Reduced interface bloat

src/ssa/Block.go

@@ -8,7 +8,7 @@ type Block struct {
 // Append adds a new instruction to the block.
 func (block *Block) Append(instr Value) Value {
 	for _, dep := range instr.Dependencies() {
-		dep.AddUser(instr)
+		dep.(HasLiveness).AddUser(instr)
 	}
 
 	block.Instructions = append(block.Instructions, instr)

src/ssa/HasLiveness.go

@@ -0,0 +1,6 @@
+package ssa
+
+type HasLiveness interface {
+	AddUser(Value)
+	Users() []Value
+}

src/ssa/HasSource.go

@@ -0,0 +1,8 @@
+package ssa
+
+import "git.urbach.dev/cli/q/src/token"
+
+type HasSource interface {
+	Start() token.Position
+	End() token.Position
+}

src/ssa/Liveness.go

@@ -8,6 +8,6 @@ func (v *Liveness) AddUser(user Value) {
 	v.users = append(v.users, user)
 }
 
-func (v *Liveness) CountUsers() int {
-	return len(v.users)
+func (v *Liveness) Users() []Value {
+	return v.users
 }

src/ssa/NoLiveness.go

@@ -1,6 +0,0 @@
-package ssa
-
-type NoLiveness struct{}
-
-func (a *NoLiveness) AddUser(user Value) { panic("value does not have liveness") }
-func (a *NoLiveness) CountUsers() int    { return 0 }

src/ssa/Return.go

@@ -11,7 +11,6 @@ type Return struct {
 	Id
 	Arguments
 	Source
-	NoLiveness
 }
 
 func (a *Return) Equals(v Value) bool {

src/ssa/Source.go

@@ -4,14 +4,10 @@ import "git.urbach.dev/cli/q/src/token"
 
 type Source token.List
 
-func (v Source) End() token.Position {
-	return v[len(v)-1].End()
-}
-
-func (v *Source) SetSource(source token.List) {
-	*v = Source(source)
-}
-
 func (v Source) Start() token.Position {
 	return v[0].Position
+}
+
+func (v Source) End() token.Position {
+	return v[len(v)-1].End()
 }

src/ssa/Value.go

@@ -1,29 +1,16 @@
 package ssa
 
 import (
-	"git.urbach.dev/cli/q/src/token"
 	"git.urbach.dev/cli/q/src/types"
 )
 
 type Value interface {
-	// Essentials
 	Debug(bool) string
+	Dependencies() []Value
+	Equals(Value) bool
 	ID() int
 	IsConst() bool
 	SetID(int)
 	String() string
 	Type() types.Type
-
-	// Arguments
-	Dependencies() []Value
-	Equals(Value) bool
-
-	// Liveness
-	AddUser(Value)
-	CountUsers() int
-
-	// Source
-	SetSource(token.List)
-	Start() token.Position
-	End() token.Position
 }