// This method formats a sequence of words (Strings obtained from
// an enumerator) into lines of text, padding the inter-word
// gaps with extra spaces to obtain lines of length lineWidth, and
// thus a straight right margin.
//
// There are the following exceptions:
// * if a word is longer than lineWidth, it is put on a line by
// itself (producing a line longer than lineWidth)
// * a single word may appear on a line by itself (producing a line
// shorter than lineWidth) if adding the next word to the line
// would make the line longer than lineWidth
// * the last line of the output is not padded with extra spaces.
//
// The algorithm for padding with extra spaces ensures that the
// spaces are evenly distributed over inter-word gaps, using modulo
// arithmetics. An Assert method call asserts that the resulting
// output line has the correct length unless the line contains only
// a single word or is the last line of the output.
public static void Format(IEnumerator <String> words, int lineWidth,
TextWriter tw)
{
lineWidth = Math.Max(0, lineWidth);
WordList curLine = new WordList();
bool moreWords = words.MoveNext();
while (moreWords)
{
while (moreWords && curLine.Length < lineWidth)
{
String word = words.Current;
if (word != null && word != "")
{
curLine.AddLast(word);
}
moreWords = words.MoveNext();
}
int wordCount = curLine.Count;
if (wordCount > 0)
{
int extraSpaces = lineWidth - curLine.Length;
if (wordCount > 1 && extraSpaces < 0) // last word goes on next line
{
int lastWordLength = curLine.GetLast.Length;
extraSpaces += 1 + lastWordLength;
wordCount -= 1;
}
else if (!moreWords) // last line, do not pad
{
extraSpaces = 0;
}
// Pad inter-word space with evenly distributed extra blanks
int holes = wordCount - 1;
int spaces = holes / 2;
StringBuilder sb = new StringBuilder();
sb.Append(curLine.RemoveFirst());
for (int i = 1; i < wordCount; i++)
{
spaces += extraSpaces;
appendBlanks(sb, 1 + spaces / holes);
spaces %= holes;
sb.Append(curLine.RemoveFirst());
}
String res = sb.ToString();
Debug.Assert(res.Length == lineWidth || wordCount == 1 || !moreWords);
tw.WriteLine(res);
}
}
tw.Flush();
}