commonmark/lib/render/renderer.js

a strongly specified, highly compatible variant of Markdown

"use strict";

function Renderer() {}

/**
 *  Walks the AST and calls member methods for each Node type.
 *
 *  @param ast {Node} The root of the abstract syntax tree.
 */
function render(ast) {
  var walker = ast.walker()
    , event
    , type;

  this.buffer = '';
  this.lastOut = '\n';

  while((event = walker.next())) {
    type = event.node.type;
    if (this[type]) {
      this[type](event.node, event.entering);
    }
  }
  return this.buffer;
}

/**
 *  Concatenate a literal string to the buffer.
 *
 *  @param str {String} The string to concatenate.
 */
function lit(str) {
  this.buffer += str;
  this.lastOut = str;
}

/**
 *  Output a newline to the buffer.
 */
function cr() {
  if (this.lastOut !== '\n') {
    this.lit('\n');
  }
}

/**
 *  Concatenate a string to the buffer possibly escaping the content.
 *
 *  Concrete renderer implementations should override this method.
 *
 *  @param str {String} The string to concatenate.
 */
function out(str) {
  this.lit(str);
}

/**
 *  Escape a string for the target renderer.
 *
 *  Abstract function that should be implemented by concrete 
 *  renderer implementations.
 *
 *  @param str {String} The string to escape.
 */
function esc(str) {
  return str;
}

Renderer.prototype.render = render;
Renderer.prototype.out = out;
Renderer.prototype.lit = lit;
Renderer.prototype.cr  = cr;
Renderer.prototype.esc  = esc;

module.exports = Renderer;