textile-js/src/jsonml.js

A full-featured JavaScript Textile parser

/*
** JSONML helper methods - http://www.jsonml.org/
**
** This provides the `JSONML` object, which contains helper
** methods for rendering JSONML to HTML.
**
** Note that the tag ! is taken to mean comment, this is however
** not specified in the JSONML spec.
*/

const singletons = require('./html').singletons;

// drop or add tab levels to JsonML tree
function reIndent (ml, shiftBy) {
  // a bit obsessive, but there we are...
  if (!shiftBy) {
    return ml;
  }
  return ml.map(function (s) {
    if (/^\n\t+/.test(s)) {
      if (shiftBy < 0) {
        s = s.slice(0, shiftBy);
      }
      else {
        for (let i = 0; i < shiftBy; i++) {
          s += '\t';
        }
      }
    }
    else if (Array.isArray(s)) {
      return reIndent(s, shiftBy);
    }
    return s;
  });
}

function escape (text, escapeQuotes) {
  return text.replace(/&(?!(#\d{2,}|#x[\da-fA-F]{2,}|[a-zA-Z][a-zA-Z1-4]{1,6});)/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, escapeQuotes ? '&quot;' : '"')
    .replace(/'/g, escapeQuotes ? '&#39;' : "'");
}

function toHTML (jsonml) {
  jsonml = jsonml.concat();

  // basic case
  if (typeof jsonml === 'string') {
    return escape(jsonml);
  }

  const tag = jsonml.shift();
  let attributes = {};
  let tagAttrs = '';
  const content = [];

  if (jsonml.length && typeof jsonml[0] === 'object' && !Array.isArray(jsonml[0])) {
    attributes = jsonml.shift();
  }

  while (jsonml.length) {
    content.push(toHTML(jsonml.shift()));
  }

  for (const a in attributes) {
    tagAttrs += (attributes[a] == null)
      ? ` ${a}`
      : ` ${a}="${escape(String(attributes[a]), true)}"`;
  }

  // be careful about adding whitespace here for inline elements
  if (tag === '!') {
    return `<!--${content.join('')}-->`;
  }
  else if (tag in singletons || (tag.indexOf(':') > -1 && !content.length)) {
    return `<${tag}${tagAttrs} />`;
  }
  else {
    return `<${tag}${tagAttrs}>${content.join('')}</${tag}>`;
  }
}

module.exports = {
  reIndent: reIndent,
  toHTML: toHTML,
  escape: escape
};