65 lines
2 KiB
Python
65 lines
2 KiB
Python
#!/usr/bin/env python3
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# Copyright (c) 2026-present, the Ladybird developers.
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#
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# SPDX-License-Identifier: BSD-2-Clause
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from typing import Callable
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class Lexer:
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def __init__(self, text: str) -> None:
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self.text = text
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self.position = 0
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def tell(self) -> int:
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return self.position
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def is_eof(self) -> bool:
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return self.position >= len(self.text)
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def peek(self, offset: int = 0) -> str:
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position = self.position + offset
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if position >= len(self.text):
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return "\0"
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return self.text[position]
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def consume(self) -> str:
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if self.is_eof():
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return "\0"
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ch = self.text[self.position]
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self.position += 1
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return ch
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def consume_specific(self, string: str) -> bool:
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if self.text.startswith(string, self.position):
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self.position += len(string)
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return True
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return False
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def next_is(self, string: str) -> bool:
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return self.text.startswith(string, self.position)
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def consume_until(self, predicate: Callable[[str], bool]) -> str:
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start = self.position
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while self.position < len(self.text) and not predicate(self.text[self.position]):
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self.position += 1
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return self.text[start : self.position]
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def consume_while(self, predicate: Callable[[str], bool]) -> str:
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start = self.position
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while self.position < len(self.text) and predicate(self.text[self.position]):
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self.position += 1
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return self.text[start : self.position]
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def ignore(self, count: int = 1) -> None:
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self.position = min(self.position + count, len(self.text))
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def ignore_until(self, ch: str) -> None:
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while self.position < len(self.text) and self.text[self.position] != ch:
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self.position += 1
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def ignore_while(self, predicate: Callable[[str], bool]) -> None:
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while self.position < len(self.text) and predicate(self.text[self.position]):
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self.position += 1
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