metadata.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {Expression, ExternalExpr, FunctionExpr, Identifiers, InvokeFunctionExpr, LiteralArrayExpr, LiteralExpr, NONE_TYPE, ReturnStatement, Statement, WrappedNodeExpr, literalMap} from '@angular/compiler';
import * as ts from 'typescript';

import {DefaultImportRecorder} from '../../imports';
import {CtorParameter, Decorator, ReflectionHost} from '../../reflection';

import {valueReferenceToExpression} from './util';


/**
 * Given a class declaration, generate a call to `setClassMetadata` with the Angular metadata
 * present on the class or its member fields.
 *
 * If no such metadata is present, this function returns `null`. Otherwise, the call is returned
 * as a `Statement` for inclusion along with the class.
 */
export function generateSetClassMetadataCall(
    clazz: ts.Declaration, reflection: ReflectionHost, defaultImportRecorder: DefaultImportRecorder,
    isCore: boolean): Statement|null {
  if (!reflection.isClass(clazz)) {
    return null;
  }
  const id = ts.updateIdentifier(reflection.getAdjacentNameOfClass(clazz));

  // Reflect over the class decorators. If none are present, or those that are aren't from
  // Angular, then return null. Otherwise, turn them into metadata.
  const classDecorators = reflection.getDecoratorsOfDeclaration(clazz);
  if (classDecorators === null) {
    return null;
  }
  const ngClassDecorators =
      classDecorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
  if (ngClassDecorators.length === 0) {
    return null;
  }
  const metaDecorators = ts.createArrayLiteral(ngClassDecorators);

  // Convert the constructor parameters to metadata, passing null if none are present.
  let metaCtorParameters: Expression = new LiteralExpr(null);
  const classCtorParameters = reflection.getConstructorParameters(clazz);
  if (classCtorParameters !== null) {
    const ctorParameters = classCtorParameters.map(
        param => ctorParameterToMetadata(param, defaultImportRecorder, isCore));
    metaCtorParameters = new FunctionExpr([], [
      new ReturnStatement(new LiteralArrayExpr(ctorParameters)),
    ]);
  }

  // Do the same for property decorators.
  let metaPropDecorators: ts.Expression = ts.createNull();
  const classMembers = reflection.getMembersOfClass(clazz).filter(
      member => !member.isStatic && member.decorators !== null && member.decorators.length > 0);
  const duplicateDecoratedMemberNames =
      classMembers.map(member => member.name).filter((name, i, arr) => arr.indexOf(name) < i);
  if (duplicateDecoratedMemberNames.length > 0) {
    // This should theoretically never happen, because the only way to have duplicate instance
    // member names is getter/setter pairs and decorators cannot appear in both a getter and the
    // corresponding setter.
    throw new Error(
        `Duplicate decorated properties found on class '${clazz.name.text}': ` +
        duplicateDecoratedMemberNames.join(', '));
  }
  const decoratedMembers =
      classMembers.map(member => classMemberToMetadata(member.name, member.decorators !, isCore));
  if (decoratedMembers.length > 0) {
    metaPropDecorators = ts.createObjectLiteral(decoratedMembers);
  }

  // Generate a pure call to setClassMetadata with the class identifier and its metadata.
  const setClassMetadata = new ExternalExpr(Identifiers.setClassMetadata);
  const fnCall = new InvokeFunctionExpr(
      /* fn */ setClassMetadata,
      /* args */
      [
        new WrappedNodeExpr(id),
        new WrappedNodeExpr(metaDecorators),
        metaCtorParameters,
        new WrappedNodeExpr(metaPropDecorators),
      ]);
  const iifeFn = new FunctionExpr([], [fnCall.toStmt()], NONE_TYPE);
  const iife = new InvokeFunctionExpr(
      /* fn */ iifeFn,
      /* args */[],
      /* type */ undefined,
      /* sourceSpan */ undefined,
      /* pure */ true);
  return iife.toStmt();
}

/**
 * Convert a reflected constructor parameter to metadata.
 */
function ctorParameterToMetadata(
    param: CtorParameter, defaultImportRecorder: DefaultImportRecorder,
    isCore: boolean): Expression {
  // Parameters sometimes have a type that can be referenced. If so, then use it, otherwise
  // its type is undefined.
  const type = param.typeValueReference !== null ?
      valueReferenceToExpression(param.typeValueReference, defaultImportRecorder) :
      new LiteralExpr(undefined);

  const mapEntries: {key: string, value: Expression, quoted: false}[] = [
    {key: 'type', value: type, quoted: false},
  ];

  // If the parameter has decorators, include the ones from Angular.
  if (param.decorators !== null) {
    const ngDecorators =
        param.decorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
    const value = new WrappedNodeExpr(ts.createArrayLiteral(ngDecorators));
    mapEntries.push({key: 'decorators', value, quoted: false});
  }
  return literalMap(mapEntries);
}

/**
 * Convert a reflected class member to metadata.
 */
function classMemberToMetadata(
    name: string, decorators: Decorator[], isCore: boolean): ts.PropertyAssignment {
  const ngDecorators =
      decorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
  const decoratorMeta = ts.createArrayLiteral(ngDecorators);
  return ts.createPropertyAssignment(name, decoratorMeta);
}

/**
 * Convert a reflected decorator to metadata.
 */
function decoratorToMetadata(decorator: Decorator): ts.ObjectLiteralExpression {
  if (decorator.identifier === null) {
    throw new Error('Illegal state: synthesized decorator cannot be emitted in class metadata.');
  }
  // Decorators have a type.
  const properties: ts.ObjectLiteralElementLike[] = [
    ts.createPropertyAssignment('type', ts.getMutableClone(decorator.identifier)),
  ];
  // Sometimes they have arguments.
  if (decorator.args !== null && decorator.args.length > 0) {
    const args = decorator.args.map(arg => ts.getMutableClone(arg));
    properties.push(ts.createPropertyAssignment('args', ts.createArrayLiteral(args)));
  }
  return ts.createObjectLiteral(properties, true);
}

/**
 * Whether a given decorator should be treated as an Angular decorator.
 *
 * Either it's used in @angular/core, or it's imported from there.
 */
function isAngularDecorator(decorator: Decorator, isCore: boolean): boolean {
  return isCore || (decorator.import !== null && decorator.import.from === '@angular/core');
}