Reuse removed vars in mangler

ResetNext identifier only when reuse is true

Fix tests - add keepClassName

Reuse vars as default

I dont know why it works - #326

Extract tracker to a separate file, Add topLevel Option

packages/babel-plugin-minify-mangle-names/__tests__/mangle-names-test.js

@@ -5,6 +5,7 @@ const babel    = require("babel-core");
 const unpad    = require("../../../utils/unpad");
 
 function transform(code, options = {}, sourceType = "script") {
+  options.reuse = false;
   return babel.transform(code,  {
     sourceType,
     plugins: [
@@ -13,6 +14,17 @@ function transform(code, options = {}, sourceType = "script") {
   }).code;
 }
 
+function transformWithSimplify(code, options = {}, sourceType = "script") {
+  options.reuse = false;
+  return babel.transform(code, {
+    sourceType,
+    plugins: [
+      require("../../babel-plugin-minify-simplify/src/index"),
+      [require("../src/index"), options]
+    ]
+  }).code;
+}
+
 describe("mangle-names", () => {
   it("should not mangle names in the global namespace", () => {
     const source = unpad(`
@@ -587,19 +599,19 @@ describe("mangle-names", () => {
     traverse.clearCache();
 
     const actual = babel.transformFromAst(first.ast, null, {
-      plugins: [require("../src/index")],
+      plugins: [[require("../src/index"), { reuse: false }]],
     }).code;
 
     const expected = unpad(`
       function f(a) {
-        var b = function (d) {
-          var e = void 0;
-          if (e) {
+        var b = function (e) {
+          var h = void 0;
+          if (h) {
             return {
               v: void 0
             };
           }
-          g(() => e);
+          g(() => h);
         };
 
         for (var d = 0; d; d++) {
@@ -635,7 +647,7 @@ describe("mangle-names", () => {
     traverse.clearCache();
 
     const actual = babel.transformFromAst(first.ast, null, {
-      plugins: [require("../src/index")],
+      plugins: [[require("../src/index"), { reuse: false }]],
     }).code;
 
     const expected = unpad(`
@@ -1149,4 +1161,54 @@ describe("mangle-names", () => {
     `);
     expect(transform(source, { topLevel: true })).toBe(source);
   });
+
+  it("should handle constant violations across multiple blocks", () => {
+    const source = unpad(`
+      function foo() {
+        var x;x;x;
+        {
+          var x;x;x;
+          function y() {
+            var x;x;x;
+            {
+              var x;x;x;
+            }
+          }
+        }
+      }
+    `);
+    const expected = unpad(`
+      function foo() {
+        var a;a;a;
+        {
+          var a;a;a;
+          function b() {
+            var c;c;c;
+            {
+              var c;c;c;
+            }
+          }
+        }
+      }
+    `);
+    expect(transform(source)).toBe(expected);
+  });
+
+  it("should work with if_return optimization changing fn scope", () => {
+    const source = unpad(`
+      function foo() {
+        if (x)
+          return;
+        function bar() {}
+        bar(a);
+      }
+    `);
+    const expected = unpad(`
+      function foo() {
+        function b() {}
+        x || b(a);
+      }
+    `);
+    expect(transformWithSimplify(source)).toBe(expected);
+  });
 });

packages/babel-plugin-minify-mangle-names/src/charset.js

@@ -0,0 +1,51 @@
+"use strict";
+
+const CHARSET = ("abcdefghijklmnopqrstuvwxyz" +
+                 "ABCDEFGHIJKLMNOPQRSTUVWXYZ$_").split("");
+
+module.exports = class Charset {
+  constructor(shouldConsider) {
+    this.shouldConsider = shouldConsider;
+    this.chars = CHARSET.slice();
+    this.frequency = {};
+    this.chars.forEach((c) => { this.frequency[c] = 0; });
+    this.finalized = false;
+  }
+
+  consider(str) {
+    if (!this.shouldConsider) {
+      return;
+    }
+
+    str.split("").forEach((c) => {
+      if (this.frequency[c] != null) {
+        this.frequency[c]++;
+      }
+    });
+  }
+
+  sort() {
+    if (this.shouldConsider) {
+      this.chars = this.chars.sort(
+        (a, b) => this.frequency[b] - this.frequency[a]
+      );
+    }
+
+    this.finalized = true;
+  }
+
+  getIdentifier(num) {
+    if (!this.finalized) {
+      throw new Error("Should sort first");
+    }
+
+    let ret = "";
+    num++;
+    do {
+      num--;
+      ret += this.chars[num % this.chars.length];
+      num = Math.floor(num / this.chars.length);
+    } while (num > 0);
+    return ret;
+  }
+};

packages/babel-plugin-minify-mangle-names/src/counted-set.js

@@ -0,0 +1,28 @@
+// Set that counts
+module.exports = class CountedSet {
+  constructor() {
+    // because you can't simply extend Builtins yet
+    this.map = new Map;
+  }
+  keys() {
+    return [...this.map.keys()];
+  }
+  has(value) {
+    return this.map.has(value);
+  }
+  add(value) {
+    if (!this.has(value)) {
+      this.map.set(value, 0);
+    }
+    this.map.set(value, this.map.get(value) + 1);
+  }
+  delete(value) {
+    if (!this.has(value)) return;
+    const count = this.map.get(value);
+    if (count <= 1) {
+      this.map.delete(value);
+    } else {
+      this.map.set(value, count - 1);
+    }
+  }
+};