statistics function

StringStatistics statistics(String str, { bool filterNonChars = true, String leftOvers = '', bool continues = false, bool inWord = false, bool ignorePunctuation = false, })

Finds the data points in StringStatistics for provided string.

Includes: character count, empty line count, line count, non-empty line count, word count, character frequencies, word frequencies, and word positions.

The default behavior of the function is to count the last substring beginning with white space as a word even if it ends without a whitespace or punctuation mark. leftOvers and continues allows for incremental counting of a string over multiple calls. leftOvers is what remained of a word from a previous string and continues indicates that the string will continue, preventing the count of the last whitespace lead substring.

ignorePunctuation facilitates checking words that include symbols.

inWord allows for incremental counting of a string over multiple calls, and prevents double counting by telling function it's still in a word.

filterNonChars removes non-chars from count.

Implementation

StringStatistics statistics(String str,
    {bool filterNonChars = true,
    String leftOvers = '',
    bool continues = false,
    bool inWord = false,
    bool ignorePunctuation = false}) {
  var charCount = 0;
  var emptyLineCount = 0;
  var lineCount = 0;
  var nonEmptyLineCount = 0;
  var wordCount = 0;
  final charFrequencies = <String, int>{};
  final wordFrequencies = <String, int>{};
  final wordPositions = <String, Set<Position>>{};

  var start = 0;
  final sb = StringBuffer();
  final chars = str.split('');
  sb.write(leftOvers);
  for (var i = 0; i < chars.length; i++) {
    final ch = chars[i];
    if (ch == '\n') {
      lineCount++;

      if (i == 0) {
        emptyLineCount++;
      } else {
        if (chars[i - 1] == '\n') {
          emptyLineCount++;
        } else {
          nonEmptyLineCount++;
        }
      }
    }

    final punctuationContinue = !ignorePunctuation && !ch.isPunctuation;
    if (ch.isChar && !ch.isWhiteSpace && punctuationContinue) {
      if (inWord == false) {
        inWord = true;
      }
    } else {
      if (inWord) wordCount++;
      inWord = false;
    }

    if (ch.isChar || !filterNonChars) {
      charFrequencies.update(ch, (v) => v + 1, ifAbsent: () => 1);
      charCount++;
    }

    if (ch.isWhiteSpace || (!ignorePunctuation && ch.isPunctuation)) {
      if (sb.isNotEmpty) {
        final sbString = sb.toString();
        wordFrequencies.update(sbString, (v) => v + 1, ifAbsent: () => 1);
        wordPositions.update(sbString, (set) {
          set.add(Position(start, i - 1));
          return set;
        }, ifAbsent: () => {Position(start, i - 1)});
      }
      start = i + 1;
      sb.clear();
    } else {
      sb.write(ch);
    }
  }

  if (!continues && sb.isNotEmpty) {
    final sbString = sb.toString();
    wordFrequencies.update(sb.toString(), (v) => v + 1, ifAbsent: () => 1);
    wordPositions.update(sbString, (set) {
      set.add(Position(start, str.length - 1));
      return set;
    }, ifAbsent: () => {Position(start, str.length - 1)});
  }

  if (!continues && inWord) wordCount++;

  return StringStatistics(charCount, wordCount, lineCount + 1, emptyLineCount,
      nonEmptyLineCount + 1, charFrequencies, wordFrequencies, wordPositions);
}