WIP

lib/pure/unicode.nim

@@ -213,6 +213,10 @@ proc toUTF8*(c: Rune): string {.rtl, extern: "nuc$1".} =
   result = ""
   fastToUTF8Copy(c, result, 0, false)
 
+proc add*(s: var string; c: Rune) =
+  let pos = s.len
+  fastToUTF8Copy(c, s, pos, false)
+
 proc `$`*(rune: Rune): string =
   ## Converts a Rune to a string
   rune.toUTF8
@@ -220,7 +224,8 @@ proc `$`*(rune: Rune): string =
 proc `$`*(runes: seq[Rune]): string =
   ## Converts a sequence of Runes to a string
   result = ""
-  for rune in runes: result.add(rune.toUTF8)
+  for rune in runes:
+    result.add rune
 
 proc runeOffset*(s: string, pos:Natural, start: Natural = 0): int =
   ## Returns the byte position of unicode character

lib/std/wordwrap.nim

@@ -0,0 +1,124 @@
+import unicode
+
+proc addSubstrExcl(self: var string, str: string; a,b: int) =
+  ## equivalent to ``self.add str.substr(a,b-1)``. Exclusive upper bound.
+  if a > b:
+    echo a, " ", b
+  assert a <= b
+
+  if a < b:
+    let idx = self.len
+    self.setLen idx + b - a
+    copyMem(self[idx].addr, str[a].unsafeAddr, b - a)
+
+let tmp ="Наши исследования позволяют сделать вывод о том, что субъект выбирает uiaetudtiraeüöätpghiacodöeronfdquiahgoüöädoiaqofhgiaeotrnuiaßqzfgiaoeurnudtitraenuitenruitarenitarenuitarentduiranetduiranetdruianetrnuiaertnuiatdenruiatdrne институциональный психоз. Важность этой функции подчеркивается тем фактом, что объект вызывает эгоцентризм. Самоактуализация аннигилирует генезис. Анима аннигилирует возрастной код. Закон просветляет аутотренинг. Наши исследования позволяют сделать вывод о том, что воспитание заметно осознаёт инсайт."
+
+proc wordWrap*(s: string, maxLineWidth = 80,
+               splitLongWords = true,
+               newLine = "\n"): string  =
+
+  var currentWordLength: int = 0
+  var currentWord: string = newStringOfCap(32)
+  var currentLineLength: int = 0
+  var currentWordLineEndMark: int = -1
+  var currentWordLengthAtLineEnd: int = -1
+
+  template handleWhitespace(): untyped =
+    if currentWord.len > 0:
+
+      if currentLineLength + 1 + currentWordLength > maxLineWidth:
+        var splitWord = splitLongWords
+        if splitLongWords:
+          # arbitrary minimum length of words to split
+          splitWord = currentWordLength > maxLineWidth div 2
+          if currentWordLengthAtLineEnd <= 3:
+            # does the current word fit in the next line?
+            if currentWordLength <= maxLineWidth:
+              splitWord = false
+
+        if splitWord:
+          result.addSubstrExcl(currentWord, 0, currentWordLineEndMark)
+          result.add newLine
+          result.addSubstrExcl(currentWord, currentWordLineEndMark, currentWord.len)
+          currentLineLength = currentWordLength - currentWordLengthAtLineEnd
+        else:
+          result.add newLine
+          currentLineLength = 0
+
+      if currentLineLength > 0:
+        result.add ' '
+        currentLineLength += 1
+
+      result.add currentWord
+      currentLineLength += currentWordLength
+
+      currentWord.setlen 0
+      currentWordLength = 0
+
+      currentWordLineEndMark = -1
+
+  for rune in s.runes:
+    if rune.isWhiteSpace:
+      handleWhitespace()
+    else:
+      currentWord.add rune
+      inc currentWordLength
+
+      if splitLongWords:
+        # the word reached the end of the current line
+        if currentLineLength + 1 + currentWordLength == maxLineWidth:
+          assert(currentWordLineEndMark == -1)
+          currentWordLineEndMark = currentWord.len
+          currentWordLengthAtLineEnd = currentWordLength
+
+        # the word reached the end of the next line
+        if currentWordLength - currentWordLengthAtLineEnd == maxLineWidth:
+          # superlong word, stop being smart.
+          result.addSubstrExcl(currentWord, 0, currentWordLineEndMark)
+          result.add newLine
+
+          currentWord.
+currentWordLineEndMark()
+          currentWordLength = currentWordLength - currentWordLengthAtLineEnd
+
+          handleWhitespace()
+          currentWordLineEndMark = maxLineWidth
+
+  handleWhitespace()
+
+echo wordWrap(tmp)
+
+
+import strutils
+
+echo strutils.wordWrap(tmp, splitLongWords=true)
+echo strutils.wordWrap(tmp, splitLongWords=false)
+
+  # result = newStringOfCap(s.len + s.len shr 6)
+  # var spaceLeft = maxLineWidth
+  # var lastSep = ""
+  # for word, isSep in tokenize(s, seps):
+  #   if isSep:
+  #     lastSep = word
+  #     spaceLeft = spaceLeft - len(word)
+  #     continue
+  #   if len(word) > spaceLeft:
+  #     if splitLongWords and len(word) > maxLineWidth:
+  #       result.add(substr(word, 0, spaceLeft-1))
+  #       var w = spaceLeft
+  #       var wordLeft = len(word) - spaceLeft
+  #       while wordLeft > 0:
+  #         result.add(newLine)
+  #         var L = min(maxLineWidth, wordLeft)
+  #         spaceLeft = maxLineWidth - L
+  #         result.add(substr(word, w, w+L-1))
+  #         inc(w, L)
+  #         dec(wordLeft, L)
+  #     else:
+  #       spaceLeft = maxLineWidth - len(word)
+  #       result.add(newLine)
+  #       result.add(word)
+  #   else:
+  #     spaceLeft = spaceLeft - len(word)
+  #     result.add(lastSep & word)
+  #     lastSep.setLen(0)