Function mapDoc

src/document/utilities/index.js:30–95

@import {Doc} from "../builders/index.js";

(doc, cb)

*/

function mapDoc(doc, cb) {
  // Avoid creating `Map`
  if (typeof doc === "string") {
    return cb(doc);
  }

  // Within a doc tree, the same subtrees can be found multiple times.
  // E.g., often this happens in conditional groups.
  // As an optimization (those subtrees can be huge) and to maintain the
  // reference structure of the tree, the mapping results are cached in
  // a map and reused.
  const mapped = new Map();

  return rec(doc);

  function rec(doc) {
    return getOrInsertComputed(mapped, doc, process);
  }

  function process(doc) {
    switch (getDocType(doc)) {
      case DOC_TYPE_ARRAY:
        return cb(doc.map(rec));

      case DOC_TYPE_FILL:
        return cb({ ...doc, parts: doc.parts.map(rec) });

      case DOC_TYPE_IF_BREAK:
        return cb({
          ...doc,
          breakContents: rec(doc.breakContents),
          flatContents: rec(doc.flatContents),
        });

      case DOC_TYPE_GROUP: {
        let { expandedStates, contents } = doc;
        if (expandedStates) {
          expandedStates = expandedStates.map(rec);
          contents = expandedStates[0];
        } else {
          contents = rec(contents);
        }
        return cb({ ...doc, contents, expandedStates });
      }

      case DOC_TYPE_ALIGN:
      case DOC_TYPE_INDENT:
      case DOC_TYPE_INDENT_IF_BREAK:
      case DOC_TYPE_LABEL:
      case DOC_TYPE_LINE_SUFFIX:
        return cb({ ...doc, contents: rec(doc.contents) });

      case DOC_TYPE_STRING:
      case DOC_TYPE_CURSOR:
      case DOC_TYPE_TRIM:
      case DOC_TYPE_LINE_SUFFIX_BOUNDARY:
      case DOC_TYPE_LINE:
      case DOC_TYPE_BREAK_PARENT: