feat: add support to line numbers in markdown

packages/saber-highlight-css/default.css

@@ -11,11 +11,12 @@
   position: absolute;
   right: 10px;
   top: 5px;
-  font-size: .75rem;
+  font-size: 0.75rem;
   color: #bdc5d1;
 }
 
-.saber-highlight-mask, .saber-highlight-code {
+.saber-highlight-mask,
+.saber-highlight-code {
   line-height: 1.5;
   background-color: transparent !important;
   text-shadow: none !important;
@@ -52,10 +53,34 @@
 
 .saber-highlight-code code,
 .saber-highlight-mask {
-  font-size: .875rem;
+  font-size: 0.875rem;
 }
 
 .code-line.highlighted {
   background: rgba(3, 169, 244, 0.121);
-  box-shadow: inset 2px 0 0 0 rgba(3, 169, 244, 0.278)
+}
+
+/* Line numbers */
+.saber-highlight-line-numbers {
+  pointer-events: none;
+  font-size: 100%;
+  float: left;
+  letter-spacing: -1px;
+  border-right: 1px solid #999;
+  user-select: none;
+  text-align: right;
+  padding-right: 0.8rem;
+  margin-right: .8rem;
+  counter-reset: linenumber;
+}
+
+.saber-highlight-line-numbers > span {
+  counter-increment: linenumber;
+  display: block;
+}
+
+.saber-highlight-line-numbers > span:before {
+  content: counter(linenumber);
+  color: #999;
+  display: block;
 }

packages/saber/lib/markdown/__test__/__snapshots__/highlight-plugin.test.js.snap

@@ -1,3 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`code block markdown.lineNumbers = true 1`] = `"<div class=\\"saber-highlight has-line-numbers\\" v-pre=\\"\\" data-lang=\\"js\\"><pre class=\\"saber-highlight-code language-js\\"><code class=\\"language-js\\"><span aria-hidden=\\"true\\" class=\\"saber-highlight-line-numbers\\"><span></span></span>const cry = Array(3).fill('ora').join(' ')</code></pre></div>"`;
+
+exports[`code block with {lineNumbers:true} 1`] = `"<div class=\\"saber-highlight has-line-numbers\\" v-pre=\\"\\" data-lang=\\"js\\"><pre class=\\"saber-highlight-code language-js\\"><code class=\\"language-js\\"><span aria-hidden=\\"true\\" class=\\"saber-highlight-line-numbers\\"><span></span></span>const cry = Array(3).fill('ora').join(' ')</code></pre></div>"`;
+
 exports[`main 1`] = `"<div class=\\"saber-highlight\\" v-pre=\\"\\" data-lang=\\"vue\\"><pre class=\\"saber-highlight-code language-vue\\"><code class=\\"language-vue\\">&lt;div&gt;hehe&lt;/div&gt;</code></pre></div>"`;

packages/saber/lib/markdown/__test__/highlight-plugin.test.js

@@ -16,3 +16,33 @@ test('main', () => {
   )
   expect(html).toMatchSnapshot()
 })
+
+test('code block with {lineNumbers:true}', () => {
+  const md = new Markdown()
+  const { env } = createEnv()
+  md.use(fenceOptionsPlugin)
+  const html = md.render(
+    `
+\`\`\`js {lineNumbers:true}
+const cry = Array(3).fill('ora').join(' ')
+\`\`\`
+  `,
+    env
+  )
+  expect(html).toMatchSnapshot()
+})
+
+test('code block markdown.lineNumbers = true', () => {
+  const md = new Markdown()
+  const { env } = createEnv()
+  md.use(fenceOptionsPlugin, { lineNumbers: true })
+  const html = md.render(
+    `
+\`\`\`js {lineNumbers:true}
+const cry = Array(3).fill('ora').join(' ')
+\`\`\`
+  `,
+    env
+  )
+  expect(html).toMatchSnapshot()
+})

packages/saber/lib/markdown/highlight-plugin.js

@@ -1,34 +1,98 @@
 const RE = /\s*{([^}]+)}/
 
 const parseOptions = str => {
+  if (!RE.test(str)) {
+    return {}
+  }
+
   const [, options] = RE.exec(str)
   const fn = new Function(`return {${options}}`) // eslint-disable-line no-new-func
   return fn()
 }
 
-module.exports = (md, { highlightedLineBackground } = {}) => {
-  const renderPreWrapper = (
+const generateLineNumbers = code =>
+  '<span aria-hidden="true" class="saber-highlight-line-numbers">' +
+  code
+    .trim()
+    .split('\n')
+    .map(() => `<span></span>`)
+    .join('') +
+  '</span>'
+
+module.exports = (
+  md,
+  { highlightedLineBackground, lineNumbers = false } = {}
+) => {
+  const renderPreWrapper = ({
     preWrapperAttrs,
     preAttrs,
     codeAttrs,
     code,
-    codeMask = ''
-  ) =>
-    `<div${preWrapperAttrs}>${codeMask}<pre${preAttrs}><code${codeAttrs}>${code.trim()}</code></pre></div>`
+    codeMask = '',
+    lines = ''
+  }) =>
+    `<div${preWrapperAttrs}>${codeMask}<pre${preAttrs}><code${codeAttrs}>${lines}${code.trim()}</code></pre></div>`
 
   md.renderer.rules.fence = (...args) => {
     const [tokens, idx, options, env, self] = args
     const token = tokens[idx]
 
+    const fenceOptions = parseOptions(token.info)
     const langName = token.info.replace(RE, '').trim()
+    const langClass = `language-${langName || 'text'}`
+    token.info = langName
 
     const code = options.highlight
       ? options.highlight(token.content, langName, env)
       : md.utils.escapeHtml(token.content)
 
+    const highlightLines = fenceOptions.highlightLines
+      ? fenceOptions.highlightLines.map(v =>
+          `${v}`.split('-').map(v => parseInt(v, 10))
+        )
+      : []
+
+    const codeMask =
+      highlightLines.length === 0
+        ? ''
+        : `<div class="saber-highlight-mask${
+            langClass ? ` ${langClass}` : ''
+          }">` +
+          md.utils
+            .escapeHtml(token.content)
+            .split('\n')
+            .map((split, index) => {
+              split = split || '&#8203;'
+              const lineNumber = index + 1
+              const inRange = highlightLines.some(([start, end]) => {
+                if (start && end) {
+                  return lineNumber >= start && lineNumber <= end
+                }
+
+                return lineNumber === start
+              })
+              if (inRange) {
+                const style = highlightedLineBackground
+                  ? ` style="background-color: ${highlightedLineBackground}"`
+                  : ''
+                return `<div class="code-line highlighted"${style}>${split}</div>`
+              }
+
+              return `<div class="code-line">${split}</div>`
+            })
+            .join('') +
+          '</div>'
+
     const renderAttrs = attrs => self.renderAttrs({ attrs })
+    const shouldGenerateLineNumbers =
+      // It might be false so check for undefined
+      fenceOptions.lineNumbers === undefined
+        ? // Defaults to global config
+          lineNumbers
+        : // If it's set to false, even if the global config says true, ignore
+          fenceOptions.lineNumbers
+    const lines = shouldGenerateLineNumbers ? generateLineNumbers(code) : ''
 
-    const langClass = `language-${langName || 'text'}`
     const preAttrs = renderAttrs([
       ...(token.attrs || []),
       ['class', ['saber-highlight-code', langClass].filter(Boolean).join(' ')]
@@ -38,56 +102,21 @@ module.exports = (md, { highlightedLineBackground } = {}) => {
       ['class', langClass]
     ])
     const preWrapperAttrs = renderAttrs([
-      ['class', 'saber-highlight'],
+      [
+        'class',
+        `saber-highlight${shouldGenerateLineNumbers ? ' has-line-numbers' : ''}`
+      ],
       ['v-pre', ''],
       ['data-lang', langName]
     ])
 
-    if (!token.info || !RE.test(token.info)) {
-      return renderPreWrapper(preWrapperAttrs, preAttrs, codeAttrs, code)
-    }
-
-    const fenceOptions = parseOptions(token.info)
-    const highlightLines =
-      fenceOptions.highlightLines &&
-      fenceOptions.highlightLines.map(v =>
-        `${v}`.split('-').map(v => parseInt(v, 10))
-      )
-    token.info = langName
-
-    const codeMask =
-      `<div class="saber-highlight-mask${langClass ? ` ${langClass}` : ''}">` +
-      md.utils
-        .escapeHtml(token.content)
-        .split('\n')
-        .map((split, index) => {
-          split = split || '&#8203;'
-          const lineNumber = index + 1
-          const inRange = highlightLines.some(([start, end]) => {
-            if (start && end) {
-              return lineNumber >= start && lineNumber <= end
-            }
-
-            return lineNumber === start
-          })
-          if (inRange) {
-            const style = highlightedLineBackground
-              ? ` style="background-color: ${highlightedLineBackground}"`
-              : ''
-            return `<div class="code-line highlighted"${style}>${split}</div>`
-          }
-
-          return `<div class="code-line">${split}</div>`
-        })
-        .join('') +
-      '</div>'
-
-    return renderPreWrapper(
+    return renderPreWrapper({
       preWrapperAttrs,
       preAttrs,
       codeAttrs,
       code,
-      codeMask
-    )
+      codeMask,
+      lines
+    })
   }
 }

packages/saber/lib/plugins/transformer-markdown.js

@@ -77,7 +77,10 @@ function transformMarkdown(api, page) {
     },
     {
       name: 'highlight',
-      resolve: require.resolve('../markdown/highlight-plugin')
+      resolve: require.resolve('../markdown/highlight-plugin'),
+      options: {
+        lineNumbers: markdown.lineNumbers
+      }
     },
     {
       name: 'link',

packages/saber/lib/utils/validateConfig.js

@@ -36,6 +36,7 @@ module.exports = (config, { dev }) => {
       options: 'object?',
       headings: 'object?',
       highlighter: 'string?',
+      lineNumbers: 'boolean?',
       // Same as the type of Saber plugins
       plugins
     },

website/pages/docs/markdown-features.md

@@ -276,6 +276,54 @@ If you want to override the font size or font family, you need to add CSS for bo
 }
 ```
 
+### Line Numbers in Code Blocks
+
+Input:
+
+````markdown
+```js {lineNumbers:true,highlightLines:['2-5']}
+[
+  {
+    text: 'A page',
+    slug: 'a-page',
+    level: 1
+  },
+  {
+    text: 'A section',
+    slug: 'a-section',
+    level: 2
+  },
+  {
+    text: 'Another section',
+    slug: 'another-section',
+    level: 3
+  }
+]
+```
+````
+
+Output:
+
+```js {lineNumbers:true,highlightLines:['2-5']}
+[
+  {
+    text: 'A page',
+    slug: 'a-page',
+    level: 1
+  },
+  {
+    text: 'A section',
+    slug: 'a-section',
+    level: 2
+  },
+  {
+    text: 'Another section',
+    slug: 'another-section',
+    level: 3
+  }
+]
+```
+
 ## Configure markdown-it
 
 Check out [markdown.options](./saber-config.md#options) for setting markdown-it options and [markdown.plugins](./saber-config.md#plugins-2) for adding markdown-it plugins.

website/pages/docs/saber-config.md

@@ -167,6 +167,13 @@ interface MarkdownPlugin {
 }
 ```
 
+### lineNumbers
+
+- Type: `boolean`
+- Default: `false`
+
+Show line numbers in code blocks.
+
 ## permalinks
 
 - Type: `Permalinks` `(page: Page) => Permalinks`