add basic lowlight extension

packages/extension-code-block-lowlight/src/code-block-lowlight.ts

@@ -0,0 +1,35 @@
+import CodeBlock from '@tiptap/extension-code-block'
+import low from 'lowlight/lib/core'
+import { LowlightPlugin } from './lowlight-plugin'
+
+export interface CodeBlockLowlightOptions {
+  languageClassPrefix: string,
+  HTMLAttributes: {
+    [key: string]: any
+  },
+  languages: {
+    [key: string]: Function
+  },
+}
+
+export const CodeBlockLowlight = CodeBlock.extend<CodeBlockLowlightOptions>({
+  name: 'codeBlockLowlight',
+
+  defaultOptions: {
+    languageClassPrefix: 'language-',
+    HTMLAttributes: {},
+    languages: {},
+  },
+
+  onBeforeCreate() {
+    Object.entries(this.options.languages).forEach(([name, mapping]) => {
+      low.registerLanguage(name, mapping)
+    })
+  },
+
+  addProseMirrorPlugins() {
+    return [
+      LowlightPlugin({ name: 'codeBlockLowlight' }),
+    ]
+  },
+})

packages/extension-code-block-lowlight/src/index.ts

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+import { CodeBlockLowlight } from './code-block-lowlight'
+
+export * from './code-block-lowlight'
+
+export default CodeBlockLowlight

packages/extension-code-block-lowlight/src/lowlight-plugin.ts

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+import { Plugin, PluginKey } from 'prosemirror-state'
+import { Decoration, DecorationSet } from 'prosemirror-view'
+import { Node as ProsemirrorNode } from 'prosemirror-model'
+import low from 'lowlight/lib/core'
+
+type NodeWithPos = {
+  node: ProsemirrorNode,
+  pos: number,
+}
+
+const findBlockNodes = (doc: ProsemirrorNode) => {
+  const nodes: NodeWithPos[] = []
+
+  doc.descendants((node, pos) => {
+    if (node.isBlock) {
+      nodes.push({
+        node,
+        pos,
+      })
+    }
+  })
+
+  return nodes
+}
+
+function getDecorations({ doc, name }: { doc: ProsemirrorNode, name: string}) {
+  const decorations: Decoration[] = []
+  const blocks = findBlockNodes(doc).filter(block => block.node.type.name === name)
+
+  function parseNodes(nodes: any[], className: string[] = []): any {
+    return nodes.map(node => {
+
+      const classes = [
+        ...className,
+        ...node.properties ? node.properties.className : [],
+      ]
+
+      if (node.children) {
+        return parseNodes(node.children, classes)
+      }
+
+      return {
+        text: node.value,
+        classes,
+      }
+    })
+  }
+
+  blocks.forEach(block => {
+    let startPos = block.pos + 1
+    const nodes = low.highlightAuto(block.node.textContent).value
+
+    parseNodes(nodes)
+      .flat()
+      .map((node: any) => {
+        const from = startPos
+        const to = from + node.text.length
+
+        startPos = to
+
+        return {
+          ...node,
+          from,
+          to,
+        }
+      })
+      .forEach((node: any) => {
+        const decoration = Decoration.inline(node.from, node.to, {
+          class: node.classes.join(' '),
+        })
+        decorations.push(decoration)
+      })
+  })
+
+  return DecorationSet.create(doc, decorations)
+}
+
+export function LowlightPlugin({ name }: { name: string }) {
+  return new Plugin({
+    key: new PluginKey('highlight'),
+
+    state: {
+      init: (_, { doc }) => getDecorations({ doc, name }),
+      apply: (transaction, decorationSet, oldState, newState) => {
+        // TODO: find way to cache decorations
+        // https://discuss.prosemirror.net/t/how-to-update-multiple-inline-decorations-on-node-change/1493
+        const oldNodeName = oldState.selection.$head.parent.type.name
+        const newNodeName = newState.selection.$head.parent.type.name
+        const oldNodes = findBlockNodes(oldState.doc)
+          .filter(node => node.node.type.name === name)
+        const newNodes = findBlockNodes(newState.doc)
+          .filter(node => node.node.type.name === name)
+
+        // Apply decorations if selection includes named node, or transaction changes named node.
+        if (transaction.docChanged && ([oldNodeName, newNodeName].includes(name)
+          || newNodes.length !== oldNodes.length)) {
+          return getDecorations({ doc: transaction.doc, name })
+        }
+
+        return decorationSet.map(transaction.mapping, transaction.doc)
+      },
+    },
+
+    props: {
+      decorations(state) {
+        return this.getState(state)
+      },
+    },
+  })
+}