Add constants to entity

entity/expression.go

@@ -622,3 +622,25 @@ func (this *Assignment) HasExplicitType () bool { return false }
 func (this *Assignment) String () string {
 	return fmt.Sprint(this.Location, "=", this.Value)
 }
+
+var _ Expression = &Constant { }
+// Constant access allows accessing an enumerated constant defined as part of a
+// type. It can be assigned to a type matching the constant declaration's type.
+// Since it contains inherent type information, it may be directly assigned to
+// an interface.
+type Constant struct {
+	// Syntax
+	Pos      errors.Position
+	TypeName string
+	Name     string
+	
+	// Semantics
+	Ty Type
+}
+func (*Constant) expression(){}
+func (this *Constant) Position () errors.Position { return this.Pos }
+func (this *Constant) Type () Type { return this.Ty }
+func (this *Constant) HasExplicitType () bool { return true }
+func (this *Constant) String () string {
+	return fmt.Sprint(this.TypeName, ".", this.Name)
+}

entity/misc.go

@@ -252,3 +252,19 @@ func Quote (in string) string {
 	}
 	return out + "'"
 }
+
+// ConstantDeclaration declares an enumerated constant as part of a Typedef.
+type ConstantDeclaration struct {
+	// Syntax
+	Pos   errors.Position
+	Name  string
+	Value Expression
+	
+	// Semantics
+	Ty Type
+}
+func (this *ConstantDeclaration) Position () errors.Position { return this.Pos }
+func (this *ConstantDeclaration) Type () Type { return this.Ty }
+func (this *ConstantDeclaration) String () string {
+	return fmt.Sprint("| ", this.Name, " ", this.Value)
+}

entity/toplevel.go

@@ -24,14 +24,16 @@ var _ TopLevel = &Typedef { }
 // Typedef binds a type to a global identifier.
 type Typedef struct {
 	// Syntax
-	Pos    errors.Position
-	Acc    Access
-	Name   string
-	Type   Type
+	Pos       errors.Position
+	Acc       Access
+	Name      string
+	Type      Type
+	Constants []*ConstantDeclaration
 
 	// Semantics
-	Unt     uuid.UUID
-	Methods map[string] *Method
+	Unt          uuid.UUID
+	Methods      map[string] *Method
+	ConstantsMap map[string] *ConstantDeclaration
 }
 func (*Typedef) topLevel(){}
 func (this *Typedef) Position () errors.Position { return this.Pos }
@@ -41,6 +43,9 @@ func (this *Typedef) String () string {
 	output := ""
 	output += fmt.Sprint(this.Acc, " ")
 	output += fmt.Sprint(this.Name, ": ", this.Type)
+	for _, constant := range this.Constants {
+		output += fmt.Sprint("\n", constant)
+	}
 	if this.Methods != nil {
 		for _, method := range this.Methods {
 			output += fmt.Sprint("\n", method)