Add brace highlighting

Use the 'matchbrace' option which is off by default.

Ref #853

cmd/micro/buffer.go

@@ -630,3 +630,58 @@ func (b *Buffer) clearCursors() {
 	b.UpdateCursors()
 	b.Cursor.ResetSelection()
 }
+
+var bracePairs = [][2]rune{
+	[2]rune{'(', ')'},
+	[2]rune{'{', '}'},
+	[2]rune{'[', ']'},
+}
+
+// FindMatchingBrace returns the location in the buffer of the matching bracket
+// It is given a brace type containing the open and closing character, (for example
+// '{' and '}') as well as the location to match from
+func (b *Buffer) FindMatchingBrace(braceType [2]rune, start Loc) Loc {
+	curLine := []rune(string(b.lines[start.Y].data))
+	startChar := curLine[start.X]
+	var i int
+	if startChar == braceType[0] {
+		for y := start.Y; y < b.NumLines; y++ {
+			l := []rune(string(b.lines[y].data))
+			xInit := 0
+			if y == start.Y {
+				xInit = start.X
+			}
+			for x := xInit; x < len(l); x++ {
+				r := l[x]
+				if r == braceType[0] {
+					i++
+				} else if r == braceType[1] {
+					i--
+					if i == 0 {
+						return Loc{x, y}
+					}
+				}
+			}
+		}
+	} else if startChar == braceType[1] {
+		for y := start.Y; y >= 0; y-- {
+			l := []rune(string(b.lines[y].data))
+			xInit := len(l) - 1
+			if y == start.Y {
+				xInit = start.X
+			}
+			for x := xInit; x >= 0; x-- {
+				r := l[x]
+				if r == braceType[0] {
+					i--
+					if i == 0 {
+						return Loc{x, y}
+					}
+				} else if r == braceType[1] {
+					i++
+				}
+			}
+		}
+	}
+	return start
+}

cmd/micro/cellview.go

@@ -69,6 +69,17 @@ func (c *CellView) Draw(buf *Buffer, top, height, left, width int) {
 		return
 	}
 
+	matchingBrace := Loc{-1, -1}
+	// bracePairs is defined in buffer.go
+	if buf.Settings["matchbrace"].(bool) {
+		for _, bp := range bracePairs {
+			r := buf.Cursor.RuneUnder(buf.Cursor.X)
+			if r == bp[0] || r == bp[1] {
+				matchingBrace = buf.FindMatchingBrace(bp, buf.Cursor.Loc)
+			}
+		}
+	}
+
 	tabsize := int(buf.Settings["tabsize"].(float64))
 	softwrap := buf.Settings["softwrap"].(bool)
 	indentrunes := []rune(buf.Settings["indentchar"].(string))
@@ -137,7 +148,12 @@ func (c *CellView) Draw(buf *Buffer, top, height, left, width int) {
 			char := line[colN]
 
 			if viewCol >= 0 {
-				c.lines[viewLine][viewCol] = &Char{Loc{viewCol, viewLine}, Loc{colN, lineN}, char, char, curStyle, 1}
+				st := curStyle
+				if colN == matchingBrace.X && lineN == matchingBrace.Y {
+					messenger.Message(matchingBrace)
+					st = curStyle.Reverse(true)
+				}
+				c.lines[viewLine][viewCol] = &Char{Loc{viewCol, viewLine}, Loc{colN, lineN}, char, char, st, 1}
 			}
 			if char == '\t' {
 				charWidth := tabsize - (viewCol+left)%tabsize

cmd/micro/settings.go

@@ -214,6 +214,7 @@ func DefaultGlobalSettings() map[string]interface{} {
 		"infobar":        true,
 		"keepautoindent": false,
 		"keymenu":        false,
+		"matchbrace":     false,
 		"mouse":          true,
 		"pluginchannels": []string{"https://raw.githubusercontent.com/micro-editor/plugin-channel/master/channel.json"},
 		"pluginrepos":    []string{},
@@ -255,6 +256,7 @@ func DefaultLocalSettings() map[string]interface{} {
 		"ignorecase":     false,
 		"indentchar":     " ",
 		"keepautoindent": false,
+		"matchbrace":     false,
 		"rmtrailingws":   false,
 		"ruler":          true,
 		"savecursor":     false,