130 lines
3 KiB
Python
130 lines
3 KiB
Python
# Copyright 2016 Google Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import sys
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from typing import Union, List, Optional
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from . import util
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KEYWORDS = 'const var procedure call begin end if then while do odd'.lower(
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).split()
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class Token(util.ReprMixin):
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__slots__ = 'val', 'line'
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def __init__(self, val: Union[str, int], line: int) -> None:
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self.val = val
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self.line = line
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def typename(self) -> str:
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return self.__class__.__name__.lower()
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class Ident(Token):
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pass
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class Keyword(Token):
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pass
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class Number(Token):
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pass
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class PeekStream:
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def __init__(self, src: List[str]) -> None:
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self.src = src
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self.at = -1
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def peek(self) -> Optional[str]:
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idx = self.at + 1
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if idx >= len(self.src):
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return None
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else:
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return self.src[idx]
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def read(self) -> Optional[str]:
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idx = self.at + 1
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if idx >= len(self.src):
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return None
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else:
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self.at = idx
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return self.src[idx]
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def __len__(self) -> int:
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return len(self.src) - self.at - 1
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def accumulate(stream: PeekStream, first: str, cond) -> str:
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out = first
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while stream:
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ch = stream.peek()
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if ch is None:
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break
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if not cond(ch):
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break
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got = stream.read()
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if got is None:
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break
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out += got
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return out
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def lex(src):
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stream = PeekStream(src)
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line = 1
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sol = True
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while stream:
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ch = stream.read()
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if ch is None:
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break
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if ch.isspace():
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if ch == '\n':
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line += 1
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sol = True
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elif ch == '#' and sol:
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while stream.peek() not in ['\n', None]:
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stream.read()
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else:
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sol = False
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if ch.isalpha():
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token = accumulate(stream, ch, str.isalnum)
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if token.lower() in KEYWORDS:
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yield Keyword(token.lower(), line)
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else:
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yield Ident(token, line)
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elif ch.isdigit():
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yield Number(int(accumulate(stream, ch, str.isdigit)), line)
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elif ch in '<>' and stream.peek() == '=':
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yield Token(ch + stream.read(), line)
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elif ch == ':' and stream.peek() == '=':
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yield Token(ch + stream.read(), line)
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else:
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yield Token(ch, line)
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def main():
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for token in lex(sys.stdin.read()):
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print(token)
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if __name__ == '__main__':
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main()
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