1 files changed, 220 insertions, 0 deletions
diff --git a/utils/markdown/list.go b/utils/markdown/list.go
new file mode 100644
index 000000000..aea71156c
--- /dev/null
+++ b/utils/markdown/list.go
@@ -0,0 +1,220 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package markdown
+
+import (
+	"strings"
+)
+
+type ListItem struct {
+	blockBase
+	markdown                    string
+	hasTrailingBlankLine        bool
+	hasBlankLineBetweenChildren bool
+
+	Indentation int
+	Children    []Block
+}
+
+func (b *ListItem) Continuation(indentation int, r Range) *continuation {
+	s := b.markdown[r.Position:r.End]
+	if strings.TrimSpace(s) == "" {
+		if b.Children == nil {
+			return nil
+		}
+		return &continuation{
+			Remaining: r,
+		}
+	}
+	if indentation < b.Indentation {
+		return nil
+	}
+	return &continuation{
+		Indentation: indentation - b.Indentation,
+		Remaining:   r,
+	}
+}
+
+func (b *ListItem) AddChild(openBlocks []Block) []Block {
+	b.Children = append(b.Children, openBlocks[0])
+	if b.hasTrailingBlankLine {
+		b.hasBlankLineBetweenChildren = true
+	}
+	b.hasTrailingBlankLine = false
+	return openBlocks
+}
+
+func (b *ListItem) AddLine(indentation int, r Range) bool {
+	isBlank := strings.TrimSpace(b.markdown[r.Position:r.End]) == ""
+	if isBlank {
+		b.hasTrailingBlankLine = true
+	}
+	return false
+}
+
+func (b *ListItem) HasTrailingBlankLine() bool {
+	return b.hasTrailingBlankLine || (len(b.Children) > 0 && b.Children[len(b.Children)-1].HasTrailingBlankLine())
+}
+
+func (b *ListItem) isLoose() bool {
+	if b.hasBlankLineBetweenChildren {
+		return true
+	}
+	for i, child := range b.Children {
+		if i < len(b.Children)-1 && child.HasTrailingBlankLine() {
+			return true
+		}
+	}
+	return false
+}
+
+type List struct {
+	blockBase
+	markdown                    string
+	hasTrailingBlankLine        bool
+	hasBlankLineBetweenChildren bool
+
+	IsLoose           bool
+	IsOrdered         bool
+	OrderedStart      int
+	BulletOrDelimiter byte
+	Children          []*ListItem
+}
+
+func (b *List) Continuation(indentation int, r Range) *continuation {
+	s := b.markdown[r.Position:r.End]
+	if strings.TrimSpace(s) == "" {
+		return &continuation{
+			Remaining: r,
+		}
+	}
+	return &continuation{
+		Indentation: indentation,
+		Remaining:   r,
+	}
+}
+
+func (b *List) AddChild(openBlocks []Block) []Block {
+	if item, ok := openBlocks[0].(*ListItem); ok {
+		b.Children = append(b.Children, item)
+		if b.hasTrailingBlankLine {
+			b.hasBlankLineBetweenChildren = true
+		}
+		b.hasTrailingBlankLine = false
+		return openBlocks
+	} else if list, ok := openBlocks[0].(*List); ok {
+		if len(list.Children) == 1 && list.IsOrdered == b.IsOrdered && list.BulletOrDelimiter == b.BulletOrDelimiter {
+			return b.AddChild(openBlocks[1:])
+		}
+	}
+	return nil
+}
+
+func (b *List) AddLine(indentation int, r Range) bool {
+	isBlank := strings.TrimSpace(b.markdown[r.Position:r.End]) == ""
+	if isBlank {
+		b.hasTrailingBlankLine = true
+	}
+	return false
+}
+
+func (b *List) HasTrailingBlankLine() bool {
+	return b.hasTrailingBlankLine || (len(b.Children) > 0 && b.Children[len(b.Children)-1].HasTrailingBlankLine())
+}
+
+func (b *List) isLoose() bool {
+	if b.hasBlankLineBetweenChildren {
+		return true
+	}
+	for i, child := range b.Children {
+		if child.isLoose() || (i < len(b.Children)-1 && child.HasTrailingBlankLine()) {
+			return true
+		}
+	}
+	return false
+}
+
+func (b *List) Close() {
+	b.IsLoose = b.isLoose()
+}
+
+func parseListMarker(markdown string, r Range) (success, isOrdered bool, orderedStart int, bulletOrDelimiter byte, markerWidth int, remaining Range) {
+	digits := 0
+	n := 0
+	for i := r.Position; i < r.End && markdown[i] >= '0' && markdown[i] <= '9'; i++ {
+		digits++
+		n = n*10 + int(markdown[i]-'0')
+	}
+	if digits > 0 {
+		if digits > 9 || r.Position+digits >= r.End {
+			return
+		}
+		next := markdown[r.Position+digits]
+		if next != '.' && next != ')' {
+			return
+		}
+		return true, true, n, next, digits + 1, Range{r.Position + digits + 1, r.End}
+	}
+	if r.Position >= r.End {
+		return
+	}
+	next := markdown[r.Position]
+	if next != '-' && next != '+' && next != '*' {
+		return
+	}
+	return true, false, 0, next, 1, Range{r.Position + 1, r.End}
+}
+
+func listStart(markdown string, indent int, r Range, matchedBlocks, unmatchedBlocks []Block) []Block {
+	afterList := false
+	if len(matchedBlocks) > 0 {
+		_, afterList = matchedBlocks[len(matchedBlocks)-1].(*List)
+	}
+	if !afterList && indent > 3 {
+		return nil
+	}
+
+	success, isOrdered, orderedStart, bulletOrDelimiter, markerWidth, remaining := parseListMarker(markdown, r)
+	if !success {
+		return nil
+	}
+
+	isBlank := strings.TrimSpace(markdown[remaining.Position:remaining.End]) == ""
+	if len(matchedBlocks) > 0 && len(unmatchedBlocks) == 0 {
+		if _, ok := matchedBlocks[len(matchedBlocks)-1].(*Paragraph); ok {
+			if isBlank || (isOrdered && orderedStart != 1) {
+				return nil
+			}
+		}
+	}
+
+	indentAfterMarker, indentBytesAfterMarker := countIndentation(markdown, remaining)
+	if !isBlank && indentAfterMarker < 1 {
+		return nil
+	}
+
+	remaining = Range{remaining.Position + indentBytesAfterMarker, remaining.End}
+	consumedIndentAfterMarker := indentAfterMarker
+	if isBlank || indentAfterMarker >= 5 {
+		consumedIndentAfterMarker = 1
+	}
+
+	listItem := &ListItem{
+		markdown:    markdown,
+		Indentation: indent + markerWidth + consumedIndentAfterMarker,
+	}
+	list := &List{
+		markdown:          markdown,
+		IsOrdered:         isOrdered,
+		OrderedStart:      orderedStart,
+		BulletOrDelimiter: bulletOrDelimiter,
+		Children:          []*ListItem{listItem},
+	}
+	ret := []Block{list, listItem}
+	if descendants := blockStartOrParagraph(markdown, indentAfterMarker-consumedIndentAfterMarker, remaining, nil, nil); descendants != nil {
+		listItem.Children = append(listItem.Children, descendants[0])
+		ret = append(ret, descendants...)
+	}
+	return ret
+}