JS: improve variable use counting

tdewolff · Apr 5, 2022 · 4532c88 · 4532c88
1 parent cc66302
commit 4532c88
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Showing 4 changed files with 37 additions and 2 deletions.
diff --git a/js/js.go b/js/js.go
@@ -584,6 +584,17 @@ func (m *jsMinifier) minifyFuncDecl(decl *js.FuncDecl, inExpr bool) {
 	if decl.Generator {
 		m.write(starBytes)
 	}
+
+	// TODO: remove function name, really necessary?
+	//if decl.Name != nil && decl.Name.Uses == 1 {
+	//	scope := decl.Body.Scope
+	//	for i, vorig := range scope.Declared {
+	//		if decl.Name == vorig {
+	//			scope.Declared = append(scope.Declared[:i], scope.Declared[i+1:]...)
+	//		}
+	//	}
+	//}
+
 	if inExpr {
 		m.renamer.renameScope(decl.Body.Scope)
 	}

diff --git a/js/js_test.go b/js/js_test.go
@@ -342,6 +342,7 @@ func TestJS(t *testing.T) {
 		{`var a=[];f();var b;f();var c;f();var e=f`, `var b,c,e,a=[];f(),f(),f(),e=f`},
 		{`var {...a}=c;for(var {...b}=d;b;b++);`, `for(var{...a}=c,{...b}=d;b;b++);`},
 		{`var o=8,p=9,x=0,y=1;x=x+2;y=y+3;var b=1,c=2,d=3`, `var o=8,p=9,x=0,y=1,x=x+2,y=y+3,b=1,c=2,d=3`},
+		//{`var name=function name(){name()}`, `var name=function(){name()}`}, // TODO
 
 		// TODO: test for variables renaming (first rename, then merge vars)
 
@@ -768,8 +769,8 @@ func TestJSVarRenaming(t *testing.T) {
 		{`!function(){var x=function(){return y};const y=5;x,y}`, `!function(){var b=function(){return a};const a=5;b,a}`},
 		{`!function(){if(1){const x=5;x;5}var y=function(){return x};y}`, `!function(){if(1){const a=5;a,5}var a=function(){return x};a}`},
 		{`!function(){var x=function(){return y};x;if(1){const y=5;y;5}}`, `!function(){var a=function(){return y};if(a,1){const a=5;a,5}}`},
-		{`!function(){var x=function(){return y};x;if(z)var y=5}`, `!function(){var b,a=function(){return b};a,z&&(b=5)}`},
-		{`!function(){var x=function(){return y};x;if(z){var y=5;5}}`, `!function(){var b,a=function(){return b};a,z&&(b=5,5)}`},
+		{`!function(){var x=function(){return y};x;if(z)var y=5}`, `!function(){var a,b=function(){return a};b,z&&(a=5)}`},
+		{`!function(){var x=function(){return y};x;if(z){var y=5;5}}`, `!function(){var a,b=function(){return a};b,z&&(a=5,5)}`},
 		{`!function(){var x,y,z=(x,y)=>x+y;x,y,z}`, `!function(){var a,b,c=(a,b)=>a+b;a,b,c}`},
 		{`!function(){var await;print({await});}`, `!function(){var a;print({await:a})}`},
 		{`function a(){var name; return {name}}`, `function a(){var a;return{name:a}}`},

diff --git a/js/stmtlist.go b/js/stmtlist.go
@@ -63,6 +63,24 @@ func optimizeStmt(i js.IStmt) js.IStmt {
 			}
 		}
 	} else if decl, ok := i.(*js.VarDecl); ok {
+		// TODO: remove function name in var name=function name(){}
+		//for _, item := range decl.List {
+		//	if v, ok := item.Binding.(*js.Var); ok && item.Default != nil {
+		//		if fun, ok := item.Default.(*js.FuncDecl); ok && fun.Name != nil && bytes.Equal(v.Data, fun.Name.Data) {
+		//			scope := fun.Body.Scope
+		//			for i, vorig := range scope.Declared {
+		//				if fun.Name == vorig {
+		//					scope.Declared = append(scope.Declared[:i], scope.Declared[i+1:]...)
+		//				}
+		//			}
+		//			scope.AddUndeclared(v)
+		//			v.Uses += fun.Name.Uses - 1
+		//			fun.Name.Link = v
+		//			fun.Name = nil
+		//		}
+		//	}
+		//}
+
 		if decl.TokenType == js.ErrorToken {
 			// convert hoisted var declaration to expression or empty (if there are no defines) statement
 			for _, item := range decl.List {

diff --git a/js/vars.go b/js/vars.go
@@ -189,6 +189,7 @@ RemoveVarsLoop:
 	for _, vbind := range vars {
 		for i, item := range decl.List {
 			if v, ok := item.Binding.(*js.Var); ok && item.Default == nil && v == vbind {
+				v.Uses--
 				decl.List = append(decl.List[:i], decl.List[i+1:]...)
 				continue RemoveVarsLoop
 			}
@@ -198,6 +199,7 @@ RemoveVarsLoop:
 		for _, decl2 := range decl.Scope.Func.VarDecls {
 			for i, item := range decl2.List {
 				if v, ok := item.Binding.(*js.Var); ok && item.Default == nil && v == vbind {
+					v.Uses--
 					decl2.List = append(decl2.List[:i], decl2.List[i+1:]...)
 					continue RemoveVarsLoop
 				}
@@ -393,6 +395,9 @@ func (m *jsMinifier) hoistVars(body *js.BlockStmt) {
 							s.AddUndeclared(ref)
 							s = s.Parent
 						}
+						if item.Default != nil {
+							ref.Uses++
+						}
 					}
 					if i < best {
 						// prepend