case insensitive search

By default, search is now case insensitive.
If you include uppercase characters in your search string, the search
will become case sensitive. This means there is no way to do a case-
insensitive search of all-lowercase strings. We could add more support
for this but we'll wait until we come across the use case

vendor/github.com/jesseduffield/gocui/view.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"sync"
 	"time"
+	"unicode"
 
 	"github.com/go-errors/errors"
 
@@ -466,18 +467,38 @@ func (v *View) Rewind() {
 	v.readOffset = 0
 }
 
+func containsUpcaseChar(str string) bool {
+	for _, ch := range str {
+		if unicode.IsUpper(ch) {
+			return true
+		}
+	}
+	return false
+}
+
 func (v *View) updateSearchPositions() {
 	if v.searcher.searchString != "" {
+		var normalizeRune func(r rune) rune
+		var normalizedSearchStr string
+		// if we have any uppercase characters we'll do a case-sensitive search
+		if containsUpcaseChar(v.searcher.searchString) {
+			normalizedSearchStr = v.searcher.searchString
+			normalizeRune = func(r rune) rune { return r }
+		} else {
+			normalizedSearchStr = strings.ToLower(v.searcher.searchString)
+			normalizeRune = unicode.ToLower
+		}
+
 		v.searcher.searchPositions = []cellPos{}
 		for y, line := range v.lines {
 		lineLoop:
 			for x, _ := range line {
-				if line[x].chr == rune(v.searcher.searchString[0]) {
-					for offset := 1; offset < len(v.searcher.searchString); offset++ {
+				if normalizeRune(line[x].chr) == rune(normalizedSearchStr[0]) {
+					for offset := 1; offset < len(normalizedSearchStr); offset++ {
 						if len(line)-1 < x+offset {
 							continue lineLoop
 						}
-						if line[x+offset].chr != rune(v.searcher.searchString[offset]) {
+						if normalizeRune(line[x+offset].chr) != rune(normalizedSearchStr[offset]) {
 							continue lineLoop
 						}
 					}