30-seconds-of-code/node_modules/hast-util-to-html/lib/element.js

'use strict'

var xtend = require('xtend')
var svg = require('property-information/svg')
var find = require('property-information/find')
var spaces = require('space-separated-tokens').stringify
var commas = require('comma-separated-tokens').stringify
var entities = require('stringify-entities')
var ccount = require('ccount')
var all = require('./all')
var constants = require('./constants')

module.exports = element

/* Constants. */
var EMPTY = ''

/* Characters. */
var SPACE = ' '
var DQ = '"'
var SQ = "'"
var EQ = '='
var LT = '<'
var GT = '>'
var SO = '/'

/* Stringify an element `node`. */
function element(ctx, node, index, parent) {
  var parentSchema = ctx.schema
  var name = node.tagName
  var value = ''
  var selfClosing
  var close
  var omit
  var root = node
  var content
  var attrs

  if (parentSchema.space === 'html' && name === 'svg') {
    ctx.schema = svg
  }

  attrs = attributes(ctx, node.properties)

  if (ctx.schema.space === 'svg') {
    omit = false
    close = true
    selfClosing = ctx.closeEmpty
  } else {
    omit = ctx.omit
    close = ctx.close
    selfClosing = ctx.voids.indexOf(name.toLowerCase()) !== -1

    if (name === 'template') {
      root = node.content
    }
  }

  content = all(ctx, root)

  /* If the node is categorised as void, but it has
   * children, remove the categorisation.  This
   * enables for example `menuitem`s, which are
   * void in W3C HTML but not void in WHATWG HTML, to
   * be stringified properly. */
  selfClosing = content ? false : selfClosing

  if (attrs || !omit || !omit.opening(node, index, parent)) {
    value = LT + name + (attrs ? SPACE + attrs : EMPTY)

    if (selfClosing && close) {
      if (!ctx.tightClose || attrs.charAt(attrs.length - 1) === SO) {
        value += SPACE
      }

      value += SO
    }

    value += GT
  }

  value += content

  if (!selfClosing && (!omit || !omit.closing(node, index, parent))) {
    value += LT + SO + name + GT
  }

  ctx.schema = parentSchema

  return value
}

/* Stringify all attributes. */
function attributes(ctx, props) {
  var values = []
  var key
  var value
  var result
  var length
  var index
  var last

  for (key in props) {
    value = props[key]

    if (value == null) {
      continue
    }

    result = attribute(ctx, key, value)

    if (result) {
      values.push(result)
    }
  }

  length = values.length
  index = -1

  while (++index < length) {
    result = values[index]
    last = null

    if (ctx.schema.space === 'html' && ctx.tight) {
      last = result.charAt(result.length - 1)
    }

    /* In tight mode, don’t add a space after quoted attributes. */
    if (index !== length - 1 && last !== DQ && last !== SQ) {
      values[index] = result + SPACE
    }
  }

  return values.join(EMPTY)
}

/* Stringify one attribute. */
function attribute(ctx, key, value) {
  var schema = ctx.schema
  var space = schema.space
  var info = find(schema, key)
  var name = info.attribute

  if (info.overloadedBoolean && (value === name || value === '')) {
    value = true
  } else if (
    info.boolean ||
    (info.overloadedBoolean && typeof value !== 'string')
  ) {
    value = Boolean(value)
  }

  if (
    value == null ||
    value === false ||
    (typeof value === 'number' && isNaN(value))
  ) {
    return EMPTY
  }

  name = attributeName(ctx, name)

  if (value === true) {
    if (space === 'html') {
      return name
    }

    value = name
  }

  return name + attributeValue(ctx, key, value, info)
}

/* Stringify the attribute name. */
function attributeName(ctx, name) {
  // Always encode without parse errors in non-HTML.
  var valid = ctx.schema.space === 'html' ? ctx.valid : 1
  var subset = constants.name[valid][ctx.safe]

  return entities(name, xtend(ctx.entities, {subset: subset}))
}

/* Stringify the attribute value. */
function attributeValue(ctx, key, value, info) {
  var options = ctx.entities
  var quote = ctx.quote
  var alternative = ctx.alternative
  var space = ctx.schema.space
  var unquoted
  var subset

  if (typeof value === 'object' && 'length' in value) {
    /* `spaces` doesn’t accept a second argument, but it’s
     * given here just to keep the code cleaner. */
    value = (info.commaSeparated ? commas : spaces)(value, {
      padLeft: !ctx.tightLists
    })
  }

  value = String(value)

  if (space !== 'html' || value || !ctx.collapseEmpty) {
    unquoted = value

    /* Check unquoted value. */
    if (space === 'html' && ctx.unquoted) {
      subset = constants.unquoted[ctx.valid][ctx.safe]
      unquoted = entities(
        value,
        xtend(options, {subset: subset, attribute: true})
      )
    }

    /* If `value` contains entities when unquoted... */
    if (space !== 'html' || !ctx.unquoted || unquoted !== value) {
      /* If the alternative is less common than `quote`, switch. */
      if (alternative && ccount(value, quote) > ccount(value, alternative)) {
        quote = alternative
      }

      subset = quote === SQ ? constants.single : constants.double
      // Always encode without parse errors in non-HTML.
      subset = subset[space === 'html' ? ctx.valid : 1][ctx.safe]

      value = entities(value, xtend(options, {subset: subset, attribute: true}))

      value = quote + value + quote
    }

    /* Don’t add a `=` for unquoted empties. */
    value = value ? EQ + value : value
  }

  return value
}