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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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