Markdown Syntax (2)

Posted on 2024/02/10, 11:25 AM By admin22

前回に続きマークダウンの話題ですが、今回文法の拡張を実際にやって見ました。

参考）
https://zenn.dev/januswel/articles/745787422d425b01e0c1
https://github.com/januswel/unified-sample/blob/main/src/plugins/transformers/zenn-message.ts

上記コードで一応変換はできますが、複数の変換を一度にしたかったので、コードの理解も合わせてチャレンジして見ました。

zenn.ts

import unified from "unified";
import { Node, Parent } from "unist";
import parser from "remark-parse";
import toHast from "remark-rehype";
import compiler from "rehype-stringify";
import visit from "unist-util-visit";
import { VFileCompatible } from "vfile";
import { H } from "mdast-util-to-hast";
import { Paragraph } from "mdast";

import { isParent, isText, isParagraph } from "./util";
import all from "./all";

const MSG_START1 = ":::msg1\n";
const MSG_START2 = ":::msg2\n";
const MSG_END = "\n:::";

function isMessage(node: unknown): node is Paragraph {
  if (!isParagraph(node)) {
    return false;
  }
  const { children } = node;
  const firstChild = children[0];
  if (!(isText(firstChild) && firstChild.value.startsWith(MSG_START1))) {
    return false;
  }
  const lastChild = children[children.length - 1];
  if (!(isText(lastChild) && lastChild.value.endsWith(MSG_END))) {
    return false;
  }
  return true;
}
function isMessage2(node: unknown): node is Paragraph {
  if (!isParagraph(node)) {
    return false;
  }
  const { children } = node;
  const firstChild = children[0];
  if (!(isText(firstChild) && firstChild.value.startsWith(MSG_START2))) {
    return false;
  }
  const lastChild = children[children.length - 1];
  if (!(isText(lastChild) && lastChild.value.endsWith(MSG_END))) {
    return false;
  }
  return true;
}

function processFirstChild(children: Array<Node>, identifier: string) {
  const firstChild = children[0];
  const firstValue = firstChild.value as string;
  if (firstValue === identifier) {
    children.shift();
  } else {
    children[0] = {
      ...firstChild,
      value: firstValue.slice(identifier.length),
    };
  }
}

function processLastChild(children: Array<Node>, identifier: string) {
  const lastIndex = children.length - 1;
  const lastChild = children[lastIndex];
  const lastValue = lastChild.value as string;
  if (lastValue === identifier) {
    children.pop();
  } else {
    children[lastIndex] = {
      ...lastChild,
      value: lastValue.slice(0, lastValue.length - identifier.length),
    };
  }
}

function visitor(node: Paragraph, index: number, parent: Parent | undefined) {
  if (!isParent(parent)) {
    return;
  }
  const children = [...node.children];
  processFirstChild(children, MSG_START1);
  processLastChild(children, MSG_END);
  parent.children[index] = {
    type: "message",
    attr: "v1",
    children,
  };
}

function visitor2(node: Paragraph, index: number, parent: Parent | undefined) {
  if (!isParent(parent)) {
    return;
  }
  let children = [...node.children];
  processFirstChild(children, MSG_START2);
  processLastChild(children, MSG_END);
  const ch = children[0]
  const aa = {...ch, attr:'attr'}
  parent.children[index] = {
    type: "message",
    attr: "v2",
    children,
  };
}

export const attacher: unified.Plugin = () => {
  return (tree: Node, _file: VFileCompatible) => {
    visit(tree, isMessage, visitor);
  };
};
export const attacher2: unified.Plugin = () => {
  return (tree: Node, _file: VFileCompatible) => {
    visit(tree, isMessage2, visitor2);
  };
};

export function handler(h: H, node: Node) {
  if(node.attr == 'v1'){
    return {
      type: "element",
      tagName: "div",
      properties: {
        className: ["text-xl"],
      },
      children: all(h, node),
    };
  }
  else{
    return {
      type: "element",
      tagName: "div",
      properties: {
        className: ["m-10","p-4"],
      },
      children: all(h, node),
    };
  }
}

const processor = unified()
  .use(parser)
  .use(attacher)
  .use(attacher2)
  .use(toHast, {
    handlers: {
      message: handler,
    },
  })
  //.use(print)
  .use(compiler);

const str = 
`
:::msg1
Hello!
:::

abcdefg

:::msg2
one two three.
:::
`
const res = processor.processSync(str).toString()
console.log(res)

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import unified from "unified";

import { Node, Parent } from "unist";

import parser from "remark-parse";

import toHast from "remark-rehype";

import compiler from "rehype-stringify";

import visit from "unist-util-visit";

import { VFileCompatible } from "vfile";

import { H } from "mdast-util-to-hast";

import { Paragraph } from "mdast";

import { isParent, isText, isParagraph } from "./util";

import all from "./all";

const MSG_START1 = ":::msg1\n";

const MSG_START2 = ":::msg2\n";

const MSG_END = "\n:::";

function isMessage(node: unknown): node is Paragraph {

if (!isParagraph(node)) {

return false;

}

const { children } = node;

const firstChild = children[0];

if (!(isText(firstChild) && firstChild.value.startsWith(MSG_START1))) {

return false;

}

const lastChild = children[children.length - 1];

if (!(isText(lastChild) && lastChild.value.endsWith(MSG_END))) {

return false;

}

return true;

}

function isMessage2(node: unknown): node is Paragraph {

if (!isParagraph(node)) {

return false;

}

const { children } = node;

const firstChild = children[0];

if (!(isText(firstChild) && firstChild.value.startsWith(MSG_START2))) {

return false;

}

const lastChild = children[children.length - 1];

if (!(isText(lastChild) && lastChild.value.endsWith(MSG_END))) {

return false;

}

return true;

}

function processFirstChild(children: Array<Node>, identifier: string) {

const firstChild = children[0];

const firstValue = firstChild.value as string;

if (firstValue === identifier) {

children.shift();

} else {

children[0] = {

...firstChild,

value: firstValue.slice(identifier.length),

};

}

function processLastChild(children: Array<Node>, identifier: string) {

const lastIndex = children.length - 1;

const lastChild = children[lastIndex];

const lastValue = lastChild.value as string;

if (lastValue === identifier) {

children.pop();

} else {

children[lastIndex] = {

...lastChild,

value: lastValue.slice(0, lastValue.length - identifier.length),

};

}

function visitor(node: Paragraph, index: number, parent: Parent | undefined) {

if (!isParent(parent)) {

return;

}

const children = [...node.children];

processFirstChild(children, MSG_START1);

processLastChild(children, MSG_END);

parent.children[index] = {

type: "message",

attr: "v1",

children,

};

}

function visitor2(node: Paragraph, index: number, parent: Parent | undefined) {

if (!isParent(parent)) {

return;

}

let children = [...node.children];

processFirstChild(children, MSG_START2);

processLastChild(children, MSG_END);

const ch = children[0]

const aa = {...ch, attr:'attr'}

parent.children[index] = {

type: "message",

attr: "v2",

children,

};

}

export const attacher: unified.Plugin = () => {

return (tree: Node, _file: VFileCompatible) => {

visit(tree, isMessage, visitor);

};

export const attacher2: unified.Plugin = () => {

return (tree: Node, _file: VFileCompatible) => {

visit(tree, isMessage2, visitor2);

};

export function handler(h: H, node: Node) {

if(node.attr == 'v1'){

return {

type: "element",

tagName: "div",

properties: {

className: ["text-xl"],

children: all(h, node),

};

}

else{

return {

type: "element",

tagName: "div",

properties: {

className: ["m-10","p-4"],

children: all(h, node),

};

}

const processor = unified()

.use(parser)

.use(attacher)

.use(attacher2)

.use(toHast, {

handlers: {

message: handler,

})

//.use(print)

.use(compiler);

const str =

:::msg1

Hello!

:::

abcdefg

:::msg2

one two three.

:::

const res = processor.processSync(str).toString()

console.log(res)

実行結果

$ npx ts-node zenn.ts 
<div class="text-xl">Hello!</div>
<p>abcdefg</p>
<div class="m-10 p-4">one two three.</div>

$ npx ts-node zenn.ts

<div class="text-xl">Hello!</div>

<p>abcdefg</p>

<div class="m-10 p-4">one two three.</div>

:::msg1, :::msg2をそれぞれ、最近流行りの、tailwindcssに変換して見ました。
ちょっと強引なやり方になってしまいました。
もっと仕組みを理解すればスマートにできると思いますが、とりあえずこれはこれでいろいろ試せました。

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