From 888c7a52dde24944f93e81b43d0b23948c7c4fb4 Mon Sep 17 00:00:00 2001
From: Christopher Chedeau <vjeuxx@gmail.com>
Date: Wed, 25 Jan 2017 13:30:09 -0800
Subject: [PATCH] Put decorators on the same line (#459)

Mobx is the only popular JavaScript library that I know about which uses decorators. They put things on the same line so we should follow their conventions.

The logic implemented here is the following: if there is one decorator, it's on the same line. If there is more than one, they are each on their own line.

Fixes #325
---
 src/printer.js                                |  5 +-
 .../__snapshots__/jsfmt.spec.js.snap          | 64 +++++++++++++++++++
 tests/decorators/jsfmt.spec.js                |  1 +
 tests/decorators/mobx.js                      | 14 ++++
 tests/decorators/multiple.js                  |  6 ++
 tests/decorators/redux.js                     |  5 ++
 6 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 tests/decorators/__snapshots__/jsfmt.spec.js.snap
 create mode 100644 tests/decorators/jsfmt.spec.js
 create mode 100644 tests/decorators/mobx.js
 create mode 100644 tests/decorators/multiple.js
 create mode 100644 tests/decorators/redux.js

diff --git a/src/printer.js b/src/printer.js
index 93aae542d..b2ce78ee1 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -51,9 +51,12 @@ function genericPrint(path, options, printPath) {
       // responsible for printing node.decorators.
       !util.getParentExportDeclaration(path)
   ) {
+    const separator = node.decorators.length === 1 &&
+      node.decorators[0].expression.type === "Identifier"
+      ? " " : hardline;
     path.each(
       function(decoratorPath) {
-        parts.push(printPath(decoratorPath), line);
+        parts.push(printPath(decoratorPath), separator);
       },
       "decorators"
     );
diff --git a/tests/decorators/__snapshots__/jsfmt.spec.js.snap b/tests/decorators/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..7f0de6828
--- /dev/null
+++ b/tests/decorators/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,64 @@
+exports[`test mobx.js 1`] = `
+"import {observable} from \"mobx\";
+
+@observer class OrderLine {
+  @observable price:number = 0;
+  @observable amount:number = 1;
+
+  constructor(price) {
+    this.price = price;
+  }
+
+  @computed get total() {
+    return this.price * this.amount;
+  }
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+import { observable } from \"mobx\";
+
+@observer class OrderLine {
+  @observable price: number = 0;
+  @observable amount: number = 1;
+
+  constructor(price) {
+    this.price = price;
+  }
+
+  @computed get total() {
+    return this.price * this.amount;
+  }
+}
+"
+`;
+
+exports[`test multiple.js 1`] = `
+"const dog = {
+  @readonly
+  @nonenumerable
+  @doubledValue
+  legs: 4
+};
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+const dog = {
+  @readonly
+  @nonenumerable
+  @doubledValue
+  legs: 4
+};
+"
+`;
+
+exports[`test redux.js 1`] = `
+"@connect(mapStateToProps, mapDispatchToProps)
+export class MyApp extends React.Component {}
+
+@connect(state => ({ todos: state.todos }))
+export class Home extends React.Component {}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+@connect(mapStateToProps, mapDispatchToProps)
+export class MyApp extends React.Component {}
+
+@connect(state => ({ todos: state.todos }))
+export class Home extends React.Component {}
+"
+`;
diff --git a/tests/decorators/jsfmt.spec.js b/tests/decorators/jsfmt.spec.js
new file mode 100644
index 000000000..939578260
--- /dev/null
+++ b/tests/decorators/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, {parser: 'babylon'});
diff --git a/tests/decorators/mobx.js b/tests/decorators/mobx.js
new file mode 100644
index 000000000..adb461b0e
--- /dev/null
+++ b/tests/decorators/mobx.js
@@ -0,0 +1,14 @@
+import {observable} from "mobx";
+
+@observer class OrderLine {
+  @observable price:number = 0;
+  @observable amount:number = 1;
+
+  constructor(price) {
+    this.price = price;
+  }
+
+  @computed get total() {
+    return this.price * this.amount;
+  }
+}
diff --git a/tests/decorators/multiple.js b/tests/decorators/multiple.js
new file mode 100644
index 000000000..3a41e7b8d
--- /dev/null
+++ b/tests/decorators/multiple.js
@@ -0,0 +1,6 @@
+const dog = {
+  @readonly
+  @nonenumerable
+  @doubledValue
+  legs: 4
+};
diff --git a/tests/decorators/redux.js b/tests/decorators/redux.js
new file mode 100644
index 000000000..481658f81
--- /dev/null
+++ b/tests/decorators/redux.js
@@ -0,0 +1,5 @@
+@connect(mapStateToProps, mapDispatchToProps)
+export class MyApp extends React.Component {}
+
+@connect(state => ({ todos: state.todos }))
+export class Home extends React.Component {}