course-renderer/src/markdown/rules/fence.ts

Manages CA School Courses file system storage and HTML conversion

// Based from markdown-it fence rule 

// fences (``` lang, ~~~ lang)

import Reader from '../reader'
import Token from '../Token'
import { HandlerOptionInterface } from '../handlers'

const TICK_MARKER = 0x60 /* ` */
const TILDE_MARKER = 0x7E /* ~ */

export function fence(reader: Reader, tokens: Token[], silent: boolean, options: HandlerOptionInterface): boolean {
    const currentLine = reader.currentLine
    
    let pos, initialPos
    
    pos = initialPos = reader.getCurrentLineStartPos()
    const marker = reader.getCharCode(pos)

    if (marker !== TICK_MARKER && marker !== TILDE_MARKER) return false
    
    let mem = pos

    pos = reader.skipChars(pos, marker)

    const len = pos - mem

    if ( len < 3 ) return false

    // Get the current line string

    const fenceLine = reader.getLine(reader.currentLine)

    const markup = fenceLine.slice(0, len)
    const params = fenceLine.slice(len)

    if (params.indexOf(String.fromCharCode(marker)) >= 0) return false

    // Since start is found, we can report success here for silent mode
    if (silent) return true

    let hasEndMarker = false

    for(;;) {
        reader.currentLine++
        reader.skipEmptyLines()

        if (reader.currentLine >= reader.maxLine) break

        pos = mem = reader.skipEmptyChars()
        let max = reader.getCurrentLineEndPos()

        if (reader.getCharCode(pos) !== marker) continue
        
        pos = reader.skipChars(pos, marker)

        if (pos - mem < len) continue

        pos = reader.skipEmptyChars(pos)

        if (pos < max) continue

        hasEndMarker = true
        
        break
    }
  
    let token: Token

    if (options.sectionMode && options.replMode) {
        const sectionTokChildren = tokens[tokens.length -1].children
        const replTok = sectionTokChildren[sectionTokChildren.length - 1];

        token = replTok.children[replTok.children.length - 1]

    } else if (options.sectionMode || options.replMode) {
        const lastToken = tokens[tokens.length - 1]
        token = lastToken.children[lastToken.children.length - 1]
    } else {
        token = tokens[tokens.length -1]
    }

    token.addCode(reader.getLines(currentLine + 1, reader.currentLine - (hasEndMarker ? 1 : 0)));

    token.addParam(params.trim());

    if (token.getCodes().length > 1) {
        // Let's check if the number of code we have is less or equal to the the number of files.

        if (token.getCodes().length > token.getFiles().length) {
            throw new Error(`Found more fence block than the number files mentioned on the annotation near ${currentLine} ${JSON.stringify(token, null, 4)}`);
        }
    }

    return true
}