angular-cn/packages/compiler/src/render3/view/util.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 {ConstantPool} from '../../constant_pool';
import * as o from '../../output/output_ast';
import * as t from '../r3_ast';

import {R3QueryMetadata} from './api';

/** Name of the temporary to use during data binding */
export const TEMPORARY_NAME = '_t';

/** Name of the context parameter passed into a template function */
export const CONTEXT_NAME = 'ctx';

/** Name of the RenderFlag passed into a template function */
export const RENDER_FLAGS = 'rf';

/** The prefix reference variables */
export const REFERENCE_PREFIX = '_r';

/** The name of the implicit context reference */
export const IMPLICIT_REFERENCE = '$implicit';

/** Name of the i18n attributes **/
export const I18N_ATTR = 'i18n';
export const I18N_ATTR_PREFIX = 'i18n-';

/** I18n separators for metadata **/
export const MEANING_SEPARATOR = '|';
export const ID_SEPARATOR = '@@';

/** Placeholder wrapper for i18n expressions **/
export const I18N_PLACEHOLDER_SYMBOL = '<27>';

/** Non bindable attribute name **/
export const NON_BINDABLE_ATTR = 'ngNonBindable';

/**
 * Creates an allocator for a temporary variable.
 *
 * A variable declaration is added to the statements the first time the allocator is invoked.
 */
export function temporaryAllocator(statements: o.Statement[], name: string): () => o.ReadVarExpr {
  let temp: o.ReadVarExpr|null = null;
  return () => {
    if (!temp) {
      statements.push(new o.DeclareVarStmt(TEMPORARY_NAME, undefined, o.DYNAMIC_TYPE));
      temp = o.variable(name);
    }
    return temp;
  };
}


export function unsupported(feature: string): never {
  if (this) {
    throw new Error(`Builder ${this.constructor.name} doesn't support ${feature} yet`);
  }
  throw new Error(`Feature ${feature} is not supported yet`);
}

export function invalid<T>(arg: o.Expression | o.Statement | t.Node): never {
  throw new Error(
      `Invalid state: Visitor ${this.constructor.name} doesn't handle ${o.constructor.name}`);
}

export function isI18NAttribute(name: string): boolean {
  return name === I18N_ATTR || name.startsWith(I18N_ATTR_PREFIX);
}

export function wrapI18nPlaceholder(content: string | number): string {
  return `${I18N_PLACEHOLDER_SYMBOL}${content}${I18N_PLACEHOLDER_SYMBOL}`;
}

export function assembleI18nTemplate(strings: Array<string>): string {
  if (!strings.length) return '';
  let acc = '';
  const lastIdx = strings.length - 1;
  for (let i = 0; i < lastIdx; i++) {
    acc += `${strings[i]}${wrapI18nPlaceholder(i)}`;
  }
  acc += strings[lastIdx];
  return acc;
}

export function asLiteral(value: any): o.Expression {
  if (Array.isArray(value)) {
    return o.literalArr(value.map(asLiteral));
  }
  return o.literal(value, o.INFERRED_TYPE);
}

export function conditionallyCreateMapObjectLiteral(keys: {[key: string]: string}): o.Expression|
    null {
  if (Object.getOwnPropertyNames(keys).length > 0) {
    return mapToExpression(keys);
  }
  return null;
}

export function mapToExpression(map: {[key: string]: any}, quoted = false): o.Expression {
  return o.literalMap(
      Object.getOwnPropertyNames(map).map(key => ({key, quoted, value: asLiteral(map[key])})));
}

/**
 *  Remove trailing null nodes as they are implied.
 */
export function trimTrailingNulls(parameters: o.Expression[]): o.Expression[] {
  while (o.isNull(parameters[parameters.length - 1])) {
    parameters.pop();
  }
  return parameters;
}

export function getQueryPredicate(
    query: R3QueryMetadata, constantPool: ConstantPool): o.Expression {
  if (Array.isArray(query.predicate)) {
    let predicate: o.Expression[] = [];
    query.predicate.forEach((selector: string): void => {
      // Each item in predicates array may contain strings with comma-separated refs
      // (for ex. 'ref, ref1, ..., refN'), thus we extract individual refs and store them
      // as separate array entities
      const selectors = selector.split(',').map(token => o.literal(token.trim()));
      predicate.push(...selectors);
    });
    return constantPool.getConstLiteral(o.literalArr(predicate), true);
  } else {
    return query.predicate;
  }
}

export function noop() {}

export class DefinitionMap {
  values: {key: string, quoted: boolean, value: o.Expression}[] = [];

  set(key: string, value: o.Expression|null): void {
    if (value) {
      this.values.push({key, value, quoted: false});
    }
  }

  toLiteralMap(): o.LiteralMapExpr { return o.literalMap(this.values); }
}

/**
 * Extract a map of properties to values for a given element or template node, which can be used
 * by the directive matching machinery.
 *
 * @param elOrTpl the element or template in question
 * @return an object set up for directive matching. For attributes on the element/template, this
 * object maps a property name to its (static) value. For any bindings, this map simply maps the
 * property name to an empty string.
 */
export function getAttrsForDirectiveMatching(elOrTpl: t.Element | t.Template):
    {[name: string]: string} {
  const attributesMap: {[name: string]: string} = {};

  elOrTpl.attributes.forEach(a => {
    if (!isI18NAttribute(a.name)) {
      attributesMap[a.name] = a.value;
    }
  });
  elOrTpl.inputs.forEach(i => { attributesMap[i.name] = ''; });
  elOrTpl.outputs.forEach(o => { attributesMap[o.name] = ''; });

  return attributesMap;
}