@specs-feup/lara/src-api/weaver/JoinPoints.ts

A js port of the popular framework for building source-to-source compilers

import { LaraJoinPoint, wrapJoinPoint } from "../LaraJoinPoint.js";
import Weaver from "./Weaver.js";
import JpPredicate from "./predicate/JpPredicate.js";

/**
 * Object which provides low-level join point-related methods.
 */
export default class JoinPoints {
  /**
   *
   * @returns the current root node of the AST
   */
  static root(): LaraJoinPoint {
    return wrapJoinPoint(Weaver.getWeaverEngine().getRootJp());
  }

  /**
   * Converts an AST node to a JointPoint.
   *
   */
  static toJoinPoint(node: any): LaraJoinPoint {
    throw new Error("JoinPoints.toJoinPoint: not implemented");
  }

  /**
   *
   * @returns all the children of the given node
   */
  private static _all_children($jp: LaraJoinPoint): LaraJoinPoint[] {
    return $jp.children;
  }

  /**
   *
   * @returns all the descendants of the given node
   */
  private static _all_descendants($jp: LaraJoinPoint): LaraJoinPoint[] {
    return $jp.descendants;
  }

  /**
   *
   * @returns all the nodes that are inside the scope of a given node
   */
  private static _all_scope_nodes($jp: LaraJoinPoint): LaraJoinPoint[] {
    return $jp.scopeNodes;
  }

  /**
   *
   * @returns all the descendants of the given node, in post order
   */
  private static _all_descendants_postorder(
    $jp: LaraJoinPoint,
    includeSelf: boolean = false
  ): LaraJoinPoint[] {
    const result: LaraJoinPoint[] = [];

    for (const child of JoinPoints._all_children($jp)) {
        result.push(...JoinPoints._all_descendants_postorder(child, true));
    }

    if (includeSelf) {
      result.push($jp);
    }

    return result;
  }

  /**
   *
   * @returns the nodes inside the scope of the given node.
   */
  static scope(
    $jp: LaraJoinPoint,
    jpType?: JpPredicate
  ): LaraJoinPoint[] {
    return JoinPoints._getNodes(jpType, JoinPoints._all_scope_nodes($jp));
  }

  /**
   *
   * @returns the children of the given node, according to the AST
   */
  static children(
    $jp: LaraJoinPoint,
    jpType?: JpPredicate
  ): LaraJoinPoint[] {
    return JoinPoints._getNodes(jpType, JoinPoints._all_children($jp));
  }

  /**
   *
   * @returns the descendants of the given node, according to the AST, preorder traversal
   */
  static descendants(
    $jp: LaraJoinPoint,
    jpType?: JpPredicate
  ): LaraJoinPoint[] {
    return JoinPoints._getNodes(jpType, JoinPoints._all_descendants($jp));
  }

  /**
   *
   * @returns the descendants of the given node, according to the AST, postorder traversal
   */
  static descendantsPostorder(
    $jp: LaraJoinPoint,
    jpType?: JpPredicate
  ): LaraJoinPoint[] {
    return JoinPoints._getNodes(
      jpType,
      JoinPoints._all_descendants_postorder($jp)
    );
  }

  /**
   *
   * @returns  the nodes related with the given node, according to the search function
   */
  private static _getNodes(
    jpType?: JpPredicate,
    $allJps: LaraJoinPoint[] = []
  ): LaraJoinPoint[] {
    // TODO: This function can be optimized by using streaming
    if (jpType === undefined) {
      return $allJps;
    }

    return $allJps.filter((jp) => jpType.isInstance(jp));    
  }

  /**
   * Iterates of attributeNames, returns the first value that is not null or undefined.
   * If no value is found for the given attributes, returns undefined
   *
   * @deprecated Just don't...
   */
  static getAttribute($jp: LaraJoinPoint, attributeNames: string[]) {
    for (const attribute of attributeNames) {
      const value = Object.getOwnPropertyDescriptor($jp, attribute)?.value;
      if (value !== undefined) {
        return value;
      }
    }

    return undefined;
  }

  /**
   * Helper method of getAttribute which throws an exception if no value is found
   *
   * @deprecated Just don't...
   */
  static getAttributeStrict($jp: LaraJoinPoint, attributeNames: string[]) {
    const value = this.getAttribute($jp, attributeNames);

    if (value === undefined) {
      throw (
        "Could not find any of the given attributes in " +
        $jp.toString() +
        ":" +
        attributeNames.join(", ")
      );
    }

    return value;
  }

  /**
   * Converts the join point to a string of code. Expects attribute 'code' to exist.
   *
   * @param $jp - join point to convert to code.
   *
   * @returns a String with the code representation of this join point.
   */
  static getCode($jp: LaraJoinPoint): string {
    const property = "code";

    for (let obj = $jp; obj !== null; obj = Object.getPrototypeOf(obj)) {
      const descriptor = Object.getOwnPropertyDescriptor(obj, property);
      if (descriptor !== undefined) {
        let attributeValue: any = undefined;
        if (Object.getOwnPropertyDescriptor(descriptor, "get")) {
          return descriptor.get?.call?.($jp);
        } else if (Object.getOwnPropertyDescriptor(descriptor, "value")) {
          return descriptor.value;
        } else {
          continue;
        }
      }
    }

    throw "JoinPoints.getCode(): expected attribute 'code' to exist";
  }
}