From 6f6b2680a328988b3fda762d22be461d84e46a14 Mon Sep 17 00:00:00 2001
From: aiyingfeng <aiyingfeng110@qq.com>
Date: Tue, 22 Aug 2023 16:06:44 +0800
Subject: [PATCH] =?UTF-8?q?13.AST=E9=81=8D=E5=8E=86=E6=96=B9=E5=BC=8Fenter?=
 =?UTF-8?q?=E5=92=8Cexit=E7=9A=84=E5=8C=BA=E5=88=AB?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../13.AST遍历方式enter和exit的区别/README.md | 92 +++++++++++++++++++
 .../decode_obfuscator.js                      | 28 ++++++
 .../decode_obfuscator1.js                     | 26 ++++++
 .../13.AST遍历方式enter和exit的区别/encode.js |  1 +
 4 files changed, 147 insertions(+)
 create mode 100644 AST抽象语法树/13.AST遍历方式enter和exit的区别/README.md
 create mode 100644 AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator.js
 create mode 100644 AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator1.js
 create mode 100644 AST抽象语法树/13.AST遍历方式enter和exit的区别/encode.js

diff --git a/AST抽象语法树/13.AST遍历方式enter和exit的区别/README.md b/AST抽象语法树/13.AST遍历方式enter和exit的区别/README.md
new file mode 100644
index 0000000..d2a9238
--- /dev/null
+++ b/AST抽象语法树/13.AST遍历方式enter和exit的区别/README.md
@@ -0,0 +1,92 @@
+# AST遍历方式enter和exit的区别
+
+测试代码
+
+```javascript
+var a = 'a' + 'b' + 'c' + d + 'e' + 'f';
+```
+
+**默认的遍历方式enter**
+
+从代码结构的角度看，enter 钩子通常与深度优先遍历的进入节点的过程相对应，符合从上到下、从外到内的思维逻辑。
+
+```javascript
+const fs = require('fs');
+const {parse} = require("@babel/parser");
+const traverse = require("@babel/traverse").default;
+const generator = require("@babel/generator").default;
+const t = require('@babel/types');
+let encode_file = "./encode.js";
+
+let js_code = fs.readFileSync(encode_file, {encoding: "utf-8"});
+let ast = parse(js_code, {
+    sourceType: 'module',
+});
+
+
+const visitor = {
+    BinaryExpression(path){
+            console.log(path.toString())
+            const {confident, value} = path.evaluate();
+            confident && path.replaceWith(t.valueToNode(value));
+    },
+}
+
+traverse(ast, visitor);
+
+// 将修改后的AST重新生成为代码
+const modifiedCode = generator(ast).code;
+console.log(modifiedCode);
+```
+
+打印内容：
+
+    'a' + 'b' + 'c' + d + 'e' + 'f'
+    'a' + 'b' + 'c' + d + 'e'
+    'a' + 'b' + 'c' + d
+    'a' + 'b' + 'c'
+    var a = "abc" + d + 'e' + 'f';
+
+**exit遍历方式**
+
+从代码结构的角度看，exit 钩子通常与深度优先遍历的离开节点的过程相对应，符合从下到上、从内到外的思维逻辑。
+
+```javascript
+const fs = require('fs');
+const {parse} = require("@babel/parser");
+const traverse = require("@babel/traverse").default;
+const generator = require("@babel/generator").default;
+const t = require('@babel/types');
+let encode_file = "./encode.js";
+
+let js_code = fs.readFileSync(encode_file, {encoding: "utf-8"});
+let ast = parse(js_code, {
+    sourceType: 'module',
+});
+
+
+const visitor = {
+    BinaryExpression: {
+        exit: function(path) {
+            console.log(path.toString())
+            const {confident, value} = path.evaluate();
+            confident && path.replaceWith(t.valueToNode(value));
+        }
+    },
+}
+
+traverse(ast, visitor);
+
+// 将修改后的AST重新生成为代码
+const modifiedCode = generator(ast).code;
+console.log(modifiedCode);
+```
+
+打印内容：
+
+    'a' + 'b'
+    "ab" + 'c'
+    "abc" + d
+    "abc" + d + 'e'
+    "abc" + d + 'e' + 'f'
+    var a = "abc" + d + 'e' + 'f';
diff --git a/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator.js b/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator.js
new file mode 100644
index 0000000..4837e2f
--- /dev/null
+++ b/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator.js
@@ -0,0 +1,28 @@
+const fs = require('fs');
+const {parse} = require("@babel/parser");
+const traverse = require("@babel/traverse").default;
+const generator = require("@babel/generator").default;
+const t = require('@babel/types');
+let encode_file = "./encode.js";
+
+let js_code = fs.readFileSync(encode_file, {encoding: "utf-8"});
+let ast = parse(js_code, {
+    sourceType: 'module',
+});
+
+
+const visitor = {
+    BinaryExpression: {
+        exit: function(path) {
+            console.log(path.toString())
+            const {confident, value} = path.evaluate();
+            confident && path.replaceWith(t.valueToNode(value));
+        }
+    },
+}
+
+traverse(ast, visitor);
+
+// 将修改后的AST重新生成为代码
+const modifiedCode = generator(ast).code;
+console.log(modifiedCode);
\ No newline at end of file
diff --git a/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator1.js b/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator1.js
new file mode 100644
index 0000000..7b1e147
--- /dev/null
+++ b/AST抽象语法树/13.AST遍历方式enter和exit的区别/decode_obfuscator1.js
@@ -0,0 +1,26 @@
+const fs = require('fs');
+const {parse} = require("@babel/parser");
+const traverse = require("@babel/traverse").default;
+const generator = require("@babel/generator").default;
+const t = require('@babel/types');
+let encode_file = "./encode.js";
+
+let js_code = fs.readFileSync(encode_file, {encoding: "utf-8"});
+let ast = parse(js_code, {
+    sourceType: 'module',
+});
+
+
+const visitor = {
+    BinaryExpression(path){
+            console.log(path.toString())
+            const {confident, value} = path.evaluate();
+            confident && path.replaceWith(t.valueToNode(value));
+    },
+}
+
+traverse(ast, visitor);
+
+// 将修改后的AST重新生成为代码
+const modifiedCode = generator(ast).code;
+console.log(modifiedCode);
\ No newline at end of file
diff --git a/AST抽象语法树/13.AST遍历方式enter和exit的区别/encode.js b/AST抽象语法树/13.AST遍历方式enter和exit的区别/encode.js
new file mode 100644
index 0000000..b86c49a
--- /dev/null
+++ b/AST抽象语法树/13.AST遍历方式enter和exit的区别/encode.js
@@ -0,0 +1 @@
+var a = 'a' + 'b' + 'c' + d + 'e' + 'f';
\ No newline at end of file