Function preprocess

src/parseTools.mjs:101–238

(filename)

// ident checked is true in our global.
// Also handles #include x.js (similar to C #include <file>)
export function preprocess(filename) {
  let text = readFile(filename);
  // Remove windows line endings, if any
  text = text.replace(/\r\n/g, '\n');

  const IGNORE = 0;
  const SHOW = 1;
  // This state is entered after we have shown one of the block of an if/elif/else sequence.
  // Once we enter this state we don't show any blocks or evaluate any
  // conditions until the sequence ends.
  const IGNORE_ALL = 2;
  const showStack = [];
  const showCurrentLine = () => showStack.every((x) => x == SHOW);

  const fileExt = filename.split('.').pop().toLowerCase();
  const isHtml = fileExt === 'html' || fileExt === 'htm' ? true : false;
  let inStyle = false;
  const lines = text.split('\n');
  // text.split yields an extra empty element at the end if text itself ends with a newline.
  if (!lines[lines.length - 1]) {
    lines.pop();
  }

  let ret = '';
  let emptyLine = false;

  pushCurrentFile(filename);
  try {
    for (const [i, line] of lines.entries()) {
      if (isHtml) {
        if (line.includes('<style') && !inStyle) {
          inStyle = true;
        }
        if (line.includes('</style') && inStyle) {
          inStyle = false;
        }
        if (inStyle) {
          if (showCurrentLine()) {
            ret += line + '\n';
          }
          continue;
        }
      }

      const trimmed = line.trim();
      if (trimmed.startsWith('#')) {
        const first = trimmed.split(' ', 1)[0];
        if (first == '#if' || first == '#ifdef' || first == '#elif') {
          if (first == '#ifdef') {
            warn('use of #ifdef in js library.  Use #if instead.');
          }
          if (first == '#elif') {
            const curr = showStack.pop();
            if (curr == SHOW || curr == IGNORE_ALL) {
              // If we showed to previous block we enter the IGNORE_ALL state
              // and stay there until endif is seen
              showStack.push(IGNORE_ALL);
              continue;