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index.js
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index.js
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import { unified } from 'unified';
import rehypeParse from 'rehype-parse';
import rehypeRaw from 'rehype-raw';
import rehypeRemark from 'rehype-remark';
import rehypeSanitize from 'rehype-sanitize';
import rehypeStringify from 'rehype-stringify';
import remarkFrontmatter from 'remark-frontmatter';
import remarkParse from 'remark-parse';
import remarkRehype from 'remark-rehype';
import remarkStringify from 'remark-stringify';
import remarkGfm from 'remark-gfm';
import { toText } from 'hast-util-to-text';
import stripMarkdown from 'strip-markdown';
import { SKIP, visit } from 'unist-util-visit';
import { fromHtml } from 'hast-util-from-html';
import { toMdast } from 'hast-util-to-mdast';
function noop() {
return () => {};
}
/*
Remark plugin to fix trailing whitespace in inline nodes.
See: https://github.com/orgs/syntax-tree/discussions/60
*/
function remarkTrailingWhitespace() {
return function (tree, file) {
visit(tree, ['strong', 'emphasis'], (node, index, parent) => {
// Remove empty nodes
if (!node.children.length) {
parent.children.splice(index, 1);
return SKIP;
}
const first = node.children[0];
// Remove image nodes from within emphasis nodes
if (first.type === 'image') {
parent.children.splice(index, 1, first);
return SKIP;
}
// Remove trailing whitespace at the beginning
if (first.type === 'text') {
const start_match = first.value.match(/^(\s+)(.*)/);
if (start_match) {
const [_, start_ws, start_text] = start_match;
parent.children.splice(index, 0, {
type: 'text',
value: start_ws
});
if (start_text) {
// has non-whitespace content
first.value = start_text;
} else {
// all-whitespace content
node.children.shift();
}
// Re-visit this node
return [SKIP, index - 1];
}
}
const last = node.children[node.children.length - 1];
if (last.type === 'text') {
const end_match = last.value.match(/(.*?)(\s+)$/);
if (end_match) {
const [_, end_text, end_ws] = end_match;
parent.children.splice(index + 1, 0, {
type: 'text',
value: end_ws
});
if (end_text) {
last.value = end_text;
} else {
node.children.pop();
}
}
}
return SKIP;
});
};
}
export async function slurp(stream) {
let arr = [],
len = 0;
for await (let chunk of stream) {
arr.push(chunk);
len += chunk.length;
}
return Buffer.concat(arr, len).toString();
}
export function toDataUrl(str) {
return `data:text/html;charset=utf-8;base64,${Buffer.from(str).toString('base64')}`;
}
/*
Remark plugin to convert mdast 'html' nodes
into mdast Markdown nodes.
*/
function remarkParseHtml() {
return function (tree, file) {
visit(tree, 'html', (node, index, parent) => {
const mdast = toMdast(fromHtml(node, { fragment: true }), {
document: false
});
parent.children.splice(index, 1, ...mdast.children);
return [SKIP, index];
});
};
}
/*
An unified.js Compiler that converts MDAST to a string.
It’s inspired by `mdast-util-to-string`, but it
separates paragraphs with `\n\n` instead of the empty string.
We can make the function very simple because the structure
produced by `strip-markdown` is predictable, and only contains
nodes of type `root`, `paragraph` and `text`.
We can’t use the `remark-stringify` Compiler because it
technically produces a Markdown string, not a regular plain-text string,
and as such will escape things with backslashes as dictated by
Markdown syntax.
See: https://github.com/remarkjs/strip-markdown/issues/28
*/
function remarkToText() {
this.compiler = function visit(node) {
if (!node) return '';
if (Array.isArray(node)) return node.map(visit).join('');
if (node.value) return node.value;
if (node.children) {
return node.children
.map(visit)
.join(node.type === 'root' ? '\n\n' : '');
}
};
}
function rehypeToText() {
this.compiler = toText;
}
export function getHtmlToMdProcessor(opts = {}) {
return (
unified()
.use(rehypeParse)
.use(rehypeRemark)
.use(remarkGfm)
// Not enabled yet, as it doesn’t treat some corner cases
// See: https://github.com/danburzo/trimd/issues/5
// .use(remarkTrailingWhitespace)
.use(remarkStringify, opts)
);
}
export function getMdToMdProcessor(opts = {}, transformFn) {
return unified()
.use(remarkParse)
.use(remarkFrontmatter, ['yaml', 'toml'])
.use(remarkGfm)
.use(remarkParseHtml)
.use(transformFn ? () => transformFn(visit) : noop)
.use(remarkStringify, opts);
}
export function getMdToHtmlProcessor(opts = {}) {
return unified()
.use(remarkParse)
.use(remarkFrontmatter, ['yaml', 'toml'])
.use(remarkGfm)
.use(remarkRehype, { allowDangerousHtml: true })
.use(rehypeRaw)
.use(opts.sanitize ? rehypeSanitize : noop)
.use(rehypeStringify);
}
export function getHtmlToHtmlProcessor(opts = {}) {
return (
unified()
.use(rehypeParse)
.use(rehypeRemark)
// Not enabled yet, as it doesn’t treat some corner cases
// See: https://github.com/danburzo/trimd/issues/5
// .use(remarkTrailingWhitespace)
.use(remarkRehype)
.use(opts.sanitize ? rehypeSanitize : noop)
.use(rehypeStringify)
);
}
export function getMdToTextProcessor() {
return unified()
.use(remarkParse)
.use(remarkFrontmatter, ['yaml', 'toml'])
.use(remarkGfm)
.use(remarkParseHtml)
.use(stripMarkdown)
.use(remarkToText);
}
export function getHtmlToTextProcessor() {
return unified().use(rehypeParse).use(rehypeToText);
}