prompt: fix some keybindings to work with multilines

- The behavior of the `Home`/`End` keys has been changed:
now, the cursor moves to the beginning/end of the entire command
(instead of the line) when these keys are pressed.

- The behavior of the `alt-b`/`alt-f` keys has been changed:
now, the cursor moves one word backward in multiline commands, and
the word delimeter characters are `\n` and ` `.

- The associated emacs keybindings has been changed:
now `ctrl-b`/`ctrl-f` allow to move over the entire multiline command.
`ctrl-a`/`ctrl-e` same as `Home`/`End`.

- Added integration tests for emacs keyset.

Closes #6

document.go

@@ -144,6 +144,36 @@ func (d *Document) FindStartOfPreviousWord() int {
 	return 0
 }
 
+// FindStartOfPreviousWordCursor finds the start of the previous word and returns
+// the associated cursor position.
+// Determines whether a rune is part of a word using `isWordPart`.
+func (d *Document) FindStartOfPreviousWordCursor(isWordPart func(rune) bool) int {
+	textBeforeCursor := []rune(d.TextBeforeCursor())
+	cursor := len(textBeforeCursor) - 1
+	for cursor >= 0 && !isWordPart(textBeforeCursor[cursor]) {
+		cursor--
+	}
+	for cursor >= 0 && isWordPart(textBeforeCursor[cursor]) {
+		cursor--
+	}
+	return cursor + 1
+}
+
+// FindEndOfCurrentWordCursor finds the end of the current word and returns
+// the cursor position exactly after the end.
+// Determines whether a rune is part of a word using `isWordPart`.
+func (d *Document) FindEndOfCurrentWordCursor(isWordPart func(rune) bool) int {
+	textAfterCursor := []rune(d.TextAfterCursor())
+	cursor := 0
+	for cursor < len(textAfterCursor) && !isWordPart(textAfterCursor[cursor]) {
+		cursor++
+	}
+	for cursor < len(textAfterCursor) && isWordPart(textAfterCursor[cursor]) {
+		cursor++
+	}
+	return d.cursorPosition + cursor
+}
+
 // FindStartOfPreviousWordWithSpace is almost the same as FindStartOfPreviousWord.
 // The only difference is to ignore contiguous spaces.
 func (d *Document) FindStartOfPreviousWordWithSpace() int {

document_test.go

@@ -1476,3 +1476,113 @@ func Test_GetCustomCursorPosition(t *testing.T) {
 		})
 	}
 }
+
+func TestFindStartOfPreviousWordCursor(t *testing.T) {
+	isWordPart := func(r rune) bool {
+		return r != '\n' && r != ' '
+	}
+	cases := []struct {
+		description    string
+		input          string
+		cursor         int
+		expectedCursor int
+	}{
+		{
+			"wo[r]d  -> [w]ord",
+			"word",
+			2,
+			0,
+		},
+		{
+			" word[] -> [w]ord ",
+			" word  ",
+			5,
+			1,
+		},
+		{
+			"строка 1\n[с]трока2\nстрока3 -> строка [1]\nстрока2\nстрока3",
+			"строка 1\nстрока2\nстрока3 ",
+			9,
+			7,
+		},
+		{
+			"слово\nслово2\n[с]лово3 -> слово\n[с]лово2\nслово3",
+			"слово\nслово2\nслово3",
+			13,
+			6,
+		},
+		{
+			"some long []  line -> some [l]ong    line",
+			"some long    line",
+			10,
+			5,
+		},
+		{
+			"[] -> []",
+			"",
+			0,
+			0,
+		},
+		{
+			"a\n\n\n\n\n\n[b]a -> [a]\n\n\n\n\n\nba",
+			"a\n\n\n\n\n\nba",
+			7,
+			0,
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.description, func(t *testing.T) {
+			d := Document{Text: tc.input, cursorPosition: tc.cursor}
+			assert.Equal(t, tc.expectedCursor, d.FindStartOfPreviousWordCursor(isWordPart))
+		})
+	}
+}
+
+func TestFindEndOfCurrentWordCursor(t *testing.T) {
+	isWordPart := func(r rune) bool {
+		return r != '\n' && r != ' '
+	}
+	cases := []struct {
+		description    string
+		input          string
+		cursor         int
+		expectedCursor int
+	}{
+		{
+			"wo[r]d -> word[]",
+			"word",
+			2,
+			4,
+		},
+		{
+			" []  word ->    word[]",
+			"    word",
+			1,
+			8,
+		},
+		{
+			"строка1\n[]строка2\nстрока3 -> строка1\n строка2[\n]строка3",
+			"строка1\n строка2\nстрока3",
+			8,
+			16,
+		},
+		{
+			"[] -> []",
+			"",
+			0,
+			0,
+		},
+		{
+			"[\n]\n\n\nслово->\n\n\n\nслово[]",
+			"\n\n\n\nслово",
+			0,
+			9,
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.description, func(t *testing.T) {
+			d := Document{Text: tc.input, cursorPosition: tc.cursor}
+			assert.Equal(t, tc.expectedCursor, d.FindEndOfCurrentWordCursor(isWordPart))
+		})
+	}
+}

emacs.go

@@ -42,18 +42,12 @@ var emacsKeyBindings = []KeyBind{
 	// Go to the End of the line
 	{
 		Key: ControlE,
-		Fn: func(buf *Buffer) {
-			x := []rune(buf.Document().TextAfterCursor())
-			buf.CursorRight(len(x))
-		},
+		Fn:  GoCmdEnd,
 	},
 	// Go to the beginning of the line
 	{
 		Key: ControlA,
-		Fn: func(buf *Buffer) {
-			x := []rune(buf.Document().TextBeforeCursor())
-			buf.CursorLeft(len(x))
-		},
+		Fn:  GoCmdBeginning,
 	},
 	// Cut the Line after the cursor
 	{
@@ -90,16 +84,12 @@ var emacsKeyBindings = []KeyBind{
 	// Right allow: Forward one character
 	{
 		Key: ControlF,
-		Fn: func(buf *Buffer) {
-			buf.CursorRight(1)
-		},
+		Fn:  GoRightChar,
 	},
 	// Left allow: Backward one character
 	{
 		Key: ControlB,
-		Fn: func(buf *Buffer) {
-			buf.CursorLeft(1)
-		},
+		Fn:  GoLeftChar,
 	},
 	// Cut the Word before the cursor.
 	{

internal/prompt_app/prompt_app.go

@@ -9,6 +9,16 @@ import (
 	"github.com/c-bata/go-prompt"
 )
 
+var (
+	ControlLeftBytes  []byte
+	ControlRightBytes []byte
+)
+
+func init() {
+	ControlLeftBytes = []byte{0x1b, 0x62}
+	ControlRightBytes = []byte{0x1b, 0x66}
+}
+
 // Console describes the console.
 type Console struct {
 	title             string
@@ -81,6 +91,23 @@ func getPromptOptions(console *Console) []prompt.Option {
 
 		prompt.OptionDisableAutoHistory(),
 		prompt.OptionReverseSearch(),
+
+		prompt.OptionAddASCIICodeBind(
+			// Move to one word left.
+			prompt.ASCIICodeBind{
+				ASCIICode: ControlLeftBytes,
+				Fn: func(buf *prompt.Buffer) {
+					prompt.GoLeftWord(buf)
+				},
+			},
+			// Move to one word right.
+			prompt.ASCIICodeBind{
+				ASCIICode: ControlRightBytes,
+				Fn: func(buf *prompt.Buffer) {
+					prompt.GoRightWord(buf)
+				},
+			},
+		),
 	}
 	args := os.Args
 	if len(args) > 1 {

key_bind.go

@@ -29,12 +29,12 @@ var commonKeyBindings = []KeyBind{
 	// Go to the End of the line
 	{
 		Key: End,
-		Fn:  GoLineEnd,
+		Fn:  GoCmdEnd,
 	},
 	// Go to the beginning of the line
 	{
 		Key: Home,
-		Fn:  GoLineBeginning,
+		Fn:  GoCmdBeginning,
 	},
 	// Delete character under the cursor
 	{

key_bind_func.go

@@ -56,13 +56,26 @@ func GoLeftChar(buf *Buffer) {
 	buf.CursorLeft(1)
 }
 
-// GoRightWord Forward one word.
+// GoRightWord moves the cursor to the end of the next word.
 func GoRightWord(buf *Buffer) {
-	buf.CursorRight(buf.Document().FindEndOfCurrentWordWithSpace())
+	buf.setCursorPosition(buf.Document().FindEndOfCurrentWordCursor(func(r rune) bool {
+		return r != '\n' && r != ' '
+	}))
 }
 
-// GoLeftWord Backward one word.
+// GoLeftWord moves the cursor to the beginning of the previous word.
 func GoLeftWord(buf *Buffer) {
-	buf.CursorLeft(len([]rune(buf.Document().TextBeforeCursor())) - buf.Document().
-		FindStartOfPreviousWordWithSpace())
+	buf.setCursorPosition(buf.Document().FindStartOfPreviousWordCursor(func(r rune) bool {
+		return r != '\n' && r != ' '
+	}))
+}
+
+// GoCmdBeginning moves the cursor to the beginning of the command.
+func GoCmdBeginning(buf *Buffer) {
+	buf.setCursorPosition(0)
+}
+
+// GoCmdEnd moves the cursor to the end of the command.
+func GoCmdEnd(buf *Buffer) {
+	buf.setCursorPosition(len([]rune(buf.Text())))
 }