70 lines
1.7 KiB
Python
70 lines
1.7 KiB
Python
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from enum import Enum
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class Tokens(Enum):
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QUOTE = 1,
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CHAR = 2,
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NEWLINE = 3
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class Lexer:
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tokens = list()
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def __init__(self):
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pass
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def lex(self, str):
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for c in str:
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if c == "'" or c == '"':
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self.tokens.append(Tokens.QUOTE)
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elif c == "\n":
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self.tokens.append(Tokens.NEWLINE)
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else:
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self.tokens.append(Tokens.CHAR)
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def __str__(self):
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return ",".join(Tokens(token).name for token in self.tokens)
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class States(Enum):
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INITIAL = 0,
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BEGINQUOTE = 1
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class Parser:
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def __init__(self):
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self.state = States.INITIAL
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self.line = 1
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def transition(self, state):
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print(f"{States(self.state).name} -> {States(state).name}")
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self.state = state
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def parse(self, tokens):
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for token in tokens:
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if self.state == States.INITIAL:
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if token == Tokens.QUOTE:
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self.transition(States.BEGINQUOTE)
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elif token == Tokens.NEWLINE:
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self.line += 1
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continue
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if self.state == States.BEGINQUOTE:
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if token == Tokens.QUOTE:
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self.transition(States.INITIAL)
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elif token == Tokens.CHAR:
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pass
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elif token == Tokens.NEWLINE:
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raise ValueError(f"Unterminated string on line {self.line}")
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continue
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if __name__ == "__main__":
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test1 = """abcdefg
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"abcde"
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'a
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bareword
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"""
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lexer = Lexer()
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lexer.lex(test1)
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# print(lexer)
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parser = Parser()
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try:
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parser.parse(lexer.tokens)
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except ValueError as error:
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print(error)
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