Move bisectRight implementation to internal/bisect

Makefile

@@ -21,8 +21,12 @@ lint: ## Run golint and go vet.
 	@go vet .
 
 .PHONY: test
-test:  ## Run the tests with race condition checking.
-	@go test -race .
+test:  ## Run tests with race condition checking.
+	@go test -race ./...
+
+.PHONY: bench
+bench:  ## Run benchmarks.
+	@go test -bench=. -run=- -benchmem ./...
 
 .PHONY: coverage
 cover:  ## Run the tests.

document.go

@@ -1,10 +1,10 @@
 package prompt
 
 import (
-	"sort"
 	"strings"
 	"unicode/utf8"
 
+	"github.com/c-bata/go-prompt/internal/bisect"
 	runewidth "github.com/mattn/go-runewidth"
 )
 
@@ -292,7 +292,7 @@ func (d *Document) lineStartIndexes() []int {
 // the first character on that line.
 func (d *Document) findLineStartIndex(index int) (pos int, lineStartIndex int) {
 	indexes := d.lineStartIndexes()
-	pos = bisectRight(indexes, index) - 1
+	pos = bisect.Right(indexes, index) - 1
 	lineStartIndex = indexes[pos]
 	return
 }
@@ -433,18 +433,6 @@ func (d *Document) leadingWhitespaceInCurrentLine() (margin string) {
 	return
 }
 
-// bisectRight to Locate the insertion point for v in a to maintain sorted order.
-func bisectRight(a []int, v int) int {
-	return bisectRightRange(a, v, 0, len(a))
-}
-
-func bisectRightRange(a []int, v int, lo, hi int) int {
-	s := a[lo:hi]
-	return sort.Search(len(s), func(i int) bool {
-		return s[i] > v
-	})
-}
-
 func indexByteNot(s string, c byte) int {
 	n := len(s)
 	for i := 0; i < n; i++ {

document_test.go

@@ -1040,18 +1040,3 @@ func TestDocument_GetEndOfLinePosition(t *testing.T) {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
 }
-
-func TestBisectRight(t *testing.T) {
-	// Thanks!! https://play.golang.org/p/y9NRj_XVIW
-	in := []int{1, 2, 3, 3, 3, 6, 7}
-
-	r := bisectRight(in, 0)
-	if r != 0 {
-		t.Errorf("number 0 should inserted at 0 position, but got %d", r)
-	}
-
-	r = bisectRight(in, 4)
-	if r != 5 {
-		t.Errorf("number 4 should inserted at 5 position, but got %d", r)
-	}
-}

internal/bisect/bisect.go

@@ -0,0 +1,15 @@
+package bisect
+
+import "sort"
+
+// Right to locate the insertion point for v in a to maintain sorted order.
+func Right(a []int, v int) int {
+	return bisectRightRange(a, v, 0, len(a))
+}
+
+func bisectRightRange(a []int, v int, lo, hi int) int {
+	s := a[lo:hi]
+	return sort.Search(len(s), func(i int) bool {
+		return s[i] > v
+	})
+}

internal/bisect/bisect_test.go

@@ -0,0 +1,50 @@
+package bisect_test
+
+import (
+	"fmt"
+	"math/rand"
+	"testing"
+
+	"github.com/c-bata/go-prompt/internal/bisect"
+)
+
+func Example() {
+	in := []int{1, 2, 3, 3, 3, 6, 7}
+	fmt.Println("Insertion position for 0 in the slice is", bisect.Right(in, 0))
+	fmt.Println("Insertion position for 4 in the slice is", bisect.Right(in, 4))
+
+	// Output:
+	// Insertion position for 0 in the slice is 0
+	// Insertion position for 4 in the slice is 5
+}
+
+func TestBisectRight(t *testing.T) {
+	// Thanks!! https://play.golang.org/p/y9NRj_XVIW
+	in := []int{1, 2, 3, 3, 3, 6, 7}
+
+	r := bisect.Right(in, 0)
+	if r != 0 {
+		t.Errorf("number 0 should inserted at 0 position, but got %d", r)
+	}
+
+	r = bisect.Right(in, 4)
+	if r != 5 {
+		t.Errorf("number 4 should inserted at 5 position, but got %d", r)
+	}
+}
+
+func BenchmarkRight(b *testing.B) {
+	rand.Seed(0)
+
+	for _, l := range []int{10, 1e2, 1e3, 1e4} {
+		x := rand.Perm(l)
+		insertion := rand.Int()
+
+		b.Run(fmt.Sprintf("arrayLength=%d", l), func(b *testing.B) {
+			b.ResetTimer()
+			for n := 0; n < b.N; n++ {
+				bisect.Right(x, insertion)
+			}
+		})
+	}
+}