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var _ = require('lodash');
var cheerio = require('cheerio');
var domSerializer = require('dom-serializer');
var slug = require('github-slugid');
var Promise = require('../utils/promise');
var location = require('../utils/location');
// Render a cheerio DOM as html
function renderDOM($, dom, options) {
if (!dom && $._root && $._root.children) {
dom = $._root.children;
}
options = options|| dom.options || $._options;
return domSerializer(dom, options);
}
function HTMLPipeline(htmlString, opts) {
_.bindAll(this);
this.opts = _.defaults(opts || {}, {
// Calcul new href for a relative link
onRelativeLink: _.identity,
// Output an image
onImage: _.identity,
// Syntax highlighting
onCodeBlock: _.identity,
// Output a svg, if returns null the svg is kept inlined
onOutputSVG: _.constant(null)
});
this.$ = cheerio.load(htmlString, {
// We should parse html without trying to normalize too much
xmlMode: false,
// SVG need some attributes to use uppercases
lowerCaseAttributeNames: false,
lowerCaseTags: false
});
}
// Transform a query of elements in the page
HTMLPipeline.prototype._transform = function(query, fn) {
var that = this;
var $elements = this.$(query);
return Promise.serie($elements, function(el) {
var $el = that.$(el);
return fn.call(that, $el);
});
};
// Normalize links
HTMLPipeline.prototype.transformLinks = function() {
return this._transform('a', function($a) {
var href = $a.attr('href');
if (!href) return;
if (location.isAnchor(href)) {
// Don't "change" anchor links
} else if (location.isRelative(href)) {
$a.attr('href', this.opts.onRelativeLink(href));
} else {
// External links
$a.attr('target', '_blank');
}
});
};
// Normalize images
HTMLPipeline.prototype.transformImages = function() {
return this._transform('img', function($img) {
return Promise(this.opts.onImage($img.attr('src')))
.then(function(filename) {
$img.attr('src', filename);
});
});
};
// Normalize code blocks
HTMLPipeline.prototype.transformCodeBlocks = function() {
return this._transform('code', function($code) {
// Extract language
var lang = _.chain(
($code.attr('class') || '').split(' ')
)
.map(function(cl) {
// Markdown
if (cl.search('lang-') === 0) return cl.slice('lang-'.length);
// Asciidoc
if (cl.search('language-') === 0) return cl.slice('language-'.length);
return null;
})
.compact()
.first()
.value();
var source = $code.text();
return Promise(this.opts.onCodeBlock(source, lang))
.then(function(blk) {
if (blk.html === false) {
$code.text(blk.body);
} else {
$code.html(blk.body);
}
});
});
};
// Add ID to headings
HTMLPipeline.prototype.transformHeadings = function() {
var that = this;
this.$('h1,h2,h3,h4,h5,h6').each(function() {
var $h = that.$(this);
// Already has an ID?
if ($h.attr('id')) return;
$h.attr('id', slug($h.text()));
});
};
// Outline SVG from the HML
HTMLPipeline.prototype.transformSvgs = function() {
var that = this;
return this._transform('svg', function($svg) {
var content = [
'<?xml version="1.0" encoding="UTF-8"?>',
renderDOM(that.$, $svg)
].join('\n');
return Promise(that.opts.onOutputSVG(content))
.then(function(filename) {
if (!filename) return;
$svg.replaceWith(that.$('<img>').attr('src', filename));
});
});
};
// Write content to the pipeline
HTMLPipeline.prototype.output = function() {
var that = this;
return Promise()
.then(this.transformLinks)
.then(this.transformImages)
.then(this.transformHeadings)
.then(this.transformCodeBlocks)
.then(this.transformSvgs)
.then(function() {
return renderDOM(that.$);
});
};
module.exports = HTMLPipeline;
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