render_tree.js

if (typeof define !== 'function') { var define = require('amdefine')(module); }

define(['./core', './markdown_helpers'], function(Markdown, MarkdownHelpers) {

  var extract_attr = MarkdownHelpers.extract_attr;

  /**
   *  renderJsonML( jsonml[, options] ) -> String
   *  - jsonml (Array): JsonML array to render to XML
   *  - options (Object): options
   *
   *  Converts the given JsonML into well-formed XML.
   *
   *  The options currently understood are:
   *
   *  - root (Boolean): wether or not the root node should be included in the
   *    output, or just its children. The default `false` is to not include the
   *    root itself.
   */
  Markdown.renderJsonML = function( jsonml, options ) {
    options = options || {};
    // include the root element in the rendered output?
    options.root = options.root || false;

    jsonml = JSON.parse(JSON.stringify(jsonml)); // Clone to prevent mutation of original reference.
    var content = [];

    if ( options.root ) {
      content.push( render_tree( jsonml ) );
    }
    else {
      jsonml.shift(); // get rid of the tag
      if ( jsonml.length && typeof jsonml[ 0 ] === "object" && !( jsonml[ 0 ] instanceof Array ) )
        jsonml.shift(); // get rid of the attributes

      while ( jsonml.length )
        content.push( render_tree( jsonml.shift() ) );
    }

    return content.join( "\n\n" );
  };


  /**
   *  toHTMLTree( markdown, [dialect] ) -> JsonML
   *  toHTMLTree( md_tree ) -> JsonML
   *  - markdown (String): markdown string to parse
   *  - dialect (String | Dialect): the dialect to use, defaults to gruber
   *  - md_tree (Markdown.JsonML): parsed markdown tree
   *
   *  Turn markdown into HTML, represented as a JsonML tree. If a string is given
   *  to this function, it is first parsed into a markdown tree by calling
   *  [[parse]].
   **/
  Markdown.toHTMLTree = function toHTMLTree( input, dialect , options ) {

    // convert string input to an MD tree
    if ( typeof input === "string" )
      input = this.parse( input, dialect );

    // Now convert the MD tree to an HTML tree

    // remove references from the tree
    var attrs = extract_attr( input ),
        refs = {};

    if ( attrs && attrs.references )
      refs = attrs.references;

    var html = convert_tree_to_html( input, refs , options );
    merge_text_nodes( html );
    return html;
  };

  /**
   *  toHTML( markdown, [dialect]  ) -> String
   *  toHTML( md_tree ) -> String
   *  - markdown (String): markdown string to parse
   *  - md_tree (Markdown.JsonML): parsed markdown tree
   *
   *  Take markdown (either as a string or as a JsonML tree) and run it through
   *  [[toHTMLTree]] then turn it into a well-formated HTML fragment.
   **/
  Markdown.toHTML = function toHTML( source , dialect , options ) {
    var input = this.toHTMLTree( source , dialect , options );

    return this.renderJsonML( input );
  };


  function escapeHTML( text ) {
    if (text && text.length > 0) {
      return text.replace( /&/g, "&" )
                 .replace( /</g, "&lt;" )
                 .replace( />/g, "&gt;" )
                 .replace( /"/g, "&quot;" )
                 .replace( /'/g, "&#39;" );
    } else {
      return "";
    }
  }

  function render_tree( jsonml ) {
    // basic case
    if ( typeof jsonml === "string" )
      return escapeHTML( jsonml );

    var tag = jsonml.shift(),
        attributes = {},
        content = [];

    if ( jsonml.length && typeof jsonml[ 0 ] === "object" && !( jsonml[ 0 ] instanceof Array ) )
      attributes = jsonml.shift();

    while ( jsonml.length )
      content.push( render_tree( jsonml.shift() ) );

    var tag_attrs = "";
    if (typeof attributes.src !== 'undefined') {
      tag_attrs += ' src="' + escapeHTML( attributes.src ) + '"';
      delete attributes.src;
    }

    for ( var a in attributes ) {
      var escaped = escapeHTML( attributes[ a ]);
      if (escaped && escaped.length) {
        tag_attrs += " " + a + '="' + escaped + '"';
      }
    }

    // be careful about adding whitespace here for inline elements
    if ( tag === "img" || tag === "br" || tag === "hr" )
      return "<"+ tag + tag_attrs + "/>";
    else
      return "<"+ tag + tag_attrs + ">" + content.join( "" ) + "</" + tag + ">";
  }

  function convert_tree_to_html( tree, references, options ) {
    var i;
    options = options || {};

    // shallow clone
    var jsonml = tree.slice( 0 );

    if ( typeof options.preprocessTreeNode === "function" )
      jsonml = options.preprocessTreeNode(jsonml, references);

    // Clone attributes if they exist
    var attrs = extract_attr( jsonml );
    if ( attrs ) {
      jsonml[ 1 ] = {};
      for ( i in attrs ) {
        jsonml[ 1 ][ i ] = attrs[ i ];
      }
      attrs = jsonml[ 1 ];
    }

    // basic case
    if ( typeof jsonml === "string" )
      return jsonml;

    // convert this node
    switch ( jsonml[ 0 ] ) {
    case "header":
      jsonml[ 0 ] = "h" + jsonml[ 1 ].level;
      delete jsonml[ 1 ].level;
      break;
    case "bulletlist":
      jsonml[ 0 ] = "ul";
      break;
    case "numberlist":
      jsonml[ 0 ] = "ol";
      break;
    case "listitem":
      jsonml[ 0 ] = "li";
      break;
    case "para":
      jsonml[ 0 ] = "p";
      break;
    case "markdown":
      jsonml[ 0 ] = "html";
      if ( attrs )
        delete attrs.references;
      break;
    case "code_block":
      jsonml[ 0 ] = "pre";
      i = attrs ? 2 : 1;
      var code = [ "code" ];
      code.push.apply( code, jsonml.splice( i, jsonml.length - i ) );
      jsonml[ i ] = code;
      break;
    case "inlinecode":
      jsonml[ 0 ] = "code";
      break;
    case "img":
      jsonml[ 1 ].src = jsonml[ 1 ].href;
      delete jsonml[ 1 ].href;
      break;
    case "linebreak":
      jsonml[ 0 ] = "br";
      break;
    case "link":
      jsonml[ 0 ] = "a";
      break;
    case "link_ref":
      jsonml[ 0 ] = "a";

      // grab this ref and clean up the attribute node
      var ref = references[ attrs.ref ];

      // if the reference exists, make the link
      if ( ref ) {
        delete attrs.ref;

        // add in the href and title, if present
        attrs.href = ref.href;
        if ( ref.title )
          attrs.title = ref.title;

        // get rid of the unneeded original text
        delete attrs.original;
      }
      // the reference doesn't exist, so revert to plain text
      else {
        return attrs.original;
      }
      break;
    case "img_ref":
      jsonml[ 0 ] = "img";

      // grab this ref and clean up the attribute node
      var ref = references[ attrs.ref ];

      // if the reference exists, make the link
      if ( ref ) {
        delete attrs.ref;

        // add in the href and title, if present
        attrs.src = ref.href;
        if ( ref.title )
          attrs.title = ref.title;

        // get rid of the unneeded original text
        delete attrs.original;
      }
      // the reference doesn't exist, so revert to plain text
      else {
        return attrs.original;
      }
      break;
    }

    // convert all the children
    i = 1;

    // deal with the attribute node, if it exists
    if ( attrs ) {
      // if there are keys, skip over it
      for ( var key in jsonml[ 1 ] ) {
        i = 2;
        break;
      }
      // if there aren't, remove it
      if ( i === 1 )
        jsonml.splice( i, 1 );
    }

    for ( ; i < jsonml.length; ++i ) {
      jsonml[ i ] = convert_tree_to_html( jsonml[ i ], references, options );
    }

    return jsonml;
  }


  // merges adjacent text nodes into a single node
  function merge_text_nodes( jsonml ) {
    // skip the tag name and attribute hash
    var i = extract_attr( jsonml ) ? 2 : 1;

    while ( i < jsonml.length ) {
      // if it's a string check the next item too
      if ( typeof jsonml[ i ] === "string" ) {
        if ( i + 1 < jsonml.length && typeof jsonml[ i + 1 ] === "string" ) {
          // merge the second string into the first and remove it
          jsonml[ i ] += jsonml.splice( i + 1, 1 )[ 0 ];
        }
        else {
          ++i;
        }
      }
      // if it's not a string recurse
      else {
        merge_text_nodes( jsonml[ i ] );
        ++i;
      }
    }
  }

  return Markdown;
});