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[BREAKING] Use plain functions for AST plugins.
This changes AST Plugins to be "plain functions" with the following interface:
```ts
import { AST, Syntax } from '@glimmer/syntax';
export type NodeVisitor = {
[P in keyof AST.Nodes]?: NodeHandler<AST.Nodes[P]>;
};
export interface ASTPluginResult {
name: string;
visitors: NodeVisitor;
}
export interface ASTPlugin {
(env: ASTPluginEnvironment): ASTPluginResult;
}
export interface ASTPluginEnvironment {
meta?: any;
syntax: Syntax;
}
```
The current system of instantiation is fairly confusing and makes a number of use cases pretty difficult (where you need to preserve some other outside state that you access from within your plugin's `transform`).
The old API can easily be reimplemented in terms of the plain functions in consumers (e.g. Ember for compatibility):
```js
let uuid = 0;
function ensurePlugin(FunctionOrPlugin: any): ASTPlugin {
if (FunctionOrPlugin.prototype && FunctionOrPlugin.prototype.transform) {
return (env) => {
return {
name: 'legacy-transform' + (++uuid) ,
visitors: {
Program(node: AST.Program) {
let plugin = new FunctionOrPlugin(env);
plugin.syntax = env.syntax;
return plugin.transform(node);
}
}
};
};
} else {
return FunctionOrPlugin;
}
}
```
A test exists for this (to ensure Ember can provide backwards compat).- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -6,10 +6,11 @@ import * as AST from "../types/nodes"; | |
| import SyntaxError from '../errors/syntax-error'; | ||
| import { Tag } from "../parser"; | ||
| import builders from "../builders"; | ||
| import traverse, { NodeVisitor } from "../traversal/traverse"; | ||
| import print from "../generation/print"; | ||
| import Walker from "../traversal/walker"; | ||
| import * as handlebars from "handlebars"; | ||
| import { assign } from '@glimmer/util'; | ||
|
|
||
| const voidMap: { | ||
| [tagName: string]: boolean | ||
|
|
@@ -307,38 +308,43 @@ export const syntax: Syntax = { | |
| }; | ||
|
|
||
| /** | ||
| ASTPlugins can make changes to the Glimmer template AST before | ||
| compilation begins. | ||
| */ | ||
| export interface ASTPlugin { | ||
| (env: ASTPluginEnvironment): ASTPluginResult; | ||
| } | ||
|
|
||
| export interface ASTPluginResult { | ||
| name: string; | ||
| visitors: NodeVisitor; | ||
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|
||
| } | ||
|
|
||
| export interface ASTPluginEnvironment { | ||
| meta?: any; | ||
| syntax: Syntax; | ||
| } | ||
|
|
||
| export interface PreprocessOptions { | ||
| plugins?: { | ||
| ast?: ASTPlugin[]; | ||
| }; | ||
| } | ||
|
|
||
| export function preprocess(html: string, options?: PreprocessOptions): AST.Program { | ||
| let ast = (typeof html === 'object') ? html : handlebars.parse(html); | ||
| let program = new TokenizerEventHandlers(html, options).acceptNode(ast); | ||
|
|
||
| if (options && options.plugins && options.plugins.ast) { | ||
| for (let i = 0, l = options.plugins.ast.length; i < l; i++) { | ||
| let transform = options.plugins.ast[i]; | ||
| let env = assign({}, options, { syntax }, { plugins: undefined }); | ||
|
|
||
| let pluginResult = transform(env); | ||
|
|
||
| traverse(program, pluginResult.visitors); | ||
| } | ||
| } | ||
|
|
||
| return program; | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,118 +1,134 @@ | ||
| import { | ||
| preprocess, | ||
| Syntax, | ||
| Walker, | ||
| AST, | ||
| ASTPlugin | ||
| } from '@glimmer/syntax'; | ||
|
|
||
| const { test } = QUnit; | ||
|
|
||
| QUnit.module('[glimmer-syntax] Plugins - AST Transforms'); | ||
|
|
||
| test('function based AST plugins can be provided to the compiler', assert => { | ||
| assert.expect(1); | ||
|
|
||
| preprocess('<div></div>', { | ||
| plugins: { | ||
| ast: [ | ||
| () => ({ | ||
| name: 'plugin-a', | ||
| visitors: { | ||
| Program() { | ||
| assert.ok(true, 'transform was called!'); | ||
| } | ||
| } | ||
| }) | ||
| ] | ||
| } | ||
| }); | ||
| }); | ||
|
|
||
| test('plugins are provided the syntax package', assert => { | ||
| assert.expect(1); | ||
|
|
||
| preprocess('<div></div>', { | ||
| plugins: { | ||
| ast: [ | ||
| ({ syntax }) => { | ||
| assert.equal(syntax.Walker, Walker); | ||
|
|
||
| return { name: 'plugin-a', visitors: {} }; | ||
| } | ||
| ] | ||
| } | ||
| }); | ||
| }); | ||
|
|
||
| test('can support the legacy AST transform API via ASTPlugin', assert => { | ||
| function ensurePlugin(FunctionOrPlugin: any): ASTPlugin { | ||
| if (FunctionOrPlugin.prototype && FunctionOrPlugin.prototype.transform) { | ||
| return (env) => { | ||
| return { | ||
| name: 'plugin-a', | ||
|
|
||
| visitors: { | ||
| Program(node: AST.Program) { | ||
| let plugin = new FunctionOrPlugin(env); | ||
|
|
||
| plugin.syntax = env.syntax; | ||
|
|
||
| return plugin.transform(node); | ||
| } | ||
| } | ||
| }; | ||
| }; | ||
| } else { | ||
| return FunctionOrPlugin; | ||
| } | ||
| } | ||
|
|
||
| class Plugin { | ||
| syntax: Syntax; | ||
|
|
||
| transform(program: AST.Program): AST.Program { | ||
| assert.ok(true, 'transform was called!'); | ||
| return program; | ||
| } | ||
| } | ||
|
|
||
| preprocess('<div></div>', { | ||
| plugins: { | ||
| ast: [ ensurePlugin(Plugin) ] | ||
| } | ||
| }); | ||
| }); | ||
|
|
||
| test('AST plugins can be chained', assert => { | ||
| assert.expect(3); | ||
|
|
||
| let first = () => { | ||
| return { | ||
| name: 'first', | ||
| visitors: { | ||
| Program(program: AST.Program) { | ||
| program['isFromFirstPlugin'] = true; | ||
| } | ||
| } | ||
| }; | ||
| }; | ||
|
|
||
| let second = () => { | ||
| return { | ||
| name: 'second', | ||
| visitors: { | ||
| Program(node: AST.Program) { | ||
| assert.equal(node['isFromFirstPlugin'], true, 'AST from first plugin is passed to second'); | ||
|
|
||
| node['isFromSecondPlugin'] = true; | ||
| } | ||
| } | ||
| }; | ||
| }; | ||
|
|
||
| let third = () => { | ||
| return { | ||
| name: 'third', | ||
| visitors: { | ||
| Program(node: AST.Program) { | ||
| assert.equal(node['isFromSecondPlugin'], true, 'AST from second plugin is passed to third'); | ||
|
|
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| node['isFromThirdPlugin'] = true; | ||
| } | ||
| } | ||
| }; | ||
| }; | ||
|
|
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| let ast = preprocess('<div></div>', { | ||
| plugins: { | ||
| ast: [first, second, third] | ||
| } | ||
| }); | ||
|
|
||
| assert.equal(ast['isFromThirdPlugin'], true, 'return value from last AST transform is used'); | ||
| }); |
The plural here is confusing and seems to imply
NodeVisitor[]instead ofNodeVisitor.