function chooseScalarStyle()

in packages/libs/codegen/src/yaml-dump/yaml-dump.ts [346:422]

• 62 lines of code
• 30 McCabe index (conditional complexity)

function chooseScalarStyle(
  string,
  singleLineOnly,
  indentPerLevel,
  lineWidth,
  testAmbiguousType,
  quotingType,
  forceQuotes,
  inblock,
) {
  let i;
  let char = 0;
  let prevChar = null;
  let hasLineBreak = false;
  let hasFoldableLine = false; // only checked if shouldTrackWidth
  const shouldTrackWidth = lineWidth !== -1;
  let previousLineBreak = -1; // count the first line correctly
  let plain = isPlainSafeFirst(codePointAt(string, 0)) && isPlainSafeLast(codePointAt(string, string.length - 1));

  if (singleLineOnly || forceQuotes) {
    // Case: no block styles.
    // Check for disallowed characters to rule out plain and single.
    for (i = 0; i < string.length; char >= 0x10000 ? (i += 2) : i++) {
      char = codePointAt(string, i);
      if (!isPrintable(char)) {
        return STYLE_DOUBLE;
      }
      plain = plain && isPlainSafe(char, prevChar, inblock);
      prevChar = char;
    }
  } else {
    // Case: block styles permitted.
    for (i = 0; i < string.length; char >= 0x10000 ? (i += 2) : i++) {
      char = codePointAt(string, i);
      if (char === CHAR_LINE_FEED) {
        hasLineBreak = true;
        // Check if any line can be folded.
        if (shouldTrackWidth) {
          hasFoldableLine =
            hasFoldableLine ||
            // Foldable line = too long, and not more-indented.
            (i - previousLineBreak - 1 > lineWidth && string[previousLineBreak + 1] !== " ");
          previousLineBreak = i;
        }
      } else if (!isPrintable(char)) {
        return STYLE_DOUBLE;
      }
      plain = plain && isPlainSafe(char, prevChar, inblock);
      prevChar = char;
    }
    // in case the end is missing a \n
    hasFoldableLine =
      hasFoldableLine ||
      (shouldTrackWidth && i - previousLineBreak - 1 > lineWidth && string[previousLineBreak + 1] !== " ");
  }
  // Although every style can represent \n without escaping, prefer block styles
  // for multiline, since they're more readable and they don't add empty lines.
  // Also prefer folding a super-long line.
  if (!hasLineBreak && !hasFoldableLine) {
    // Strings interpretable as another type have to be quoted;
    // e.g. the string 'true' vs. the boolean true.
    if (plain && !forceQuotes && !testAmbiguousType(string)) {
      return STYLE_PLAIN;
    }
    return quotingType === QUOTING_TYPE_DOUBLE ? STYLE_DOUBLE : STYLE_SINGLE;
  }
  // Edge case: block indentation indicator can only have one digit.
  if (indentPerLevel > 9 && needIndentIndicator(string)) {
    return STYLE_DOUBLE;
  }
  // At this point we know block styles are valid.
  // Prefer literal style unless we want to fold.
  if (!forceQuotes) {
    return hasFoldableLine ? STYLE_FOLDED : STYLE_LITERAL;
  }
  return quotingType === QUOTING_TYPE_DOUBLE ? STYLE_DOUBLE : STYLE_SINGLE;
}