Add method to access P2PKH and P2SH hash arrays.

This change adds the Hash160 methods to AddressPubKeyHash and
AddressScriptHash so the hash may be accessed as an array, rather than
a byte slice with the ScriptAddress method of the Address interface.
In situations where arrays are more appropiate than slices (such as
for map keys), accessing the array directly this way can significantly
improve performance by reducing copying into local arrays.

address.go

@@ -250,6 +250,13 @@ func (a *AddressPubKeyHash) String() string {
 	return a.EncodeAddress()
 }
 
+// Hash160 returns the underlying array of the pubkey hash.  This can be useful
+// when an array is more appropiate than a slice (for example, when used as map
+// keys).
+func (a *AddressPubKeyHash) Hash160() *[ripemd160.Size]byte {
+	return &a.hash
+}
+
 // AddressScriptHash is an Address for a pay-to-script-hash (P2SH)
 // transaction.
 type AddressScriptHash struct {
@@ -331,6 +338,13 @@ func (a *AddressScriptHash) String() string {
 	return a.EncodeAddress()
 }
 
+// Hash160 returns the underlying array of the script hash.  This can be useful
+// when an array is more appropiate than a slice (for example, when used as map
+// keys).
+func (a *AddressScriptHash) Hash160() *[ripemd160.Size]byte {
+	return &a.hash
+}
+
 // PubKeyFormat describes what format to use for a pay-to-pubkey address.
 type PubKeyFormat int
 

address_test.go

@@ -529,12 +529,28 @@ func TestAddresses(t *testing.T) {
 				saddr, _ = hex.DecodeString(d.String())
 			}
 
-			// Check script address.
+			// Check script address, as well as the Hash160 method for P2PKH and
+			// P2SH addresses.
 			if !bytes.Equal(saddr, decoded.ScriptAddress()) {
 				t.Errorf("%v: script addresses do not match:\n%x != \n%x",
 					test.name, saddr, decoded.ScriptAddress())
 				return
 			}
+			switch a := decoded.(type) {
+			case *btcutil.AddressPubKeyHash:
+				if h := a.Hash160()[:]; !bytes.Equal(saddr, h) {
+					t.Errorf("%v: hashes do not match:\n%x != \n%x",
+						test.name, saddr, h)
+					return
+				}
+
+			case *btcutil.AddressScriptHash:
+				if h := a.Hash160()[:]; !bytes.Equal(saddr, h) {
+					t.Errorf("%v: hashes do not match:\n%x != \n%x",
+						test.name, saddr, h)
+					return
+				}
+			}
 
 			// Ensure the address is for the expected network.
 			if !decoded.IsForNet(test.net) {

test_coverage.txt

@@ -3,29 +3,31 @@ github.com/conformal/btcutil/base58.go	 Base58Decode			 100.00% (20/20)
 github.com/conformal/btcutil/base58.go	 Base58Encode			 100.00% (15/15)
 github.com/conformal/btcutil/block.go	 Block.Tx			 100.00% (12/12)
 github.com/conformal/btcutil/block.go	 Block.Transactions		 100.00% (11/11)
-github.com/conformal/btcutil/amount.go	 NewAmount			 100.00% (9/9)
 github.com/conformal/btcutil/address.go	 encodeAddress			 100.00% (9/9)
+github.com/conformal/btcutil/amount.go	 NewAmount			 100.00% (9/9)
 github.com/conformal/btcutil/amount.go	 AmountUnit.String		 100.00% (8/8)
 github.com/conformal/btcutil/block.go	 NewBlockFromBytes		 100.00% (7/7)
 github.com/conformal/btcutil/tx.go	 NewTxFromBytes			 100.00% (7/7)
 github.com/conformal/btcutil/tx.go	 Tx.Sha				 100.00% (5/5)
-github.com/conformal/btcutil/address.go	 checkBitcoinNet		 100.00% (5/5)
 github.com/conformal/btcutil/block.go	 Block.Sha			 100.00% (5/5)
+github.com/conformal/btcutil/address.go	 checkBitcoinNet		 100.00% (5/5)
+github.com/conformal/btcutil/hash160.go	 calcHash			 100.00% (2/2)
 github.com/conformal/btcutil/amount.go	 Amount.Format			 100.00% (2/2)
 github.com/conformal/btcutil/address.go	 NewAddressScriptHash		 100.00% (2/2)
-github.com/conformal/btcutil/hash160.go	 calcHash			 100.00% (2/2)
+github.com/conformal/btcutil/block.go	 OutOfRangeError.Error		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.MsgBlock			 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKeyHash.EncodeAddress 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKeyHash.ScriptAddress 100.00% (1/1)
+github.com/conformal/btcutil/address.go	 AddressPubKeyHash.Hash160	 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressScriptHash.EncodeAddress 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressScriptHash.ScriptAddress 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressScriptHash.String	 100.00% (1/1)
+github.com/conformal/btcutil/address.go	 AddressScriptHash.Hash160	 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKey.EncodeAddress	 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKey.ScriptAddress	 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKey.String		 100.00% (1/1)
 github.com/conformal/btcutil/amount.go	 Amount.ToUnit			 100.00% (1/1)
 github.com/conformal/btcutil/amount.go	 Amount.String			 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 OutOfRangeError.Error		 100.00% (1/1)
+github.com/conformal/btcutil/block.go	 Block.MsgBlock			 100.00% (1/1)
 github.com/conformal/btcutil/block.go	 Block.Height			 100.00% (1/1)
 github.com/conformal/btcutil/block.go	 Block.SetHeight		 100.00% (1/1)
 github.com/conformal/btcutil/block.go	 NewBlock			 100.00% (1/1)
@@ -38,8 +40,8 @@ github.com/conformal/btcutil/tx.go	 NewTx				 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 AddressPubKeyHash.String	 100.00% (1/1)
 github.com/conformal/btcutil/address.go	 DecodeAddress			 95.65% (22/23)
 github.com/conformal/btcutil/appdata.go	 appDataDir			 92.00% (23/25)
-github.com/conformal/btcutil/address.go	 NewAddressScriptHashFromHash	 91.67% (11/12)
 github.com/conformal/btcutil/address.go	 NewAddressPubKeyHash		 91.67% (11/12)
+github.com/conformal/btcutil/address.go	 NewAddressScriptHashFromHash	 91.67% (11/12)
 github.com/conformal/btcutil/address.go	 EncodePrivateKey		 90.91% (20/22)
 github.com/conformal/btcutil/block.go	 Block.TxLoc			 88.89% (8/9)
 github.com/conformal/btcutil/block.go	 Block.Bytes			 88.89% (8/9)
@@ -47,13 +49,13 @@ github.com/conformal/btcutil/address.go	 AddressPubKey.serialize	 85.71% (6/7)
 github.com/conformal/btcutil/address.go	 DecodePrivateKey		 83.33% (20/24)
 github.com/conformal/btcutil/address.go	 NewAddressPubKey		 83.33% (15/18)
 github.com/conformal/btcutil/block.go	 Block.TxSha			 75.00% (3/4)
-github.com/conformal/btcutil/address.go	 AddressPubKey.IsForNet		 60.00% (3/5)
-github.com/conformal/btcutil/address.go	 AddressPubKeyHash.IsForNet	 60.00% (3/5)
 github.com/conformal/btcutil/address.go	 AddressScriptHash.IsForNet	 60.00% (3/5)
+github.com/conformal/btcutil/address.go	 AddressPubKeyHash.IsForNet	 60.00% (3/5)
+github.com/conformal/btcutil/address.go	 AddressPubKey.IsForNet		 60.00% (3/5)
 github.com/conformal/btcutil/certgen.go	 NewTLSCertPair			 0.00% (0/50)
 github.com/conformal/btcutil/address.go	 AddressPubKey.AddressPubKeyHash 0.00% (0/3)
+github.com/conformal/btcutil/address.go	 AddressPubKey.Format		 0.00% (0/1)
 github.com/conformal/btcutil/appdata.go	 AppDataDir			 0.00% (0/1)
 github.com/conformal/btcutil/address.go	 AddressPubKey.SetFormat	 0.00% (0/1)
-github.com/conformal/btcutil/address.go	 AddressPubKey.Format		 0.00% (0/1)
+github.com/conformal/btcutil		 ------------------------------- 78.89% (299/379)
-github.com/conformal/btcutil		 ------------------------------- 78.78% (297/377)