Add multiline prefixes

_example/bang-executor/main.go

@@ -10,6 +10,7 @@ import (
 func main() {
 	p := prompt.New(
 		executor,
+		prompt.WithPrefix(">>> "),
 		prompt.WithExecuteOnEnterCallback(ExecuteOnEnter),
 	)
 
@@ -18,7 +19,7 @@ func main() {
 
 func ExecuteOnEnter(input string, indentSize int) (int, bool) {
 	char, _ := utf8.DecodeLastRuneInString(input)
-	return 1, char == '!'
+	return 0, char == '!'
 }
 
 func executor(s string) {

constructor.go

@@ -13,7 +13,7 @@ const DefaultIndentSize = 2
 // that constitute a single indentation level.
 func WithIndentSize(i int) Option {
 	return func(p *Prompt) error {
-		p.indentSize = i
+		p.renderer.indentSize = i
 		return nil
 	}
 }
@@ -319,6 +319,7 @@ func New(executor Executor, opts ...Option) *Prompt {
 		reader: NewStdinReader(),
 		renderer: &Render{
 			out:                          defaultWriter,
+			indentSize:                   DefaultIndentSize,
 			prefixCallback:               DefaultPrefixCallback,
 			prefixTextColor:              Blue,
 			prefixBGColor:                DefaultColor,
@@ -342,7 +343,6 @@ func New(executor Executor, opts ...Option) *Prompt {
 		history:                NewHistory(),
 		completion:             NewCompletionManager(6),
 		executeOnEnterCallback: DefaultExecuteOnEnterCallback,
-		indentSize:             DefaultIndentSize,
 		keyBindMode:            EmacsKeyBind, // All the above assume that bash is running in the default Emacs setting
 	}
 

prompt.go

@@ -2,6 +2,8 @@ package prompt
 
 import (
 	"bytes"
+	"fmt"
+	"log"
 	"os"
 	"strings"
 	"time"
@@ -50,7 +52,6 @@ type Prompt struct {
 	ASCIICodeBindings      []ASCIICodeBind
 	keyBindMode            KeyBindMode
 	completionOnDown       bool
-	indentSize             int // How many spaces constitute a single indentation level
 	exitChecker            ExitChecker
 	executeOnEnterCallback ExecuteOnEnterCallback
 	skipClose              bool
@@ -131,14 +132,14 @@ func (p *Prompt) Run() {
 	}
 }
 
-// func Log(format string, a ...any) {
-// 	f, err := os.OpenFile("log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
-// 	if err != nil {
-// 		log.Fatalf("error opening file: %v", err)
-// 	}
-// 	defer f.Close()
-// 	fmt.Fprintf(f, format, a...)
-// }
+func Log(format string, a ...any) {
+	f, err := os.OpenFile("log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		log.Fatalf("error opening file: %v", err)
+	}
+	defer f.Close()
+	fmt.Fprintf(f, format, a...)
+}
 
 func (p *Prompt) feed(b []byte) (shouldExit bool, userInput *UserInput) {
 	key := GetKey(b)
@@ -150,11 +151,11 @@ func (p *Prompt) feed(b []byte) (shouldExit bool, userInput *UserInput) {
 keySwitch:
 	switch key {
 	case Enter, ControlJ, ControlM:
-		indent, execute := p.executeOnEnterCallback(p.buf.Text(), p.indentSize)
+		indent, execute := p.executeOnEnterCallback(p.buf.Text(), p.renderer.indentSize)
 		if !execute {
 			p.buf.NewLine(false)
 			var indentStrBuilder strings.Builder
-			indentUnitCount := indent * p.indentSize
+			indentUnitCount := indent * p.renderer.indentSize
 			for i := 0; i < indentUnitCount; i++ {
 				indentStrBuilder.WriteRune(IndentUnit)
 			}
@@ -180,7 +181,7 @@ keySwitch:
 		for _, byt := range b {
 			switch byt {
 			case '\t':
-				for i := 0; i < p.indentSize; i++ {
+				for i := 0; i < p.renderer.indentSize; i++ {
 					newBytes = append(newBytes, IndentUnit)
 				}
 			default:
@@ -201,7 +202,7 @@ keySwitch:
 				break keySwitch
 			}
 		}
-		p.buf.DeleteBeforeCursor(istrings.RuneNumber(p.indentSize))
+		p.buf.DeleteBeforeCursor(istrings.RuneNumber(p.renderer.indentSize))
 	case ControlC:
 		p.renderer.BreakLine(p.buf, p.lexer)
 		p.buf = NewBuffer()
@@ -395,7 +396,7 @@ func (p *Prompt) readBuffer(bufCh chan []byte, stopCh chan struct{}) {
 					// translate \t into two spaces
 					// to avoid problems with cursor positions
 					case '\t':
-						for i := 0; i < p.indentSize; i++ {
+						for i := 0; i < p.renderer.indentSize; i++ {
 							newBytes = append(newBytes, IndentUnit)
 						}
 					default:

render.go

@@ -3,11 +3,14 @@ package prompt
 import (
 	"runtime"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/elk-language/go-prompt/debug"
 	istrings "github.com/elk-language/go-prompt/strings"
 )
 
+const multilinePrefixCharacter = '.'
+
 // Render to render prompt information from state of Buffer.
 type Render struct {
 	out               Writer
@@ -16,6 +19,7 @@ type Render struct {
 	title             string
 	row               uint16
 	col               istrings.Width
+	indentSize        int // How many spaces constitute a single indentation level
 
 	previousCursor Position
 
@@ -46,12 +50,12 @@ func (r *Render) Setup() {
 	}
 }
 
-func (r *Render) renderPrefix() {
+func (r *Render) renderPrefix(prefix string) {
 	r.out.SetColor(r.prefixTextColor, r.prefixBGColor, false)
 	if _, err := r.out.WriteString("\r"); err != nil {
 		panic(err)
 	}
-	if _, err := r.out.WriteString(r.prefixCallback()); err != nil {
+	if _, err := r.out.WriteString(prefix); err != nil {
 		panic(err)
 	}
 	r.out.SetColor(DefaultColor, DefaultColor, false)
@@ -184,10 +188,11 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager, lexer Lex
 	defer func() { debug.AssertNoError(r.out.Flush()) }()
 	r.clear(r.previousCursor)
 
-	line := buffer.Text()
+	text := buffer.Text()
 	prefix := r.prefixCallback()
 	prefixWidth := istrings.GetWidth(prefix)
-	cursor := positionAtEndOfString(prefix+line, r.col)
+	cursor := positionAtEndOfString(text, r.col)
+	cursor.X += prefixWidth
 
 	// prepare area
 	y := cursor.Y
@@ -202,25 +207,14 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager, lexer Lex
 	r.out.HideCursor()
 	defer r.out.ShowCursor()
 
-	r.renderPrefix()
-
-	if lexer != nil {
-		r.lex(lexer, line)
-	} else {
-		r.out.SetColor(r.inputTextColor, r.inputBGColor, false)
-		if _, err := r.out.WriteString(line); err != nil {
-			panic(err)
-		}
-	}
+	r.renderText(lexer, text)
 
 	r.out.SetColor(DefaultColor, DefaultColor, false)
 
 	r.lineWrap(&cursor)
 
 	targetCursor := buffer.DisplayCursorPosition(r.col)
-	if targetCursor.Y == 0 {
-		targetCursor.X += prefixWidth
-	}
+	targetCursor.X += prefixWidth
 	cursor = r.move(cursor, targetCursor)
 
 	r.renderCompletion(buffer, completion)
@@ -237,13 +231,7 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager, lexer Lex
 
 		rest := buffer.Document().TextAfterCursor()
 
-		if lexer != nil {
-			r.lex(lexer, rest)
-		} else {
-			if _, err := r.out.WriteString(rest); err != nil {
-				panic(err)
-			}
-		}
+		r.renderText(lexer, text)
 
 		r.out.SetColor(DefaultColor, DefaultColor, false)
 
@@ -256,25 +244,109 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager, lexer Lex
 	r.previousCursor = cursor
 }
 
+func (r *Render) renderText(lexer Lexer, text string) {
+	if lexer != nil {
+		r.lex(lexer, text)
+		return
+	}
+
+	prefix := r.prefixCallback()
+	multilinePrefix := r.getMultilinePrefix(prefix)
+	firstIteration := true
+	var lineBuffer strings.Builder
+	for _, char := range text {
+		lineBuffer.WriteRune(char)
+		if char != '\n' {
+			continue
+		}
+
+		r.renderLine(prefix, lineBuffer.String(), r.inputTextColor)
+		lineBuffer.Reset()
+		if firstIteration {
+			prefix = multilinePrefix
+			firstIteration = false
+		}
+	}
+
+	r.renderLine(prefix, lineBuffer.String(), r.inputTextColor)
+}
+
+func (r *Render) renderLine(prefix, line string, color Color) {
+	r.renderPrefix(prefix)
+	r.writeString(line, color)
+}
+
+func (r *Render) writeString(text string, color Color) {
+	r.out.SetColor(color, r.inputBGColor, false)
+	if _, err := r.out.WriteString(text); err != nil {
+		panic(err)
+	}
+}
+
+func (r *Render) getMultilinePrefix(prefix string) string {
+	var spaceCount int
+	var dotCount int
+	var nonSpaceCharSeen bool
+	for {
+		if len(prefix) == 0 {
+			break
+		}
+		char, size := utf8.DecodeLastRuneInString(prefix)
+		prefix = prefix[:len(prefix)-size]
+		if nonSpaceCharSeen {
+			dotCount++
+			continue
+		}
+		if char != ' ' {
+			nonSpaceCharSeen = true
+			dotCount++
+			continue
+		}
+		spaceCount++
+	}
+
+	var multilinePrefixBuilder strings.Builder
+
+	for i := 0; i < dotCount; i++ {
+		multilinePrefixBuilder.WriteByte(multilinePrefixCharacter)
+	}
+	for i := 0; i < spaceCount; i++ {
+		multilinePrefixBuilder.WriteByte(IndentUnit)
+	}
+
+	return multilinePrefixBuilder.String()
+}
+
 // lex processes the given input with the given lexer
 // and writes the result
 func (r *Render) lex(lexer Lexer, input string) {
 	lexer.Init(input)
 	s := input
 
+	prefix := r.prefixCallback()
+	r.renderPrefix(prefix)
+	multilinePrefix := r.getMultilinePrefix(prefix)
 	for {
 		token, ok := lexer.Next()
 		if !ok {
 			break
 		}
 
-		a := strings.SplitAfter(s, token.Lexeme())
-		s = strings.TrimPrefix(s, a[0])
+		text := strings.SplitAfter(s, token.Lexeme())[0]
+		s = strings.TrimPrefix(s, text)
 
-		r.out.SetColor(token.Color(), r.inputBGColor, false)
-		if _, err := r.out.WriteString(a[0]); err != nil {
-			panic(err)
+		var lineBuffer strings.Builder
+		for _, char := range text {
+			lineBuffer.WriteRune(char)
+			if char != '\n' {
+				continue
+			}
+
+			r.writeString(lineBuffer.String(), token.Color())
+			r.renderPrefix(multilinePrefix)
+			lineBuffer.Reset()
 		}
+		r.writeString(lineBuffer.String(), token.Color())
 	}
 }
 
@@ -284,16 +356,8 @@ func (r *Render) BreakLine(buffer *Buffer, lexer Lexer) {
 	cursor := positionAtEndOfString(buffer.Document().TextBeforeCursor()+r.prefixCallback(), r.col)
 	r.clear(cursor)
 
-	r.renderPrefix()
-
-	if lexer != nil {
-		r.lex(lexer, buffer.Document().Text+"\n")
-	} else {
-		r.out.SetColor(r.inputTextColor, r.inputBGColor, false)
-		if _, err := r.out.WriteString(buffer.Document().Text + "\n"); err != nil {
-			panic(err)
-		}
-	}
+	text := buffer.Document().Text + "\n"
+	r.renderText(lexer, text)
 
 	r.out.SetColor(DefaultColor, DefaultColor, false)