internal/rosa: toolchain type methods

This improves readability for toolchain-specific checks.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -137,10 +137,40 @@ const (
 	_toolchainEnd
 )
 
+// isStage0 returns whether t is a stage0 toolchain.
+func (t Toolchain) isStage0() bool {
+	switch t {
+	case toolchainGentoo, toolchainStage0:
+		return true
+	default:
+		return false
+	}
+}
+
+// isIntermediate returns whether t is an intermediate toolchain.
+func (t Toolchain) isIntermediate() bool {
+	switch t {
+	case toolchainIntermediateGentoo, toolchainIntermediate:
+		return true
+	default:
+		return false
+	}
+}
+
+// isStd returns whether t is considered functionally equivalent to [Std].
+func (t Toolchain) isStd() bool {
+	switch t {
+	case toolchainStdGentoo, Std:
+		return true
+	default:
+		return false
+	}
+}
+
 // stage0Concat concatenates s and values. If the current toolchain is
 // toolchainStage0, stage0Concat returns s as is.
 func stage0Concat[S ~[]E, E any](t Toolchain, s S, values ...E) S {
-	if t == toolchainStage0 || t == toolchainGentoo {
+	if t.isStage0() {
 		return s
 	}
 	return slices.Concat(s, values)
@@ -149,7 +179,7 @@ func stage0Concat[S ~[]E, E any](t Toolchain, s S, values ...E) S {
 // stage0ExclConcat concatenates s and values. If the current toolchain is not
 // toolchainStage0, stage0ExclConcat returns s as is.
 func stage0ExclConcat[S ~[]E, E any](t Toolchain, s S, values ...E) S {
-	if t == toolchainStage0 || t == toolchainGentoo {
+	if t.isStage0() {
 		return slices.Concat(s, values)
 	}
 	return s
@@ -269,7 +299,7 @@ mkdir -vp /work/system/bin
 
 	case toolchainIntermediateGentoo, toolchainStdGentoo,
 		toolchainIntermediate, Std:
-		if t == toolchainIntermediateGentoo || t == toolchainIntermediate {
+		if t.isIntermediate() {
 			name += "-std"
 		}