Function formatFunctionDescription

src/adapter/objectPreview/index.ts:402–471

(description: string, characterBudget: number)

}

function formatFunctionDescription(description: string, characterBudget: number): string {
  const builder = new BudgetStringBuilder(characterBudget);
  const text = description
    .replace(/^function [gs]et /, 'function ')
    .replace(/^function [gs]et\(/, 'function(')
    .replace(/^[gs]et /, '');

  // This set of best-effort regular expressions captures common function descriptions.
  // Ideally, some parser would provide prefix, arguments, function body text separately.
  const asyncMatch = text.match(/^(async\s+function)/);
  const isGenerator = text.startsWith('function*');
  const isGeneratorShorthand = text.startsWith('*');
  const isBasic = !isGenerator && text.startsWith('function');
  const isClass = text.startsWith('class ') || text.startsWith('class{');
  const firstArrowIndex = text.indexOf('=>');
  const isArrow = !asyncMatch && !isGenerator && !isBasic && !isClass && firstArrowIndex > 0;

  let textAfterPrefix: string;
  if (isClass) {
    textAfterPrefix = text.substring('class'.length);
    const classNameMatch = /^[^{\s]+/.exec(textAfterPrefix.trim());
    let className = '';
    if (classNameMatch) className = classNameMatch[0].trim() || '';
    addToken('class', textAfterPrefix, className);
  } else if (asyncMatch) {
    textAfterPrefix = text.substring(asyncMatch[1].length);
    addToken('async ƒ', textAfterPrefix, nameAndArguments(textAfterPrefix));
  } else if (isGenerator) {
    textAfterPrefix = text.substring('function*'.length);
    addToken('ƒ*', textAfterPrefix, nameAndArguments(textAfterPrefix));
  } else if (isGeneratorShorthand) {
    textAfterPrefix = text.substring('*'.length);
    addToken('ƒ*', textAfterPrefix, nameAndArguments(textAfterPrefix));
  } else if (isBasic) {
    textAfterPrefix = text.substring('function'.length);
    addToken('ƒ', textAfterPrefix, nameAndArguments(textAfterPrefix));
  } else if (isArrow) {
    let abbreviation = text;
    if (text.length > maxArrowFunctionCharacterLength) {
      abbreviation = text.substring(0, firstArrowIndex + 2) + ' {\u2026}';
    }
    addToken('', text, abbreviation);
  } else {
    addToken('ƒ', text, nameAndArguments(text));
  }
  return builder.build();

  function nameAndArguments(contents: string): string {
    const startOfArgumentsIndex = contents.indexOf('(');
    const endOfArgumentsMatch = contents.match(/\)\s*{/);
    const endIndex = (endOfArgumentsMatch && endOfArgumentsMatch.index) || 0;
    if (startOfArgumentsIndex !== -1 && endOfArgumentsMatch && endIndex > startOfArgumentsIndex) {
      const name = contents.substring(0, startOfArgumentsIndex).trim() || '';
      const args = contents.substring(startOfArgumentsIndex, endIndex + 1);
      return name + args;
    }
    return '()';
  }