Merge pull request #4 from jf-tech/tests

bug fix: replace can be nil/empty

readers.go

@@ -49,6 +49,7 @@ type BytesReplacingReader struct {
 const defaultBufSize = int(4096)
 
 // NewBytesReplacingReader creates a new `*BytesReplacingReader`.
+// `search` cannot be nil/empty. `replace` can.
 func NewBytesReplacingReader(r io.Reader, search, replace []byte) *BytesReplacingReader {
 	return (&BytesReplacingReader{}).Reset(r, search, replace)
 }
@@ -60,24 +61,15 @@ func max(a, b int) int {
 	return b
 }
 
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 // Reset allows reuse of a previous allocated `*BytesReplacingReader` for buf allocation optimization.
+// `search` cannot be nil/empty. `replace` can.
 func (r *BytesReplacingReader) Reset(r1 io.Reader, search1, replace1 []byte) *BytesReplacingReader {
 	if r1 == nil {
 		panic("io.Reader cannot be nil")
 	}
 	if len(search1) == 0 {
 		panic("search token cannot be nil/empty")
 	}
-	if len(replace1) == 0 {
-		panic("replace token cannot be nil/empty")
-	}
 	r.r = r1
 	r.search = search1
 	r.searchLen = len(search1)
@@ -86,12 +78,19 @@ func (r *BytesReplacingReader) Reset(r1 io.Reader, search1, replace1 []byte) *By
 	r.lenDelta = r.replaceLen - r.searchLen // could be negative
 	r.err = nil
 	bufSize := max(defaultBufSize, max(r.searchLen, r.replaceLen))
-	if r.buf == nil || cap(r.buf) < bufSize {
+	if r.buf == nil || len(r.buf) < bufSize {
 		r.buf = make([]byte, bufSize)
 	}
 	r.buf0 = 0
 	r.buf1 = 0
-	r.max = min(cap(r.buf), (cap(r.buf)/r.replaceLen)*r.searchLen)
+	r.max = len(r.buf)
+	if r.searchLen < r.replaceLen {
+		// If len(search) < len(replace), then we have to assume the worst case:
+		// what's the max bound value such that if we have consecutive 'search' filling up
+		// the buf up to buf[:max], and all of them are placed with 'replace', and the final
+		// result won't end up exceed the len(buf)?
+		r.max = (len(r.buf) / r.replaceLen) * r.searchLen
+	}
 	return r
 }
 

readers_test.go

@@ -55,6 +55,13 @@ func TestBytesReplacingReader(t *testing.T) {
 			replace:  []byte{9},
 			expected: []byte{1, 9, 2, 3, 4, 5, 6, 7, 8},
 		},
+		{
+			name:     "strip out search, no replace",
+			input:    []byte{1, 2, 3, 2, 2, 3, 4, 2, 3, 2, 8},
+			search:   []byte{2, 3, 2},
+			replace:  []byte{},
+			expected: []byte{1, 2, 3, 4, 8},
+		},
 		{
 			name:     "len(replace) == len(search)",
 			input:    []byte{1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5},
@@ -85,9 +92,6 @@ func TestBytesReplacingReader(t *testing.T) {
 	assert.PanicsWithValue(t, "search token cannot be nil/empty", func() {
 		(&BytesReplacingReader{}).Reset(strings.NewReader("test"), nil, []byte("est"))
 	})
-	assert.PanicsWithValue(t, "replace token cannot be nil/empty", func() {
-		NewBytesReplacingReader(strings.NewReader("test"), []byte("est"), nil)
-	})
 }
 
 func createTestInput(length int, numTarget int) []byte {
@@ -151,7 +155,7 @@ func BenchmarkBytesReplacingReader_50KBLength_1000Targets(b *testing.B) {
 	}
 }
 
-func BenchmarkRegularReader_50KBLength_100Targets(b *testing.B) {
+func BenchmarkRegularReader_50KBLength_1000Targets(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		_, _ = ioutil.ReadAll(bytes.NewReader(testInput50KBLength1000Targets))
 	}