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// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
// See License.txt for license information.
// This package implements a parser for the subset of the CommonMark spec necessary for us to do
// server-side processing. It is not a full implementation and lacks many features. But it is
// complete enough to efficiently and accurately allow us to do what we need to like rewrite image
// URLs for proxying.
package markdown
import (
"strings"
)
func isEscapable(c rune) bool {
return c > ' ' && (c < '0' || (c > '9' && (c < 'A' || (c > 'Z' && (c < 'a' || (c > 'z' && c <= '~'))))))
}
func isEscapableByte(c byte) bool {
return isEscapable(rune(c))
}
func isWhitespace(c rune) bool {
switch c {
case ' ', '\t', '\n', '\u000b', '\u000c', '\r':
return true
default:
return false
}
}
func isWhitespaceByte(c byte) bool {
return isWhitespace(rune(c))
}
func isNumeric(c rune) bool {
return c >= '0' && c <= '9'
}
func isNumericByte(c byte) bool {
return isNumeric(rune(c))
}
func isHex(c rune) bool {
return isNumeric(c) || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')
}
func isHexByte(c byte) bool {
return isHex(rune(c))
}
func isAlphanumeric(c rune) bool {
return isNumeric(c) || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
}
func isAlphanumericByte(c byte) bool {
return isAlphanumeric(rune(c))
}
func nextNonWhitespace(markdown string, position int) int {
for offset, c := range []byte(markdown[position:]) {
if !isWhitespaceByte(c) {
return position + offset
}
}
return len(markdown)
}
func nextLine(markdown string, position int) (linePosition int, skippedNonWhitespace bool) {
for i := position; i < len(markdown); i++ {
c := markdown[i]
if c == '\r' {
if i+1 < len(markdown) && markdown[i+1] == '\n' {
return i + 2, skippedNonWhitespace
}
return i + 1, skippedNonWhitespace
} else if c == '\n' {
return i + 1, skippedNonWhitespace
} else if !isWhitespaceByte(c) {
skippedNonWhitespace = true
}
}
return len(markdown), skippedNonWhitespace
}
func countIndentation(markdown string, r Range) (spaces, bytes int) {
for i := r.Position; i < r.End; i++ {
if markdown[i] == ' ' {
spaces++
bytes++
} else if markdown[i] == '\t' {
spaces += 4
bytes++
} else {
break
}
}
return
}
func trimLeftSpace(markdown string, r Range) Range {
s := markdown[r.Position:r.End]
trimmed := strings.TrimLeftFunc(s, isWhitespace)
return Range{r.Position, r.End - (len(s) - len(trimmed))}
}
func trimRightSpace(markdown string, r Range) Range {
s := markdown[r.Position:r.End]
trimmed := strings.TrimRightFunc(s, isWhitespace)
return Range{r.Position, r.End - (len(s) - len(trimmed))}
}
func relativeToAbsolutePosition(ranges []Range, position int) int {
rem := position
for _, r := range ranges {
l := r.End - r.Position
if rem < l {
return r.Position + rem
}
rem -= l
}
if len(ranges) == 0 {
return 0
}
return ranges[len(ranges)-1].End
}
func trimBytesFromRanges(ranges []Range, bytes int) (result []Range) {
rem := bytes
for _, r := range ranges {
if rem == 0 {
result = append(result, r)
continue
}
l := r.End - r.Position
if rem < l {
result = append(result, Range{r.Position + rem, r.End})
rem = 0
continue
}
rem -= l
}
return
}
func Parse(markdown string) (*Document, []*ReferenceDefinition) {
lines := ParseLines(markdown)
return ParseBlocks(markdown, lines)
}
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