fix: char class ^- edge case (#42)

Author: mdjastrzebski

README.md

@@ -13,17 +13,20 @@ This library allows users to create regular expressions in a structured way, mak
 const hexColor = /^#?([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$/;
 
 // After
-const hexDigit = charClass(charRange('a', 'f'), charRange('A', 'F'), charRange('0', '9'));
+const hexDigit = charClass(
+  charRange('a', 'f'), //
+  charRange('A', 'F'),
+  charRange('0', '9'),
+);
 
-// prettier-ignore
 const hexColor = buildRegex(
   startOfString,
   optionally('#'),
   capture(
     choiceOf(
-      repeat({ count: 6 }, hexDigit),
-      repeat({ count: 3 }, hexDigit),
-    )
+      repeat({ count: 6 }, hexDigit), // #rrggbb
+      repeat({ count: 3 }, hexDigit), // #rgb
+    ),
   ),
   endOfString,
 );
@@ -73,11 +76,11 @@ const currencyAmount = buildRegex([
   choiceOf(
     '$',
     '€',
-    repeat({ count: 3 }, charRange('A', 'Z')) // ISO currency code
+    repeat({ count: 3 }, charRange('A', 'Z')), // ISO currency code
   ),
   capture(
     oneOrMore(digit), // Integer part
-    optionally(['.', repeat({ count: 2 }, digit)]) // Fractional part
+    optionally(['.', repeat({ count: 2 }, digit)]), // Fractional part
   ),
 ]);
 ```

package.json

@@ -144,7 +144,7 @@
     "quoteProps": "consistent",
     "singleQuote": true,
     "tabWidth": 2,
-    "trailingComma": "es5",
+    "trailingComma": "all",
     "useTabs": false
   },
   "react-native-builder-bob": {

src/components/__tests__/character-class.test.ts

@@ -88,6 +88,12 @@ test('`anyOf` moves hyphen to the last position', () => {
   expect(anyOf('a-bc')).toHavePattern(/[abc-]/);
 });
 
+test('`anyOf` edge case caret and  hyphen', () => {
+  expect(anyOf('^-')).toHavePattern(/[\^-]/);
+  expect(anyOf('-^')).toHavePattern(/[\^-]/);
+  expect(anyOf('-^a')).toHavePattern(/[a^-]/);
+});
+
 test('`anyOf` throws on empty text', () => {
   expect(() => anyOf('')).toThrowErrorMatchingInlineSnapshot(
     `"\`anyOf\` should received at least one character"`

src/components/character-class.ts

@@ -129,13 +129,17 @@ function encodeCharacterClass(this: CharacterClass): EncodeOutput {
   // first (or last) place in order to treat it as hyphen character and not a range.
   // See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions/Character_classes#types
   const hyphen = this.chars.includes('-') ? '-' : '';
-  const otherChars = this.chars.filter((c) => c !== '-').join('');
+  const caret = this.chars.includes('^') ? '^' : '';
+  const otherChars = this.chars.filter((c) => c !== '-' && c !== '^').join('');
   const ranges = this.ranges.map(({ start, end }) => `${start}-${end}`).join('');
   const isInverted = this.isInverted ? '^' : '';
 
+  let pattern = `[${isInverted}${ranges}${otherChars}${caret}${hyphen}]`;
+  if (pattern === '[^-]') pattern = '[\\^-]';
+
   return {
     precedence: 'atom',
-    pattern: `[${isInverted}${ranges}${otherChars}${hyphen}]`,
+    pattern,
   };
 }