Marginally better bytecode builder line API

2 files changed, 36 insertions, 8 deletions

diff --git a/pkg/lang/vm/code/builder.go b/pkg/lang/vm/code/builder.go
index 3aa6b6b..51820fb 100644
--- a/pkg/lang/vm/code/builder.go
+++ b/pkg/lang/vm/code/builder.go
@@ -8,12 +8,17 @@ import (
 type Builder struct {
 	code      []byte
 	debugInfo DebugInfo
+
+	currentLine int
+	lineStart   int
 }
 
 func NewBuilder() Builder {
 	return Builder{
-		code:      make([]byte, 0, 64),
-		debugInfo: NewDebugInfo("unknown file"),
+		code:        make([]byte, 0, 64),
+		debugInfo:   NewDebugInfo("unknown file"),
+		lineStart:   -1,
+		currentLine: -1,
 	}
 }
 
@@ -39,8 +44,33 @@ func (b *Builder) AppendRaw(raw Raw) {
 	b.code = append(b.code, raw...)
 }
 
-func (b *Builder) AppendLine(line int) {
-	b.debugInfo.AppendLine(len(b.code)-1, line)
+func (b *Builder) StartLine(line int) {
+	if b.lineStart != -1 {
+		panic("line already started")
+	}
+
+	b.currentLine = line
+	b.lineStart = len(b.code)
+}
+
+func (b *Builder) EndLine() {
+	defer func() {
+		b.currentLine = -1
+		b.lineStart = -1
+	}()
+
+	if b.lineStart == -1 {
+		panic("line not started")
+	}
+
+	if b.lineStart == len(b.code) {
+		println("line empty")
+		return
+	}
+
+	println("line start", b.lineStart)
+
+	b.debugInfo.AppendLine(len(b.code)-1, b.currentLine)
 }
 
 func (b *Builder) SetInt(at int, x int64) {
diff --git a/pkg/lang/vm/text/compiler.go b/pkg/lang/vm/text/compiler.go
index 68889eb..28bc9a7 100644
--- a/pkg/lang/vm/text/compiler.go
+++ b/pkg/lang/vm/text/compiler.go
@@ -47,11 +47,9 @@ func (cpl *Compiler) Compile() (code.Code, error) {
 
 		cpl.codePos += len(line)
 
+		builder.StartLine(cpl.src.Loc().Row - 1)
 		builder.AppendRaw(line)
-
-		if len(line) > 0 {
-			builder.AppendLine(cpl.src.Loc().Row - 1)
-		}
+		builder.EndLine()
 	}
 
 	if err := cpl.linkLabels(&builder); err != nil {