mdast/index.js

/*
 * md ast - pluggable markdown parser
 */


const syntax = {
    bold: {
        paired: true,
        recursive: true,
        startRegexp: /\s\*\*\S.*/,
        endRegexp:   /\S\*\*\s/,
        content: {
            start: {
                point: 'start',
                offset: 3
            },
            end: {
                point: 'end',
                offset: 1
            }
        },
        forward: {
            point: 'endEnd', //start, startEnd, end, endEnd
            offset: -1
        }
    },
    bold2: {
        paired: true,
        recursive: true,
        startRegexp:  /__\S.*/,
        endRegexp:    /\S__\s/,
        content: {
            start: {
                point: 'start',
                offset: 3
            },
            end: {
                point: 'end',
                offset: 1
            }
        },
        forward: {
            point: 'endEnd', //start, startEnd, end, endEnd
            offset: -1
        }
    },
    italic: {
        paired: true,
        recursive: true,
        startRegexp: /\s\*\S.*/,
        endRegexp:   /\S\*\s/,
        content: {
            start: {
                point: 'start',
                offset: 2
            },
            end: {
                point: 'end',
                offset: 1
            }
        },
        forward: {
            point: 'endEnd', //start, startEnd, end, endEnd
            offset: -1
        }
    },
    italic2: {
        paired: true,
        recursive: true,
        startRegexp:  /_\S.*/,
        endRegexp:   /\S_\s/,
        content: {
            start: {
                point: 'start',
                offset: 2
            },
            end: {
                point: 'end',
                offset: 1
            }
        },
        forward: {
            point: 'endEnd', //start, startEnd, end, endEnd
            offset: -1
        }
    },
}

function findNearest(md, mdTags){
    let nearest, nearestMatch = {index: Infinity};
    for (let [mdTag, {paired, 
                        recursive, 
                        startRegexp, 
                        endRegexp, 
                        content: {start, 
                                    end}, 
                        forward}] of  Object.entries(mdTags)) {

        let match = md.match(startRegexp)
        if (match && match.index < nearestMatch.index){
            nearestMatch = match
            nearest = mdTag
        }
    }
    return [nearest, nearestMatch]
}


function buildAST(md, mdTags=syntax, tree=[], path=[]){
    console.log(findNearest(md, mdTags))
}

buildAST("I just __love__ __bold text__.	")