fix(match): Support empty lines and comments in match expressions (closes #1956) (#2201)

* refactor(match): Extract var and remove ifBreak

Match arms are never combined onto a single line, so ifBreak is not
needed.

* feat(match): Support empty lines between arms

* feat(match): Print leading comments

* feat(match): Print trailing comments

Author: claytonrcarter

src/printer.js

@@ -53,6 +53,7 @@ const {
   normalizeMagicMethodName,
   getNextNonSpaceNonCommentCharacterIndex,
   isNextLineEmpty,
+  isPreviousLineEmpty,
 } = require("./util");
 
 function isMinVersion(actualVersion, requiredVersion) {
@@ -2886,27 +2887,59 @@ function printNode(path, options, print) {
       return path.call(print, "name");
     }
     case "match": {
+      const lastArmIndex = node.arms.length - 1;
       const arms = path.map((armPath, armIdx) => {
+        const armNode = armPath.getValue();
+
+        const maybeLeadingComment = comments.hasLeadingComment(armNode)
+          ? [comments.printComments(armNode.leadingComments, options), hardline]
+          : [];
+        const maybeTrailingComma =
+          armIdx < lastArmIndex || options.trailingCommaPHP ? "," : "";
+        const maybeTrailingComment = comments.hasTrailingComment(armNode)
+          ? [
+              " ",
+              comments.printComments(
+                armNode.comments.filter((c) => c.trailing),
+                options
+              ),
+            ]
+          : [];
+
         const conds =
-          armPath.getValue().conds === null
+          armNode.conds === null
             ? "default"
             : armPath.map(
                 (condPath, condIdx) =>
                   [",", line, print(condPath)].slice(condIdx === 0 ? 2 : 0),
                 "conds"
               );
         const body = armPath.call(print, "body");
+        const maybeEmptyLineBetweenArms =
+          armIdx > 0 &&
+          isPreviousLineEmpty(options.originalText, armNode, options)
+            ? hardline
+            : "";
+
         return [
-          ",",
+          "",
           hardline,
-          group([group([conds, indent(line)]), "=> ", body]),
+          maybeEmptyLineBetweenArms,
+          ...maybeLeadingComment,
+          group([
+            group([conds, indent(line)]),
+            "=> ",
+            body,
+            maybeTrailingComma,
+            ...maybeTrailingComment,
+          ]),
         ].slice(armIdx > 0 ? 0 : 1);
       }, "arms");
       return group([
         "match (",
         group([softline, indent(path.call(print, "cond")), softline]),
         ") {",
-        group(indent([...arms, options.trailingCommaPHP ? ifBreak(",") : ""])),
+        group(indent([...arms])),
         " ",
         softline,
         "}",

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

@@ -4824,6 +4824,57 @@ list(
 ================================================================================
 `;
 
+exports[`match.php 1`] = `
+====================================options=====================================
+parsers: ["php"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<?php
+
+$withComments = match($v) {
+
+    // first comment
+
+    'a' => 1,
+
+
+
+    /*
+     * second comment
+     */
+
+
+
+    'b' => 2,
+    // leading comment ...
+    'c' => 3,              /* ... and trailing comment */
+    'd'           // fourth comment
+        => 4,
+    default => null            // final comment
+};
+
+=====================================output=====================================
+<?php
+
+$withComments = match ($v) {
+    // first comment
+    "a" => 1,
+
+    /*
+     * second comment
+     */
+    "b" => 2,
+    // leading comment ...
+    "c" => 3, /* ... and trailing comment */
+    "d" // fourth comment
+        => 4,
+    default => null, // final comment
+};
+
+================================================================================
+`;
+
 exports[`method.php 1`] = `
 ====================================options=====================================
 parsers: ["php"]

tests/comments/match.php

@@ -0,0 +1,23 @@
+<?php
+
+$withComments = match($v) {
+
+    // first comment
+
+    'a' => 1,
+
+
+
+    /*
+     * second comment
+     */
+
+
+
+    'b' => 2,
+    // leading comment ...
+    'c' => 3,              /* ... and trailing comment */
+    'd'           // fourth comment
+        => 4,
+    default => null            // final comment
+};

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

@@ -52,6 +52,20 @@ $extraLongMatch = match($a) {
     'cd' => [],
     default => [],
 };
+
+// Whitespace in match expressions is handled like in function/method arguments:
+// - none above the first arm or below the last arm
+// - empty lines are preserved between arms
+// - multiple empty lines are collapsed into one
+match ($a) {
+
+    'a' => 1,
+
+
+    'b' => 2
+
+};
+
 =====================================output=====================================
 <?php
 
@@ -124,6 +138,16 @@ $extraLongMatch = match ($a) {
     default => []
 };
 
+// Whitespace in match expressions is handled like in function/method arguments:
+// - none above the first arm or below the last arm
+// - empty lines are preserved between arms
+// - multiple empty lines are collapsed into one
+match ($a) {
+    "a" => 1,
+
+    "b" => 2
+};
+
 ================================================================================
 `;
 
@@ -179,6 +203,20 @@ $extraLongMatch = match($a) {
     'cd' => [],
     default => [],
 };
+
+// Whitespace in match expressions is handled like in function/method arguments:
+// - none above the first arm or below the last arm
+// - empty lines are preserved between arms
+// - multiple empty lines are collapsed into one
+match ($a) {
+
+    'a' => 1,
+
+
+    'b' => 2
+
+};
+
 =====================================output=====================================
 <?php
 
@@ -251,5 +289,15 @@ $extraLongMatch = match ($a) {
     default => [],
 };
 
+// Whitespace in match expressions is handled like in function/method arguments:
+// - none above the first arm or below the last arm
+// - empty lines are preserved between arms
+// - multiple empty lines are collapsed into one
+match ($a) {
+    "a" => 1,
+
+    "b" => 2,
+};
+
 ================================================================================
 `;

tests/match/match.php

@@ -41,4 +41,17 @@
     => 'some really long value in the return part of the match statement',
     'cd' => [],
     default => [],
-};
+};
+
+// Whitespace in match expressions is handled like in function/method arguments:
+// - none above the first arm or below the last arm
+// - empty lines are preserved between arms
+// - multiple empty lines are collapsed into one
+match ($a) {
+
+    'a' => 1,
+
+
+    'b' => 2
+
+};