pro-docs/libs/codemirror/addon/fold/markdown-fold.js

// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: https://codemirror.net/LICENSE

;(function (mod) {
    if (typeof exports == 'object' && typeof module == 'object')
        // CommonJS
        mod(require('../../lib/codemirror'))
    else if (typeof define == 'function' && define.amd)
        // AMD
        define(['../../lib/codemirror'], mod)
    // Plain browser env
    else mod(CodeMirror)
})(function (CodeMirror) {
    'use strict'

    CodeMirror.registerHelper('fold', 'markdown', function (cm, start) {
        var maxDepth = 100

        function isHeader(lineNo) {
            var tokentype = cm.getTokenTypeAt(CodeMirror.Pos(lineNo, 0))
            return tokentype && /\bheader\b/.test(tokentype)
        }

        function headerLevel(lineNo, line, nextLine) {
            var match = line && line.match(/^#+/)
            if (match && isHeader(lineNo)) return match[0].length
            match = nextLine && nextLine.match(/^[=\-]+\s*$/)
            if (match && isHeader(lineNo + 1)) return nextLine[0] == '=' ? 1 : 2
            return maxDepth
        }

        var firstLine = cm.getLine(start.line),
            nextLine = cm.getLine(start.line + 1)
        var level = headerLevel(start.line, firstLine, nextLine)
        if (level === maxDepth) return undefined

        var lastLineNo = cm.lastLine()
        var end = start.line,
            nextNextLine = cm.getLine(end + 2)
        while (end < lastLineNo) {
            if (headerLevel(end + 1, nextLine, nextNextLine) <= level) break
            ++end
            nextLine = nextNextLine
            nextNextLine = cm.getLine(end + 2)
        }

        return {
            from: CodeMirror.Pos(start.line, firstLine.length),
            to: CodeMirror.Pos(end, cm.getLine(end).length),
        }
    })
})