412 lines
11 KiB
Python
412 lines
11 KiB
Python
"""
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The Buffer class provides the functionality required by a parser-driven lexer.
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Line analysis and caching are done so the parser can freely move with goto(p)
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to any position in the parsed text, and still recover accurate information
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about source lines and content.
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"""
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from __future__ import annotations
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import re
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from itertools import repeat, takewhile
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from pathlib import Path
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from typing import Any
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from .exceptions import ParseError
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from .infos import (
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CommentInfo,
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LineIndexInfo,
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LineInfo,
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ParserConfig,
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PosLine,
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UndefinedStr,
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)
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from .tokenizing import Tokenizer
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from .util import (
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contains_sublist,
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extend_list,
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identity,
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)
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from .util.misc import cached_re_compile, match_to_find
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DEFAULT_WHITESPACE_RE = re.compile(r'(?m)\s+')
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# for backwards compatibility with existing parsers
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LineIndexEntry = LineIndexInfo
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class Buffer(Tokenizer):
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def __init__(
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self, text, /, config: ParserConfig | None = None, **settings: Any,
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):
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super().__init__()
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config = ParserConfig.new(config=config, owner=self, **settings)
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self.config = config
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text = str(text)
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self.text = self.original_text = text
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self.whitespace_re = self.build_whitespace_re(config.whitespace)
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self.nameguard = (
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config.nameguard
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if config.nameguard is not None
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else bool(self.whitespace_re) or bool(config.namechars)
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)
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self._namechar_set = set(config.namechars)
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self._pos = 0
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self._len = 0
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self._linecount = 0
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self._lines: list[str] = []
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self._line_index: list[LineIndexInfo] = []
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self._line_cache: list[PosLine] = []
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self._comment_index: list[CommentInfo] = []
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self._preprocess()
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self._postprocess()
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@property
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def filename(self):
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return self.config.filename
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@property
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def ignorecase(self):
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return self.config.ignorecase
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@property
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def whitespace(self):
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return self.config.whitespace
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@staticmethod
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def build_whitespace_re(whitespace):
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if type(whitespace) is UndefinedStr:
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return DEFAULT_WHITESPACE_RE
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if whitespace in {None, ''}:
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return None
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elif isinstance(whitespace, re.Pattern):
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return whitespace
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elif whitespace:
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return cached_re_compile(whitespace)
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else:
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return None
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def _preprocess(self, *args, **kwargs):
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lines, index = self._preprocess_block(self.filename, self.text)
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self._lines = lines
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self._line_index = index
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self.text = self.join_block_lines(lines)
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def _postprocess(self):
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cache, count = PosLine.build_line_cache(self._lines)
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self._line_cache = cache
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self._linecount = count
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self._len = len(self.text)
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def _preprocess_block(self, name, block, **kwargs):
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lines = self.split_block_lines(block)
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index = LineIndexInfo.block_index(name, len(lines))
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return self.process_block(name, lines, index, **kwargs)
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def split_block_lines(self, block):
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return block.splitlines(True)
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def join_block_lines(self, lines):
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return ''.join(lines)
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def process_block(self, name, lines, index, **kwargs):
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return lines, index
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def include(self, lines, index, i, j, name, block, **kwargs):
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blines, bindex = self._preprocess_block(name, block, **kwargs)
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assert len(blines) == len(bindex)
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lines[i:j] = blines
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index[i:j] = bindex
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assert len(lines) == len(index)
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return j + len(blines) - 1
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def include_file(self, source, name, lines, index, i, j):
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text, filename = self.get_include(source, name)
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return self.include(lines, index, i, j, filename, text)
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def get_include(self, source, filename):
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source = Path(source).resolve()
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base = source.parent
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include = base / filename
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try:
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with include.open() as f:
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return f.read(), include
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except OSError as e:
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raise ParseError(f'include not found: {include}') from e
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def replace_lines(self, i, j, name, block):
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lines = self.split_block_lines(self.text)
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index = list(self._line_index)
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endline = self.include(lines, index, i, j, name, block)
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self.text = self.join_block_lines(lines)
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self._line_index = index
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self._postprocess()
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newtext = self.join_block_lines(lines[j + 1: endline + 2])
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return endline, newtext
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@property
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def pos(self):
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return self._pos
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@pos.setter
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def pos(self, p):
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self.goto(p)
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@property
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def line(self):
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return self.posline()
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@property
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def col(self):
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return self.poscol()
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def posline(self, pos=None):
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if pos is None:
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pos = self._pos
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return self._line_cache[pos].line
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def poscol(self, pos=None):
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if pos is None:
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pos = self._pos
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start = self._line_cache[pos].start
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return pos - start
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def atend(self):
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return self._pos >= self._len
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def ateol(self):
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return self.atend() or self.current in '\r\n'
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@property
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def current(self):
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if self._pos >= self._len:
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return None
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return self.text[self._pos]
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def at(self, p):
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if p >= self._len:
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return None
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return self.text[p]
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def peek(self, n=1):
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return self.at(self._pos + n)
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def next(self):
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if self.atend():
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return None
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c = self.text[self._pos]
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self._pos += 1
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return c
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def goto(self, pos):
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self._pos = max(0, min(len(self.text), pos))
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def move(self, n):
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self.goto(self.pos + n)
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def comments(self, p, clear=False):
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if not self.config.comment_recovery or not self._comment_index:
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return CommentInfo([], [])
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n = self.posline(p)
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if n >= len(self._comment_index):
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return CommentInfo([], [])
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eolcmm = []
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if n < len(self._comment_index):
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eolcmm = self._comment_index[n].eol
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if clear:
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self._comment_index[n].eol = []
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cmm = []
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while n >= 0 and self._comment_index[n].inline:
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cmm.insert(0, self._comment_index[n].inline)
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if clear:
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self._comment_index[n].inline = []
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n -= 1
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return CommentInfo(cmm, eolcmm)
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def _index_comments(self, comments, selector):
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if comments and self.config.comment_recovery:
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n = self.line
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extend_list(
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self._comment_index, n, default=CommentInfo.new_comment,
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)
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previous = selector(self._comment_index[n])
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if not contains_sublist(
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previous, comments,
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): # FIXME: will discard repeated comments
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previous.extend(comments)
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def _eat_regex(self, regex):
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if not regex:
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return
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while self._matchre_fast(regex):
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pass
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def _eat_regex_list(self, regex):
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if not regex:
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return []
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regex = cached_re_compile(regex)
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return list(takewhile(identity, map(self.matchre, repeat(regex))))
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def eat_whitespace(self):
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return self._eat_regex(self.whitespace_re)
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def eat_comments(self):
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comments = self._eat_regex_list(self.config.comments)
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self._index_comments(comments, lambda x: x.inline)
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def eat_eol_comments(self):
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comments = self._eat_regex_list(self.config.eol_comments)
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self._index_comments(comments, lambda x: x.eol)
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def next_token(self):
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p = None
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while self._pos != p:
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p = self._pos
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self.eat_eol_comments()
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self.eat_comments()
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self.eat_whitespace()
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def skip_to(self, c):
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p = self._pos
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le = self._len
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while p < le and self.text[p] != c:
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p += 1
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self.goto(p)
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return self.pos
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def skip_past(self, c):
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self.skip_to(c)
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self.next()
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return self.pos
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def skip_to_eol(self):
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return self.skip_to('\n')
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def scan_space(self):
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return (
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self.whitespace_re and self._scanre(self.whitespace_re) is not None
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)
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def is_space(self):
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return self.scan_space()
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def is_name_char(self, c):
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return c is not None and (c.isalnum() or c in self._namechar_set)
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def match(self, token: str) -> str | None:
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if token is None:
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return self.atend()
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p = self.pos
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if self.ignorecase:
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is_match = self.text[p: p + len(token)].lower() == token.lower()
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else:
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is_match = self.text[p: p + len(token)] == token
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if not is_match:
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return None
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self.move(len(token))
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partial_match = (
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self.nameguard
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and token
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and token[0].isalpha()
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and self.is_name_char(self.current)
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and all(self.is_name_char(t) for t in token)
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)
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if partial_match:
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self.goto(p)
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return None
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return token
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def _matchre_fast(self, pattern):
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if not (match := self._scanre(pattern)):
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return
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self.move(len(match.group()))
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def matchre(self, pattern):
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if not (match := self._scanre(pattern)):
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return None
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matched = match.group()
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token = match_to_find(match)
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self.move(len(matched))
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return token
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def _scanre(self, pattern):
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cre = cached_re_compile(pattern)
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return cre.match(self.text, self.pos)
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@property
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def linecount(self):
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return self._linecount
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def line_info(self, pos=None):
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if pos is None:
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pos = self._pos
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# -2 to skip over sentinel
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pos = min(pos, len(self._line_cache) - 2)
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start, line, length = self._line_cache[pos]
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end = start + length
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col = pos - start
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text = self.text[start:end]
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# only required to support includes
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n = min(len(self._line_index) - 1, line)
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filename, line = self._line_index[n]
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return LineInfo(filename, line, col, start, end, text)
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def lookahead_pos(self):
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if self.atend():
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return ''
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info = self.line_info()
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return '~%d:%d' % (info.line + 1, info.col + 1)
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def lookahead(self):
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if self.atend():
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return ''
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info = self.line_info()
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text = info.text[info.col: info.col + 1 + 80]
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text = self.split_block_lines(text)[0].rstrip()
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return f'{text}'
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def get_line(self, n=None):
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if n is None:
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n = self.line
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return self._lines[n]
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def get_lines(self, start=None, end=None):
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if start is None:
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start = 0
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if end is None:
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end = len(self._lines)
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return self._lines[start: end + 1]
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def line_index(self, start=0, end=None):
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if end is None:
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end = len(self._line_index)
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return self._line_index[start: 1 + end]
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def __repr__(self):
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return '%s@%d' % (type(self).__name__, self.pos)
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def __json__(self, seen=None):
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return None
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