feat: basic wordBoundary implementations

Author: mdjastrzebski

src/constructs/__tests__/anchors.test.tsx

@@ -1,5 +1,7 @@
-import { endOfString, startOfString } from '../anchors';
-import { oneOrMore } from '../quantifiers';
+import { buildRegExp } from '../../builders';
+import { endOfString, startOfString, wordBoundary } from '../anchors';
+import { any, notWhitespace } from '../character-class';
+import { oneOrMore, zeroOrMore } from '../quantifiers';
 
 test('`startOfString` basic cases', () => {
   expect(startOfString).toEqualRegex(/^/);
@@ -18,3 +20,18 @@ test('`endOfString` basic cases', () => {
 test('`endOfString` regex tests', () => {
   expect([oneOrMore('a'), endOfString]).toMatchGroups('a aa aaa', ['aaa']);
 });
+
+test('`wordBoundary` basic cases', () => {
+  expect(wordBoundary).toEqualRegex(/\b/);
+  expect([wordBoundary, 'a', 'b']).toEqualRegex(/\bab/);
+});
+
+test('`wordBoundary` regex tests', () => {
+  expect(
+    buildRegExp([wordBoundary, 'a', zeroOrMore(notWhitespace)], { global: true }),
+  ).toMatchGroups('a ba ab aa', ['a', 'ab', 'aa']);
+
+  expect(
+    buildRegExp([zeroOrMore(notWhitespace), 'a', wordBoundary], { global: true }),
+  ).toMatchGroups('a ba ab aa', ['a', 'ba', 'aa']);
+});

src/constructs/anchors.ts

@@ -18,6 +18,18 @@ export const endOfString: Anchor = {
   encode: encodeAnchor,
 };
 
+export const wordBoundary: Anchor = {
+  type: 'anchor',
+  symbol: '\\b',
+  encode: encodeAnchor,
+};
+
+export const notWordBoundary: Anchor = {
+  type: 'anchor',
+  symbol: '\\B',
+  encode: encodeAnchor,
+};
+
 function encodeAnchor(this: Anchor): EncodeResult {
   return {
     precedence: 'sequence',