add MarshalJSON and UnmarshalJSON to BitArray (#200)

See CHANGELOG

CHANGELOG.md

@@ -1,13 +1,20 @@
 # Changelog
 
-## 0.8.2 (April 12th, 2018)
+## 0.8.2 (April 23rd, 2018)
 
 FEATURES:
 
+ - [pubsub] TagMap, NewTagMap
+ - [merkle] SimpleProofsFromMap()
+ - [common] IsASCIIText()
+ - [common] PrefixEndBytes // e.g. increment or nil
+ - [common] BitArray.MarshalJSON/.UnmarshalJSON
+ - [common] BitArray uses 'x' not 'X' for String() and above.
  - [db] DebugDB shows better colorized output
 
 BUG FIXES:
 
+ - [common] Fix TestParallelAbort nondeterministic failure #201/#202
  - [db] PrefixDB Iterator/ReverseIterator fixes
  - [db] DebugDB fixes
 

common/bit_array.go

@@ -3,6 +3,7 @@ package common
 import (
 	"encoding/binary"
 	"fmt"
+	"regexp"
 	"strings"
 	"sync"
 )
@@ -249,13 +250,14 @@ func (bA *BitArray) PickRandom() (int, bool) {
 	return 0, false
 }
 
+// String returns a string representation of BitArray: BA{<bit-string>},
+// where <bit-string> is a sequence of 'x' (1) and '_' (0).
+// The <bit-string> includes spaces and newlines to help people.
+// For a simple sequence of 'x' and '_' characters with no spaces or newlines,
+// see the MarshalJSON() method.
+// Example: "BA{_x_}" or "nil-BitArray" for nil.
 func (bA *BitArray) String() string {
-	if bA == nil {
+	return bA.StringIndented("")
-		return "nil-BitArray"
-	}
-	bA.mtx.Lock()
-	defer bA.mtx.Unlock()
-	return bA.stringIndented("")
 }
 
 func (bA *BitArray) StringIndented(indent string) string {
@@ -268,12 +270,11 @@ func (bA *BitArray) StringIndented(indent string) string {
 }
 
 func (bA *BitArray) stringIndented(indent string) string {
-
 	lines := []string{}
 	bits := ""
 	for i := 0; i < bA.Bits; i++ {
 		if bA.getIndex(i) {
-			bits += "X"
+			bits += "x"
 		} else {
 			bits += "_"
 		}
@@ -282,10 +283,10 @@ func (bA *BitArray) stringIndented(indent string) string {
 			bits = ""
 		}
 		if i%10 == 9 {
-			bits += " "
+			bits += indent
 		}
 		if i%50 == 49 {
-			bits += " "
+			bits += indent
 		}
 	}
 	if len(bits) > 0 {
@@ -320,3 +321,58 @@ func (bA *BitArray) Update(o *BitArray) {
 
 	copy(bA.Elems, o.Elems)
 }
+
+// MarshalJSON implements json.Marshaler interface by marshaling bit array
+// using a custom format: a string of '-' or 'x' where 'x' denotes the 1 bit.
+func (bA *BitArray) MarshalJSON() ([]byte, error) {
+	if bA == nil {
+		return []byte("null"), nil
+	}
+
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	bits := `"`
+	for i := 0; i < bA.Bits; i++ {
+		if bA.getIndex(i) {
+			bits += `x`
+		} else {
+			bits += `_`
+		}
+	}
+	bits += `"`
+	return []byte(bits), nil
+}
+
+var bitArrayJSONRegexp = regexp.MustCompile(`\A"([_x]*)"\z`)
+
+// UnmarshalJSON implements json.Unmarshaler interface by unmarshaling a custom
+// JSON description.
+func (bA *BitArray) UnmarshalJSON(bz []byte) error {
+	b := string(bz)
+	if b == "null" {
+		// This is required e.g. for encoding/json when decoding
+		// into a pointer with pre-allocated BitArray.
+		bA.Bits = 0
+		bA.Elems = nil
+		return nil
+	}
+
+	// Validate 'b'.
+	match := bitArrayJSONRegexp.FindStringSubmatch(b)
+	if match == nil {
+		return fmt.Errorf("BitArray in JSON should be a string of format %q but got %s", bitArrayJSONRegexp.String(), b)
+	}
+	bits := match[1]
+
+	// Construct new BitArray and copy over.
+	numBits := len(bits)
+	bA2 := NewBitArray(numBits)
+	for i := 0; i < numBits; i++ {
+		if bits[i] == 'x' {
+			bA2.SetIndex(i, true)
+		}
+	}
+	*bA = *bA2
+	return nil
+}

common/bit_array_test.go

@@ -2,8 +2,10 @@ package common
 
 import (
 	"bytes"
+	"encoding/json"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -210,8 +212,56 @@ func TestUpdateNeverPanics(t *testing.T) {
 }
 
 func TestNewBitArrayNeverCrashesOnNegatives(t *testing.T) {
-	bitList := []int{-127, -128, -1<<31}
+	bitList := []int{-127, -128, -1 << 31}
 	for _, bits := range bitList {
 		_ = NewBitArray(bits)
 	}
 }
+
+func TestJSONMarshalUnmarshal(t *testing.T) {
+
+	bA1 := NewBitArray(0)
+
+	bA2 := NewBitArray(1)
+
+	bA3 := NewBitArray(1)
+	bA3.SetIndex(0, true)
+
+	bA4 := NewBitArray(5)
+	bA4.SetIndex(0, true)
+	bA4.SetIndex(1, true)
+
+	testCases := []struct {
+		bA           *BitArray
+		marshalledBA string
+	}{
+		{nil, `null`},
+		{bA1, `null`},
+		{bA2, `"_"`},
+		{bA3, `"x"`},
+		{bA4, `"xx___"`},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.bA.String(), func(t *testing.T) {
+			bz, err := json.Marshal(tc.bA)
+			require.NoError(t, err)
+
+			assert.Equal(t, tc.marshalledBA, string(bz))
+
+			var unmarshalledBA *BitArray
+			err = json.Unmarshal(bz, &unmarshalledBA)
+			require.NoError(t, err)
+
+			if tc.bA == nil {
+				require.Nil(t, unmarshalledBA)
+			} else {
+				require.NotNil(t, unmarshalledBA)
+				assert.EqualValues(t, tc.bA.Bits, unmarshalledBA.Bits)
+				if assert.EqualValues(t, tc.bA.String(), unmarshalledBA.String()) {
+					assert.EqualValues(t, tc.bA.Elems, unmarshalledBA.Elems)
+				}
+			}
+		})
+	}
+}

common/string.go

@@ -57,3 +57,18 @@ func SplitAndTrim(s, sep, cutset string) []string {
 	}
 	return spl
 }
+
+// Returns true if s is a non-empty printable non-tab ascii character.
+func IsASCIIText(s string) bool {
+	if len(s) == 0 {
+		return false
+	}
+	for _, b := range []byte(s) {
+		if 32 <= b && b <= 126 {
+			// good
+		} else {
+			return false
+		}
+	}
+	return true
+}

common/string_test.go

@@ -49,3 +49,18 @@ func TestSplitAndTrim(t *testing.T) {
 		assert.Equal(t, tc.expected, SplitAndTrim(tc.s, tc.sep, tc.cutset), "%s", tc.s)
 	}
 }
+
+func TestIsASCIIText(t *testing.T) {
+	notASCIIText := []string{
+		"", "\xC2", "\xC2\xA2", "\xFF", "\x80", "\xF0", "\n", "\t",
+	}
+	for _, v := range notASCIIText {
+		assert.False(t, IsHex(v), "%q is not ascii-text", v)
+	}
+	asciiText := []string{
+		" ", ".", "x", "$", "_", "abcdefg;", "-", "0x00", "0", "123",
+	}
+	for _, v := range asciiText {
+		assert.True(t, IsASCIIText(v), "%q is ascii-text", v)
+	}
+}