Add support for markdown to HTML conversion (matrix). Closes #663 (#670)

This uses our own gomatrix lib with the SendHTML function which
adds HTML to formatted_body in matrix.
golang-commonmark is used to convert markdown into valid HTML.

vendor/gitlab.com/golang-commonmark/markdown/table.go

@@ -0,0 +1,229 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package markdown
+
+import (
+	"regexp"
+	"strings"
+)
+
+func getLine(s *StateBlock, line int) string {
+	pos := s.BMarks[line] + s.BlkIndent
+	max := s.EMarks[line]
+	if pos >= max {
+		return ""
+	}
+	return s.Src[pos:max]
+}
+
+func escapedSplit(s string) (result []string) {
+	pos := 0
+	escapes := 0
+	lastPos := 0
+	backTicked := false
+	lastBackTick := 0
+
+	for pos < len(s) {
+		ch := s[pos]
+		if ch == '`' {
+			if backTicked {
+				backTicked = false
+				lastBackTick = pos
+			} else if escapes%2 == 0 {
+				backTicked = true
+				lastBackTick = pos
+			}
+		} else if ch == '|' && (escapes%2 == 0) && !backTicked {
+			result = append(result, s[lastPos:pos])
+			lastPos = pos + 1
+		}
+
+		if ch == '\\' {
+			escapes++
+		} else {
+			escapes = 0
+		}
+
+		pos++
+
+		if pos == len(s) && backTicked {
+			backTicked = false
+			pos = lastBackTick + 1
+		}
+	}
+
+	return append(result, s[lastPos:])
+}
+
+var rColumn = regexp.MustCompile("^:?-+:?$")
+
+func ruleTable(s *StateBlock, startLine, endLine int, silent bool) bool {
+	if !s.Md.Tables {
+		return false
+	}
+
+	if startLine+2 > endLine {
+		return false
+	}
+
+	nextLine := startLine + 1
+
+	if s.SCount[nextLine] < s.BlkIndent {
+		return false
+	}
+
+	if s.SCount[nextLine]-s.BlkIndent >= 4 {
+		return false
+	}
+
+	pos := s.BMarks[nextLine] + s.TShift[nextLine]
+	if pos >= s.EMarks[nextLine] {
+		return false
+	}
+
+	src := s.Src
+	ch := src[pos]
+	pos++
+
+	if ch != '|' && ch != '-' && ch != ':' {
+		return false
+	}
+
+	for pos < s.EMarks[nextLine] {
+		ch = src[pos]
+		if ch != '|' && ch != '-' && ch != ':' && !byteIsSpace(ch) {
+			return false
+		}
+		pos++
+	}
+
+	//
+
+	lineText := getLine(s, startLine+1)
+
+	columns := strings.Split(lineText, "|")
+	var aligns []Align
+	for i := 0; i < len(columns); i++ {
+		t := strings.TrimSpace(columns[i])
+		if t == "" {
+			if i == 0 || i == len(columns)-1 {
+				continue
+			}
+			return false
+		}
+
+		if !rColumn.MatchString(t) {
+			return false
+		}
+
+		if t[len(t)-1] == ':' {
+			if t[0] == ':' {
+				aligns = append(aligns, AlignCenter)
+			} else {
+				aligns = append(aligns, AlignRight)
+			}
+		} else if t[0] == ':' {
+			aligns = append(aligns, AlignLeft)
+		} else {
+			aligns = append(aligns, AlignNone)
+		}
+	}
+
+	lineText = strings.TrimSpace(getLine(s, startLine))
+	if strings.IndexByte(lineText, '|') == -1 {
+		return false
+	}
+	if s.SCount[startLine]-s.BlkIndent >= 4 {
+		return false
+	}
+	columns = escapedSplit(strings.TrimSuffix(strings.TrimPrefix(lineText, "|"), "|"))
+	columnCount := len(columns)
+	if columnCount > len(aligns) {
+		return false
+	}
+
+	if silent {
+		return true
+	}
+
+	tableTok := &TableOpen{
+		Map: [2]int{startLine, 0},
+	}
+	s.PushOpeningToken(tableTok)
+	s.PushOpeningToken(&TheadOpen{
+		Map: [2]int{startLine, startLine + 1},
+	})
+	s.PushOpeningToken(&TrOpen{
+		Map: [2]int{startLine, startLine + 1},
+	})
+
+	for i := 0; i < len(columns); i++ {
+		s.PushOpeningToken(&ThOpen{
+			Align: aligns[i],
+			Map:   [2]int{startLine, startLine + 1},
+		})
+		s.PushToken(&Inline{
+			Content: strings.TrimSpace(columns[i]),
+			Map:     [2]int{startLine, startLine + 1},
+		})
+		s.PushClosingToken(&ThClose{})
+	}
+
+	s.PushClosingToken(&TrClose{})
+	s.PushClosingToken(&TheadClose{})
+
+	tbodyTok := &TbodyOpen{
+		Map: [2]int{startLine + 2, 0},
+	}
+	s.PushOpeningToken(tbodyTok)
+
+	for nextLine = startLine + 2; nextLine < endLine; nextLine++ {
+		if s.SCount[nextLine] < s.BlkIndent {
+			break
+		}
+
+		lineText = strings.TrimSpace(getLine(s, nextLine))
+		if strings.IndexByte(lineText, '|') == -1 {
+			break
+		}
+		if s.SCount[nextLine]-s.BlkIndent >= 4 {
+			break
+		}
+		columns = escapedSplit(strings.TrimPrefix(strings.TrimSuffix(lineText, "|"), "|"))
+
+		if len(columns) < len(aligns) {
+			columns = append(columns, make([]string, len(aligns)-len(columns))...)
+		} else if len(columns) > len(aligns) {
+			columns = columns[:len(aligns)]
+		}
+
+		s.PushOpeningToken(&TrOpen{})
+		for i := 0; i < columnCount; i++ {
+			tdOpen := TdOpen{}
+			if i < len(aligns) {
+				tdOpen.Align = aligns[i]
+			}
+			s.PushOpeningToken(&tdOpen)
+
+			inline := Inline{}
+			if i < len(columns) {
+				inline.Content = strings.TrimSpace(columns[i])
+			}
+			s.PushToken(&inline)
+
+			s.PushClosingToken(&TdClose{})
+		}
+		s.PushClosingToken(&TrClose{})
+	}
+
+	s.PushClosingToken(&TbodyClose{})
+	s.PushClosingToken(&TableClose{})
+
+	tableTok.Map[1] = nextLine
+	tbodyTok.Map[1] = nextLine
+	s.Line = nextLine
+
+	return true
+}