nodeMatcher.js

/**
 * returns a function that returns true when node matches the matcher.
 * matchers can be built recursively. If a property of a matcher is a function, it is evaluated.
 *
 * @see https://astexplorer.net/ to explore how ESTree nodes are structured
 * @example nodeMatcher({type: `Identifier`, name: `foo`})(node)
 *
 * @param {Obj} matcher
 * @param {Obj} refObj
 * @param {string} refKey
 * @return {(node: Obj) => boolean}
 */
exports.nodeMatcher = function nodeMatcher(matcher, refObj = null, refKey = ``) {
  return function (node) {
    // typeof null === `object`. handle that case
    if (node === null || typeof node !== `object`) {
      return false;
    }

    for (const [prop, matchValue] of Object.entries(matcher)) {
      const nodeValue = node[prop];
      if (!(typeof matchValue === `function` && matchValue(nodeValue)) && matchValue !== nodeValue) {
        // uncomment for debugging why a node didn't match
        // console.log(`nodeMatcher '${prop}'`, typeof matchValue !== `function` ? `${matchValue} !== ${nodeValue}` : ``);
        return false;
      }
    }

    // if refObj is passed and node matches, save node reference
    // this makes it easier to traverse an AST and capture reference of nodes of interest
    if (refObj) {
      refObj[refKey] = node;
    }

    return true;
  };
};

/**
 * returns a function that returns true when node matches any of the matchers.
 *
 * @param {Array<(node: Obj) => boolean>} matchers
 * @return {(node: Obj) => boolean}
 */
exports.anyMatcher = function anyMatcher(matchers) {
  return function (node) {
    for (const matcher of matchers) {
      if (matcher(node)) {
        return true;
      }
    }
    return false;
  };
};

/**
 * returns a function that returns true when node matches all of the matchers.
 *
 * @param {Array<(node: Obj) => boolean>} matchers
 * @return {(node: Obj) => boolean}
 */
exports.allMatcher = function allMatcher(matchers) {
  return function (node) {
    for (const matcher of matchers) {
      if (!matcher(node)) {
        return false;
      }
    }
    return true;
  };
};