add bold and strikethrough tag (#76)

src/internal/parser.pegjs

@@ -241,6 +241,10 @@ bold
 	= "**" content:(!"**" i:inline { return i; })+ "**"
 {
 	return BOLD(mergeText(content));
+}
+	/ "<b>" content:(!"</b>" i:inline { return i; })+ "</b>"
+{
+	return BOLD(mergeText(content));
 }
 	/ "__" content:$(!"__" c:([a-z0-9]i / _) { return c; })+ "__"
 {
@@ -287,6 +291,10 @@ strike
 {
 	return STRIKE(mergeText(content));
 }
+	/ "<s>" content:(!("</s>" / LF) i:inline { return i; })+ "</s>"
+{
+	return STRIKE(mergeText(content));
+}
 
 // inline: inlineCode
 

test/parser.ts

@@ -362,6 +362,44 @@ hoge`;
 		});
 	});
 
+	describe('bold tag', () => {
+		it('basic', () => {
+			const input = '<b>abc</b>';
+			const output = [
+				BOLD([
+					TEXT('abc')
+				])
+			];
+			assert.deepStrictEqual(mfm.parse(input), output);
+		});
+		it('inline syntax allowed inside', () => {
+			const input = '<b>123~~abc~~123</b>';
+			const output = [
+				BOLD([
+					TEXT('123'),
+					STRIKE([
+						TEXT('abc')
+					]),
+					TEXT('123')
+				])
+			];
+			assert.deepStrictEqual(mfm.parse(input), output);
+		});
+		it('line breaks', () => {
+			const input = '<b>123\n~~abc~~\n123</b>';
+			const output = [
+				BOLD([
+					TEXT('123\n'),
+					STRIKE([
+						TEXT('abc')
+					]),
+					TEXT('\n123')
+				])
+			];
+			assert.deepStrictEqual(mfm.parse(input), output);
+		});
+	});
+
 	describe('bold', () => {
 		it('basic', () => {
 			const input = '**abc**';
@@ -556,6 +594,16 @@ hoge`;
 		});
 	});
 
+	describe('strike tag', () => {
+		it('basic', () => {
+			const input = '<s>foo</s>';
+			const output = [STRIKE([
+				TEXT('foo')
+			])];
+			assert.deepStrictEqual(mfm.parse(input), output);
+		});
+	});
+
 	describe('strike', () => {
 		it('basic', () => {
 			const input = '~~foo~~';