Implemented mfrac tag use cases

__test__/index.test.ts

@@ -395,4 +395,77 @@ describe('#convert', () => {
       });
     });
   });
+
+  describe('given mfrac tag', () => {
+    describe('containing single char contents', () => {
+      test('convert mfrac wrap inside \\frac command', () => {
+        const mathml = `
+          <root>
+            <math>
+              <mfrac>
+                <mi>x</mi>
+                <mn>3</mn>
+              </mfrac>
+            </math>
+          </root>
+        `;
+
+        const result = MathMLToLaTeX.convert(mathml);
+
+        expect(result).toMatch('\\frac{x}{3}');
+      });
+    });
+  });
+
+  describe('containing multiple char contents', () => {
+    test('convert mfrac wrap inside \\frac command', () => {
+      const mathml = `
+        <root>
+          <math>
+            <mfrac>
+              <mrow>
+                <mi>a</mi>
+                <mo>+</mo>
+                <mi>2</mi>
+              </mrow>
+              <mrow>
+                <mi>b</mi>
+                <mo>-</mo>
+                <mi>3</mi>
+              </mrow>
+            </mfrac>
+          </math>
+        </root>
+      `;
+
+      const result = MathMLToLaTeX.convert(mathml);
+
+      expect(result).toMatch('\\frac{a + 2}{b - 3}');
+    });
+  });
+
+  describe('containing two contents with bevelled attribute marked as true', () => {
+    test('convert mfrac joining its two char contents with //', () => {
+      const mathml = `
+        <root>
+          <math>
+            <mfrac bevelled="true">
+              <mn>1</mn>
+              <mrow>
+                <msup>
+                  <mi>x</mi>
+                  <mn>3</mn>
+                </msup>
+                <mo>+</mo>
+                <mn>3</mn>
+              </mrow>
+            </mfrac>
+          </math>
+        </root>
+      `;
+
+      const result = MathMLToLaTeX.convert(mathml);
+      expect(result).toMatch('1/\\left(x^{3} + 3\\right)');
+    });
+  });
 });

src/converters/mathml-interfaces-to-latex/mathml-tag-to-latex/Dispatcher.ts

@@ -1,4 +1,4 @@
-import { Math, MathMLTag, MI, MO, MN, MSqrt, MRow, MSup, MFenced } from './mathml-tags';
+import { Math, MathMLTag, MI, MO, MN, MSqrt, MRow, MSup, MFenced, MFrac } from './mathml-tags';
 
 export class Dispatcher {
   private _name: string;
@@ -31,6 +31,8 @@ export class Dispatcher {
         return new MSup(this._value, this._attributes, this._children);
       case 'mfenced':
         return new MFenced(this._value, this._attributes, this._children);
+      case 'mfrac':
+        return new MFrac(this._value, this._attributes, this._children);
       default:
         return new MathMLTag(this._name, this._value, this._attributes, this._children);
     }

src/converters/mathml-interfaces-to-latex/mathml-tag-to-latex/mathml-tags/MFrac.ts

@@ -0,0 +1,28 @@
+import { MathMLTag } from './MathMLTag';
+import { InvalidNumberOfChild } from '../../../../errors';
+import { ParenthesisWrapper } from '../../../../../utils/wrappers';
+
+export class MFrac extends MathMLTag {
+  constructor(value: string, attributes: Record<string, string>, children: MathMLTag[]) {
+    super('mfrac', value, attributes, children);
+  }
+
+  convert(): string {
+    if (this._children.length !== 2) throw new InvalidNumberOfChild(this._name, 2, this._children.length);
+
+    const num = this._children[0].convert();
+    const den = this._children[1].convert();
+
+    if (this._isBevelled) return `${this._wrapIfMoreThanOneChar(num)}/${this._wrapIfMoreThanOneChar(den)}`;
+
+    return `\\frac{${num}}{${den}}`;
+  }
+
+  private _wrapIfMoreThanOneChar(str: string): string {
+    return new ParenthesisWrapper().wrapIfMoreThanOneChar(str);
+  }
+
+  private get _isBevelled(): boolean {
+    return !!this._attributes.bevelled;
+  }
+}

src/converters/mathml-interfaces-to-latex/mathml-tag-to-latex/mathml-tags/MSup.ts

@@ -1,5 +1,6 @@
 import { MathMLTag } from './MathMLTag';
 import { BracketWrapper, ParenthesisWrapper } from '../../../../../utils/wrappers';
+import { InvalidNumberOfChild } from '../../../../errors';
 
 export class MSup extends MathMLTag {
   constructor(value: string, attributes: Record<string, string>, children: MathMLTag[]) {
@@ -7,7 +8,7 @@ export class MSup extends MathMLTag {
   }
 
   convert(): string {
-    if (this._children.length !== 2) throw new InvalidNumberOfChild(this._children.length);
+    if (this._children.length !== 2) throw new InvalidNumberOfChild(this._name, 2, this._children.length);
 
     const base = this._children[0].convert();
     const exponent = this._children[1].convert();
@@ -15,9 +16,3 @@ export class MSup extends MathMLTag {
     return `${new ParenthesisWrapper().wrapIfMoreThanOneChar(base)}^${new BracketWrapper().wrap(exponent)}`;
   }
 }
-
-class InvalidNumberOfChild extends Error {
-  constructor(numberOfChild: number) {
-    super(`msup tag must have exactly 2 children. It's actually ${numberOfChild}`);
-  }
-}

src/converters/mathml-interfaces-to-latex/mathml-tag-to-latex/mathml-tags/index.ts

@@ -7,3 +7,4 @@ export { MSqrt } from './MSqrt';
 export { MRow } from './MRow';
 export { MSup } from './MSup';
 export { MFenced } from './MFenced';
+export { MFrac } from './MFrac';

src/errors/InvalidNumberOfChild.ts

@@ -0,0 +1,5 @@
+export class InvalidNumberOfChild extends Error {
+  constructor(tagName: string, expectedNumberOfChild: number, currentNumberOfChild: number) {
+    super(`${tagName} tag must have exactly ${expectedNumberOfChild} children. It's actually ${currentNumberOfChild}`);
+  }
+}

src/errors/index.ts

@@ -0,0 +1 @@
+export { InvalidNumberOfChild } from './InvalidNumberOfChild';