fix: parsing negative number

Close GH-123

Author: zackad

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## unreleased
 
+### Bugfixes
+- [GH-123](https://github.com/zackad/prettier-plugin-twig/issues/123) Fix parsing negative number
+
 ---
 ## 0.15.0 (2025-02-01)
 

src/melody/melody-parser/Lexer.js

@@ -354,7 +354,10 @@ export default class Lexer {
                     return this.createToken(TokenTypes.ARROW, pos);
                 }
             default: {
-                if (isDigit(input.lac(0))) {
+                if (
+                    isDigit(input.lac(0)) ||
+                    (input.la(0) === "-" && isDigit(input.lac(1)))
+                ) {
                     input.next();
                     return this.matchNumber(pos);
                 }
@@ -601,6 +604,11 @@ export default class Lexer {
     matchNumber(pos) {
         const input = this.input;
         let c;
+
+        // check for negative number
+        if (input.la(0) === "-" && isDigit(input.lac(1))) {
+            input.next();
+        }
         while ((c = input.lac(0)) !== EOF) {
             if (!isDigit(c)) {
                 break;

tests/Expressions/__snapshots__/negative_number.snap.twig

@@ -0,0 +1,5 @@
+{# https://github.com/zackad/prettier-plugin-twig/issues/123 #}
+{% set x = -2 %}
+{% set x = -2.092 %}
+{{ '00001'|slice(-2, 2) }}
+{{ '00001'|slice(2, -2) }}

tests/Expressions/jsfmt.spec.js

@@ -38,6 +38,14 @@ describe("Expressions", () => {
         });
         await expect(actual).toMatchFileSnapshot(snapshotFile);
     });
+
+    it("should handle negative number without space", async () => {
+        const { actual, snapshotFile } = await run_spec(import.meta.url, {
+            source: "negative_number.twig"
+        });
+        await expect(actual).toMatchFileSnapshot(snapshotFile);
+    });
+
     it("should handle mapping expressions", async () => {
         const { actual, snapshotFile } = await run_spec(import.meta.url, {
             source: "mappingExpression.twig"

tests/Expressions/negative_number.twig

@@ -0,0 +1,5 @@
+{# https://github.com/zackad/prettier-plugin-twig/issues/123 #}
+{% set x = -2 %}
+{% set x = -2.092 %}
+{{ "00001"|slice(-2, 2) }}
+{{ "00001"|slice(2, -2) }}