docs: update docs and demo for Value usage, fixes #568

benchmark/demo.js

@@ -8,17 +8,6 @@ const engine = new Liquid({
   extname: '.liquid'
 })
 
-engine.registerTag('header', {
-  parse: function (token) {
-    const [key, val] = token.args.split(':')
-    this[key] = val
-  },
-  render: function (ctx) {
-    const title = this.liquid.evalValue(this.content, ctx)
-    return `<h1>${title}</h1>`
-  }
-})
-
 function demo () {
   console.log('         demo')
   console.log('------------------------')

demo/nodejs/index.js

@@ -1,4 +1,4 @@
-const { Liquid } = require('liquidjs')
+const { Liquid, Tag, Value } = require('liquidjs')
 
 const engine = new Liquid({
   extname: '.liquid',
@@ -11,13 +11,13 @@ const engine = new Liquid({
   partials: './partials'
 })
 
-engine.registerTag('header', {
-  parse: function (token) {
-    const [key, val] = token.args.split(':')
-    this[key] = val
-  },
-  render: async function (scope, emitter) {
-    const title = await this.liquid.evalValue(this.content, scope)
+engine.registerTag('header', class HeaderTag extends Tag {
+  constructor (token, remainTokens, liquid) {
+    super(token, remainTokens, liquid)
+    this.value = new Value(token.args, liquid)
+  }
+  * render (ctx, emitter) {
+    const title = yield this.value.value(ctx)
     emitter.write(`<h1>${title}</h1>`)
   }
 })

demo/nodejs/todolist.liquid

@@ -1,5 +1,5 @@
 {% layout 'html.liquid' %}
-{%header content: title | capitalize%}
+{%header title | capitalize%}
 <ul>
   {% for todo in todos %}
     {% render 'todo.liquid' with todo, index: forloop.index%}

demo/typescript/index.ts

@@ -1,24 +1,25 @@
-import { Liquid, TagToken, Context, Emitter } from 'liquidjs'
+import { Value, Liquid, TagToken, Context, Emitter, Tag, TopLevelToken } from 'liquidjs'
 
 const engine = new Liquid({
   root: __dirname,
   extname: '.liquid'
 })
 
-engine.registerTag('header', {
-  parse: function (token: TagToken) {
-    const [key, val] = token.args.split(':')
-    this[key] = val
-  },
-  render: async function (context: Context, emitter: Emitter) {
-    const title = await this.liquid.evalValue(this['content'], context)
+engine.registerTag('header', class HeaderTag extends Tag {
+  private value: Value
+  constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
+    super(token, remainTokens, liquid)
+    this.value = new Value(token.args, liquid)
+  }
+  * render (ctx: Context, emitter: Emitter) {
+    const title = yield this.value.value(ctx)
     emitter.write(`<h1>${title}</h1>`)
   }
 })
 
-const ctx = {
+const scope = {
   todos: ['fork and clone', 'make it better', 'make a pull request'],
   title: 'Welcome to liquidjs!'
 }
 
-engine.renderFile('todolist', ctx).then(console.log)
+engine.renderFile('todolist', scope).then(console.log)

demo/typescript/todolist.liquid

@@ -1,4 +1,4 @@
-{%header content: title | capitalize%}
+{%header title | capitalize%}
 
 <ul>
   {% for todo in todos %}

demo/typescript/tsconfig.json

@@ -1,7 +1,9 @@
 {
   "compilerOptions": {
-      "types": [
-        "node"
-      ]
+    "target": "es6",
+    "moduleResolution": "node",
+    "types": [
+      "node"
+    ]
   }
 }

docs/source/tutorials/register-filters-tags.md

@@ -6,14 +6,14 @@ title: Register Filters/Tags
 
 ```typescript
 // Usage: {% upper name %}
-import { TagToken, Context, Emitter, TopLevelToken } from 'liquidjs'
+import { Value, TagToken, Context, Emitter, TopLevelToken } from 'liquidjs'
 
 engine.registerTag('upper', {
     parse: function(tagToken: TagToken, remainTokens: TopLevelToken[]) {
-        this.str = tagToken.args; // name
+        this.value = new Value(token.args, liquid)
     },
     render: function*(ctx: Context) {
-        const str = yield this.liquid.evalValue(this.str, ctx); // 'alice'
+        const str = yield this.value.value(ctx); // 'alice'
         return str.toUpperCase() // 'ALICE'
     }
 });
@@ -41,7 +41,7 @@ engine.registerTag('upper', class UpperTag extends Tag {
 });
 ```
 
-See existing tag implementations here: <https://github.com/harttle/liquidjs/tree/master/src/builtin/tags>
+See existing tag implementations here: <https://github.com/harttle/liquidjs/tree/master/src/tags>
 See demo example here: https://github.com/harttle/liquidjs/blob/master/demo/typescript/index.ts
 
 ## Register Filters
@@ -58,7 +58,7 @@ Filter arguments will be passed to the registered filter function, for example:
 engine.registerFilter('add', (initial, arg1, arg2) => initial + arg1 + arg2)
 ```
 
-See existing filter implementations here: <https://github.com/harttle/liquidjs/tree/master/src/builtin/filters>
+See existing filter implementations here: <https://github.com/harttle/liquidjs/tree/master/src/filters>
 
 ## Unregister Tags/Filters
 

docs/source/tutorials/sync-and-async.md

@@ -24,67 +24,93 @@ The synchronous version of methods contains a `Sync` suffix:
 
 ## Implement Sync-Compatible Tags 
 
-### Requirements
+LiquidJS uses a generator-based async implementation to support both async and sync in one piece of tag implementation. For example, below `UpperTag` can be used in both `engine.renderSync()` and `engine.render()`.
 
-All builtin tags are *sync-compatible* and safe to use for both sync and async APIs. To make your custom tag *sync-compatible*, you'll need to avoid return a `Promise`. That means the `render(context, emitter)`:
+```typescript
+import { TagToken, Context, Emitter, TopLevelToken, Value, Tag, Liquid } from 'liquidjs'
+
+// Usage: {% upper "alice" %}
+// Output: ALICE
+engine.registerTag('upper', class UpperTag extends Tag {
+  private value: Value
+  constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
+    super(token, remainTokens, liquid)
+    this.value = new Value(token.args, liquid)
+  }
+  * render (ctx: Context, emitter: Emitter) {
+    const title = yield this.value.value(ctx)
+    emitter.write(title.toUpperCase())
+  }
+})
+```
+
+All builtin tags are implemented this way and safe to use in both sync and async (I'll call it *sync-compatible*). To make your custom tag *sync-compatible*, you'll need to:
+
+- declare render function as `* render()`, in which
+- do not directly `return <Promise>`, and
+- do not call any APIs that returns a Promise.
 
-- Should not directly `return <Promise>`, and
-- Should not be declared as `async`.
+## Call APIs that return a Promise
+
+But LiquidJS is Promise-friendly, right? You can still call Promise-based functions and wait for that Promise within tag implementations. Just replace `await` with `yield`. e.g. we're calling `fs.readFile()` which returns a `Promise`:
+
+```typescript
+  * render (ctx: Context, emitter: Emitter) {
+    const file = yield this.value.value(ctx)
+    const title = yield fs.readFile(file, 'utf8')
+    emitter.write(title.toUpperCase())
+  }
+```
+
+Now that this `* render()` calls an API that returns a Promise, so it's no longer *sync-compatible*.
 
 {% note info Non Sync-Compatible Tags %}
 Non <em>sync-compatible</em> tags are also valid tags, will work just fine for asynchronous API calls. When called synchronously, tags that return a <code>Promise</code> will be rendered as <code>[object Promise]</code>.
 {% endnote %}
 
-### Await Promises
-But LiquidJS is Promise-friendly, right? You can still call Promise-based functions and wait for that Promise within tag implementations. Just replace `await` with `yield` and keep `* render()` instead of `async render()`. e.g.
+## Convert LiquidJS async Generator to Promise
+
+You can convert a Generator to Promise by [toPromise][toPromise], for example:
 
 ```typescript
-import { TagToken, Context, Emitter, TopLevelToken } from 'liquidjs'
+import { TagToken, Context, Emitter, TopLevelToken, Value, Tag, Liquid, toPromise } from 'liquidjs'
 
 // Usage: {% upper "alice" %}
 // Output: ALICE
-engine.registerTag('upper', {
-    parse: function(tagToken: TagToken, remainTokens: TopLevelToken[]) {
-        this.str = tagToken.args
-    },
-    * render: function(ctx: Context) {
-        // _evalValue will behave synchronously when called by synchronous API
-        // in which case `ctx.sync == true`
-        var str = yield this.liquid._evalValue(this.str, ctx)
-        return str.toUpperCase()
-    }
+engine.registerTag('upper', class UpperTag extends Tag {
+  private value: Value
+  constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
+    super(token, remainTokens, liquid)
+    this.value = new Value(token.args, liquid)
+  }
+  async render (ctx: Context, emitter: Emitter) {
+    const title = await toPromise(this.value.value(ctx))
+    emitter.write(title.toUpperCase())
+  }
 })
 ```
 
-See this JSFiddle: <http://jsfiddle.net/ctj364up/6/>.
-
-## Async-only Tags
+## Async only Tags
 
-For tags that intended to be used only by async API, or those cannot be implemented synchronously, there's no difference between using generator-base syntax or async syntax. I'll call them *async-only tags*.
-
-For example, if the above `this.liquid._evalValue()` doesn't respect `ctx.sync` and always returns a Promise, even if the tag is implemented using `* render()` and `yield this.liquid._evalValue()`, it will be rendered as `<object Promise>` anyway.
-
-For *async-only tags*, you can use async syntax at will. Be careful some APIs in LiquidJS return Promises and others return Generators. You'll need [toPromise][toPromise] API to convert a Generator to a Promise, for example:
+If your tag is intend to be used only asynchronously, it can be declared as `async render()` so you can use `await` in its implementation directly:
 
 ```typescript
-import { TagToken, Context, Emitter, TopLevelToken, toPromise } from 'liquidjs'
+import { toPromise, TagToken, Context, Emitter, TopLevelToken, Value, Tag, Liquid } from 'liquidjs'
 
 // Usage: {% upper "alice" %}
 // Output: ALICE
-engine.registerTag('upper', {
-    parse: function(tagToken: TagToken, remainTokens: TopLevelToken[]) {
-        this.str = tagToken.args; // name
-    },
-    render: async function(ctx: Context) {
-        var str = await toPromise(this.liquid._evalValue(this.str, ctx));
-        // Or use the alternate API that returns a Promise
-        // var str = await this.liquid.evalValue(this.str, ctx);
-        return str.toUpperCase()
-    }
-});
+engine.registerTag('upper', class UpperTag extends Tag {
+  private value: Value
+  constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
+    super(token, remainTokens, liquid)
+    this.value = new Value(token.args, liquid)
+  }
+  async render (ctx: Context, emitter: Emitter) {
+    const title = await toPromise(this.value.value(ctx))
+    emitter.write(`<h1>${title}</h1>`)
+  }
+})
 ```
 
-See this JSFiddle: <http://jsfiddle.net/ctj364up/5/>.
-
 [Liquid]: /api/classes/liquid_.liquid.html
 [toPromise]: /api/modules/liquid_.html#toPromise

docs/source/zh-cn/tutorials/register-filters-tags.md

@@ -8,10 +8,10 @@ title: 注册标签和过滤器
 // 使用方式: {% upper name %}
 engine.registerTag('upper', {
     parse: function(tagToken, remainTokens) {
-        this.str = tagToken.args; // name
+        this.value = new Value(token.args, liquid)
     },
-    render: async function(scope, hash) {
-        var str = await this.liquid.evalValue(this.str, scope); // 'alice'
+    render: function*(scope, hash) {
+        const str = yield this.value.value(ctx); // 'alice'
         return str.toUpperCase()  // 'Alice'
     }
 });
@@ -20,7 +20,26 @@ engine.registerTag('upper', {
 * `parse`: 从 `remainTokens` 中读取后续的标签/输出/HTML，直到找到你期望的结束标签。
 * `render`: 把 scope 数据和此前解析得到的 Token 结合，输出 HTML 字符串。
 
-查看已有的标签实现：<https://github.com/harttle/liquidjs/tree/master/src/builtin/tags>
+对于更复杂的标签实现，可以提供一个继承自 `Tag` 的类：
+
+```typescript
+// Usage: {% upper name:"alice" %}
+import { Hash, Tag, TagToken, Context, Emitter, TopLevelToken, Liquid } from 'liquidjs'
+
+engine.registerTag('upper', class UpperTag extends Tag {
+    private hash: Hash
+    constructor(tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
+        super(tagToken, remainTokens, liquid)
+        this.hash = new Hash(tagToken.args)
+    }
+    * render(ctx: Context) {
+        const hash = yield this.hash.render();
+        return hash.name.toUpperCase() // 'ALICE'
+    }
+});
+```
+
+可以参考已有的标签实现：<https://github.com/harttle/liquidjs/tree/master/src/tags>
 
 ## 注册过滤器
 
@@ -36,7 +55,7 @@ engine.registerFilter('upper', v => v.toUpperCase())
 engine.registerFilter('add', (initial, arg1, arg2) => initial + arg1 + arg2)
 ```
 
-查看已有的过滤器实现：<https://github.com/harttle/liquidjs/tree/master/src/builtin/filters>。对于复杂的标签，也可以用一个类来实现：
+查看已有的过滤器实现：<https://github.com/harttle/liquidjs/tree/master/src/filters>。对于复杂的标签，也可以用一个类来实现：
 
 ```typescript
 // Usage: {% upper name:"alice" %}