'use strict'
var is = require('unist-util-is')
var element = require('hast-util-is-element')
var before = require('./util/siblings').before
var first = require('./util/first')
var place = require('./util/place')
var whiteSpaceLeft = require('./util/white-space-left')
var closing = require('./closing')
var omission = require('./omission')
var own = {}.hasOwnProperty
var uniqueHeadMetadata = ['title', 'base']
var meta = ['meta', 'link', 'script', 'style', 'template']
var tableContainers = ['thead', 'tbody']
var tableRow = 'tr'
module.exports = omission({
html: html,
head: head,
body: body,
colgroup: colgroup,
tbody: tbody
})
/* Whether to omit ``. */
function html(node) {
var head = first(node)
return !head || !is('comment', head)
}
/* Whether to omit ``. */
function head(node) {
var children = node.children
var length = children.length
var map = {}
var index = -1
var child
var name
while (++index < length) {
child = children[index]
name = child.tagName
if (element(child, uniqueHeadMetadata)) {
if (own.call(map, name)) {
return false
}
map[name] = true
}
}
return Boolean(length)
}
/* Whether to omit ``. */
function body(node) {
var head = first(node, true)
return (
!head ||
(!is('comment', head) && !whiteSpaceLeft(head) && !element(head, meta))
)
}
/* Whether to omit ``.
* The spec describes some logic for the opening tag,
* but it’s easier to implement in the closing tag, to
* the same effect, so we handle it there instead. */
function colgroup(node, index, parent) {
var prev = before(parent, index)
var head = first(node, true)
/* Previous colgroup was already omitted. */
if (element(prev, 'colgroup') && closing(prev, place(parent, prev), parent)) {
return false
}
return head && element(head, 'col')
}
/* Whether to omit ``. */
function tbody(node, index, parent) {
var prev = before(parent, index)
var head = first(node)
/* Previous table section was already omitted. */
if (
element(prev, tableContainers) &&
closing(prev, place(parent, prev), parent)
) {
return false
}
return head && element(head, tableRow)
}