lexbase

This module implements a base object of a lexer with efficient buffer handling. Only at line endings checks are necessary if the buffer needs refilling.

Imports

strutils, streams

Types

BaseLexer = object of RootObj
  bufpos*: int               ## the current position within the buffer
  buf*: string               ## the buffer itself
  input: Stream              ## the input stream
  lineNumber*: int           ## the current line number
  sentinel: int
  lineStart: int
  offsetBase*: int
  refillChars: set[char]

the base lexer. Inherit your lexer from this object. Source Edit

Consts

EndOfFile = '\x00'

end of file marker Source Edit

NewLines = {'\c', '\n'}

Source Edit

Procs

proc close(L: var BaseLexer) {...}{.raises: [Exception, IOError, OSError],
                               tags: [WriteIOEffect].}

closes the base lexer. This closes L's associated stream too. Source Edit

proc handleCR(L: var BaseLexer; pos: int): int {...}{.raises: [IOError, OSError],
    tags: [ReadIOEffect].}

Call this if you scanned over 'c' in the buffer; it returns the position to continue the scanning from. pos must be the position of the 'c'. Source Edit

proc handleLF(L: var BaseLexer; pos: int): int {...}{.raises: [IOError, OSError],
    tags: [ReadIOEffect].}

Call this if you scanned over 'L' in the buffer; it returns the position to continue the scanning from. pos must be the position of the 'L'. Source Edit

proc handleRefillChar(L: var BaseLexer; pos: int): int {...}{.
    raises: [IOError, OSError], tags: [ReadIOEffect].}

Call this if a terminator character other than a new line is scanned at pos; it returns the position to continue the scanning from. Source Edit

proc open(L: var BaseLexer; input: Stream; bufLen: int = 8192;
          refillChars: set[char] = NewLines) {...}{.raises: [IOError, OSError],
    tags: [ReadIOEffect].}

inits the BaseLexer with a stream to read from. Source Edit

proc getColNumber(L: BaseLexer; pos: int): int {...}{.raises: [], tags: [].}

retrieves the current column. Source Edit

proc getCurrentLine(L: BaseLexer; marker: bool = true): string {...}{.raises: [],
    tags: [].}

retrieves the current line. Source Edit