refactor(parser): refactoring

src/parser/block/blockquote.ts

@@ -2,6 +2,7 @@
 import { combine, some } from '../../combinator';
 import { verify } from './util/verification';
 import { block as block_ } from '../source/block';
+import { firstline } from '../source/line';
 import { block } from '../block';
 import { unescsource } from '../source/unescapable';
 import { squash } from '../squash';
@@ -26,7 +27,7 @@ export const blockquote: BlockquoteParser = verify(block_(source => {
       p.appendChild(html('blockquote'))
     , top);
   while (true) {
-    if (source.split('\n', 1).shift()!.trim() === '') break;
+    if (firstline(source).trim() === '') break;
     const diff = (source.match(syntax) || [indent])[0].length - indent.length;
     if (diff > 0) {
       bottom = source.slice(0, diff).split('')

src/parser/block/dlist.ts

@@ -2,6 +2,7 @@
 import { combine, some } from '../../combinator';
 import { verify } from './util/verification';
 import { block } from '../source/block';
+import { firstline } from '../source/line';
 import { indexer, defineIndex } from './util/indexer';
 import { InlineParser, inline } from '../inline';
 import { squash } from '../squash';
@@ -15,7 +16,7 @@ export const dlist: DListParser = verify(block(source => {
   if (!whole) return;
   const el = html('dl');
   while (true) {
-    const line = source.split('\n', 1)[0];
+    const line = firstline(source);
     if (line.trim() === '') break;
     switch (line.slice(0, 2).trim()) {
       case '~': {
@@ -33,7 +34,7 @@ export const dlist: DListParser = verify(block(source => {
         const texts = [line.slice(line.slice(0, 2).trim() === ':' ? 1 : 0)];
         source = source.slice(line.length + 1);
         while (true) {
-          const line = source.split('\n', 1)[0];
+          const line = firstline(source);
           if (line.trim() === '' || line.search(separator) === 0) break;
           void texts.push(line);
           source = source.slice(line.length + 1);

src/parser/block/extension/placeholder.ts

@@ -3,6 +3,7 @@ import { some } from '../../../combinator';
 import { verify } from '../util/verification';
 import { block as block_ } from '../../source/block';
 import { block } from '../../block';
+import { firstline } from '../../source/line';
 import { unescsource } from '../../source/unescapable';
 
 const syntax = /^(~{3,})([^\n]*)\n(?:[^\n]*\n)*?\1[^\S\n]*(?:\n|$)/;
@@ -15,11 +16,11 @@ export const placeholder: ExtensionParser.PlaceholderParser = verify(block_(sour
   source = source.slice(source.indexOf('\n') + 1);
   const lines: string[] = [];
   while (true) {
-    const line = source.split('\n', 1)[0];
+    const line = firstline(source);
     if (line.startsWith(`${bracket}`) && line.trim() === `${bracket}`) break;
     void lines.push((some(unescsource)(`${line}\n`) || [[] as Text[]])[0].reduce((acc, n) => acc + n.textContent, ''));
     source = source.slice(line.length + 1);
     if (source === '') return;
   }
-  return [[message], source.slice(source.split('\n', 1)[0].length + 1)];
+  return [[message], source.slice(firstline(source).length + 1)];
 }));

src/parser/block/olist.ts

@@ -2,6 +2,7 @@
 import { verify } from './util/verification';
 import { combine, some } from '../../combinator';
 import { block } from '../source/block';
+import { firstline } from '../source/line';
 import { match } from '../source/validation';
 import { ulist } from './ulist';
 import { indent, fillOListFlag } from './util/indent';
@@ -19,7 +20,7 @@ export const olist: OListParser = verify(block(source => {
     'type': Number.isFinite(+index) ? '1' : index === index.toLowerCase() ? 'a' : 'A',
   });
   while (true) {
-    const line = source.split('\n', 1)[0];
+    const line = firstline(source);
     if (line.trim() === '') break;
     if (!match(line, '', syntax)) return;
     const text = line.slice(line.split(/\s/, 1)[0].length + 1).trim();

src/parser/block/table.ts

@@ -2,6 +2,7 @@
 import { verify } from './util/verification';
 import { some } from '../../combinator';
 import { block } from '../source/block';
+import { firstline } from '../source/line';
 import { inline } from '../inline';
 import { squash } from '../squash';
 import { html } from 'typed-dom';
@@ -38,7 +39,7 @@ export const table: TableParser = verify(block(source => {
         : aligns[i]));
   void table.appendChild(html('tbody'));
   while (true) {
-    const line = source.split('\n', 1)[0];
+    const line = firstline(source);
     if (line.trim() === '') break;
     const [cols = [], rest = line] = parse(line) || [];
     if (rest.length !== 0) return;
@@ -66,6 +67,6 @@ function parse(row: string): [DocumentFragment[], string] | undefined {
     assert(rest.length < row.length);
     row = rest;
     void cols.push(squash(col, document.createDocumentFragment()));
-    if (row.search(rowend) === 0) return [cols, row.slice(row.split('\n')[0].length + 1)];
+    if (row.search(rowend) === 0) return [cols, row.slice(firstline(row).length + 1)];
   }
 }

src/parser/block/ulist.ts

@@ -2,6 +2,7 @@
 import { verify } from './util/verification';
 import { combine, some } from '../../combinator';
 import { block } from '../source/block';
+import { firstline } from '../source/line';
 import { match } from '../source/validation';
 import { olist } from './olist';
 import { indent, fillOListFlag } from './util/indent';
@@ -17,7 +18,7 @@ export const ulist: UListParser = verify(block(source => {
   if (!whole) return;
   const el = html('ul');
   while (true) {
-    const line = source.split('\n', 1)[0];
+    const line = firstline(source);
     if (line.trim() === '') break;
     if (!match(line, flag, syntax)) return;
     const [text, checkbox = ''] = line.slice(line.split(/\s/, 1)[0].length + 1).trim().match(content)!;

src/parser/block/util/indent.ts

@@ -1,12 +1,14 @@
-const syntax = /^\s*/;
+import { firstline } from '../../source/line';
+
+const syntax = /^\s*/;
 
 export function indent(source: string): [string, string] | undefined {
-  const [indent = ''] = source.split('\n', 1)[0].match(syntax) || [];
+  const [indent = ''] = firstline(source).match(syntax) || [];
   if (indent === '') return;
   const lines: string[] = [];
   let rest = source;
   while (true) {
-    const line = rest.split('\n', 1)[0];
+    const line = firstline(rest);
     if (!line.startsWith(indent)) break;
     if (line.slice(indent.length).trim() === '') break;
     void lines.push(line.slice(indent.length));

src/parser/block/util/verification.ts

@@ -1,11 +1,12 @@
 import { Result } from '../../../combinator';
+import { firstline } from '../../source/line';
 
 export function verify<T extends Result<any, any>>(parser: (source: string) => T): (source: string) => T {
   return source => {
     const result = parser(source);
     if (!result) return result;
     assert(result[0].length < 2);
-    if (result[1].split('\n', 1)[0].trim() !== '') return undefined as T;
+    if (firstline(result[1]).trim() !== '') return undefined as T;
     return result;
   };
 }

src/parser/source/line.ts

@@ -7,9 +7,9 @@ export function line<S extends Parser<any, any>[], R>(parser: Parser<R, S>, enti
   return source => {
     if (source.length === 0) return;
     if (force) {
-      const src = source.split('\n', 1)[0];
+      const src = firstline(source);
       const rst = source.slice(src.length + 1);
-      const result = line(parser, entire, false)(`${src}${source.length > src.length ? source[src.length] : ''}`);
+      const result = line(parser, entire, false)(src + (source.length > src.length ? source[src.length] : ''));
       return result
         ? [result[0], result[1] + rst]
         : undefined;
@@ -25,9 +25,16 @@ export function line<S extends Parser<any, any>[], R>(parser: Parser<R, S>, enti
   };
 }
 
+export function firstline(source: string): string {
+  const i = source.indexOf('\n');
+  return i === -1
+    ? source
+    : source.slice(0, i);
+}
+
 export const emptyline: EmptyLineParser = line(s => s.trim() === '' ? [[], ''] : undefined, true, true);
 export const nonemptyline: NonemptyLineParser = line(s => s.trim() !== '' ? [[], ''] : undefined, true, true);
 
 const invisible = /^(?:\\?\s)*?\\?$/;
-export const visibleline: VisibleLineParser = line(s => s.search(invisible) === -1 ? [[], ''] : undefined, true, true);
+export const visibleline: VisibleLineParser = line(s => s.search(invisible) !== 0 ? [[], ''] : undefined, true, true);
 export const invisibleline: InvisibleLineParser = line(s => s.search(invisible) === 0 ? [[], ''] : undefined, true, true);