像做游戏一样编程的网站,盐城网站开发代理咨询,做音乐网站要什么源码,山东聊城做网站此代码可以解决大部分 while if else 控制流平坦化原理#xff1a; 先将 if 语句转为 switch 语句#xff0c;再将 switch 分支合并#xff0c;最后删除已合并的分支#xff08;具体看代码#xff09; 实现效果图 首先安装依赖#xff1a;
npm install babel/parser
npm…此代码可以解决大部分 while if else 控制流平坦化原理 先将 if 语句转为 switch 语句再将 switch 分支合并最后删除已合并的分支具体看代码 实现效果图 首先安装依赖
npm install babel/parser
npm install babel/generator
npm install babel/traverse
npm install babel/types代码
/*
* 控制流平坦化 if语句转 switch* */
function del_code(name, consequent) {// 删除合并分支后多余的 赋值和break代码let assignment_bool, break_bool;for (let i consequent.length - 1; i 0; i--) {if (consequent[i].type BreakStatement) {if (break_bool) {consequent.splice(i, 1);} else {break_bool true;}} else if (consequent[i].type ExpressionStatement consequent[i].expression.type AssignmentExpression consequent[i].expression.left.name name) {if (assignment_bool) {consequent.splice(i, 1);} else {assignment_bool true;}}}
}function merge_branch(name, key, cases_dict) {// 用于递归合并 switch 分支let {consequent} cases_dict[key];let value -1;for (let i in consequent) {if (consequent[i].type ExpressionStatement consequent[i].expression.type AssignmentExpression consequent[i].expression.left.name name consequent[i].expression.right.type NumericLiteral) {value consequent[i].expression.right.value;break;}}if (value ! -1 cases_dict.hasOwnProperty(value)) {del_cases_dict[value] 1;return consequent.concat(merge_branch(name, value, cases_dict)); // 继续下一分支的合并}return consequent;
}const fs require(fs);
const {parse} require(babel/parser);
const traverse require(babel/traverse).default;
const generator require(babel/generator).default;
const types require(babel/types);const js_code fs.readFileSync(./test.js, utf8);
const ast_code parse(js_code);switch_cases_dict {};
break_node types.breakStatement();traverse(ast_code, {IfStatement: {enter(path) {var name path.node.test.left.name;if (path.node.test.operator ) { // 如果判断符号是 if (switch_cases_dict[name] undefined) {switch_cases_dict[name] [];}path.node.consequent.body.push(break_node);switch_cases_dict[name].push(types.switchCase(path.node.test.right, path.node.consequent.body));if (path.node.alternate.type BlockStatement) {path.node.alternate.body.push(break_node);let num path.node.test.right.value 1;switch_cases_dict[name].push(types.switchCase(types.numericLiteral(num),path.node.alternate.body,));}}},exit(path) {var name path.node.test.left.name;if (path.parentPath.parentPath.type WhileStatement switch_cases_dict[name].length ! 0) {console.log(name, if 已替换 switch);path.replaceWith(types.switchStatement(discriminant types.identifier(name),cases switch_cases_dict[name]));}}},SwitchStatement: {enter(path) {del_cases_dict {}; // 待删除的 分支语句let cases_dict {};let cases_list path.node.cases;let {name} path.node.discriminant;if (switch_cases_dict.hasOwnProperty(name)) {console.log(name, switch 分支合并);for (let i in cases_list) {cases_dict[cases_list[i].test.value] cases_list[i]}for (let key in cases_dict) { // 合并分支并删除多余代码cases_dict[key].consequent merge_branch(name, key, cases_dict);del_code(name, cases_dict[key].consequent);}for (let key in del_cases_dict) {delete cases_dict[key]; // 删除多余分支}path.node.cases Object.values(cases_dict);}},}
})// console.log(generator(ast_code).code)
fs.writeFileSync(./demo.js, generator(ast_code).code, utf8)注以上js解出来的代码在某些分支会出现多次 return 语句当然并不影响运行。我暂时没找到出现这种问题的原因在哪里如果您找到请务必和我说下另您也可以在 del_code 函数中删除多的 return 语句
