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diff --git a/rod/lexbase.nim b/rod/lexbase.nim
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+#
+#
+#           The Nimrod Compiler
+#        (c) Copyright 2008 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+# Base Object of a lexer with efficient buffer handling. In fact
+# I believe that this is the most efficient method of buffer
+# handling that exists! Only at line endings checks are necessary
+# if the buffer needs refilling.
+
+import 
+  llstream, strutils
+
+const 
+  Lrz* = ' '
+  Apo* = '\''
+  Tabulator* = '\x09'
+  ESC* = '\x1B'
+  CR* = '\x0D'
+  FF* = '\x0C'
+  LF* = '\x0A'
+  BEL* = '\x07'
+  BACKSPACE* = '\x08'
+  VT* = '\x0B'
+
+const 
+  EndOfFile* = '\0'           # end of file marker
+                              # A little picture makes everything clear :-)
+                              #  buf:
+                              #  "Example Text\n ha!"   bufLen = 17
+                              #   ^pos = 0     ^ sentinel = 12
+                              #
+  NewLines* = {CR, LF}
+
+type 
+  TBaseLexer* = object of TObject
+    bufpos*: int
+    buf*: cstring
+    bufLen*: int              # length of buffer in characters
+    stream*: PLLStream        # we read from this stream
+    LineNumber*: int          # the current line number
+                              # private data:
+    sentinel*: int
+    lineStart*: int           # index of last line start in buffer
+  
+
+proc openBaseLexer*(L: var TBaseLexer, inputstream: PLLStream, 
+                    bufLen: int = 8192)
+  # 8K is a reasonable buffer size
+proc closeBaseLexer*(L: var TBaseLexer)
+proc getCurrentLine*(L: TBaseLexer, marker: bool = true): string
+proc getColNumber*(L: TBaseLexer, pos: int): int
+proc HandleCR*(L: var TBaseLexer, pos: int): int
+  # Call this if you scanned over CR in the buffer; it returns the
+  # position to continue the scanning from. `pos` must be the position
+  # of the CR.
+proc HandleLF*(L: var TBaseLexer, pos: int): int
+  # Call this if you scanned over LF in the buffer; it returns the the
+  # position to continue the scanning from. `pos` must be the position
+  # of the LF.
+# implementation
+
+const 
+  chrSize = sizeof(char)
+
+proc closeBaseLexer(L: var TBaseLexer) = 
+  dealloc(L.buf)
+  LLStreamClose(L.stream)
+
+proc FillBuffer(L: var TBaseLexer) = 
+  var 
+    charsRead, toCopy, s: int # all are in characters,
+                              # not bytes (in case this
+                              # is not the same)
+    oldBufLen: int
+  # we know here that pos == L.sentinel, but not if this proc
+  # is called the first time by initBaseLexer()
+  assert(L.sentinel < L.bufLen)
+  toCopy = L.BufLen - L.sentinel - 1
+  assert(toCopy >= 0)
+  if toCopy > 0: 
+    MoveMem(L.buf, addr(L.buf[L.sentinel + 1]), toCopy * chrSize) # "moveMem" handles overlapping regions
+  charsRead = LLStreamRead(L.stream, addr(L.buf[toCopy]), 
+                           (L.sentinel + 1) * chrSize) div chrSize
+  s = toCopy + charsRead
+  if charsRead < L.sentinel + 1: 
+    L.buf[s] = EndOfFile      # set end marker
+    L.sentinel = s
+  else: 
+    # compute sentinel:
+    dec(s)                    # BUGFIX (valgrind)
+    while true: 
+      assert(s < L.bufLen)
+      while (s >= 0) and not (L.buf[s] in NewLines): Dec(s)
+      if s >= 0: 
+        # we found an appropriate character for a sentinel:
+        L.sentinel = s
+        break 
+      else: 
+        # rather than to give up here because the line is too long,
+        # double the buffer's size and try again:
+        oldBufLen = L.BufLen
+        L.bufLen = L.BufLen * 2
+        L.buf = cast[cstring](realloc(L.buf, L.bufLen * chrSize))
+        assert(L.bufLen - oldBuflen == oldBufLen)
+        charsRead = LLStreamRead(L.stream, addr(L.buf[oldBufLen]), 
+                                 oldBufLen * chrSize) div chrSize
+        if charsRead < oldBufLen: 
+          L.buf[oldBufLen + charsRead] = EndOfFile
+          L.sentinel = oldBufLen + charsRead
+          break 
+        s = L.bufLen - 1
+
+proc fillBaseLexer(L: var TBaseLexer, pos: int): int = 
+  assert(pos <= L.sentinel)
+  if pos < L.sentinel: 
+    result = pos + 1          # nothing to do
+  else: 
+    fillBuffer(L)
+    L.bufpos = 0              # XXX: is this really correct?
+    result = 0
+  L.lineStart = result
+
+proc HandleCR(L: var TBaseLexer, pos: int): int = 
+  assert(L.buf[pos] == CR)
+  inc(L.linenumber)
+  result = fillBaseLexer(L, pos)
+  if L.buf[result] == LF: 
+    result = fillBaseLexer(L, result)
+
+proc HandleLF(L: var TBaseLexer, pos: int): int = 
+  assert(L.buf[pos] == LF)
+  inc(L.linenumber)
+  result = fillBaseLexer(L, pos) #L.lastNL := result-1; // BUGFIX: was: result;
+  
+proc skip_UTF_8_BOM(L: var TBaseLexer) = 
+  if (L.buf[0] == '\xEF') and (L.buf[1] == '\xBB') and (L.buf[2] == '\xBF'): 
+    inc(L.bufpos, 3)
+    inc(L.lineStart, 3)
+
+proc openBaseLexer(L: var TBaseLexer, inputstream: PLLStream, bufLen: int = 8192) = 
+  assert(bufLen > 0)
+  L.bufpos = 0
+  L.bufLen = bufLen
+  L.buf = cast[cstring](alloc(bufLen * chrSize))
+  L.sentinel = bufLen - 1
+  L.lineStart = 0
+  L.linenumber = 1            # lines start at 1
+  L.stream = inputstream
+  fillBuffer(L)
+  skip_UTF_8_BOM(L)
+
+proc getColNumber(L: TBaseLexer, pos: int): int = 
+  result = abs(pos - L.lineStart)
+
+proc getCurrentLine(L: TBaseLexer, marker: bool = true): string = 
+  var i: int
+  result = ""
+  i = L.lineStart
+  while not (L.buf[i] in {CR, LF, EndOfFile}): 
+    add(result, L.buf[i])
+    inc(i)
+  result = result & "\n"
+  if marker: 
+    result = result & RepeatChar(getColNumber(L, L.bufpos)) & '^' & "\n"
+  
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