ing stuff

packages/english-verbs/lib/index.ts

@@ -13,6 +13,8 @@ export interface ExtraParams {
   WILL?: boolean;
 }
 
+// helpers
+
 function getIrregularPreterit(verbsInfo: VerbsInfo, verb: string): string {
   if (verbsInfo && verbsInfo[verb] && verbsInfo[verb].length != 0) {
     const verbInfo = verbsInfo[verb];
@@ -26,6 +28,27 @@ function getIrregularPreterit(verbsInfo: VerbsInfo, verb: string): string {
   }
 }
 
+const consonants = 'bcdfghjklmnpqrstvxzw';
+export function getIng(verb: string): string {
+  if (verb.match(new RegExp(`[${consonants}]e$`, 'g'))) {
+    // If  the  infinitive  ends  with  a  consonant followed by an –e,
+    // you have to take off the –e to form your present participle.
+    return verb.substring(0, verb.length - 1) + 'ing';
+  } else if (verb.match(new RegExp(`[aeiou][${consonants}]$`, 'g'))) {
+    // If  the  infinitive  ends  with one  vowel  followed  by  one  consonant(except  of –y),
+    // you  have  to  double  this consonant to form your present participle.
+    return verb + verb.charAt(verb.length - 1) + 'ing';
+  } else if (verb.endsWith('ie')) {
+    // If the infinitive ends with –ie,
+    // the letters are replaced by –y followed by –ing in the past participle form.
+    return verb.substring(0, verb.length - 2) + 'y' + 'ing';
+  } else {
+    return verb + 'ing';
+  }
+}
+
+// 1 per tense
+
 function getSimplePast(verbsInfo: VerbsInfo, verb: string, number: Numbers): string {
   let irregular: string;
   if (verb === 'be') {

packages/english-verbs/test/test.js

@@ -51,6 +51,26 @@ const testCases = {
   FUTURE: [['rest', 'S', 'will rest']],
 };
 
+// https://www.usingenglish.com/reference/irregular-verbs/shoe.html
+const testCasesIng = [
+  ['find', 'finding'],
+  ['laugh', 'laughing'],
+  ['wash', 'washing'],
+  ['arise', 'arising'],
+  ['become', 'becoming'],
+  ['have', 'having'],
+  ['get', 'getting'],
+  ['let', 'letting'],
+  ['plan', 'planning'],
+  ['die', 'dying'],
+  ['lie', 'lying'],
+  ['dare', 'daring'],
+  ['ban', 'banning'],
+  ['fit', 'fitting'],
+  ['shoe', 'shoeing'],
+  ['pay', 'paying'],
+];
+
 describe('english-verbs', function() {
   describe('#getConjugation()', function() {
     describe('nominal cases', function() {
@@ -86,6 +106,16 @@ describe('english-verbs', function() {
         });
       }
     });
+    describe('ing form', function() {
+      for (let i = 0; i < testCasesIng.length; i++) {
+        const testCase = testCasesIng[i];
+        const verb = testCase[0];
+        const expected = testCase[1];
+        it(`${verb} => ${expected}`, function() {
+          assert.equal(EnglishVerbs.getIng(verb), expected);
+        });
+      }
+    });
     describe('edge cases', function() {
       it(`null verb`, function() {
         assert.throws(() => EnglishVerbs.getConjugation(null, null, 'PRESENT', 'S'), /verb/);