improve `compress` (#3814)

- avoid identifier overflow through consecutive API calls
- simplify `reduce_vars`
- enhance `unsafe` `evaluate`

1 files changed, 17 insertions, 12 deletions

diff --git a/lib/scope.js b/lib/scope.js
index ad33c5e0..adbfe4ac 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -43,23 +43,21 @@
 
 "use strict";
 
-function SymbolDef(scope, orig, init) {
+function SymbolDef(id, scope, orig, init) {
+    this.eliminated = 0;
+    this.global = false;
+    this.id = id;
+    this.init = init;
+    this.lambda = orig instanceof AST_SymbolLambda;
+    this.mangled_name = null;
     this.name = orig.name;
     this.orig = [ orig ];
-    this.init = init;
-    this.eliminated = 0;
-    this.scope = scope;
     this.references = [];
     this.replaced = 0;
-    this.global = false;
-    this.mangled_name = null;
+    this.scope = scope;
     this.undeclared = false;
-    this.id = SymbolDef.next_id++;
-    this.lambda = orig instanceof AST_SymbolLambda;
 }
 
-SymbolDef.next_id = 1;
-
 SymbolDef.prototype = {
     unmangleable: function(options) {
         return this.global && !options.toplevel
@@ -151,6 +149,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             scope.def_variable(node).defun = defun;
         }
     });
+    self.next_def_id = 0;
     self.walk(tw);
 
     // pass 2: find back references and eval
@@ -240,12 +239,18 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     }
 });
 
+AST_Scope.DEFMETHOD("make_def", function(orig, init) {
+    var top = this;
+    while (top.parent_scope) top = top.parent_scope;
+    return new SymbolDef(++top.next_def_id, this, orig, init);
+});
+
 AST_Toplevel.DEFMETHOD("def_global", function(node) {
     var globals = this.globals, name = node.name;
     if (globals.has(name)) {
         return globals.get(name);
     } else {
-        var g = new SymbolDef(this, node);
+        var g = this.make_def(node);
         g.undeclared = true;
         g.global = true;
         globals.set(name, g);
@@ -310,7 +315,7 @@ AST_Scope.DEFMETHOD("def_variable", function(symbol, init) {
         def.orig.push(symbol);
         if (def.init instanceof AST_Function) def.init = init;
     } else {
-        def = new SymbolDef(this, symbol, init);
+        def = this.make_def(symbol, init);
         this.variables.set(symbol.name, def);
         def.global = !this.parent_scope;
     }