cleanup needsParens (#935)

src/fast-path.js

@@ -264,26 +264,12 @@ FPp.needsParens = function(assumeExpressionContext) {
         parent.object === node;
 
     case "UpdateExpression":
-      switch (parent.type) {
+      if (parent.type === "UnaryExpression") {
-        case "MemberExpression":
+        return node.prefix &&
-          return name === "object" && parent.object === node;
-
-        case "TaggedTemplateExpression":
-        case "NewExpression":
-          return true;
-
-        case "UnaryExpression":
-          if (
-            node.prefix &&
           ((node.operator === "++" && parent.operator === "+") ||
-              (node.operator === "--" && parent.operator === "-"))
+              (node.operator === "--" && parent.operator === "-"));
-          ) {
-            return true;
       }
-
+      // else fall through
-          return false;
-      }
-
     case "UnaryExpression":
       switch (parent.type) {
         case "UnaryExpression":
@@ -292,9 +278,20 @@ FPp.needsParens = function(assumeExpressionContext) {
 
         case "MemberExpression":
           return name === "object" && parent.object === node;
+
+        case "TaggedTemplateExpression":
+          return true;
+
+        case "NewExpression":
+        case "CallExpression":
+          return name === "callee" && parent.callee == node;
+
+        default:
+          return false;
       }
 
     case "BinaryExpression":
+      // TODO https://github.com/prettier/prettier/issues/907 this is not complete
       if (
         node.operator === "in" &&
         parent.type === "ForStatement" &&
@@ -302,11 +299,10 @@ FPp.needsParens = function(assumeExpressionContext) {
       ) {
         return true;
       }
-
       if (node.operator === "in" && parent.type === "AssignmentExpression") {
         return true;
       }
-
+      // else fall through
     case "LogicalExpression":
       switch (parent.type) {
         case "CallExpression":
@@ -371,6 +367,7 @@ FPp.needsParens = function(assumeExpressionContext) {
       if (parent.type === "UnaryExpression") {
         return true;
       }
+      // else fall through
     case "AwaitExpression":
       switch (parent.type) {
         case "TaggedTemplateExpression":
@@ -419,18 +416,13 @@ FPp.needsParens = function(assumeExpressionContext) {
     case "AssignmentExpression":
       if (parent.type === "ArrowFunctionExpression" && parent.body === node) {
         return node.left.type === "ObjectPattern";
-      }
+      } else if (
-      if (
         parent.type === "ForStatement" &&
         (parent.init === node || parent.update === node)
       ) {
         return false;
-      }
+      } else if (parent.type === "ExpressionStatement") {
-      if (parent.type === "ExpressionStatement") {
+        return node.left.type === "ObjectPattern";
-        if (node.left.type === "ObjectPattern") {
-          return true;
-        }
-        return false;
       }
       return true;
 
@@ -458,7 +450,7 @@ FPp.needsParens = function(assumeExpressionContext) {
           return name === "object" && parent.object === node;
 
         default:
-          return n.ObjectPattern.check(node.left) && this.firstInStatement();
+          return false;
       }
 
     case "FunctionExpression":
@@ -516,16 +508,14 @@ FPp.needsParens = function(assumeExpressionContext) {
           if (parent.test === node) {
             return true;
           }
-      }
+        default:
-
           return false;
+      }
 
     case "StringLiteral":
-      if (parent.type === "ExpressionStatement") {
+      return parent.type === "ExpressionStatement"; // to avoid becoming a directive
-        return true;
   }
 
-    default:
   if (
     parent.type === "NewExpression" &&
     name === "callee" &&
@@ -533,14 +523,14 @@ FPp.needsParens = function(assumeExpressionContext) {
   ) {
     return containsCallExpression(node);
   }
-  }
 
   if (
     assumeExpressionContext !== true &&
     !this.canBeFirstInStatement() &&
     this.firstInStatement()
-  )
+  ) {
     return true;
+  }
 
   return false;
 };

tests/unary_expression/__snapshots__/jsfmt.spec.js.snap

@@ -7,12 +7,16 @@ x--;
 -+1;
 x + + + + 1;
 x + (+ (+ (+ 1)))
+x * +y;
++x * y;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!x;
 x++;
 x--;
 -+1;
-x + (+(+(+1)));
+x + +(+(+1));
-x + (+(+(+1)));
+x + +(+(+1));
+x * +y;
++x * y;
 "
 `;

tests/unary_expression/urnary_expression.js

@@ -4,3 +4,5 @@ x--;
 -+1;
 x + + + + 1;
 x + (+ (+ (+ 1)))
+x * +y;
++x * y;