import COMMONMARK_RULES from './commonmark-rules'
import Rules from './rules'
import { extend } from './utilities'
import RootNode from './root-node'
import Node from './node'
var reduce = Array.prototype.reduce
var leadingNewLinesRegExp = /^\n*/
var trailingNewLinesRegExp = /\n*$/
var escapes = [
[/\\/g, '\\\\'],
[/\*/g, '\\*'],
[/^-/g, '\\-'],
[/^\+ /g, '\\+ '],
[/^(=+)/g, '\\$1'],
[/^(#{1,6}) /g, '\\$1 '],
[/`/g, '\\`'],
[/^~~~/g, '\\~~~'],
[/\[/g, '\\['],
[/\]/g, '\\]'],
[/^>/g, '\\>'],
[/_/g, '\\_'],
[/^(\d+)\. /g, '$1\\. ']
]
export default function TurndownService (options) {
if (!(this instanceof TurndownService)) return new TurndownService(options)
var defaults = {
rules: COMMONMARK_RULES,
headingStyle: 'setext',
hr: '* * *',
bulletListMarker: '*',
codeBlockStyle: 'indented',
fence: '```',
emDelimiter: '_',
strongDelimiter: '**',
linkStyle: 'inlined',
linkReferenceStyle: 'full',
br: ' ',
blankReplacement: function (content, node) {
return node.isBlock ? '\n\n' : ''
},
keepReplacement: function (content, node) {
return node.isBlock ? '\n\n' + node.outerHTML + '\n\n' : node.outerHTML
},
defaultReplacement: function (content, node) {
return node.isBlock ? '\n\n' + content + '\n\n' : content
}
}
this.options = extend({}, defaults, options)
this.rules = new Rules(this.options)
}
TurndownService.prototype = {
/**
* The entry point for converting a string or DOM node to Markdown
* @public
* @param {String|HTMLElement} input The string or DOM node to convert
* @returns A Markdown representation of the input
* @type String
*/
turndown: function (input) {
if (!canConvert(input)) {
throw new TypeError(
input + ' is not a string, or an element/document/fragment node.'
)
}
if (input === '') return ''
var output = process.call(this, new RootNode(input))
return postProcess.call(this, output)
},
/**
* Add one or more plugins
* @public
* @param {Function|Array} plugin The plugin or array of plugins to add
* @returns The Turndown instance for chaining
* @type Object
*/
use: function (plugin) {
if (Array.isArray(plugin)) {
for (var i = 0; i < plugin.length; i++) this.use(plugin[i])
} else if (typeof plugin === 'function') {
plugin(this)
} else {
throw new TypeError('plugin must be a Function or an Array of Functions')
}
return this
},
/**
* Adds a rule
* @public
* @param {String} key The unique key of the rule
* @param {Object} rule The rule
* @returns The Turndown instance for chaining
* @type Object
*/
addRule: function (key, rule) {
this.rules.add(key, rule)
return this
},
/**
* Keep a node (as HTML) that matches the filter
* @public
* @param {String|Array|Function} filter The unique key of the rule
* @returns The Turndown instance for chaining
* @type Object
*/
keep: function (filter) {
this.rules.keep(filter)
return this
},
/**
* Remove a node that matches the filter
* @public
* @param {String|Array|Function} filter The unique key of the rule
* @returns The Turndown instance for chaining
* @type Object
*/
remove: function (filter) {
this.rules.remove(filter)
return this
},
/**
* Escapes Markdown syntax
* @public
* @param {String} string The string to escape
* @returns A string with Markdown syntax escaped
* @type String
*/
escape: function (string) {
return escapes.reduce(function (accumulator, escape) {
return accumulator.replace(escape[0], escape[1])
}, string)
}
}
/**
* Reduces a DOM node down to its Markdown string equivalent
* @private
* @param {HTMLElement} parentNode The node to convert
* @returns A Markdown representation of the node
* @type String
*/
function process (parentNode) {
var self = this
return reduce.call(parentNode.childNodes, function (output, node) {
node = new Node(node)
var replacement = ''
if (node.nodeType === 3) {
replacement = node.isCode ? node.nodeValue : self.escape(node.nodeValue)
} else if (node.nodeType === 1) {
replacement = replacementForNode.call(self, node)
}
return join(output, replacement)
}, '')
}
/**
* Appends strings as each rule requires and trims the output
* @private
* @param {String} output The conversion output
* @returns A trimmed version of the ouput
* @type String
*/
function postProcess (output) {
var self = this
this.rules.forEach(function (rule) {
if (typeof rule.append === 'function') {
output = join(output, rule.append(self.options))
}
})
return output.replace(/^[\t\r\n]+/, '').replace(/[\t\r\n\s]+$/, '')
}
/**
* Converts an element node to its Markdown equivalent
* @private
* @param {HTMLElement} node The node to convert
* @returns A Markdown representation of the node
* @type String
*/
function replacementForNode (node) {
var rule = this.rules.forNode(node)
var content = process.call(this, node)
var whitespace = node.flankingWhitespace
if (whitespace.leading || whitespace.trailing) content = content.trim()
return (
whitespace.leading +
rule.replacement(content, node, this.options) +
whitespace.trailing
)
}
/**
* Determines the new lines between the current output and the replacement
* @private
* @param {String} output The current conversion output
* @param {String} replacement The string to append to the output
* @returns The whitespace to separate the current output and the replacement
* @type String
*/
function separatingNewlines (output, replacement) {
var newlines = [
output.match(trailingNewLinesRegExp)[0],
replacement.match(leadingNewLinesRegExp)[0]
].sort()
var maxNewlines = newlines[newlines.length - 1]
return maxNewlines.length < 2 ? maxNewlines : '\n\n'
}
function join (string1, string2) {
var separator = separatingNewlines(string1, string2)
// Remove trailing/leading newlines and replace with separator
string1 = string1.replace(trailingNewLinesRegExp, '')
string2 = string2.replace(leadingNewLinesRegExp, '')
return string1 + separator + string2
}
/**
* Determines whether an input can be converted
* @private
* @param {String|HTMLElement} input Describe this parameter
* @returns Describe what it returns
* @type String|Object|Array|Boolean|Number
*/
function canConvert (input) {
return (
input != null && (
typeof input === 'string' ||
(input.nodeType && (
input.nodeType === 1 || input.nodeType === 9 || input.nodeType === 11
))
)
)
}
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