Fix void context transform !cond && ok() => cond || ok()

Close #45

Author: Constellation

lib/pass/remove-context-sensitive-expressions.js

@@ -1,4 +1,5 @@
 /*
+  Copyright (C) 2012 Mihai Bazon <[email protected]>
   Copyright (C) 2012 Yusuke Suzuki <[email protected]>
 
   Redistribution and use in source and binary forms, with or without
@@ -43,13 +44,20 @@
                     continue;
                 }
             } else if (expr.type === Syntax.LogicalExpression) {
-                if (expr.left.type === Syntax.UnaryExpression) {
-                    if (expr.left.operator === '!') {
-                        // !cond && ok() => cond || ok()
-                        modified = true;
-                        expr.left = expr.left.argument;
-                        expr.operator = (expr.operator === '||') ? '&&' : '||';
-                    }
+                if (expr.left.type === Syntax.UnaryExpression && expr.left.operator === '!' &&
+                    expr.right.type === Syntax.UnaryExpression && expr.right.operator === '!') {
+                    // !cond && !ok() => !(cond || ok())
+                    // this introduces more optimizations
+                    modified = true;
+                    expr.left = expr.left.argument;
+                    expr.right = expr.right.argument;
+                    expr.operator = (expr.operator === '||') ? '&&' : '||';
+                    expr = common.moveLocation(expr, {
+                        type: Syntax.UnaryExpression,
+                        operator: '!',
+                        argument: expr
+                    });
+                    continue;
                 }
             } else if (expr.type === Syntax.ConditionalExpression) {
                 if (expr.test.type === Syntax.UnaryExpression && expr.test.operator === '!') {
@@ -74,6 +82,13 @@
                     expr = expr.argument;
                     continue;
                 }
+            } else if (expr.type === Syntax.LogicalExpression) {
+                if (expr.left.type === Syntax.UnaryExpression && expr.left.operator === '!') {
+                    // !cond && ok() => cond || ok()
+                    modified = true;
+                    expr.left = expr.left.argument;
+                    expr.operator = (expr.operator === '||') ? '&&' : '||';
+                }
             }
             break;
         } while (true);

test/compare/remove-context-sensitive-expression-6.expected.js

@@ -0,0 +1 @@
+!ok||ok2()

test/compare/remove-context-sensitive-expression-6.js

@@ -0,0 +1,2 @@
+// Because of global environment
+if (!ok || ok2());

test/compare/remove-context-sensitive-expression-7.expected.js

@@ -0,0 +1 @@
+(function(){ok&&ok2()}())

test/compare/remove-context-sensitive-expression-7.js

@@ -0,0 +1,3 @@
+(function () {
+    if (!ok || ok2());
+}());

test/compare/remove-context-sensitive-expression-8.expected.js

@@ -0,0 +1 @@
+(function(){while(!ok||ok2())ok3()}())

test/compare/remove-context-sensitive-expression-8.js

@@ -0,0 +1,5 @@
+(function () {
+    while (!ok || ok2()) {
+        ok3();
+    }
+}());

test/compare/remove-context-sensitive-expression-9.expected.js

@@ -0,0 +1 @@
+(function(){while(!(ok&&ok2()))ok3()}())

test/compare/remove-context-sensitive-expression-9.js

@@ -0,0 +1,8 @@
+// TODO(Constellation):
+// This transformation sometimes make script bigger size.
+// So we should handle it in post processing pass.
+(function () {
+    while (!ok || !ok2()) {
+        ok3();
+    }
+}());