Add support for configurable line ends

README.md

@@ -252,6 +252,7 @@ the formatter falls back to a compact style with no extra spaces or indentation.
 |------------------------------|----------------------|--------------------------------------------------------|
 | `indentationLevel`           | `number`             | Base indentation level for the document.               |
 | `indentationCharacter`       | `'space'\|'tab'`     | Character used for indentation.                        |
+| `lineEnding`                 | `'lf'\|'crlf'`       | Newline sequence to use in the document.               |
 | `string.quote`               | `'single'\|'double'` | Quotation style for string values.                     |
 | `property.quote`             | `'single'\|'double'` | Quotation style for property keys.                     |
 | `property.unquoted`          | `boolean`            | Allow unquoted property keys when valid.               |

src/formatting.ts

@@ -11,6 +11,7 @@ export type BlockFormatting = {
 export type Formatting = {
     indentationLevel?: number,
     indentationCharacter?: 'space' | 'tab',
+    lineEnding?: 'lf' | 'crlf',
     string?: {
         quote?: 'single' | 'double',
     },

src/node/structureNode.ts

@@ -164,12 +164,7 @@ export abstract class JsonStructureNode extends JsonValueNode {
                     if (indentationSize > 0 && manipulator.matchesNext(node => endToken.isEquivalent(node))) {
                         // If the following token is the end token, always indent.
                         // This ensures it won't consume the indentation of the end delimiter.
-                        manipulator.node(
-                            new JsonTokenNode({
-                                type: JsonTokenType.NEWLINE,
-                                value: '\n',
-                            }),
-                        );
+                        manipulator.node(this.getNewlineToken(formatting));
 
                         if (
                             manipulator.matchesToken(JsonTokenType.WHITESPACE)
@@ -187,12 +182,7 @@ export abstract class JsonStructureNode extends JsonValueNode {
                 previousMatched = currentMatched;
 
                 if (manipulator.matchesPreviousToken(JsonTokenType.LINE_COMMENT)) {
-                    manipulator.insert(
-                        new JsonTokenNode({
-                            type: JsonTokenType.NEWLINE,
-                            value: '\n',
-                        }),
-                    );
+                    manipulator.insert(this.getNewlineToken(formatting));
                 } else if (
                     manipulator.position > 1
                     && !currentMatched
@@ -373,6 +363,10 @@ export abstract class JsonStructureNode extends JsonValueNode {
                 }
             }
 
+            if (NEWLINE(token)) {
+                formatting.lineEnding = token.value.includes('\r\n') ? 'crlf' : 'lf';
+            }
+
             if (inlineComma && index > 0 && tokens[index - 1].depth === 0) {
                 if (!NEWLINE(token)) {
                     blockFormatting.commaSpacing = WHITESPACE(token);
@@ -485,10 +479,7 @@ export abstract class JsonStructureNode extends JsonValueNode {
             return;
         }
 
-        const newLine = new JsonTokenNode({
-            type: JsonTokenType.NEWLINE,
-            value: '\n',
-        });
+        const newLine = this.getNewlineToken(formatting);
 
         manipulator.token(newLine, optional);
 
@@ -511,6 +502,13 @@ export abstract class JsonStructureNode extends JsonValueNode {
         });
     }
 
+    private getNewlineToken(formatting: Formatting): JsonTokenNode {
+        return new JsonTokenNode({
+            type: JsonTokenType.NEWLINE,
+            value: formatting.lineEnding === 'crlf' ? '\r\n' : '\n',
+        });
+    }
+
     private static* iterate(
         parent: JsonCompositeNode,
         maxDepth: number,

test/functional.test.ts

@@ -214,6 +214,13 @@ describe('Functional test', () => {
             input: "'\uD83C\uDFBC'",
             expected: '🎼',
         },
+        {
+            input: '{\r\n  "foo": "1",\r\n  "bar": "2"\r\n}',
+            expected: {
+                foo: '1',
+                bar: '2',
+            },
+        },
     ])('should parse $input', ({input, expected}) => {
         const parser = new JsonParser(input);
         const node = parser.parseValue();
@@ -334,6 +341,17 @@ describe('Functional test', () => {
                 node.set('bar', 2);
             },
         },
+        {
+            description: 'use \\r\\n line endings when detected',
+            // language=JSON
+            input: '{\r\n  "foo": "1"\r\n}',
+            // language=JSON
+            output: '{\r\n  "foo": "1",\r\n  "bar": "2"\r\n}',
+            type: JsonObjectNode,
+            mutation: (node: JsonObjectNode): void => {
+                node.set('bar', '2');
+            },
+        },
         {
             description: 'use the same indentation character as the the parent',
             // language=JSON
@@ -3028,6 +3046,28 @@ describe('Functional test', () => {
                 node.set('bar', 'qux');
             },
         },
+        {
+            description: 'preserve carriage return and line feed as line ending',
+            // language=JSON5
+            input: '{\r\n  "foo": 1,\r\n  "bar": 2\r\n}',
+            // language=JSON5
+            output: '{\r\n  "foo": 1\r\n}',
+            type: JsonObjectNode,
+            mutation: (node: JsonObjectNode): void => {
+                node.delete('bar');
+            },
+        },
+        {
+            description: 'detect carriage return and line feed as line ending',
+            // language=JSON5
+            input: '{\r\n  "foo": 1,\r\n  "bar": 2\r\n}',
+            // language=JSON5
+            output: '{\r\n  "foo": 1\r\n}',
+            type: JsonObjectNode,
+            mutation: (node: JsonObjectNode): void => {
+                node.delete('bar');
+            },
+        },
     ])('should $description', ({input, output, type, mutation, format}) => {
         const node = JsonParser.parse(input, type);