'use strict'
var convert = require('unist-util-is/convert')
var element = require('hast-util-is-element')
var before = require('./util/siblings').before
var first = require('./util/first')
var place = require('./util/place')
var whiteSpaceStart = require('./util/white-space-start')
var closing = require('./closing')
var omission = require('./omission')
var isComment = convert('comment')
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 || !isComment(head)
}
// Whether to omit ``.
function head(node) {
var children = node.children
var length = children.length
var seen = []
var index = -1
var child
var name
while (++index < length) {
child = children[index]
name = child.tagName
if (element(child, uniqueHeadMetadata)) {
if (seen.indexOf(name) !== -1) {
return false
}
seen.push(name)
}
}
return length !== 0
}
// Whether to omit ``.
function body(node) {
var head = first(node, true)
return (
!head ||
(!isComment(head) && !whiteSpaceStart(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 previous = before(parent, index)
var head = first(node, true)
// Previous colgroup was already omitted.
if (
element(previous, 'colgroup') &&
closing(previous, place(parent, previous), parent)
) {
return false
}
return head && element(head, 'col')
}
// Whether to omit ``.
function tbody(node, index, parent) {
var previous = before(parent, index)
var head = first(node)
// Previous table section was already omitted.
if (
element(previous, tableContainers) &&
closing(previous, place(parent, previous), parent)
) {
return false
}
return head && element(head, tableRow)
}