173 lines
4.9 KiB
Python
173 lines
4.9 KiB
Python
# SPDX-License-Identifier: MIT
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from .errors import ExpectedClosingQuoteError, InvalidEndOfQuotedStringError, UnexpectedQuoteError
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# map from opening quotes to closing quotes
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_quotes = {
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'"': '"',
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"‘": "’", # noqa: RUF001
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"‚": "‛", # noqa: RUF001
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"“": "”",
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"„": "‟",
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"⹂": "⹂",
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"「": "」",
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"『": "』",
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"〝": "〞",
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"﹁": "﹂",
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"﹃": "﹄",
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"＂": "＂", # noqa: RUF001
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"｢": "｣",
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"«": "»",
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"‹": "›", # noqa: RUF001
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"《": "》",
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"〈": "〉",
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}
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_all_quotes = set(_quotes.keys()) | set(_quotes.values())
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class StringView:
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def __init__(self, buffer: str) -> None:
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self.index = 0
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self.buffer = buffer
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self.end = len(buffer)
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self.previous = 0
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@property
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def current(self):
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return None if self.eof else self.buffer[self.index]
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@property
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def eof(self):
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return self.index >= self.end
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def undo(self) -> None:
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self.index = self.previous
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def skip_ws(self):
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pos = 0
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while not self.eof:
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try:
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current = self.buffer[self.index + pos]
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if not current.isspace():
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break
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pos += 1
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except IndexError:
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break
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self.previous = self.index
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self.index += pos
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return self.previous != self.index
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def skip_string(self, string: str) -> bool:
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strlen = len(string)
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if self.buffer[self.index : self.index + strlen] == string:
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self.previous = self.index
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self.index += strlen
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return True
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return False
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def read_rest(self):
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result = self.buffer[self.index :]
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self.previous = self.index
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self.index = self.end
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return result
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def read(self, n):
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result = self.buffer[self.index : self.index + n]
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self.previous = self.index
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self.index += n
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return result
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def get(self):
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try:
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result = self.buffer[self.index + 1]
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except IndexError:
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result = None
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self.previous = self.index
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self.index += 1
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return result
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def get_word(self):
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pos = 0
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while not self.eof:
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try:
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current = self.buffer[self.index + pos]
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if current.isspace():
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break
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pos += 1
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except IndexError:
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break
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self.previous = self.index
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result = self.buffer[self.index : self.index + pos]
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self.index += pos
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return result
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def get_quoted_word(self):
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current = self.current
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if current is None:
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return None
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close_quote = _quotes.get(current)
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is_quoted = bool(close_quote)
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if is_quoted:
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result = []
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_escaped_quotes = (current, close_quote)
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else:
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result = [current]
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_escaped_quotes = _all_quotes
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while not self.eof:
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current = self.get()
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if not current:
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if is_quoted:
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# unexpected EOF
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raise ExpectedClosingQuoteError(str(close_quote))
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return "".join(result)
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# currently we accept strings in the format of "hello world"
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# to embed a quote inside the string you must escape it: "a \"world\""
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if current == "\\":
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next_char = self.get()
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if not next_char:
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# string ends with \ and no character after it
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if is_quoted:
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# if we're quoted then we're expecting a closing quote
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raise ExpectedClosingQuoteError(str(close_quote))
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# if we aren't then we just let it through
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return "".join(result)
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if next_char in _escaped_quotes:
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# escaped quote
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result.append(next_char)
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else:
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# different escape character, ignore it
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self.undo()
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result.append(current)
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continue
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if not is_quoted and current in _all_quotes:
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# we aren't quoted
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raise UnexpectedQuoteError(current)
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# closing quote
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if is_quoted and current == close_quote:
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next_char = self.get()
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valid_eof = not next_char or next_char.isspace()
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if not valid_eof:
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raise InvalidEndOfQuotedStringError(str(next_char))
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# we're quoted so it's okay
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return "".join(result)
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if current.isspace() and not is_quoted:
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# end of word found
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return "".join(result)
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result.append(current)
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def __repr__(self) -> str:
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return (
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f"<StringView pos: {self.index} prev: {self.previous} end: {self.end} eof: {self.eof}>"
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)
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