JavaScript: Format ThrowStatement like ReturnStatement (#7070)

changelog_unreleased/javascript/pr-7070.md

@@ -0,0 +1,24 @@
+# Format `throw` like `return` ([#7070](https://github.com/prettier/prettier/pull/7070) by [@sosukesuzuki](https://github.com/sosukesuzuki))
+
+<!-- prettier-ignore -->
+```js
+// Input
+function foo() {
+  throw this.hasPlugin("dynamicImports") && this.lookahead().type === tt.parenLeft.right;
+}
+
+// Prettier stable
+function foo() {
+  throw this.hasPlugin("dynamicImports") &&
+    this.lookahead().type === tt.parenLeft.right;
+}
+
+
+// Prettier master
+function foo() {
+  throw (
+    this.hasPlugin("dynamicImports") &&
+    this.lookahead().type === tt.parenLeft.right
+  );
+}
+``` 

src/language-js/needs-parens.js

@@ -759,6 +759,7 @@ function needsParens(path, options) {
           parent.type !== "OptionalCallExpression" &&
           parent.type !== "Property" &&
           parent.type !== "ReturnStatement" &&
+          parent.type !== "ThrowStatement" &&
           parent.type !== "TypeCastExpression" &&
           parent.type !== "VariableDeclarator")
       );

src/language-js/printer-estree.js

@@ -597,6 +597,7 @@ function printPathNoParens(path, options, print, args) {
       // indented accordingly. We should indent sub-expressions where the first case isn't indented.
       const shouldNotIndent =
         parent.type === "ReturnStatement" ||
+        parent.type === "ThrowStatement" ||
         (parent.type === "JSXExpressionContainer" &&
           parentParent.type === "JSXAttribute") ||
         (n.type !== "NGPipeExpression" &&
@@ -608,6 +609,7 @@ function printPathNoParens(path, options, print, args) {
         (n !== parent.body && parent.type === "ForStatement") ||
         (parent.type === "ConditionalExpression" &&
           parentParent.type !== "ReturnStatement" &&
+          parentParent.type !== "ThrowStatement" &&
           parentParent.type !== "CallExpression" &&
           parentParent.type !== "OptionalCallExpression") ||
         parent.type === "TemplateLiteral";
@@ -1121,48 +1123,10 @@ function printPathNoParens(path, options, print, args) {
       return concat(parts);
     }
     case "ReturnStatement":
-      parts.push("return");
-
-      if (n.argument) {
-        if (returnArgumentHasLeadingComment(options, n.argument)) {
-          parts.push(
-            concat([
-              " (",
-              indent(concat([hardline, path.call(print, "argument")])),
-              hardline,
-              ")"
-            ])
-          );
-        } else if (
-          n.argument.type === "LogicalExpression" ||
-          n.argument.type === "BinaryExpression" ||
-          n.argument.type === "SequenceExpression"
-        ) {
-          parts.push(
-            group(
-              concat([
-                ifBreak(" (", " "),
-                indent(concat([softline, path.call(print, "argument")])),
-                softline,
-                ifBreak(")")
-              ])
-            )
-          );
-        } else {
-          parts.push(" ", path.call(print, "argument"));
-        }
-      }
-
-      if (hasDanglingComments(n)) {
-        parts.push(
-          " ",
-          comments.printDanglingComments(path, options, /* sameIndent */ true)
-        );
-      }
-
-      parts.push(semi);
-
-      return concat(parts);
+      return concat([
+        "return",
+        printReturnAndThrowArgument(path, options, print)
+      ]);
     case "NewExpression":
     case "OptionalCallExpression":
     case "CallExpression": {
@@ -2030,7 +1994,10 @@ function printPathNoParens(path, options, print, args) {
 
       return concat(["catch ", path.call(print, "body")]);
     case "ThrowStatement":
-      return concat(["throw ", path.call(print, "argument"), semi]);
+      return concat([
+        "throw",
+        printReturnAndThrowArgument(path, options, print)
+      ]);
     // Note: ignoring n.lexical because it has no printing consequences.
     case "SwitchStatement":
       return concat([
@@ -5957,6 +5924,53 @@ function printArrayItems(path, options, printPath, print) {
   return concat(printedElements);
 }
 
+function printReturnAndThrowArgument(path, options, print) {
+  const node = path.getValue();
+  const semi = options.semi ? ";" : "";
+  const parts = [];
+
+  if (node.argument) {
+    if (returnArgumentHasLeadingComment(options, node.argument)) {
+      parts.push(
+        concat([
+          " (",
+          indent(concat([hardline, path.call(print, "argument")])),
+          hardline,
+          ")"
+        ])
+      );
+    } else if (
+      node.argument.type === "LogicalExpression" ||
+      node.argument.type === "BinaryExpression" ||
+      node.argument.type === "SequenceExpression"
+    ) {
+      parts.push(
+        group(
+          concat([
+            ifBreak(" (", " "),
+            indent(concat([softline, path.call(print, "argument")])),
+            softline,
+            ifBreak(")")
+          ])
+        )
+      );
+    } else {
+      parts.push(" ", path.call(print, "argument"));
+    }
+  }
+
+  if (hasDanglingComments(node)) {
+    parts.push(
+      " ",
+      comments.printDanglingComments(path, options, /* sameIndent */ true)
+    );
+  }
+
+  parts.push(semi);
+
+  return concat(parts);
+}
+
 function willPrintOwnComments(path /*, options */) {
   const node = path.getValue();
   const parent = path.getParentNode();

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

@@ -0,0 +1,173 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`binaryish.js 1`] = `
+====================================options=====================================
+parsers: ["flow", "typescript", "babel"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+function f() {
+  throw (
+    property.isIdentifier() &&
+     FUNCTIONS[property.node.name] &&
+     (object.isIdentifier(JEST_GLOBAL) ||
+       (callee.isMemberExpression() && shouldHoistExpression(object))) &&
+    FUNCTIONS[property.node.name](expr.get('arguments'))
+  );
+
+  throw (
+    chalk.bold(
+      'No tests found related to files changed since last commit.\\n',
+    ) +
+    chalk.dim(
+      patternInfo.watch ?
+        'Press \`a\` to run all tests, or run Jest with \`--watchAll\`.' :
+        'Run Jest without \`-o\` to run all tests.',
+    )
+  );
+
+  throw !filePath.includes(coverageDirectory) &&
+    !filePath.endsWith(\`.\${SNAPSHOT_EXTENSION}\`);
+}
+
+=====================================output=====================================
+function f() {
+  throw (
+    property.isIdentifier() &&
+    FUNCTIONS[property.node.name] &&
+    (object.isIdentifier(JEST_GLOBAL) ||
+      (callee.isMemberExpression() && shouldHoistExpression(object))) &&
+    FUNCTIONS[property.node.name](expr.get("arguments"))
+  );
+
+  throw (
+    chalk.bold("No tests found related to files changed since last commit.\\n") +
+    chalk.dim(
+      patternInfo.watch
+        ? "Press \`a\` to run all tests, or run Jest with \`--watchAll\`."
+        : "Run Jest without \`-o\` to run all tests."
+    )
+  );
+
+  throw (
+    !filePath.includes(coverageDirectory) &&
+    !filePath.endsWith(\`.\${SNAPSHOT_EXTENSION}\`)
+  );
+}
+
+================================================================================
+`;
+
+exports[`comment.js 1`] = `
+====================================options=====================================
+parsers: ["flow", "typescript", "babel"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+function x() {
+  throw func2
+      //comment
+      .bar();
+}
+ 
+function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+}
+ 
+fn(function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+});
+
+=====================================output=====================================
+function x() {
+  throw (
+    func2
+      //comment
+      .bar()
+  );
+}
+
+function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+}
+
+fn(function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+});
+
+================================================================================
+`;
+
+exports[`jsx.js 1`] = `
+====================================options=====================================
+parsers: ["flow", "typescript", "babel"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+function foo() {
+  throw <Bar />;
+}
+
+function foo() {
+  throw <Bar>baz</Bar>;
+}
+
+function foo() {
+  throw <Bar baz={baz} />;
+}
+
+function foo() {
+  throw <Bar baz={baz}>foo</Bar>;
+}
+
+function foo() {
+  throw <></>;
+}
+
+function foo() {
+  throw <>foo</>;
+}
+
+=====================================output=====================================
+function foo() {
+  throw <Bar />;
+}
+
+function foo() {
+  throw <Bar>baz</Bar>;
+}
+
+function foo() {
+  throw <Bar baz={baz} />;
+}
+
+function foo() {
+  throw <Bar baz={baz}>foo</Bar>;
+}
+
+function foo() {
+  throw <></>;
+}
+
+function foo() {
+  throw <>foo</>;
+}
+
+================================================================================
+`;

tests/throw_statement/binaryish.js

@@ -0,0 +1,23 @@
+function f() {
+  throw (
+    property.isIdentifier() &&
+     FUNCTIONS[property.node.name] &&
+     (object.isIdentifier(JEST_GLOBAL) ||
+       (callee.isMemberExpression() && shouldHoistExpression(object))) &&
+    FUNCTIONS[property.node.name](expr.get('arguments'))
+  );
+
+  throw (
+    chalk.bold(
+      'No tests found related to files changed since last commit.\n',
+    ) +
+    chalk.dim(
+      patternInfo.watch ?
+        'Press `a` to run all tests, or run Jest with `--watchAll`.' :
+        'Run Jest without `-o` to run all tests.',
+    )
+  );
+
+  throw !filePath.includes(coverageDirectory) &&
+    !filePath.endsWith(`.${SNAPSHOT_EXTENSION}`);
+}

tests/throw_statement/comment.js

@@ -0,0 +1,21 @@
+function x() {
+  throw func2
+      //comment
+      .bar();
+}
+ 
+function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+}
+ 
+fn(function f() {
+  throw (
+    foo
+      // comment
+      .bar()
+  );
+});

tests/throw_statement/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, ["flow", "typescript", "babel"]);

tests/throw_statement/jsx.js

@@ -0,0 +1,23 @@
+function foo() {
+  throw <Bar />;
+}
+
+function foo() {
+  throw <Bar>baz</Bar>;
+}
+
+function foo() {
+  throw <Bar baz={baz} />;
+}
+
+function foo() {
+  throw <Bar baz={baz}>foo</Bar>;
+}
+
+function foo() {
+  throw <></>;
+}
+
+function foo() {
+  throw <>foo</>;
+}