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;