angular-docs-cn/modules/@angular/compiler/src/template_ast.ts

import {AST} from './expression_parser/ast';
import {isPresent} from '../src/facade/lang';
import {
  CompileDirectiveMetadata,
  CompileTokenMetadata,
  CompileProviderMetadata,
} from './compile_metadata';
import {ParseSourceSpan} from './parse_util';
import {SecurityContext} from '../core_private';

/**
 * An Abstract Syntax Tree node representing part of a parsed Angular template.
 */
export interface TemplateAst {
  /**
   * The source span from which this node was parsed.
   */
  sourceSpan: ParseSourceSpan;

  /**
   * Visit this node and possibly transform it.
   */
  visit(visitor: TemplateAstVisitor, context: any): any;
}

/**
 * A segment of text within the template.
 */
export class TextAst implements TemplateAst {
  constructor(public value: string, public ngContentIndex: number,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any { return visitor.visitText(this, context); }
}

/**
 * A bound expression within the text of a template.
 */
export class BoundTextAst implements TemplateAst {
  constructor(public value: AST, public ngContentIndex: number,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitBoundText(this, context);
  }
}

/**
 * A plain attribute on an element.
 */
export class AttrAst implements TemplateAst {
  constructor(public name: string, public value: string, public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any { return visitor.visitAttr(this, context); }
}

/**
 * A binding for an element property (e.g. `[property]="expression"`).
 */
export class BoundElementPropertyAst implements TemplateAst {
  constructor(public name: string, public type: PropertyBindingType,
              public securityContext: SecurityContext, public value: AST, public unit: string,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitElementProperty(this, context);
  }
}

/**
 * A binding for an element event (e.g. `(event)="handler()"`).
 */
export class BoundEventAst implements TemplateAst {
  constructor(public name: string, public target: string, public handler: AST,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitEvent(this, context);
  }
  get fullName() {
    if (isPresent(this.target)) {
      return `${this.target}:${this.name}`;
    } else {
      return this.name;
    }
  }
}

/**
 * A reference declaration on an element (e.g. `let someName="expression"`).
 */
export class ReferenceAst implements TemplateAst {
  constructor(public name: string, public value: CompileTokenMetadata,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitReference(this, context);
  }
}

/**
 * A variable declaration on a <template> (e.g. `var-someName="someLocalName"`).
 */
export class VariableAst implements TemplateAst {
  constructor(public name: string, public value: string, public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitVariable(this, context);
  }
}

/**
 * An element declaration in a template.
 */
export class ElementAst implements TemplateAst {
  constructor(public name: string, public attrs: AttrAst[],
              public inputs: BoundElementPropertyAst[], public outputs: BoundEventAst[],
              public references: ReferenceAst[], public directives: DirectiveAst[],
              public providers: ProviderAst[], public hasViewContainer: boolean,
              public children: TemplateAst[], public ngContentIndex: number,
              public sourceSpan: ParseSourceSpan) {}

  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitElement(this, context);
  }
}

/**
 * A `<template>` element included in an Angular template.
 */
export class EmbeddedTemplateAst implements TemplateAst {
  constructor(public attrs: AttrAst[], public outputs: BoundEventAst[],
              public references: ReferenceAst[], public variables: VariableAst[],
              public directives: DirectiveAst[], public providers: ProviderAst[],
              public hasViewContainer: boolean, public children: TemplateAst[],
              public ngContentIndex: number, public sourceSpan: ParseSourceSpan) {}

  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitEmbeddedTemplate(this, context);
  }
}

/**
 * A directive property with a bound value (e.g. `*ngIf="condition").
 */
export class BoundDirectivePropertyAst implements TemplateAst {
  constructor(public directiveName: string, public templateName: string, public value: AST,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitDirectiveProperty(this, context);
  }
}

/**
 * A directive declared on an element.
 */
export class DirectiveAst implements TemplateAst {
  constructor(public directive: CompileDirectiveMetadata,
              public inputs: BoundDirectivePropertyAst[],
              public hostProperties: BoundElementPropertyAst[], public hostEvents: BoundEventAst[],
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitDirective(this, context);
  }
}

/**
 * A provider declared on an element
 */
export class ProviderAst implements TemplateAst {
  constructor(public token: CompileTokenMetadata, public multiProvider: boolean,
              public eager: boolean, public providers: CompileProviderMetadata[],
              public providerType: ProviderAstType, public sourceSpan: ParseSourceSpan) {}

  visit(visitor: TemplateAstVisitor, context: any): any {
    // No visit method in the visitor for now...
    return null;
  }
}

export enum ProviderAstType {
  PublicService,
  PrivateService,
  Component,
  Directive,
  Builtin
}

/**
 * Position where content is to be projected (instance of `<ng-content>` in a template).
 */
export class NgContentAst implements TemplateAst {
  constructor(public index: number, public ngContentIndex: number,
              public sourceSpan: ParseSourceSpan) {}
  visit(visitor: TemplateAstVisitor, context: any): any {
    return visitor.visitNgContent(this, context);
  }
}

/**
 * Enumeration of types of property bindings.
 */
export enum PropertyBindingType {

  /**
   * A normal binding to a property (e.g. `[property]="expression"`).
   */
  Property,

  /**
   * A binding to an element attribute (e.g. `[attr.name]="expression"`).
   */
  Attribute,

  /**
   * A binding to a CSS class (e.g. `[class.name]="condition"`).
   */
  Class,

  /**
   * A binding to a style rule (e.g. `[style.rule]="expression"`).
   */
  Style
}

/**
 * A visitor for {@link TemplateAst} trees that will process each node.
 */
export interface TemplateAstVisitor {
  visitNgContent(ast: NgContentAst, context: any): any;
  visitEmbeddedTemplate(ast: EmbeddedTemplateAst, context: any): any;
  visitElement(ast: ElementAst, context: any): any;
  visitReference(ast: ReferenceAst, context: any): any;
  visitVariable(ast: VariableAst, context: any): any;
  visitEvent(ast: BoundEventAst, context: any): any;
  visitElementProperty(ast: BoundElementPropertyAst, context: any): any;
  visitAttr(ast: AttrAst, context: any): any;
  visitBoundText(ast: BoundTextAst, context: any): any;
  visitText(ast: TextAst, context: any): any;
  visitDirective(ast: DirectiveAst, context: any): any;
  visitDirectiveProperty(ast: BoundDirectivePropertyAst, context: any): any;
}

/**
 * Visit every node in a list of {@link TemplateAst}s with the given {@link TemplateAstVisitor}.
 */
export function templateVisitAll(visitor: TemplateAstVisitor, asts: TemplateAst[],
                                 context: any = null): any[] {
  var result = [];
  asts.forEach(ast => {
    var astResult = ast.visit(visitor, context);
    if (isPresent(astResult)) {
      result.push(astResult);
    }
  });
  return result;
}