From a24e7ee976787915c4d8f232bc980174674edb0b Mon Sep 17 00:00:00 2001
From: Mihai Bazon <mihai@bazon.net>
Date: Wed, 26 Sep 2012 12:16:16 +0300
Subject: [PATCH] checkpoint (refactoring, WIP)

---
 lib/ast.js       | 36 +++++++++++++++++++++++++++-
 lib/compress.js  | 62 ++++++++++++------------------------------------
 lib/transform.js | 15 ++----------
 3 files changed, 52 insertions(+), 61 deletions(-)

diff --git a/lib/ast.js b/lib/ast.js
index 3291ed83..3e6e1771 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -709,5 +709,39 @@ TreeWalker.prototype = {
     },
     parent: function(n) {
         return this.stack[this.stack.length - 2 - (n || 0)];
-    }
+    },
+    push: function (node) {
+        this.stack.push(node);
+    },
+    pop: function() {
+        return this.stack.pop();
+    },
+    self: function() {
+        return this.stack[this.stack.length - 1];
+    },
+    find_parent: function(type) {
+        var stack = this.stack;
+        for (var i = stack.length; --i >= 0;) {
+            var x = stack[i];
+            if (x instanceof type) return x;
+        }
+    },
+    in_boolean_context: function() {
+        var stack = this.stack;
+        var i = stack.length, self = stack[--i];
+        while (i > 0) {
+            var p = stack[--i];
+            if ((p instanceof AST_If           && p.condition === self) ||
+                (p instanceof AST_Conditional  && p.condition === self) ||
+                (p instanceof AST_DWLoop       && p.condition === self) ||
+                (p instanceof AST_For          && p.condition === self) ||
+                (p instanceof AST_UnaryPrefix  && p.operator == "!" && p.expression === self))
+            {
+                return true;
+            }
+            if (!(p instanceof AST_Binary && (p.operator == "&&" || p.operator == "||")))
+                return false;
+            self = p;
+        }
+    },
 };
diff --git a/lib/compress.js b/lib/compress.js
index d2e530bb..4161842d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -53,7 +53,10 @@
 // squeezing nodes.
 
 function Compressor(options, false_by_default) {
-    options = defaults(options, {
+    if (!(this instanceof Compressor))
+        return new Compressor(options, false_by_default);
+    TreeTransformer.call(this, this.before, this.after);
+    this.options = defaults(options, {
         sequences     : !false_by_default,
         properties    : !false_by_default,
         dead_code     : !false_by_default,
@@ -73,48 +76,17 @@ function Compressor(options, false_by_default) {
 
         warnings      : true
     });
-    var stack = [];
-    function in_boolean_context() {
-        var i = stack.length, self = stack[--i];
-        while (i > 0) {
-            var p = stack[--i];
-            if ((p instanceof AST_If           && p.condition === self) ||
-                (p instanceof AST_Conditional  && p.condition === self) ||
-                (p instanceof AST_DWLoop       && p.condition === self) ||
-                (p instanceof AST_For          && p.condition === self) ||
-                (p instanceof AST_UnaryPrefix  && p.operator == "!" && p.expression === self))
-            {
-                return true;
-            }
-            if (!(p instanceof AST_Binary && (p.operator == "&&" || p.operator == "||")))
-                return false;
-            self = p;
-        }
-    };
-    function find_parent(type) {
-        for (var i = stack.length; --i >= 0;) {
-            var x = stack[i];
-            if (x instanceof type) return x;
-        }
-    };
-    return {
-        option    : function(key) { return options[key] },
-        push_node : function(node) { stack.push(node) },
-        pop_node  : function() { return stack.pop() },
-        stack     : function() { return stack },
-        self      : function() { return stack[stack.length - 1] },
-        parent    : function(n) {
-            return stack[stack.length - 2 - (n || 0)];
-        },
-        warn      : function() {
-            if (options.warnings)
-                AST_Node.warn.apply(AST_Node, arguments);
-        },
-        in_boolean_context: in_boolean_context,
-        find_parent: find_parent,
-    };
 };
 
+Compressor.prototype = new TreeTransformer;
+defaults(Compressor.prototype, {
+    option: function(key) { return this.options[key] },
+    warn: function() {
+        if (this.options.warnings)
+            AST_Node.warn.apply(AST_Node, arguments);
+    }
+});
+
 (function(undefined){
 
     AST_Node.DEFMETHOD("optimize", function(){
@@ -1551,13 +1523,13 @@ function Compressor(options, false_by_default) {
 
     function SQUEEZE(nodetype, squeeze) {
         nodetype.DEFMETHOD("squeeze", function(compressor){
-            compressor.push_node(this);
+            compressor.push(this);
             var self = this.clone(), opt;
             opt = squeeze(self, compressor);
             if (opt !== undefined) self = opt;
             opt = self.optimize(compressor);
             if (opt !== undefined) self = opt;
-            compressor.pop_node();
+            compressor.pop();
             return self;
         });
     };
@@ -1689,10 +1661,6 @@ function Compressor(options, false_by_default) {
         self.expression = self.expression.squeeze(compressor);
     });
 
-    SQUEEZE(AST_UnaryPrefix, function(self, compressor){
-        self.expression = self.expression.squeeze(compressor);
-    });
-
     SQUEEZE(AST_Binary, function(self, compressor){
         self.left = self.left.squeeze(compressor);
         self.right = self.right.squeeze(compressor);
diff --git a/lib/transform.js b/lib/transform.js
index df51eac3..6f89679d 100644
--- a/lib/transform.js
+++ b/lib/transform.js
@@ -45,22 +45,11 @@
 // XXX: eventually I should refactor the compressor to use this infrastructure.
 
 function TreeTransformer(before, after) {
+    TreeWalker.call(this);
     this.before = before;
     this.after = after;
-    this.stack = [];
 }
-
-TreeTransformer.prototype = {
-    push: function (node) {
-        this.stack.push(node);
-    },
-    pop: function() {
-        return this.stack.pop();
-    },
-    parent: function (n) {
-        return this.stack[this.stack.length - 2 - (n || 0)];
-    }
-};
+TreeTransformer.prototype = new TreeWalker;
 
 (function(undefined){
 
-- 
2.34.1