1 files changed, 75 insertions, 0 deletions
diff --git a/utils/markdown/reference_definition.go b/utils/markdown/reference_definition.go
new file mode 100644
index 000000000..e2d0be350
--- /dev/null
+++ b/utils/markdown/reference_definition.go
@@ -0,0 +1,75 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package markdown
+
+type ReferenceDefinition struct {
+	RawDestination Range
+
+	markdown string
+	rawLabel string
+	rawTitle string
+}
+
+func (d *ReferenceDefinition) Destination() string {
+	return Unescape(d.markdown[d.RawDestination.Position:d.RawDestination.End])
+}
+
+func (d *ReferenceDefinition) Label() string {
+	return d.rawLabel
+}
+
+func (d *ReferenceDefinition) Title() string {
+	return Unescape(d.rawTitle)
+}
+
+func parseReferenceDefinition(markdown string, ranges []Range) (*ReferenceDefinition, []Range) {
+	raw := ""
+	for _, r := range ranges {
+		raw += markdown[r.Position:r.End]
+	}
+
+	label, next, ok := parseLinkLabel(raw, 0)
+	if !ok {
+		return nil, nil
+	}
+	position := next
+
+	if position >= len(raw) || raw[position] != ':' {
+		return nil, nil
+	}
+	position++
+
+	destination, next, ok := parseLinkDestination(raw, nextNonWhitespace(raw, position))
+	if !ok {
+		return nil, nil
+	}
+	position = next
+
+	absoluteDestination := relativeToAbsolutePosition(ranges, destination.Position)
+	ret := &ReferenceDefinition{
+		RawDestination: Range{absoluteDestination, absoluteDestination + destination.End - destination.Position},
+		markdown:       markdown,
+		rawLabel:       raw[label.Position:label.End],
+	}
+
+	if position < len(raw) && isWhitespaceByte(raw[position]) {
+		title, next, ok := parseLinkTitle(raw, nextNonWhitespace(raw, position))
+		if !ok {
+			if nextLine, skippedNonWhitespace := nextLine(raw, position); !skippedNonWhitespace {
+				return ret, trimBytesFromRanges(ranges, nextLine)
+			}
+			return nil, nil
+		}
+		if nextLine, skippedNonWhitespace := nextLine(raw, next); !skippedNonWhitespace {
+			ret.rawTitle = raw[title.Position:title.End]
+			return ret, trimBytesFromRanges(ranges, nextLine)
+		}
+	}
+
+	if nextLine, skippedNonWhitespace := nextLine(raw, position); !skippedNonWhitespace {
+		return ret, trimBytesFromRanges(ranges, nextLine)
+	}
+
+	return nil, nil
+}