Merge branch 'master' of github.com:Araq/Nimrod

4 files changed, 573 insertions, 265 deletions

diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 57d06a988..cb0dcfe00 100755
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -933,22 +933,31 @@ proc genNew(p: BProc, e: PNode) =
   var
     a, b: TLoc
     reftype, bt: PType
+    sizeExpr: PRope
   refType = skipTypes(e.sons[1].typ, abstractVarRange)
   InitLocExpr(p, e.sons[1], a)
   initLoc(b, locExpr, a.t, OnHeap)
+  # 'genNew' also handles 'unsafeNew':
+  if e.len == 3:
+    var se: TLoc
+    InitLocExpr(p, e.sons[2], se)
+    sizeExpr = se.rdLoc
+  else:
+    sizeExpr = ropef("sizeof($1)",
+        getTypeDesc(p.module, skipTypes(reftype.sons[0], abstractRange)))
   let args = [getTypeDesc(p.module, reftype),
               genTypeInfo(p.module, refType),
-              getTypeDesc(p.module, skipTypes(reftype.sons[0], abstractRange))]
+              sizeExpr]
   if a.s == OnHeap and optRefcGc in gGlobalOptions:
     # use newObjRC1 as an optimization; and we don't need 'keepAlive' either
     if canFormAcycle(a.t):
       lineCg(p, cpsStmts, "if ($1) #nimGCunref($1);$n", a.rdLoc)
     else:
       lineCg(p, cpsStmts, "if ($1) #nimGCunrefNoCycle($1);$n", a.rdLoc)
-    b.r = ropecg(p.module, "($1) #newObjRC1($2, sizeof($3))", args)
+    b.r = ropecg(p.module, "($1) #newObjRC1($2, $3)", args)
     lineCg(p, cpsStmts, "$1 = $2;$n", a.rdLoc, b.rdLoc)
   else:
-    b.r = ropecg(p.module, "($1) #newObj($2, sizeof($3))", args)
+    b.r = ropecg(p.module, "($1) #newObj($2, $3)", args)
     genAssignment(p, a, b, {needToKeepAlive})  # set the object type:
   bt = skipTypes(refType.sons[0], abstractRange)
   genObjectInit(p, cpsStmts, bt, a, false)
diff --git a/compiler/ccgmerge.nim b/compiler/ccgmerge.nim
index df7e7f68b..027cd5780 100644
--- a/compiler/ccgmerge.nim
+++ b/compiler/ccgmerge.nim
@@ -145,20 +145,47 @@ proc atEndMark(buf: cstring, pos: int): bool =
   while s < NimMergeEndMark.len and buf[pos+s] == NimMergeEndMark[s]: inc s
   result = s == NimMergeEndMark.len
 
+when false:
+  proc readVerbatimSection(L: var TBaseLexer): PRope = 
+    var pos = L.bufpos
+    var buf = L.buf
+    result = newMutableRope(30_000)
+    while true:
+      case buf[pos]
+      of CR:
+        pos = lexbase.HandleCR(L, pos)
+        buf = L.buf
+        result.data.add(tnl)
+      of LF:
+        pos = lexbase.HandleLF(L, pos)
+        buf = L.buf
+        result.data.add(tnl)
+      of '\0':
+        InternalError("ccgmerge: expected: " & NimMergeEndMark)
+        break
+      else: 
+        if atEndMark(buf, pos):
+          inc pos, NimMergeEndMark.len
+          break
+        result.data.add(buf[pos])
+        inc pos
+    L.bufpos = pos
+    freezeMutableRope(result)
+
 proc readVerbatimSection(L: var TBaseLexer): PRope = 
   var pos = L.bufpos
   var buf = L.buf
-  result = newMutableRope(30_000)
+  var r = newStringOfCap(30_000)
   while true:
     case buf[pos]
     of CR:
       pos = lexbase.HandleCR(L, pos)
       buf = L.buf
-      result.data.add(tnl)
+      r.add(tnl)
     of LF:
       pos = lexbase.HandleLF(L, pos)
       buf = L.buf
-      result.data.add(tnl)
+      r.add(tnl)
     of '\0':
       InternalError("ccgmerge: expected: " & NimMergeEndMark)
       break
@@ -166,10 +193,10 @@ proc readVerbatimSection(L: var TBaseLexer): PRope =
       if atEndMark(buf, pos):
         inc pos, NimMergeEndMark.len
         break
-      result.data.add(buf[pos])
+      r.add(buf[pos])
       inc pos
   L.bufpos = pos
-  freezeMutableRope(result)
+  result = r.toRope
 
 proc readKey(L: var TBaseLexer, result: var string) =
   var pos = L.bufpos
diff --git a/compiler/docgen.nim b/compiler/docgen.nim
index 5d46be874..e06277f91 100755
--- a/compiler/docgen.nim
+++ b/compiler/docgen.nim
@@ -350,9 +350,11 @@ proc CommandRstAux(filename, outExt: string) =
   var d = newDocumentor(filen, options.gConfigVars)
   var rst = parseRst(readFile(filen), filen, 0, 1, d.hasToc,
                      {roSupportRawDirective})
-  d.modDesc = newMutableRope(30_000)
-  renderRstToOut(d[], rst, d.modDesc.data)
-  freezeMutableRope(d.modDesc)
+  var modDesc = newStringOfCap(30_000)
+  #d.modDesc = newMutableRope(30_000)
+  renderRstToOut(d[], rst, modDesc)
+  #freezeMutableRope(d.modDesc)
+  d.modDesc = toRope(modDesc)
   writeOutput(d, filename, outExt)
   generateIndex(d)
 
diff --git a/compiler/ropes.nim b/compiler/ropes.nim
index 50c89e4d9..f27bf70f7 100755
--- a/compiler/ropes.nim
+++ b/compiler/ropes.nim
@@ -58,266 +58,536 @@
 import 
   msgs, strutils, platform, hashes, crc, options
 
+const
+  PayloadSize = 64_000 # dummy size for range checking
+
 type
   TFormatStr* = string # later we may change it to CString for better
                        # performance of the code generator (assignments 
                        # copy the format strings
                        # though it is not necessary)
-  PRope* = ref TRope
-  TRope*{.acyclic.} = object of TObject # the empty rope is represented 
-                                        # by nil to safe space
-    left*, right*: PRope
-    length*: int
-    data*: string             # != nil if a leaf
-  
-  TRopeSeq* = seq[PRope]
-
-proc con*(a, b: PRope): PRope
-proc con*(a: PRope, b: string): PRope
-proc con*(a: string, b: PRope): PRope
-proc con*(a: varargs[PRope]): PRope
-proc app*(a: var PRope, b: PRope)
-proc app*(a: var PRope, b: string)
-proc prepend*(a: var PRope, b: PRope)
-proc toRope*(s: string): PRope
-proc toRope*(i: BiggestInt): PRope
-proc ropeLen*(a: PRope): int
-proc writeRopeIfNotEqual*(r: PRope, filename: string): bool
-proc ropeToStr*(p: PRope): string
-proc ropef*(frmt: TFormatStr, args: varargs[PRope]): PRope
-proc appf*(c: var PRope, frmt: TFormatStr, args: varargs[PRope])
-proc RopeEqualsFile*(r: PRope, f: string): bool
-  # returns true if the rope r is the same as the contents of file f
-proc RopeInvariant*(r: PRope): bool
-  # exported for debugging
-# implementation
-
-proc ropeLen(a: PRope): int = 
-  if a == nil: result = 0
-  else: result = a.length
-  
-proc newRope(data: string = nil): PRope = 
-  new(result)
-  if data != nil: 
-    result.length = len(data)
-    result.data = data
-
-proc newMutableRope*(capacity = 30): PRope =
-  ## creates a new rope that supports direct modifications of the rope's
-  ## 'data' and 'length' fields.
-  new(result)
-  result.data = newStringOfCap(capacity)
-
-proc freezeMutableRope*(r: PRope) {.inline.} =
-  r.length = r.data.len
-
-var 
-  cache: array[0..2048*2 -1, PRope]
-
-proc RopeInvariant(r: PRope): bool = 
-  if r == nil: 
-    result = true
-  else: 
-    result = true #
-                  #    if r.data <> snil then
-                  #      result := true
-                  #    else begin
-                  #      result := (r.left <> nil) and (r.right <> nil);
-                  #      if result then result := ropeInvariant(r.left);
-                  #      if result then result := ropeInvariant(r.right);
-                  #    end 
-
-proc insertInCache(s: string): PRope = 
-  var h = hash(s) and high(cache)
-  result = cache[h]
-  if isNil(result) or result.data != s:
-    result = newRope(s)
-    cache[h] = result
-  
-proc toRope(s: string): PRope =
-  if s.len == 0:
+
+when true:
+  # working version:
+  type
+    PRope* = ref TRope
+    TRope*{.acyclic.} = object of TObject # the empty rope is represented 
+                                          # by nil to safe space
+      left*, right*: PRope
+      length*: int
+      data*: string             # != nil if a leaf
+    
+    TRopeSeq* = seq[PRope]
+
+  proc con*(a, b: PRope): PRope
+  proc con*(a: PRope, b: string): PRope
+  proc con*(a: string, b: PRope): PRope
+  proc con*(a: varargs[PRope]): PRope
+  proc app*(a: var PRope, b: PRope)
+  proc app*(a: var PRope, b: string)
+  proc prepend*(a: var PRope, b: PRope)
+  proc toRope*(s: string): PRope
+  proc toRope*(i: BiggestInt): PRope
+  proc ropeLen*(a: PRope): int
+  proc writeRopeIfNotEqual*(r: PRope, filename: string): bool
+  proc ropeToStr*(p: PRope): string
+  proc ropef*(frmt: TFormatStr, args: varargs[PRope]): PRope
+  proc appf*(c: var PRope, frmt: TFormatStr, args: varargs[PRope])
+  proc RopeEqualsFile*(r: PRope, f: string): bool
+    # returns true if the rope r is the same as the contents of file f
+  proc RopeInvariant*(r: PRope): bool
+    # exported for debugging
+  # implementation
+
+  proc ropeLen(a: PRope): int = 
+    if a == nil: result = 0
+    else: result = a.length
+    
+  proc newRope(data: string = nil): PRope = 
+    new(result)
+    if data != nil: 
+      result.length = len(data)
+      result.data = data
+
+  proc newMutableRope*(capacity = 30): PRope =
+    ## creates a new rope that supports direct modifications of the rope's
+    ## 'data' and 'length' fields.
+    new(result)
+    result.data = newStringOfCap(capacity)
+
+  proc freezeMutableRope*(r: PRope) {.inline.} =
+    r.length = r.data.len
+
+  var 
+    cache: array[0..2048*2 -1, PRope]
+
+  proc RopeInvariant(r: PRope): bool = 
+    if r == nil: 
+      result = true
+    else: 
+      result = true #
+                    #    if r.data <> snil then
+                    #      result := true
+                    #    else begin
+                    #      result := (r.left <> nil) and (r.right <> nil);
+                    #      if result then result := ropeInvariant(r.left);
+                    #      if result then result := ropeInvariant(r.right);
+                    #    end 
+
+  proc insertInCache(s: string): PRope = 
+    var h = hash(s) and high(cache)
+    result = cache[h]
+    if isNil(result) or result.data != s:
+      result = newRope(s)
+      cache[h] = result
+    
+  proc toRope(s: string): PRope =
+    if s.len == 0:
+      result = nil
+    else:
+      result = insertInCache(s)
+    assert(RopeInvariant(result))
+
+  proc RopeSeqInsert(rs: var TRopeSeq, r: PRope, at: Natural) = 
+    var length = len(rs)
+    if at > length: 
+      setlen(rs, at + 1)
+    else: 
+      setlen(rs, length + 1)    # move old rope elements:
+    for i in countdown(length, at + 1): 
+      rs[i] = rs[i - 1] # this is correct, I used pen and paper to validate it
+    rs[at] = r
+
+  proc newRecRopeToStr(result: var string, resultLen: var int, r: PRope) = 
+    var stack = @[r]
+    while len(stack) > 0: 
+      var it = pop(stack)
+      while it.data == nil: 
+        add(stack, it.right)
+        it = it.left
+      assert(it.data != nil)
+      CopyMem(addr(result[resultLen]), addr(it.data[0]), it.length)
+      Inc(resultLen, it.length)
+      assert(resultLen <= len(result))
+
+  proc ropeToStr(p: PRope): string = 
+    if p == nil: 
+      result = ""
+    else: 
+      result = newString(p.length)
+      var resultLen = 0
+      newRecRopeToStr(result, resultLen, p)
+
+  proc con(a, b: PRope): PRope = 
+    if a == nil: result = b
+    elif b == nil: result = a
+    else:
+      result = newRope()
+      result.length = a.length + b.length
+      result.left = a
+      result.right = b
+
+  proc con(a: PRope, b: string): PRope = result = con(a, toRope(b))
+  proc con(a: string, b: PRope): PRope = result = con(toRope(a), b)
+
+  proc con(a: varargs[PRope]): PRope = 
+    for i in countup(0, high(a)): result = con(result, a[i])
+
+  proc toRope(i: BiggestInt): PRope = result = toRope($i)
+
+  proc app(a: var PRope, b: PRope) = a = con(a, b)
+  proc app(a: var PRope, b: string) = a = con(a, b)
+  proc prepend(a: var PRope, b: PRope) = a = con(b, a)
+
+  proc writeRope*(f: TFile, c: PRope) = 
+    var stack = @[c]
+    while len(stack) > 0: 
+      var it = pop(stack)
+      while it.data == nil: 
+        add(stack, it.right)
+        it = it.left
+        assert(it != nil)
+      assert(it.data != nil)
+      write(f, it.data)
+
+  proc WriteRope*(head: PRope, filename: string, useWarning = false) =
+    var f: tfile
+    if open(f, filename, fmWrite):
+      if head != nil: WriteRope(f, head)
+      close(f)
+    else:
+      rawMessage(if useWarning: warnCannotOpenFile else: errCannotOpenFile,
+                 filename)
+
+  proc ropef(frmt: TFormatStr, args: varargs[PRope]): PRope = 
+    var i = 0
+    var length = len(frmt)
     result = nil
-  else:
-    result = insertInCache(s)
-  assert(RopeInvariant(result))
-
-proc RopeSeqInsert(rs: var TRopeSeq, r: PRope, at: Natural) = 
-  var length = len(rs)
-  if at > length: 
-    setlen(rs, at + 1)
-  else: 
-    setlen(rs, length + 1)    # move old rope elements:
-  for i in countdown(length, at + 1): 
-    rs[i] = rs[i - 1] # this is correct, I used pen and paper to validate it
-  rs[at] = r
-
-proc newRecRopeToStr(result: var string, resultLen: var int, r: PRope) = 
-  var stack = @[r]
-  while len(stack) > 0: 
-    var it = pop(stack)
-    while it.data == nil: 
-      add(stack, it.right)
-      it = it.left
-    assert(it.data != nil)
-    CopyMem(addr(result[resultLen]), addr(it.data[0]), it.length)
-    Inc(resultLen, it.length)
-    assert(resultLen <= len(result))
-
-proc ropeToStr(p: PRope): string = 
-  if p == nil: 
-    result = ""
-  else: 
-    result = newString(p.length)
-    var resultLen = 0
-    newRecRopeToStr(result, resultLen, p)
-
-proc con(a, b: PRope): PRope = 
-  if a == nil: result = b
-  elif b == nil: result = a
-  else:
-    result = newRope()
-    result.length = a.length + b.length
-    result.left = a
-    result.right = b
-
-proc con(a: PRope, b: string): PRope = result = con(a, toRope(b))
-proc con(a: string, b: PRope): PRope = result = con(toRope(a), b)
-
-proc con(a: varargs[PRope]): PRope = 
-  for i in countup(0, high(a)): result = con(result, a[i])
-
-proc toRope(i: BiggestInt): PRope = result = toRope($i)
-
-proc app(a: var PRope, b: PRope) = a = con(a, b)
-proc app(a: var PRope, b: string) = a = con(a, b)
-proc prepend(a: var PRope, b: PRope) = a = con(b, a)
-
-proc writeRope*(f: TFile, c: PRope) = 
-  var stack = @[c]
-  while len(stack) > 0: 
-    var it = pop(stack)
-    while it.data == nil: 
-      add(stack, it.right)
-      it = it.left
-      assert(it != nil)
-    assert(it.data != nil)
-    write(f, it.data)
-
-proc WriteRope*(head: PRope, filename: string, useWarning = false) =
-  var f: tfile
-  if open(f, filename, fmWrite):
-    if head != nil: WriteRope(f, head)
-    close(f)
-  else:
-    rawMessage(if useWarning: warnCannotOpenFile else: errCannotOpenFile,
-               filename)
-
-proc ropef(frmt: TFormatStr, args: varargs[PRope]): PRope = 
-  var i = 0
-  var length = len(frmt)
-  result = nil
-  var num = 0
-  while i <= length - 1: 
-    if frmt[i] == '$': 
-      inc(i)                  # skip '$'
-      case frmt[i]
-      of '$': 
-        app(result, "$")
-        inc(i)
-      of '#': 
-        inc(i)
-        app(result, args[num])
-        inc(num)
-      of '0'..'9': 
-        var j = 0
-        while true: 
-          j = (j * 10) + Ord(frmt[i]) - ord('0')
+    var num = 0
+    while i <= length - 1: 
+      if frmt[i] == '$': 
+        inc(i)                  # skip '$'
+        case frmt[i]
+        of '$': 
+          app(result, "$")
           inc(i)
-          if (i > length + 0 - 1) or not (frmt[i] in {'0'..'9'}): break 
-        num = j
-        if j > high(args) + 1: 
-          internalError("ropes: invalid format string $" & $(j))
-        else:
-          app(result, args[j - 1])
-      of 'n':
-        if optLineDir notin gOptions: app(result, tnl)
-        inc i
-      of 'N':
-        app(result, tnl)
-        inc(i)
-      else: InternalError("ropes: invalid format string $" & frmt[i])
-    var start = i
-    while i < length:
-      if frmt[i] != '$': inc(i)
-      else: break
-    if i - 1 >= start: 
-      app(result, substr(frmt, start, i - 1))
-  assert(RopeInvariant(result))
-
-proc appf(c: var PRope, frmt: TFormatStr, args: varargs[PRope]) = 
-  app(c, ropef(frmt, args))
-
-const 
-  bufSize = 1024              # 1 KB is reasonable
-
-proc auxRopeEqualsFile(r: PRope, bin: var tfile, buf: Pointer): bool = 
-  if r.data != nil:
-    if r.length > bufSize: 
-      internalError("ropes: token too long")
-      return
-    var readBytes = readBuffer(bin, buf, r.length)
-    result = readBytes == r.length and
-        equalMem(buf, addr(r.data[0]), r.length) # BUGFIX
-  else: 
-    result = auxRopeEqualsFile(r.left, bin, buf)
-    if result: result = auxRopeEqualsFile(r.right, bin, buf)
-  
-proc RopeEqualsFile(r: PRope, f: string): bool = 
-  var bin: tfile
-  result = open(bin, f)
-  if not result: 
-    return                    # not equal if file does not exist
-  var buf = alloc(BufSize)
-  result = auxRopeEqualsFile(r, bin, buf)
-  if result: 
-    result = readBuffer(bin, buf, bufSize) == 0 # really at the end of file?
-  dealloc(buf)
-  close(bin)
-
-proc crcFromRopeAux(r: PRope, startVal: TCrc32): TCrc32 = 
-  if r.data != nil: 
+        of '#': 
+          inc(i)
+          app(result, args[num])
+          inc(num)
+        of '0'..'9': 
+          var j = 0
+          while true: 
+            j = (j * 10) + Ord(frmt[i]) - ord('0')
+            inc(i)
+            if (i > length + 0 - 1) or not (frmt[i] in {'0'..'9'}): break 
+          num = j
+          if j > high(args) + 1: 
+            internalError("ropes: invalid format string $" & $(j))
+          else:
+            app(result, args[j - 1])
+        of 'n':
+          if optLineDir notin gOptions: app(result, tnl)
+          inc i
+        of 'N':
+          app(result, tnl)
+          inc(i)
+        else: InternalError("ropes: invalid format string $" & frmt[i])
+      var start = i
+      while i < length:
+        if frmt[i] != '$': inc(i)
+        else: break
+      if i - 1 >= start: 
+        app(result, substr(frmt, start, i - 1))
+    assert(RopeInvariant(result))
+
+  proc appf(c: var PRope, frmt: TFormatStr, args: varargs[PRope]) = 
+    app(c, ropef(frmt, args))
+
+  const 
+    bufSize = 1024              # 1 KB is reasonable
+
+  proc auxRopeEqualsFile(r: PRope, bin: var tfile, buf: Pointer): bool = 
+    if r.data != nil:
+      if r.length > bufSize: 
+        internalError("ropes: token too long")
+        return
+      var readBytes = readBuffer(bin, buf, r.length)
+      result = readBytes == r.length and
+          equalMem(buf, addr(r.data[0]), r.length) # BUGFIX
+    else: 
+      result = auxRopeEqualsFile(r.left, bin, buf)
+      if result: result = auxRopeEqualsFile(r.right, bin, buf)
+    
+  proc RopeEqualsFile(r: PRope, f: string): bool = 
+    var bin: tfile
+    result = open(bin, f)
+    if not result: 
+      return                    # not equal if file does not exist
+    var buf = alloc(BufSize)
+    result = auxRopeEqualsFile(r, bin, buf)
+    if result: 
+      result = readBuffer(bin, buf, bufSize) == 0 # really at the end of file?
+    dealloc(buf)
+    close(bin)
+
+  proc crcFromRopeAux(r: PRope, startVal: TCrc32): TCrc32 = 
+    if r.data != nil: 
+      result = startVal
+      for i in countup(0, len(r.data) - 1): 
+        result = updateCrc32(r.data[i], result)
+    else: 
+      result = crcFromRopeAux(r.left, startVal)
+      result = crcFromRopeAux(r.right, result)
+
+  proc newCrcFromRopeAux(r: PRope, startVal: TCrc32): TCrc32 = 
+    # XXX profiling shows this is actually expensive
+    var stack: TRopeSeq = @[r]
     result = startVal
-    for i in countup(0, len(r.data) - 1): 
-      result = updateCrc32(r.data[i], result)
-  else: 
-    result = crcFromRopeAux(r.left, startVal)
-    result = crcFromRopeAux(r.right, result)
-
-proc newCrcFromRopeAux(r: PRope, startVal: TCrc32): TCrc32 = 
-  # XXX profiling shows this is actually expensive
-  var stack: TRopeSeq = @[r]
-  result = startVal
-  while len(stack) > 0: 
-    var it = pop(stack)
-    while it.data == nil: 
-      add(stack, it.right)
-      it = it.left
-    assert(it.data != nil)
+    while len(stack) > 0: 
+      var it = pop(stack)
+      while it.data == nil: 
+        add(stack, it.right)
+        it = it.left
+      assert(it.data != nil)
+      var i = 0
+      var L = len(it.data)
+      while i < L: 
+        result = updateCrc32(it.data[i], result)
+        inc(i)
+
+  proc crcFromRope(r: PRope): TCrc32 = 
+    result = newCrcFromRopeAux(r, initCrc32)
+
+  proc writeRopeIfNotEqual(r: PRope, filename: string): bool = 
+    # returns true if overwritten
+    var c: TCrc32
+    c = crcFromFile(filename)
+    if c != crcFromRope(r): 
+      writeRope(r, filename)
+      result = true
+    else: 
+      result = false
+
+else:
+  # optimized but broken version:
+
+  type
+    PRope* = ref TRope
+    TRope*{.acyclic.} = object of TObject # the empty rope is represented 
+                                          # by nil to safe space
+      left, right: PRope
+      L: int                            # < 0 if a leaf
+      d: array [0..PayloadSize, char]             # != nil if a leaf
+    
+    TRopeSeq* = seq[PRope]
+
+  proc con*(a, b: PRope): PRope
+  proc con*(a: PRope, b: string): PRope
+  proc con*(a: string, b: PRope): PRope
+  proc con*(a: varargs[PRope]): PRope
+  proc app*(a: var PRope, b: PRope)
+  proc app*(a: var PRope, b: string)
+  proc prepend*(a: var PRope, b: PRope)
+  proc toRope*(s: string): PRope
+  proc toRope*(i: BiggestInt): PRope
+  proc ropeLen*(a: PRope): int
+  proc writeRopeIfNotEqual*(r: PRope, filename: string): bool
+  proc ropeToStr*(p: PRope): string
+  proc ropef*(frmt: TFormatStr, args: varargs[PRope]): PRope
+  proc appf*(c: var PRope, frmt: TFormatStr, args: varargs[PRope])
+  proc RopeEqualsFile*(r: PRope, f: string): bool
+    # returns true if the rope r is the same as the contents of file f
+  proc RopeInvariant*(r: PRope): bool
+    # exported for debugging
+  # implementation
+
+  proc ropeLen(a: PRope): int = 
+    if a == nil: result = 0
+    else: result = a.L.abs
+    
+  proc newRope(data: string = nil): PRope =
+    if data != nil:
+      unsafeNew(result, sizeof(TRope)-PayloadSize+len(data)+1)
+      result.L = -len(data)
+      # copy including '\0':
+      copyMem(addr result.d, cstring(data), len(data))
+    else:
+      unsafeNew(result, sizeof(TRope)-PayloadSize+1)
+
+  proc eqContent(r: PRope, s: string): bool =
+    assert r.L < 0
+    if -r.L == s.len:
+      result = equalMem(addr(r.d), cstring(s), s.len)
+
+  when false:
+    proc newMutableRope*(capacity = 30): PRope =
+      ## creates a new rope that supports direct modifications of the rope's
+      ## 'data' and 'length' fields.
+      new(result)
+      result.data = newStringOfCap(capacity)
+
+    proc freezeMutableRope*(r: PRope) {.inline.} =
+      r.length = r.data.len
+
+  var 
+    cache: array[0..2048*2 -1, PRope]
+
+  proc RopeInvariant(r: PRope): bool = 
+    if r == nil: 
+      result = true
+    else: 
+      result = true #
+                    #    if r.data <> snil then
+                    #      result := true
+                    #    else begin
+                    #      result := (r.left <> nil) and (r.right <> nil);
+                    #      if result then result := ropeInvariant(r.left);
+                    #      if result then result := ropeInvariant(r.right);
+                    #    end 
+
+  proc insertInCache(s: string): PRope = 
+    var h = hash(s) and high(cache)
+    result = cache[h]
+    if isNil(result) or not eqContent(result, s):
+      result = newRope(s)
+      cache[h] = result
+    
+  proc toRope(s: string): PRope =
+    if s.len == 0:
+      result = nil
+    else:
+      result = insertInCache(s)
+    assert(RopeInvariant(result))
+
+  proc RopeSeqInsert(rs: var TRopeSeq, r: PRope, at: Natural) = 
+    var length = len(rs)
+    if at > length: 
+      setlen(rs, at + 1)
+    else: 
+      setlen(rs, length + 1)    # move old rope elements:
+    for i in countdown(length, at + 1): 
+      rs[i] = rs[i - 1] # this is correct, I used pen and paper to validate it
+    rs[at] = r
+
+  proc newRecRopeToStr(result: var string, resultLen: var int, r: PRope) = 
+    var stack = @[r]
+    while len(stack) > 0: 
+      var it = pop(stack)
+      while it.L >= 0:
+        add(stack, it.right)
+        it = it.left
+      assert(it.L < 0)
+      CopyMem(addr(result[resultLen]), addr(it.d[0]), -it.L)
+      Inc(resultLen, -it.L)
+      assert(resultLen <= len(result))
+
+  proc ropeToStr(p: PRope): string = 
+    if p == nil: 
+      result = ""
+    else:
+      result = newString(p.L.abs)
+      var resultLen = 0
+      newRecRopeToStr(result, resultLen, p)
+
+  proc con(a, b: PRope): PRope = 
+    if a == nil: result = b
+    elif b == nil: result = a
+    else:
+      result = newRope()
+      result.L = a.L.abs + b.L.abs
+      result.left = a
+      result.right = b
+
+  proc con(a: PRope, b: string): PRope = result = con(a, toRope(b))
+  proc con(a: string, b: PRope): PRope = result = con(toRope(a), b)
+
+  proc con(a: varargs[PRope]): PRope = 
+    for i in countup(0, high(a)): result = con(result, a[i])
+
+  proc toRope(i: BiggestInt): PRope = result = toRope($i)
+
+  proc app(a: var PRope, b: PRope) = a = con(a, b)
+  proc app(a: var PRope, b: string) = a = con(a, b)
+  proc prepend(a: var PRope, b: PRope) = a = con(b, a)
+
+  proc writeRope*(f: TFile, c: PRope) =
+    var stack = @[c]
+    while len(stack) > 0:
+      var it = pop(stack)
+      while it.L >= 0:
+        add(stack, it.right)
+        it = it.left
+        assert(it != nil)
+      assert(it.L < 0)
+      write(f, cstring(it.d), -it.L)
+
+  proc WriteRope*(head: PRope, filename: string, useWarning = false) =
+    var f: tfile
+    if open(f, filename, fmWrite):
+      if head != nil: WriteRope(f, head)
+      close(f)
+    else:
+      rawMessage(if useWarning: warnCannotOpenFile else: errCannotOpenFile,
+                 filename)
+
+  proc ropef(frmt: TFormatStr, args: varargs[PRope]): PRope = 
     var i = 0
-    var L = len(it.data)
-    while i < L: 
-      result = updateCrc32(it.data[i], result)
-      inc(i)
-
-proc crcFromRope(r: PRope): TCrc32 = 
-  result = newCrcFromRopeAux(r, initCrc32)
-
-proc writeRopeIfNotEqual(r: PRope, filename: string): bool = 
-  # returns true if overwritten
-  var c: TCrc32
-  c = crcFromFile(filename)
-  if c != crcFromRope(r): 
-    writeRope(r, filename)
-    result = true
-  else: 
-    result = false
+    var length = len(frmt)
+    result = nil
+    var num = 0
+    while i <= length - 1: 
+      if frmt[i] == '$': 
+        inc(i)                  # skip '$'
+        case frmt[i]
+        of '$': 
+          app(result, "$")
+          inc(i)
+        of '#': 
+          inc(i)
+          app(result, args[num])
+          inc(num)
+        of '0'..'9': 
+          var j = 0
+          while true: 
+            j = (j * 10) + Ord(frmt[i]) - ord('0')
+            inc(i)
+            if (i > length + 0 - 1) or not (frmt[i] in {'0'..'9'}): break 
+          num = j
+          if j > high(args) + 1: 
+            internalError("ropes: invalid format string $" & $(j))
+          else:
+            app(result, args[j - 1])
+        of 'n':
+          if optLineDir notin gOptions: app(result, tnl)
+          inc i
+        of 'N':
+          app(result, tnl)
+          inc(i)
+        else: InternalError("ropes: invalid format string $" & frmt[i])
+      var start = i
+      while i < length:
+        if frmt[i] != '$': inc(i)
+        else: break
+      if i - 1 >= start: 
+        app(result, substr(frmt, start, i - 1))
+    assert(RopeInvariant(result))
+
+  proc appf(c: var PRope, frmt: TFormatStr, args: varargs[PRope]) = 
+    app(c, ropef(frmt, args))
+
+  const 
+    bufSize = 1024              # 1 KB is reasonable
+
+  proc auxRopeEqualsFile(r: PRope, bin: var tfile, buf: Pointer): bool = 
+    if r.L < 0:
+      if -r.L > bufSize: 
+        internalError("ropes: token too long")
+        return
+      var readBytes = readBuffer(bin, buf, -r.L)
+      result = readBytes == -r.L and
+          equalMem(buf, addr(r.d[0]), readBytes)
+    else:
+      result = auxRopeEqualsFile(r.left, bin, buf)
+      if result: result = auxRopeEqualsFile(r.right, bin, buf)
+    
+  proc RopeEqualsFile(r: PRope, f: string): bool = 
+    var bin: tfile
+    result = open(bin, f)
+    if not result: 
+      return                    # not equal if file does not exist
+    var buf = alloc(BufSize)
+    result = auxRopeEqualsFile(r, bin, buf)
+    if result: 
+      result = readBuffer(bin, buf, bufSize) == 0 # really at the end of file?
+    dealloc(buf)
+    close(bin)
+
+  proc newCrcFromRopeAux(r: PRope, startVal: TCrc32): TCrc32 = 
+    # XXX profiling shows this is actually expensive
+    var stack: TRopeSeq = @[r]
+    result = startVal
+    while len(stack) > 0: 
+      var it = pop(stack)
+      while it.L >= 0:
+        add(stack, it.right)
+        it = it.left
+      assert(it.L < 0)
+      var i = 0
+      var L = -it.L
+      while i < L:
+        result = updateCrc32(it.d[i], result)
+        inc(i)
+
+  proc crcFromRope(r: PRope): TCrc32 = 
+    result = newCrcFromRopeAux(r, initCrc32)
+
+  proc writeRopeIfNotEqual(r: PRope, filename: string): bool = 
+    # returns true if overwritten
+    var c: TCrc32
+    c = crcFromFile(filename)
+    if c != crcFromRope(r): 
+      writeRope(r, filename)
+      result = true
+    else: 
+      result = false