feat: implement cursor functions

.github/settings.yml

@@ -4,7 +4,7 @@ repository:
   # See https://developer.github.com/v3/repos/#edit for all available settings.
 
   # A short description of the repository that will show up on GitHub
-  description: 🔹 Golang module
+  description: 🔹 Golang module to utilize ANSI functions, like moving the cursor
 
   # A comma-separated list of topics to set on the repository
   topics: atomicgo, go, golang, golang-library

.gitignore

@@ -28,3 +28,4 @@ gen
 ### macOS
 # General
 .DS_Store
+experimenting

cursor.go

@@ -0,0 +1,110 @@
+package cursor
+
+import (
+	"fmt"
+	"strings"
+)
+
+const (
+	ansiPrefix = "\x1b["
+
+	upTemplate    = "%dA"
+	downTemplate  = "%dB"
+	leftTemplate  = "%dD"
+	rightTemplate = "%dC"
+
+	nextLineTemplate     = "%dE"
+	previousLineTemplate = "%dF"
+
+	positionTemplate        = "%d;%dH"
+	savePositionTemplate    = "s"
+	restorePositionTemplate = "u"
+
+	openAlternativeScreenTemplate  = "?1049h"
+	closeAlternativeScreenTemplate = "?1049l"
+
+	clearDisplayTemplate = "%dJ"
+	clearLineTemplate    = "%dK"
+
+	showTemplate = "?25h"
+	hideTemplate = "?25l"
+)
+
+// Move cursor.
+
+// Up moves the cursor n cells up. If the cursor is already at the edge of the screen, this has no effect.
+func Up(n int) {
+	fmt.Printf(ansiPrefix+upTemplate, n)
+}
+
+// Down moves the cursor n cells down. If the cursor is already at the edge of the screen, this has no effect.
+func Down(n int) {
+	fmt.Printf(ansiPrefix+downTemplate, n)
+}
+
+// Left moves the cursor n cells left. If the cursor is already at the edge of the screen, this has no effect.
+func Left(n int) {
+	fmt.Printf(ansiPrefix+leftTemplate, n)
+}
+
+// Right moves the cursor n cells right. If the cursor is already at the edge of the screen, this has no effect.
+func Right(n int) {
+	fmt.Printf(ansiPrefix+rightTemplate, n)
+}
+
+// Move moves the cursor to a specific row and column.
+func Move(row int, column int) {
+	fmt.Printf(ansiPrefix+positionTemplate, row, column)
+}
+
+func NextLine(n int) {
+	fmt.Printf(ansiPrefix+nextLineTemplate, n)
+}
+
+func PrevLine(n int) {
+	fmt.Printf(ansiPrefix+previousLineTemplate, n)
+}
+
+func SavePosition() {
+	fmt.Print(ansiPrefix + savePositionTemplate)
+}
+
+func RestorePosition() {
+	fmt.Print(ansiPrefix + restorePositionTemplate)
+}
+
+// Alternative screen.
+
+func OpenAlternativeScreen() {
+	fmt.Print(ansiPrefix + openAlternativeScreenTemplate)
+}
+
+func CloseAlternativeScreen() {
+	fmt.Print(ansiPrefix + closeAlternativeScreenTemplate)
+}
+
+// Erase
+
+func ClearScreen() {
+	fmt.Printf(ansiPrefix+clearDisplayTemplate, 2)
+	Move(1, 1)
+}
+
+func ClearLine() {
+	fmt.Printf(ansiPrefix+clearLineTemplate, 2)
+}
+
+func ClearLines(n int) {
+	clear := fmt.Sprintf(ansiPrefix+clearLineTemplate, 2)
+	fmt.Print(clear + strings.Repeat(fmt.Sprintf(ansiPrefix+upTemplate, 1)+clear, n))
+}
+
+// Show and hide cursor
+
+func Show() {
+	fmt.Printf(ansiPrefix + showTemplate)
+}
+
+func Hide() {
+	fmt.Printf(ansiPrefix + hideTemplate)
+}

cursor_test.go

@@ -0,0 +1,144 @@
+package cursor
+
+import (
+	"io"
+	"testing"
+
+	"github.com/atomicgo/testutil"
+)
+
+func equal(t *testing.T, output string, input func(w io.Writer) error) {
+	t.Helper()
+	in, _ := testutil.CaptureStdout(input)
+	if in != output {
+		t.Errorf("Input: '%s' is not equal to '%s'", in, output)
+	}
+}
+
+func TestClearLine(t *testing.T) {
+	equal(t, "\x1b[2K", func(w io.Writer) error {
+		ClearLine()
+
+		return nil
+	})
+}
+
+func TestClearLines(t *testing.T) {
+	equal(t, "\x1b[2K\x1b[1A\x1b[2K\x1b[1A\x1b[2K\x1b[1A\x1b[2K", func(w io.Writer) error {
+		ClearLines(3)
+
+		return nil
+	})
+}
+
+func TestClearScreen(t *testing.T) {
+	equal(t, "\x1b[2J\x1b[1;1H", func(w io.Writer) error {
+		ClearScreen()
+
+		return nil
+	})
+}
+
+func TestCloseAlternativeScreen(t *testing.T) {
+	equal(t, "\x1b[?1049l", func(w io.Writer) error {
+		CloseAlternativeScreen()
+
+		return nil
+	})
+}
+
+func TestDown(t *testing.T) {
+	equal(t, "\x1b[6B", func(w io.Writer) error {
+		Down(6)
+
+		return nil
+	})
+}
+
+func TestHide(t *testing.T) {
+	equal(t, "\x1b[?25l", func(w io.Writer) error {
+		Hide()
+
+		return nil
+	})
+}
+
+func TestLeft(t *testing.T) {
+	equal(t, "\x1b[6D", func(w io.Writer) error {
+		Left(6)
+
+		return nil
+	})
+}
+
+func TestMove(t *testing.T) {
+	equal(t, "\x1b[6;7H", func(w io.Writer) error {
+		Move(6, 7)
+
+		return nil
+	})
+}
+
+func TestNextLine(t *testing.T) {
+	equal(t, "\x1b[6E", func(w io.Writer) error {
+		NextLine(6)
+
+		return nil
+	})
+}
+
+func TestOpenAlternativeScreen(t *testing.T) {
+	equal(t, "\x1b[?1049h", func(w io.Writer) error {
+		OpenAlternativeScreen()
+
+		return nil
+	})
+}
+
+func TestPrevLine(t *testing.T) {
+	equal(t, "\x1b[6F", func(w io.Writer) error {
+		PrevLine(6)
+
+		return nil
+	})
+}
+
+func TestRestorePosition(t *testing.T) {
+	equal(t, "\x1b[u", func(w io.Writer) error {
+		RestorePosition()
+
+		return nil
+	})
+}
+
+func TestRight(t *testing.T) {
+	equal(t, "\x1b[6C", func(w io.Writer) error {
+		Right(6)
+
+		return nil
+	})
+}
+
+func TestSavePosition(t *testing.T) {
+	equal(t, "\x1b[s", func(w io.Writer) error {
+		SavePosition()
+
+		return nil
+	})
+}
+
+func TestShow(t *testing.T) {
+	equal(t, "\x1b[?25h", func(w io.Writer) error {
+		Show()
+
+		return nil
+	})
+}
+
+func TestUp(t *testing.T) {
+	equal(t, "\x1b[6A", func(w io.Writer) error {
+		Up(6)
+
+		return nil
+	})
+}

doc.go

@@ -1,9 +1,4 @@
 /*
-Package template is used to generate new AtomicGo repositories.
-
-Write the description of the module here. You can use **markdown**!
-This description should clearly explain what the package does.
-
-Example description: https://golang.org/src/encoding/gob/doc.go
+Package cursor contains methods to move the cursor inside a terminal.
 */
-package template
+package cursor

go.mod

@@ -1,3 +1,5 @@
-module github.com/atomicgo/template
+module github.com/atomicgo/cursor
 
 go 1.15
+
+require github.com/atomicgo/testutil v0.0.1 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/atomicgo/testutil v0.0.1 h1:3Si1wzSCaGihKYc2w3brYbBDWZ2/4MayjzzzUTL7esA=
+github.com/atomicgo/testutil v0.0.1/go.mod h1:/hQIxa6fUSFwnzJd096BeLtDdRBbssw1MZN6FhUCOLs=