从loader到ast树

const loaderUtils = require("loader-utils");
module.exports = function (content, map, meta) {
    
    console.log('前置钩子', this.data.value);
    const options = loaderUtils.getOptions(this);
    console.log('配置文件', options);
    // tofo content进行遍历的过程
    return content+'console.log(1)';
}
//pitch的前置钩子
module.exports.pitch = function (r, prerequest, data) {
    data.value = "京城一灯"
}

const path = require('path');
module.exports = {
    module: {
        rules: [
            {
                test: /.m?js$/,
                exclude: /(node_modules|bower_components)/,
                use: {
                    loader: path.resolve('./loader/index.js'),
                    options: {
                        data:"自定义的配置"
                    }
                }
            }
        ]
    }
}

const acorn = require('acorn');
const walk = require('acorn-walk');
const result = acorn.parse("const a=20");
walk.simple(result, {
    Literal(node) {
        console.log(`Found a literal:${node.value}`);
    }
});

const esprima = require('esprima');
const estraverse = require('estraverse');
const escodegen = require('escodegen');

const code = `const view = {
    a: 3,
    init: () => {
        console.log(this.a);
    },
    render: () => {
        a = 4;
    }
}`;
const ast = esprima.parse(code);
// console.log(ast);
/*Script {
    type: 'Program',
        body:
    [ VariableDeclaration {
        type: 'VariableDeclaration',
        declarations: [Array],
        kind: 'const' } ],
        sourceType: 'script' }*/

estraverse.traverse(ast, {
    enter: function (node) {
        // console.log(node);
        if (node.type == 'VariableDeclaration') {
            node.kind = 'var';
        }
    }
});

const reg_code = escodegen.generate(ast);
console.log(JSON.stringify(reg_code, null, 4));

const {
    Tapable,
    SyncHook,
    SyncBailHook,
    AsyncParallelHook,
    AsyncSeriesHook
} = require("tapable");

let queue = new SyncHook(["name"]);
//订阅
queue.tap("1", function (name, name2) {
    console.log("1", name, name2);
    return 1;
});
queue.tap("2", function (name) {
    console.log("1", name);
    return 2;
});
queue.tap("3", function (name) {
    console.log("1", name);
    return 3;
});
//执行用call
queue.call("webpack", "webpack-cli");