From 504c82a0e7edab55d2c9b326309151a9d7f32750 Mon Sep 17 00:00:00 2001
From: Konstantin Yegupov <kyegupov4@gmail.com>
Date: Thu, 31 Jan 2019 01:12:57 +1000
Subject: [PATCH] compiler: support for byte arrays as keys in maps

---
 compiler/map.go  |  4 ++++
 interp/values.go |  7 +++++++
 testdata/map.go  | 12 ++++++++++++
 testdata/map.txt |  2 ++
 4 files changed, 25 insertions(+)

diff --git a/compiler/map.go b/compiler/map.go
index 88547b1f..dc5ddead 100644
--- a/compiler/map.go
+++ b/compiler/map.go
@@ -120,6 +120,10 @@ func hashmapIsBinaryKey(keyType types.Type) bool {
 			}
 		}
 		return true
+	case *types.Array:
+		return hashmapIsBinaryKey(keyType.Elem())
+	case *types.Named:
+		return hashmapIsBinaryKey(keyType.Underlying())
 	default:
 		return false
 	}
diff --git a/interp/values.go b/interp/values.go
index c4f6e302..a6b5336a 100644
--- a/interp/values.go
+++ b/interp/values.go
@@ -451,6 +451,13 @@ func (v *MapValue) Value() llvm.Value {
 				keyBuf[i] = byte(n)
 				n >>= 8
 			}
+		} else if key.Type().TypeKind() == llvm.ArrayTypeKind &&
+			key.Type().ElementType().TypeKind() == llvm.IntegerTypeKind &&
+			key.Type().ElementType().IntTypeWidth() == 8 {
+			keyBuf = make([]byte, v.Eval.TargetData.TypeAllocSize(key.Type()))
+			for i := range keyBuf {
+				keyBuf[i] = byte(llvm.ConstExtractValue(llvmKey, []uint32{uint32(i)}).ZExtValue())
+			}
 		} else {
 			panic("interp: map key type not implemented: " + key.Type().String())
 		}
diff --git a/testdata/map.go b/testdata/map.go
index 5b97bf5d..fdf61502 100644
--- a/testdata/map.go
+++ b/testdata/map.go
@@ -15,6 +15,13 @@ var testmap2 = map[string]int{
 	"eleven": 11,
 	"twelve": 12,
 }
+
+type ArrayKey [4]byte
+
+var testMapArrayKey = map[ArrayKey]int{
+	ArrayKey([4]byte{1, 2, 3, 4}): 1234,
+	ArrayKey([4]byte{4, 3, 2, 1}): 4321,
+}
 var testmapIntInt = map[int]int{1: 1, 2: 4, 3: 9}
 
 func main() {
@@ -35,6 +42,11 @@ func main() {
 	println(testmapIntInt[2])
 	testmapIntInt[2] = 42
 	println(testmapIntInt[2])
+
+	arrKey := ArrayKey([4]byte{4, 3, 2, 1})
+	println(testMapArrayKey[arrKey])
+	testMapArrayKey[arrKey] = 5555
+	println(testMapArrayKey[arrKey])
 }
 
 func readMap(m map[string]int, key string) {
diff --git a/testdata/map.txt b/testdata/map.txt
index a11e421c..a41522f7 100644
--- a/testdata/map.txt
+++ b/testdata/map.txt
@@ -52,3 +52,5 @@ false true 2
 true false 0
 4
 42
+4321
+5555