markdown-it/lib/parser_block.mjs

/** internal
 * class ParserBlock
 *
 * Block-level tokenizer.
 **/

import Ruler from './ruler.mjs'
import StateBlock from './rules_block/state_block.mjs'

import r_table from './rules_block/table.mjs'
import r_code from './rules_block/code.mjs'
import r_fence from './rules_block/fence.mjs'
import r_blockquote from './rules_block/blockquote.mjs'
import r_hr from './rules_block/hr.mjs'
import r_list from './rules_block/list.mjs'
import r_reference from './rules_block/reference.mjs'
import r_html_block from './rules_block/html_block.mjs'
import r_heading from './rules_block/heading.mjs'
import r_lheading from './rules_block/lheading.mjs'
import r_paragraph from './rules_block/paragraph.mjs'

const _rules = [
  // First 2 params - rule name & source. Secondary array - list of rules,
  // which can be terminated by this one.
  ['table',      r_table,      ['paragraph', 'reference']],
  ['code',       r_code],
  ['fence',      r_fence,      ['paragraph', 'reference', 'blockquote', 'list']],
  ['blockquote', r_blockquote, ['paragraph', 'reference', 'blockquote', 'list']],
  ['hr',         r_hr,         ['paragraph', 'reference', 'blockquote', 'list']],
  ['list',       r_list,       ['paragraph', 'reference', 'blockquote']],
  ['reference',  r_reference],
  ['html_block', r_html_block, ['paragraph', 'reference', 'blockquote']],
  ['heading',    r_heading,    ['paragraph', 'reference', 'blockquote']],
  ['lheading',   r_lheading],
  ['paragraph',  r_paragraph]
]

/**
 * new ParserBlock()
 **/
function ParserBlock () {
  /**
   * ParserBlock#ruler -> Ruler
   *
   * [[Ruler]] instance. Keep configuration of block rules.
   **/
  this.ruler = new Ruler()

  for (let i = 0; i < _rules.length; i++) {
    this.ruler.push(_rules[i][0], _rules[i][1], { alt: (_rules[i][2] || []).slice() })
  }
}

// Generate tokens for input range
//
ParserBlock.prototype.tokenize = function (state, startLine, endLine) {
  const rules = this.ruler.getRules('')
  const len = rules.length
  const maxNesting = state.md.options.maxNesting
  let line = startLine
  let hasEmptyLines = false

  while (line < endLine) {
    state.line = line = state.skipEmptyLines(line)
    if (line >= endLine) { break }

    // Termination condition for nested calls.
    // Nested calls currently used for blockquotes & lists
    if (state.sCount[line] < state.blkIndent) { break }

    // If nesting level exceeded - skip tail to the end. That's not ordinary
    // situation and we should not care about content.
    if (state.level >= maxNesting) {
      state.line = endLine
      break
    }

    // Try all possible rules.
    // On success, rule should:
    //
    // - update `state.line`
    // - update `state.tokens`
    // - return true
    const prevLine = state.line
    let ok = false

    for (let i = 0; i < len; i++) {
      ok = rules[i](state, line, endLine, false)
      if (ok) {
        if (prevLine >= state.line) {
          throw new Error("block rule didn't increment state.line")
        }
        break
      }
    }

    // this can only happen if user disables paragraph rule
    if (!ok) throw new Error('none of the block rules matched')

    // set state.tight if we had an empty line before current tag
    // i.e. latest empty line should not count
    state.tight = !hasEmptyLines

    // paragraph might "eat" one newline after it in nested lists
    if (state.isEmpty(state.line - 1)) {
      hasEmptyLines = true
    }

    line = state.line

    if (line < endLine && state.isEmpty(line)) {
      hasEmptyLines = true
      line++
      state.line = line
    }
  }
}

/**
 * ParserBlock.parse(str, md, env, outTokens)
 *
 * Process input string and push block tokens into `outTokens`
 **/
ParserBlock.prototype.parse = function (src, md, env, outTokens) {
  if (!src) { return }

  const state = new this.State(src, md, env, outTokens)

  this.tokenize(state, state.line, state.lineMax)
}

ParserBlock.prototype.State = StateBlock

export default ParserBlock