complete and total overhaul like i promised. things are much easier to reason about. still not working yet though.

nexgb/xgbgen/field.go

@@ -0,0 +1,170 @@
+package main
+
+type Field interface {
+	Initialize(p *Protocol)
+	SrcName() string
+	XmlName() string
+	Size() Size
+
+	Define(c *Context)
+	Read(c *Context)
+}
+
+func (pad *PadField) Initialize(p *Protocol) {}
+
+type PadField struct {
+	Bytes uint
+}
+
+func (p *PadField) SrcName() string {
+	panic("illegal to take source name of a pad field")
+}
+
+func (p *PadField) XmlName() string {
+	panic("illegal to take XML name of a pad field")
+}
+
+func (p *PadField) Size() Size {
+	return newFixedSize(p.Bytes)
+}
+
+type SingleField struct {
+	srcName string
+	xmlName string
+	Type Type
+}
+
+func (f *SingleField) Initialize(p *Protocol) {
+	f.srcName = SrcName(f.XmlName())
+	f.Type = f.Type.(*Translation).RealType(p)
+}
+
+func (f *SingleField) SrcName() string {
+	return f.srcName
+}
+
+func (f *SingleField) XmlName() string {
+	return f.xmlName
+}
+
+func (f *SingleField) Size() Size {
+	return f.Type.Size()
+}
+
+type ListField struct {
+	srcName string
+	xmlName string
+	Type Type
+	LengthExpr Expression
+}
+
+func (f *ListField) SrcName() string {
+	return f.srcName
+}
+
+func (f *ListField) XmlName() string {
+	return f.xmlName
+}
+
+func (f *ListField) Size() Size {
+	return newExpressionSize(f.LengthExpr).Multiply(f.Type.Size())
+}
+
+func (f *ListField) Initialize(p *Protocol) {
+	f.srcName = SrcName(f.XmlName())
+	f.Type = f.Type.(*Translation).RealType(p)
+	if f.LengthExpr != nil {
+		f.LengthExpr.Initialize(p)
+	}
+}
+
+type LocalField struct {
+	*SingleField
+}
+
+type ExprField struct {
+	srcName string
+	xmlName string
+	Type Type
+	Expr Expression
+}
+
+func (f *ExprField) SrcName() string {
+	return f.srcName
+}
+
+func (f *ExprField) XmlName() string {
+	return f.xmlName
+}
+
+func (f *ExprField) Size() Size {
+	return f.Type.Size()
+}
+
+func (f *ExprField) Initialize(p *Protocol) {
+	f.srcName = SrcName(f.XmlName())
+	f.Type = f.Type.(*Translation).RealType(p)
+	f.Expr.Initialize(p)
+}
+
+type ValueField struct {
+	MaskType Type
+	MaskName string
+	ListName string
+}
+
+func (f *ValueField) SrcName() string {
+	panic("it is illegal to call SrcName on a ValueField field")
+}
+
+func (f *ValueField) XmlName() string {
+	panic("it is illegal to call XmlName on a ValueField field")
+}
+
+func (f *ValueField) Size() Size {
+	return f.MaskType.Size()
+}
+
+func (f *ValueField) Initialize(p *Protocol) {
+	f.MaskType = f.MaskType.(*Translation).RealType(p)
+	f.MaskName = SrcName(f.MaskName)
+	f.ListName = SrcName(f.ListName)
+}
+
+type SwitchField struct {
+	Name string
+	Expr Expression
+	Bitcases []*Bitcase
+}
+
+func (f *SwitchField) SrcName() string {
+	panic("it is illegal to call SrcName on a SwitchField field")
+}
+
+func (f *SwitchField) XmlName() string {
+	panic("it is illegal to call XmlName on a SwitchField field")
+}
+
+// XXX: This is a bit tricky. The size has to be represented as a non-concrete
+// expression that finds *which* bitcase fields are included, and sums the
+// sizes of those fields.
+func (f *SwitchField) Size() Size {
+	return newFixedSize(0)
+}
+
+func (f *SwitchField) Initialize(p *Protocol) {
+	f.Name = SrcName(f.Name)
+	f.Expr.Initialize(p)
+	for _, bitcase := range f.Bitcases {
+		bitcase.Expr.Initialize(p)
+		for _, field := range bitcase.Fields {
+			field.Initialize(p)
+		}
+	}
+}
+
+type Bitcase struct {
+	Fields []Field
+	Expr Expression
+}
+