'use strict';
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const path = require('path');
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const assert = require('assert');
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const RENDER = Symbol.for('contextView#render');
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const RENDER_STRING = Symbol.for('contextView#renderString');
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const GET_VIEW_ENGINE = Symbol.for('contextView#getViewEngine');
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const SET_LOCALS = Symbol.for('contextView#setLocals');
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/**
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* View instance for each request.
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*
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* It will find the view engine, and render it.
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* The view engine should be registered in {@link ViewManager}.
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*/
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class ContextView {
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constructor(ctx) {
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this.ctx = ctx;
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this.app = this.ctx.app;
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this.viewManager = ctx.app.view;
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this.config = ctx.app.view.config;
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}
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/**
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* Render a file by view engine
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* @param {String} name - the file path based on root
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* @param {Object} [locals] - data used by template
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* @param {Object} [options] - view options, you can use `options.viewEngine` to specify view engine
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* @return {Promise<String>} result - return a promise with a render result
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*/
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render(...args) {
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return this[RENDER](...args);
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}
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/**
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* Render a template string by view engine
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* @param {String} tpl - template string
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* @param {Object} [locals] - data used by template
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* @param {Object} [options] - view options, you can use `options.viewEngine` to specify view engine
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* @return {Promise<String>} result - return a promise with a render result
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*/
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renderString(...args) {
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return this[RENDER_STRING](...args);
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}
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// ext -> viewEngineName -> viewEngine
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async [RENDER](name, locals, options = {}) {
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// retrieve fullpath matching name from `config.root`
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const filename = await this.viewManager.resolve(name);
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options.name = name;
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options.root = filename.replace(path.normalize(name), '').replace(/[\/\\]$/, '');
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options.locals = locals;
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// get the name of view engine,
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// if viewEngine is specified in options, don't match extension
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let viewEngineName = options.viewEngine;
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if (!viewEngineName) {
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const ext = path.extname(filename);
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viewEngineName = this.viewManager.extMap.get(ext);
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}
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// use the default view engine that is configured if no matching above
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if (!viewEngineName) {
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viewEngineName = this.config.defaultViewEngine;
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}
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assert(viewEngineName, `Can't find viewEngine for ${filename}`);
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// get view engine and render
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const view = this[GET_VIEW_ENGINE](viewEngineName);
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return await view.render(filename, this[SET_LOCALS](locals), options);
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}
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[RENDER_STRING](tpl, locals, options) {
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let viewEngineName = options && options.viewEngine;
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if (!viewEngineName) {
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viewEngineName = this.config.defaultViewEngine;
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}
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assert(viewEngineName, 'Can\'t find viewEngine');
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// get view engine and render
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const view = this[GET_VIEW_ENGINE](viewEngineName);
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return view.renderString(tpl, this[SET_LOCALS](locals), options);
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}
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[GET_VIEW_ENGINE](name) {
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// get view engine
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const ViewEngine = this.viewManager.get(name);
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assert(ViewEngine, `Can't find ViewEngine "${name}"`);
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// use view engine to render
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const engine = new ViewEngine(this.ctx);
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// wrap render and renderString to support both async function and generator function
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if (engine.render) engine.render = this.app.toAsyncFunction(engine.render);
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if (engine.renderString) engine.renderString = this.app.toAsyncFunction(engine.renderString);
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return engine;
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}
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/**
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* set locals for view, inject `locals.ctx`, `locals.request`, `locals.helper`
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* @param {Object} locals - locals
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* @return {Object} locals
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* @private
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*/
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[SET_LOCALS](locals) {
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return Object.assign({
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ctx: this.ctx,
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request: this.ctx.request,
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helper: this.ctx.helper,
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}, this.ctx.locals, locals);
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}
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}
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module.exports = ContextView;
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