Implement string.dump

256lights · Jan 22, 2025 · 15c7053 · 15c7053
1 parent c7fc7f4
commit 15c7053
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Showing 2 changed files with 43 additions and 4 deletions.
diff --git a/internal/lua/lua.go b/internal/lua/lua.go
@@ -1763,6 +1763,27 @@ func (l *State) Load(r io.ByteScanner, chunkName Source, mode string) (err error
 	return nil
 }
 
+// Dump marshals the function at the top of the stack into a binary chunk.
+// If stripDebug is true,
+// the binary representation may not include all debug information about the function,
+// to save space.
+func (l *State) Dump(stripDebug bool) ([]byte, error) {
+	if l.Top() < 1 {
+		return nil, errMissingArguments
+	}
+
+	l.init()
+	top := l.stack[len(l.stack)-1]
+	f, ok := top.(luaFunction)
+	if !ok {
+		if valueType(top) == TypeFunction {
+			return nil, errors.New("cannot dump a Go function")
+		}
+		return nil, fmt.Errorf("cannot dump a %s", l.typeName(top))
+	}
+	return f.proto.MarshalBinary()
+}
+
 // Next pops a key from the stack,
 // and pushes a key–value pair from the table at the given index,
 // the “next” pair after the given key.
@@ -1992,7 +2013,11 @@ const typeNameMetafield = "__name"
 func (l *State) typeName(v value) string {
 	switch v := v.(type) {
 	case *table:
-		if s, ok := v.get(stringValue{s: typeNameMetafield}).(stringValue); ok {
+		if s, ok := v.meta.get(stringValue{s: typeNameMetafield}).(stringValue); ok {
+			return s.s
+		}
+	case *userdata:
+		if s, ok := v.meta.get(stringValue{s: typeNameMetafield}).(stringValue); ok {
 			return s.s
 		}
 	}

diff --git a/internal/lua/stringlib.go b/internal/lua/stringlib.go
@@ -39,9 +39,9 @@ const StringLibraryName = "string"
 // [string manipulation library]: https://www.lua.org/manual/5.4/manual.html#6.4
 func OpenString(ctx context.Context, l *State) (int, error) {
 	NewLib(l, map[string]Function{
-		"byte": stringByte,
-		"char": stringChar,
-		// "dump":     stringDump,
+		"byte":     stringByte,
+		"char":     stringChar,
+		"dump":     stringDump,
 		"find":     stringFind,
 		"format":   stringFormat,
 		"gmatch":   stringGMatch,
@@ -144,6 +144,20 @@ func stringChar(ctx context.Context, l *State) (int, error) {
 	return 1, nil
 }
 
+func stringDump(ctx context.Context, l *State) (int, error) {
+	stripDebug := l.ToBoolean(2)
+	if got, want := l.Type(1), TypeFunction; got != want {
+		return 0, NewTypeError(l, 1, want.String())
+	}
+	l.SetTop(1)
+	chunk, err := l.Dump(stripDebug)
+	if err != nil {
+		return 0, err
+	}
+	l.PushString(string(chunk))
+	return 1, nil
+}
+
 func stringFind(ctx context.Context, l *State) (int, error) {
 	s, err := CheckString(l, 1)
 	if err != nil {