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writing a remark 13 variable plugin
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// reference plugin: | |
// https://github.com/remarkjs/remark-gfm/blob/main/index.js | |
// which wraps: | |
// https://github.com/micromark/micromark-extension-gfm-strikethrough/blob/56aef3a974c1b9baee72279e93f9c1fe7205a9af/index.js#L23 | |
const remark = require('remark'); | |
const Compiler = (tree) => { | |
return tree; | |
}; | |
function identityCompiler() { | |
this.Compiler = Compiler; | |
} | |
function plugin() { | |
const data = this.data(); | |
add('micromarkExtensions', create()); | |
// add('fromMarkdownExtensions', fromMarkdown) | |
function add(field, value) { | |
if (data[field]) data[field].push(value) | |
else data[field] = [value] | |
} | |
function create() { | |
const openTokenizer = { | |
tokenize: openTokenize, | |
// resolveAll: resolveAllStrikethrough | |
} | |
return { | |
text: { | |
123: openTokenizer, | |
125: openTokenizer, | |
} | |
}; | |
const remark = require('remark'); | |
const visit = require('unist-util-visit'); | |
const Compiler = (tree) => { | |
return tree; | |
}; | |
function identityCompiler() { | |
this.Compiler = Compiler; | |
} | |
function fromMarkdown() { | |
function enterExtension(token) { | |
this.enter({type: 'placeholder', children: [], value: token.text}, token); | |
} | |
function exitExtension(token) { | |
this.exit(token); | |
} | |
return { | |
transforms: [], | |
canContainEols: [], | |
enter: { | |
placeholder: enterExtension, | |
}, | |
exit: { | |
placeholder: exitExtension, | |
} | |
}; | |
} | |
function plugin(options) { | |
const { mapping } = options; | |
return function() { | |
const data = this.data(); | |
add('micromarkExtensions', create()); | |
add('fromMarkdownExtensions', fromMarkdown()); | |
function add(field, value) { | |
if (data[field]) data[field].push(value) | |
else data[field] = [value] | |
} | |
function create() { | |
const tokenizer = { | |
tokenize: tokenize, | |
}; | |
return { | |
text: { | |
123: tokenizer, | |
}, | |
}; | |
} | |
const OPEN_BRACE = 123; | |
const CLOSE_BRACE = 125; | |
function tokenize(effects, ok, notok) { | |
let walkingState = 'starting'; // 'starting' | 'consuming' | 'ending' | |
let openBraceCount = 0; | |
let closeBraceCount = 0; | |
let consumed = ''; | |
function start(charCode) { | |
effects.enter('placeholder'); | |
return walk(charCode); | |
} | |
function walk(charCode) { | |
if (walkingState === 'starting') { | |
if (charCode === OPEN_BRACE) { | |
openBraceCount++; | |
if (openBraceCount === 2) { | |
walkingState = 'consuming'; | |
} | |
effects.consume(charCode); | |
return walk; | |
} else { | |
return notok(charCode); | |
} | |
} else if (walkingState === 'consuming') { | |
const char = String.fromCharCode(charCode); | |
if (char.match(/[a-zA-Z0-9_-]/)) { | |
consumed += char; | |
effects.consume(charCode); | |
return walk; | |
} else if (charCode === CLOSE_BRACE) { | |
walkingState = 'ending'; | |
closeBraceCount++; | |
effects.consume(charCode); | |
return walk; | |
} else { | |
return notok(charCode); | |
} | |
} else if (walkingState === 'ending') { | |
if (charCode === CLOSE_BRACE) { | |
closeBraceCount++; | |
if (closeBraceCount === 2) { | |
// celebrate | |
effects.consume(charCode); | |
const token = effects.exit('placeholder'); | |
token.text = consumed; | |
return ok(charCode); | |
} | |
effects.consume(charCode); | |
return walk; | |
} else { | |
return notok(charCode); | |
} | |
} | |
} | |
return start; | |
} | |
return function transform(tree) { | |
visit( | |
tree, | |
'placeholder', | |
(node) => { | |
const variableName = node.value; | |
node.type = 'text'; | |
delete node.children; | |
if (mapping.hasOwnProperty(variableName)) { | |
// mapping exists 🚀 | |
node.value = mapping[variableName]; | |
} else { | |
// bad 👎 | |
node.value = `{variable "${variableName}" undefined}` | |
} | |
} | |
) | |
return tree; | |
} | |
} | |
} | |
result = remark() | |
.use(identityCompiler) | |
.use(plugin({ mapping: { cat: 'Erwin' } })) | |
.process( | |
'check out this {{dog}}!!', | |
(err, file) => { | |
if (err) { | |
console.error(err); | |
} else { | |
console.log(file.result.children[0]); | |
} | |
} | |
); |
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