trie: rework and document key encoding

'encode' and 'decode' are meaningless because the code deals with three
encodings. Document the encodings and give a name to each one.

trie/encoding_test.go

@@ -17,113 +17,88 @@
 package trie
 
 import (
-	"encoding/hex"
+	"bytes"
 	"testing"
-
-	checker "gopkg.in/check.v1"
 )
 
-func TestEncoding(t *testing.T) { checker.TestingT(t) }
-
-type TrieEncodingSuite struct{}
-
-var _ = checker.Suite(&TrieEncodingSuite{})
-
-func (s *TrieEncodingSuite) TestCompactEncode(c *checker.C) {
-	// even compact encode
-	test1 := []byte{1, 2, 3, 4, 5}
-	res1 := compactEncode(test1)
-	c.Assert(res1, checker.DeepEquals, []byte("\x11\x23\x45"))
-
-	// odd compact encode
-	test2 := []byte{0, 1, 2, 3, 4, 5}
-	res2 := compactEncode(test2)
-	c.Assert(res2, checker.DeepEquals, []byte("\x00\x01\x23\x45"))
-
-	//odd terminated compact encode
-	test3 := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
-	res3 := compactEncode(test3)
-	c.Assert(res3, checker.DeepEquals, []byte("\x20\x0f\x1c\xb8"))
-
-	// even terminated compact encode
-	test4 := []byte{15, 1, 12, 11, 8 /*term*/, 16}
-	res4 := compactEncode(test4)
-	c.Assert(res4, checker.DeepEquals, []byte("\x3f\x1c\xb8"))
-}
-
-func (s *TrieEncodingSuite) TestCompactHexDecode(c *checker.C) {
-	exp := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
-	res := compactHexDecode([]byte("verb"))
-	c.Assert(res, checker.DeepEquals, exp)
-}
-
-func (s *TrieEncodingSuite) TestCompactHexEncode(c *checker.C) {
-	exp := []byte("verb")
-	res := compactHexEncode([]byte{7, 6, 6, 5, 7, 2, 6, 2, 16})
-	c.Assert(res, checker.DeepEquals, exp)
-}
-
-func (s *TrieEncodingSuite) TestCompactDecode(c *checker.C) {
-	// odd compact decode
-	exp := []byte{1, 2, 3, 4, 5}
-	res := compactDecode([]byte("\x11\x23\x45"))
-	c.Assert(res, checker.DeepEquals, exp)
-
-	// even compact decode
-	exp = []byte{0, 1, 2, 3, 4, 5}
-	res = compactDecode([]byte("\x00\x01\x23\x45"))
-	c.Assert(res, checker.DeepEquals, exp)
-
-	// even terminated compact decode
-	exp = []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
-	res = compactDecode([]byte("\x20\x0f\x1c\xb8"))
-	c.Assert(res, checker.DeepEquals, exp)
-
-	// even terminated compact decode
-	exp = []byte{15, 1, 12, 11, 8 /*term*/, 16}
-	res = compactDecode([]byte("\x3f\x1c\xb8"))
-	c.Assert(res, checker.DeepEquals, exp)
-}
-
-func (s *TrieEncodingSuite) TestDecodeCompact(c *checker.C) {
-	exp, _ := hex.DecodeString("012345")
-	res := decodeCompact([]byte{0, 1, 2, 3, 4, 5})
-	c.Assert(res, checker.DeepEquals, exp)
-
-	exp, _ = hex.DecodeString("012345")
-	res = decodeCompact([]byte{0, 1, 2, 3, 4, 5, 16})
-	c.Assert(res, checker.DeepEquals, exp)
-
-	exp, _ = hex.DecodeString("abcdef")
-	res = decodeCompact([]byte{10, 11, 12, 13, 14, 15})
-	c.Assert(res, checker.DeepEquals, exp)
-}
-
-func BenchmarkCompactEncode(b *testing.B) {
-
-	testBytes := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
-	for i := 0; i < b.N; i++ {
-		compactEncode(testBytes)
+func TestHexCompact(t *testing.T) {
+	tests := []struct{ hex, compact []byte }{
+		// empty keys, with and without terminator.
+		{hex: []byte{}, compact: []byte{0x00}},
+		{hex: []byte{16}, compact: []byte{0x20}},
+		// odd length, no terminator
+		{hex: []byte{1, 2, 3, 4, 5}, compact: []byte{0x11, 0x23, 0x45}},
+		// even length, no terminator
+		{hex: []byte{0, 1, 2, 3, 4, 5}, compact: []byte{0x00, 0x01, 0x23, 0x45}},
+		// odd length, terminator
+		{hex: []byte{15, 1, 12, 11, 8, 16 /*term*/}, compact: []byte{0x3f, 0x1c, 0xb8}},
+		// even length, terminator
+		{hex: []byte{0, 15, 1, 12, 11, 8, 16 /*term*/}, compact: []byte{0x20, 0x0f, 0x1c, 0xb8}},
+	}
+	for _, test := range tests {
+		if c := hexToCompact(test.hex); !bytes.Equal(c, test.compact) {
+			t.Errorf("hexToCompact(%x) -> %x, want %x", test.hex, c, test.compact)
+		}
+		if h := compactToHex(test.compact); !bytes.Equal(h, test.hex) {
+			t.Errorf("compactToHex(%x) -> %x, want %x", test.compact, h, test.hex)
+		}
 	}
 }
 
-func BenchmarkCompactDecode(b *testing.B) {
-	testBytes := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
-	for i := 0; i < b.N; i++ {
-		compactDecode(testBytes)
+func TestHexKeybytes(t *testing.T) {
+	tests := []struct{ key, hexIn, hexOut []byte }{
+		{key: []byte{}, hexIn: []byte{16}, hexOut: []byte{16}},
+		{key: []byte{}, hexIn: []byte{}, hexOut: []byte{16}},
+		{
+			key:    []byte{0x12, 0x34, 0x56},
+			hexIn:  []byte{1, 2, 3, 4, 5, 6, 16},
+			hexOut: []byte{1, 2, 3, 4, 5, 6, 16},
+		},
+		{
+			key:    []byte{0x12, 0x34, 0x5},
+			hexIn:  []byte{1, 2, 3, 4, 0, 5, 16},
+			hexOut: []byte{1, 2, 3, 4, 0, 5, 16},
+		},
+		{
+			key:    []byte{0x12, 0x34, 0x56},
+			hexIn:  []byte{1, 2, 3, 4, 5, 6},
+			hexOut: []byte{1, 2, 3, 4, 5, 6, 16},
+		},
+	}
+	for _, test := range tests {
+		if h := keybytesToHex(test.key); !bytes.Equal(h, test.hexOut) {
+			t.Errorf("keybytesToHex(%x) -> %x, want %x", test.key, h, test.hexOut)
+		}
+		if k := hexToKeybytes(test.hexIn); !bytes.Equal(k, test.key) {
+			t.Errorf("hexToKeybytes(%x) -> %x, want %x", test.hexIn, k, test.key)
+		}
 	}
 }
 
-func BenchmarkCompactHexDecode(b *testing.B) {
+func BenchmarkHexToCompact(b *testing.B) {
+	testBytes := []byte{0, 15, 1, 12, 11, 8, 16 /*term*/}
+	for i := 0; i < b.N; i++ {
+		hexToCompact(testBytes)
+	}
+}
+
+func BenchmarkCompactToHex(b *testing.B) {
+	testBytes := []byte{0, 15, 1, 12, 11, 8, 16 /*term*/}
+	for i := 0; i < b.N; i++ {
+		compactToHex(testBytes)
+	}
+}
+
+func BenchmarkKeybytesToHex(b *testing.B) {
 	testBytes := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
 	for i := 0; i < b.N; i++ {
-		compactHexDecode(testBytes)
+		keybytesToHex(testBytes)
 	}
 }
 
-func BenchmarkDecodeCompact(b *testing.B) {
+func BenchmarkHexToKeybytes(b *testing.B) {
 	testBytes := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
 	for i := 0; i < b.N; i++ {
-		decodeCompact(testBytes)
+		hexToKeybytes(testBytes)
 	}
 }