type != 'symbol':
+ # We have to be careful what expressions we add here. Otherwise expressions
+ # like "a + b[0]" become ambiguous to the parser.
+ success, index, list_expression = _or_parser(
+ _symbol_expression_parser,
+ _parenthesized_expression_parser,
+ )(index, tokens)
+
+ if not success:
return failure
- name = tokens[index].match
- index += 1
- if tokens[index].type != 'open_parenthese':
+ success, index, index_expression = _bracket_wrapped_parser(_expression_parser)(
+ index,
+ tokens,
+ )
+
+ if not success:
return failure
- index += 1
- success, index, argument = _addition_level_expression_parser(index, tokens)
+ while success and index < len(tokens):
+ # "list_expression" is actually the full list item expression if the next parse attempt doesn't succeed
+ # We can't give this a better name without a bunch of checks, however.
+ list_expression = FurListItemExpression(
+ list_expression=list_expression,
+ index_expression=index_expression,
+ )
+
+ success, index, index_expression = _bracket_wrapped_parser(_expression_parser)(
+ index,
+ tokens,
+ )
+
+ return True, index, list_expression
+
+def _function_call_expression_parser(index, tokens):
+ failure = (False, index, None)
+
+ # We have to be careful what expressions we add here. Otherwise expressions
+ # like "a + b()" become ambiguous to the parser.
+ success, index, function = _or_parser(
+ _symbol_expression_parser,
+ _parenthesized_expression_parser,
+ )(index, tokens)
if not success:
return failure
- if tokens[index].type != 'close_parenthese':
+ success, index, arguments = _parenthese_wrapped_parser(_comma_separated_expression_list_parser)(
+ index,
+ tokens,
+ )
+
+ if not success:
return failure
- index += 1
- return True, index, FunctionCall(name=name, arguments=(argument,))
+ while success and index < len(tokens):
+ # "function" is actually the full function call if the next parse attempt doesn't succeed
+ # We can't give this a better name without a bunch of checks, however.
+ function = FurFunctionCallExpression(
+ function=function,
+ arguments=arguments,
+ )
+
+ success, index, arguments = _parenthese_wrapped_parser(_comma_separated_expression_list_parser)(
+ index,
+ tokens,
+ )
+
+ return True, index, function
+
+def _if_expression_parser(index, tokens):
+ failure = (False, index, None)
+
+ if tokens[index].match == 'if':
+ index += 1
+ else:
+ return failure
+
+ success, index, condition_expression = _or_level_expression_parser(index, tokens)
+
+ if not success:
+ raise Exception('Expected condition after "if" on line {}'.format(tokens[index].line))
+
+ if tokens[index].match == 'do':
+ index += 1
+ else:
+ raise Exception('Expected "do" after "if" on line {}'.format(tokens[index].line))
+
+
+ success, index, if_statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
+ _, index, _ = consume_newlines(index, tokens)
+
+ if tokens[index].match == 'else':
+ index += 1
+ success, index, else_statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
+ _, index, _ = consume_newlines(index, tokens)
+ else:
+ else_statement_list = ()
+
+ if tokens[index].match == 'end':
+ index += 1
+ else:
+ raise Exception('Expected "end" after "if" on line {}'.format(tokens[index].line))
+
+ return (
+ True,
+ index,
+ FurIfExpression(
+ condition_expression=condition_expression,
+ if_statement_list=if_statement_list,
+ else_statement_list=else_statement_list,
+ ),
+ )
+
+_expression_parser = _or_parser(
+ _or_level_expression_parser,
+ _if_expression_parser, # This should always be at the top level
+)
+
+def _expression_statement_parser(index, tokens):
+ failure = (False, index, None)
+
+ success, index, expression = _expression_parser(index, tokens)
+
+ if not success:
+ return failure
+
+ return (True, index, FurExpressionStatement(expression=expression))
+
+BUILTINS = {'print', 'pow'}
+
+def _assignment_statement_parser(index, tokens):
+ failure = (False, index, None)
+
+ if tokens[index].type == 'symbol':
+ target = tokens[index].match
+ target_assignment_line = tokens[index].line
+
+ index += 1
+ else:
+ return failure
+
+
+ if tokens[index].type == 'assignment_operator':
+ if target in BUILTINS:
+ raise Exception(
+ 'Trying to assign to builtin "{}" on line {}'.format(target, target_assignment_line),
+ )
+ assignment_operator_index = index
+ else:
+ return failure
+
+ success, index, expression = _expression_parser(index + 1, tokens)
+
+ if not success:
+ raise Exception(
+ 'Expected expression after assignment operator on line {}'.format(
+ tokens[assignment_operator_index].line
+ )
+ )
+
+ return True, index, FurAssignmentStatement(target=target, expression=expression)
+
+def _function_definition_statement_parser(index, tokens):
+ failure = (False, index, None)
+
+ if tokens[index].type == 'keyword' and tokens[index].match == 'def':
+ index += 1
+ else:
+ return failure
+
+ if tokens[index].type == 'symbol':
+ name = tokens[index].match
+ index += 1
+ else:
+ raise Exception('Expected function name, found "{}" on line {}'.format(
+ tokens[index].match,
+ tokens[index].line,
+ ))
+
+ if tokens[index].type == 'open_parenthese':
+ index += 1
+ else:
+ raise Exception('Expected "(", found "{}" on line {}'.format(
+ tokens[index].match,
+ tokens[index].line,
+ ))
+
+ success, index, argument_name_list = _comma_separated_list_parser(_symbol_expression_parser)(
+ index,
+ tokens,
+ )
+
+ if tokens[index].type == 'close_parenthese':
+ index += 1
+ else:
+ raise Exception('Expected ")", found "{}" on line {}'.format(
+ tokens[index].match,
+ tokens[index].line,
+ ))
+
+ if tokens[index].match == 'do':
+ index += 1
+ else:
+ return failure
+
+ success, index, statement_list = _zero_or_more_parser(tuple, _statement_parser)(index, tokens)
+
+ _, index, _ = consume_newlines(index, tokens)
+
+ if tokens[index].type == 'keyword' and tokens[index].match == 'end':
+ index += 1
+ else:
+ return failure
+
+ return True, index, FurFunctionDefinitionStatement(
+ name=name,
+ argument_name_list=tuple(an.symbol for an in argument_name_list),
+ statement_list=statement_list,
+ )
+
+def _statement_parser(index, tokens):
+ _, index, _ = consume_newlines(index, tokens)
+
+ if index == len(tokens):
+ return (False, index, None)
+
+ return _or_parser(
+ _assignment_statement_parser,
+ _expression_statement_parser,
+ _function_definition_statement_parser,
+ )(index, tokens)
def _program_formatter(statement_list):
return FurProgram(statement_list=statement_list)
-_program_parser = _zero_or_more_parser(_program_formatter, _function_call_parser)
+_program_parser = _zero_or_more_parser(_program_formatter, _statement_parser)
def _parse(parser, tokens):
success, index, result = parser(0, tokens)
raise Exception('Unable to parse')
-
def parse(tokens):
return _parse(_program_parser, tokens)
(
True,
1,
- FurStringLiteralExpression(value='Hello, world'),
+ FurStringLiteralExpression(string='Hello, world'),
),
)
- class FunctionCallParserTests(unittest.TestCase):
+ class FurFunctionCallExpressionParserTests(unittest.TestCase):
def test_parses_function_with_string_literal_argument(self):
self.assertEqual(
- _function_call_parser(0, tokenization.tokenize("print('Hello, world')")),
+ _function_call_expression_parser(0, tokenization.tokenize("print('Hello, world')")),
(
True,
4,
- FunctionCall(
+ FurFunctionCallExpression(
name='print',
- arguments=(FurStringLiteralExpression(value='Hello, world'),),
+ arguments=(FurStringLiteralExpression(string='Hello, world'),),
),
),
)