remark-frontmatter/index.js

'use strict';

var xtend = require('xtend');
var matters = require('./lib/matters');
var parse = require('./lib/parse');
var compile = require('./lib/compile');

module.exports = frontmatter;

function frontmatter(options) {
  var parser = this.Parser;
  var compiler = this.Compiler;
  var config = matters(options || ['yaml']);

  if (isRemarkParser(parser)) {
    attachParser(parser, config);
  }

  if (isRemarkCompiler(compiler)) {
    attachCompiler(compiler, config);
  }
}

function attachParser(parser, matters) {
  var proto = parser.prototype;
  var tokenizers = wrap(parse, matters);
  var names = [];
  var key;

  for (key in tokenizers) {
    names.push(key);
  }

  proto.blockMethods = names.concat(proto.blockMethods);
  proto.blockTokenizers = xtend(tokenizers, proto.blockTokenizers);
}

function attachCompiler(compiler, matters) {
  var proto = compiler.prototype;
  proto.visitors = xtend(wrap(compile, matters), proto.visitors);
}

function wrap(func, matters) {
  var result = {};
  var length = matters.length;
  var index = -1;
  var tuple;

  while (++index < length) {
    tuple = func(matters[index]);
    result[tuple[0]] = tuple[1];
  }

  return result;
}

function isRemarkParser(parser) {
  return Boolean(
    parser &&
    parser.prototype &&
    parser.prototype.blockTokenizers
  );
}

function isRemarkCompiler(compiler) {
  return Boolean(
    compiler &&
    compiler.prototype &&
    compiler.prototype.visitors
  );
}