RegExParser with working test cases
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@ -1,20 +1,39 @@
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class RegExp:
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def __init__(self, *args):
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self.args = args
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def __repr__(self):
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args = ", ".join(map(repr, self.args))
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return f"{self.__class__.__name__}({args})"
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def __eq__(self, other):
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return type(self) is type(other) and self.args == other.args
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class Any(RegExp): pass
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class Normal(RegExp): pass
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class Or(RegExp): pass
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class Str(RegExp): pass
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class ZeroOrMore(RegExp): pass
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class Any(RegExp):
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pass
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class Normal(RegExp):
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pass
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class Or(RegExp):
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pass
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class Str(RegExp):
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pass
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class ZeroOrMore(RegExp):
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pass
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# Your task is to build an AST using those nodes.
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# See sample tests or test output for examples of usage.
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def parse_regexp(indata):
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return RegExParser(indata).compile()
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@ -46,6 +65,8 @@ class RegExParser:
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if any([not string or string.count("|") > 1 for string in sequences]):
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return False
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elif isinstance(sequences, str) and sequences.count("|") > 1:
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return False
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if self.pattern.find("*") == 0:
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return False
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@ -57,33 +78,47 @@ class RegExParser:
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@staticmethod
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def parse_sequences(pattern):
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left_paren = pattern.find('(')
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right_paren = pattern.rfind(')')
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if left_paren == -1 and right_paren == -1:
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return [pattern]
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if left_paren == -1 or right_paren == -1:
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return None
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if left_paren > right_paren:
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return None
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left_side = pattern[:left_paren]
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middle = pattern[left_paren + 1: right_paren]
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right_side = pattern[right_paren + 1:]
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result = []
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if left_side:
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result.append(left_side)
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buffer = []
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depth = 0
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if middle:
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result.append(RegExParser.parse_sequences(middle))
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left_paren_count = pattern.count("(")
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right_paren_count = pattern.count(")")
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if left_paren_count == -1 and right_paren_count == -1:
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return [pattern]
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if left_paren_count == -1 or right_paren_count == -1:
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return None
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if left_paren_count > right_paren_count:
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return None
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if right_side:
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result.append(right_side)
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for c in pattern:
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if c == "(":
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if depth == 0:
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if buffer:
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result.append("".join(buffer))
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buffer = []
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else:
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buffer.append(c)
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depth += 1
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return result
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elif c == ")":
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depth -= 1
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if depth < 0:
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return None
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elif depth == 0:
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group = "".join(buffer)
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result.append(RegExParser.parse_sequences(group))
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buffer = []
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else:
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buffer.append(c)
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else:
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buffer.append(c)
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if buffer:
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result.append("".join(buffer))
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return result if len(result) > 1 else result[0]
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@staticmethod
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def parse_regex(sequences) -> RegExp | None:
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@ -106,15 +141,50 @@ class RegExParser:
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else:
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result: list[RegExp] = []
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for sequence_idx in range(len(sequences)):
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sequence_idx = 0
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while sequence_idx < len(sequences):
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current_sequence = sequences[sequence_idx]
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if sequence_idx < len(sequences) - 1:
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next_sequence = sequences[sequence_idx + 1]
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if isinstance(next_sequence, str) and next_sequence.startswith("*"):
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if isinstance(next_sequence, str) and next_sequence.startswith(
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"*|"
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):
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next_sequence = next_sequence[2:]
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if next_sequence:
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sequence_idx += 1
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else:
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sequence_idx += 2
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next_sequence = sequences[sequence_idx]
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regex = Or(
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ZeroOrMore(RegExParser.parse_regex(current_sequence)),
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RegExParser.parse_regex(next_sequence),
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)
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if regex:
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result.append(regex)
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elif isinstance(next_sequence, str) and next_sequence.startswith(
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"*"
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):
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next_sequence = next_sequence[1:]
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regex = ZeroOrMore(RegExParser.parse_regex(current_sequence))
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if regex:
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result.append(regex)
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elif isinstance(next_sequence, str) and next_sequence.startswith(
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"|"
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):
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next_sequence = next_sequence[1:]
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if next_sequence:
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sequence_idx += 1
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else:
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sequence_idx += 2
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next_sequence = sequences[sequence_idx]
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regex = Or(
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RegExParser.parse_regex(current_sequence),
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RegExParser.parse_regex(next_sequence),
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)
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if regex:
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result.append(regex)
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else:
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regex = RegExParser.parse_regex(current_sequence)
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if regex:
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@ -124,9 +194,10 @@ class RegExParser:
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if regex:
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result.append(regex)
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sequence_idx += 1
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return Str(result) if len(result) > 1 else result[0]
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@staticmethod
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def get_type(sequence) -> RegExp:
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regex: RegExp
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@ -154,17 +225,9 @@ class RegExParser:
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return regex
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if __name__ == "__main__":
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test_cases = [
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"",
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"(",
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"(hi!",
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")(",
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"a|t|y",
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"a**",
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"]K\nBYg<y)eoqj9+~Nim,$#-LkOM\\0E6zxC1^:WfD4A/v`@w.%J8_s(x|[\rI",
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"((aa)|ab)*|a"
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]
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test_cases = ["((aa)|ab)*|a"]
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for test_case in test_cases:
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print("---------------------")
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