matterbridge/vendor/github.com/mattermost/mattermost-server/v5/shared/markdown/links.go

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2020-08-09 22:29:54 +00:00
// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.
package markdown
import (
"unicode/utf8"
)
func parseLinkDestination(markdown string, position int) (raw Range, next int, ok bool) {
if position >= len(markdown) {
return
}
if markdown[position] == '<' {
isEscaped := false
for offset, c := range []byte(markdown[position+1:]) {
if isEscaped {
isEscaped = false
if isEscapableByte(c) {
continue
}
}
if c == '\\' {
isEscaped = true
} else if c == '<' {
break
} else if c == '>' {
return Range{position + 1, position + 1 + offset}, position + 1 + offset + 1, true
} else if isWhitespaceByte(c) {
break
}
}
}
openCount := 0
isEscaped := false
for offset, c := range []byte(markdown[position:]) {
if isEscaped {
isEscaped = false
if isEscapableByte(c) {
continue
}
}
switch c {
case '\\':
isEscaped = true
case '(':
openCount++
case ')':
if openCount < 1 {
return Range{position, position + offset}, position + offset, true
}
openCount--
default:
if isWhitespaceByte(c) {
return Range{position, position + offset}, position + offset, true
}
}
}
return Range{position, len(markdown)}, len(markdown), true
}
func parseLinkTitle(markdown string, position int) (raw Range, next int, ok bool) {
if position >= len(markdown) {
return
}
originalPosition := position
var closer byte
switch markdown[position] {
case '"', '\'':
closer = markdown[position]
case '(':
closer = ')'
default:
return
}
position++
for position < len(markdown) {
switch markdown[position] {
case '\\':
position++
if position < len(markdown) && isEscapableByte(markdown[position]) {
position++
}
case closer:
return Range{originalPosition + 1, position}, position + 1, true
default:
position++
}
}
return
}
func parseLinkLabel(markdown string, position int) (raw Range, next int, ok bool) {
if position >= len(markdown) || markdown[position] != '[' {
return
}
originalPosition := position
position++
for position < len(markdown) {
switch markdown[position] {
case '\\':
position++
if position < len(markdown) && isEscapableByte(markdown[position]) {
position++
}
case '[':
return
case ']':
if position-originalPosition >= 1000 && utf8.RuneCountInString(markdown[originalPosition:position]) >= 1000 {
return
}
return Range{originalPosition + 1, position}, position + 1, true
default:
position++
}
}
return
}
// As a non-standard feature, we allow image links to specify dimensions of the image by adding "=WIDTHxHEIGHT"
// after the image destination but before the image title like ![alt](http://example.com/image.png =100x200 "title").
// Both width and height are optional, but at least one of them must be specified.
func parseImageDimensions(markdown string, position int) (raw Range, next int, ok bool) {
if position >= len(markdown) {
return
}
originalPosition := position
// Read =
position += 1
if position >= len(markdown) {
return
}
// Read width
hasWidth := false
for position < len(markdown)-1 && isNumericByte(markdown[position]) {
hasWidth = true
position += 1
}
// Look for early end of dimensions
if isWhitespaceByte(markdown[position]) || markdown[position] == ')' {
return Range{originalPosition, position - 1}, position, true
}
// Read the x
if (markdown[position] != 'x' && markdown[position] != 'X') || position == len(markdown)-1 {
return
}
position += 1
// Read height
hasHeight := false
for position < len(markdown)-1 && isNumericByte(markdown[position]) {
hasHeight = true
position += 1
}
// Make sure the there's no trailing characters
if !isWhitespaceByte(markdown[position]) && markdown[position] != ')' {
return
}
if !hasWidth && !hasHeight {
// At least one of width or height is required
return
}
return Range{originalPosition, position - 1}, position, true
}