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improve ByteString lastIndexOf #2153

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51 changes: 50 additions & 1 deletion actor-tests/src/test/scala/org/apache/pekko/util/ByteStringSpec.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -852,7 +852,6 @@ class ByteStringSpec extends AnyWordSpec with Matchers with Checkers {
compact.indexOf('e'.toByte) should ===(3)
compact.indexOf('f'.toByte) should ===(4)
compact.indexOf('g'.toByte) should ===(5)

}
"indexOf (specialized) from offset" in {
ByteString.empty.indexOf(5.toByte, -1) should ===(-1)
Expand Down Expand Up @@ -1001,6 +1000,56 @@ class ByteStringSpec extends AnyWordSpec with Matchers with Checkers {
byteStringLong.indexOf('z', 2, 24) should ===(-1)
byteStringLong.indexOf('a', 2, 24) should ===(-1)
}
"lastIndexOf (specialized)" in {
ByteString.empty.lastIndexOf(5.toByte, -1) should ===(-1)
ByteString.empty.lastIndexOf(5.toByte, 0) should ===(-1)
ByteString.empty.lastIndexOf(5.toByte, 1) should ===(-1)
ByteString.empty.lastIndexOf(5.toByte) should ===(-1)
val byteString1 = ByteString1.fromString("abb")
byteString1.lastIndexOf('d'.toByte) should ===(-1)
byteString1.lastIndexOf('d'.toByte, -1) should ===(-1)
byteString1.lastIndexOf('d'.toByte, 4) should ===(-1)
byteString1.lastIndexOf('d'.toByte, 1) should ===(-1)
byteString1.lastIndexOf('d'.toByte, 0) should ===(-1)
byteString1.lastIndexOf('a'.toByte, -1) should ===(-1)
byteString1.lastIndexOf('a'.toByte) should ===(0)
byteString1.lastIndexOf('a'.toByte, 0) should ===(0)
byteString1.lastIndexOf('a'.toByte, 1) should ===(0)
byteString1.lastIndexOf('b'.toByte) should ===(2)
byteString1.lastIndexOf('b'.toByte, 2) should ===(2)
byteString1.lastIndexOf('b'.toByte, 1) should ===(1)
byteString1.lastIndexOf('b'.toByte, 0) should ===(-1)

val byteStrings = ByteStrings(ByteString1.fromString("abb"), ByteString1.fromString("efg"))
byteStrings.lastIndexOf('e'.toByte) should ===(3)
byteStrings.lastIndexOf('e'.toByte, 6) should ===(3)
byteStrings.lastIndexOf('e'.toByte, 4) should ===(3)
byteStrings.lastIndexOf('e'.toByte, 1) should ===(-1)
byteStrings.lastIndexOf('e'.toByte, 0) should ===(-1)
byteStrings.lastIndexOf('e'.toByte, -1) should ===(-1)

byteStrings.lastIndexOf('b'.toByte) should ===(2)
byteStrings.lastIndexOf('b'.toByte, 6) should ===(2)
byteStrings.lastIndexOf('b'.toByte, 4) should ===(2)
byteStrings.lastIndexOf('b'.toByte, 1) should ===(1)
byteStrings.lastIndexOf('b'.toByte, 0) should ===(-1)
byteStrings.lastIndexOf('b'.toByte, -1) should ===(-1)

val compact = byteStrings.compact
compact.lastIndexOf('e'.toByte) should ===(3)
compact.lastIndexOf('e'.toByte, 6) should ===(3)
compact.lastIndexOf('e'.toByte, 4) should ===(3)
compact.lastIndexOf('e'.toByte, 1) should ===(-1)
compact.lastIndexOf('e'.toByte, 0) should ===(-1)
compact.lastIndexOf('e'.toByte, -1) should ===(-1)

compact.lastIndexOf('b'.toByte) should ===(2)
compact.lastIndexOf('b'.toByte, 6) should ===(2)
compact.lastIndexOf('b'.toByte, 4) should ===(2)
compact.lastIndexOf('b'.toByte, 1) should ===(1)
compact.lastIndexOf('b'.toByte, 0) should ===(-1)
compact.lastIndexOf('b'.toByte, -1) should ===(-1)
}
"copyToArray" in {
val byteString = ByteString(1, 2) ++ ByteString(3) ++ ByteString(4)

Expand Down
139 changes: 138 additions & 1 deletion actor/src/main/scala/org/apache/pekko/util/ByteString.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -314,6 +314,32 @@ object ByteString {
else -1
}

override def lastIndexOf[B >: Byte](elem: B, end: Int): Int = {
if (end < 0) -1
else {
var found = -1
var i = math.min(end, length - 1)
while (i >= 0 && found == -1) {
if (bytes(i) == elem) found = i
i -= 1
}
found
}
}

override def lastIndexOf(elem: Byte, end: Int): Int = {
if (end < 0) -1
else {
var found = -1
var i = math.min(end, length - 1)
while (i >= 0 && found == -1) {
if (bytes(i) == elem) found = i
i -= 1
}
found
}
}

override def slice(from: Int, until: Int): ByteString =
if (from <= 0 && until >= length) this
else if (from >= length || until <= 0 || from >= until) ByteString.empty
Expand Down Expand Up @@ -554,7 +580,6 @@ object ByteString {
i += 1
}
-1

}

// the calling code already adds the startIndex so this method does not need to
Expand All @@ -575,6 +600,32 @@ object ByteString {
else -1
}

override def lastIndexOf[B >: Byte](elem: B, end: Int): Int = {
if (end < 0) -1
else {
var found = -1
var i = math.min(end, length - 1)
while (i >= 0 && found == -1) {
if (bytes(startIndex + i) == elem) found = i
i -= 1
}
found
}
}

override def lastIndexOf(elem: Byte, end: Int): Int = {
if (end < 0) -1
else {
var found = -1
var i = math.min(end, length - 1)
while (i >= 0 && found == -1) {
if (bytes(startIndex + i) == elem) found = i
i -= 1
}
found
}
}

override def copyToArray[B >: Byte](dest: Array[B], start: Int, len: Int): Int = {
// min of the bytes available to copy, bytes there is room for in dest and the requested number of bytes
val toCopy = math.min(math.min(len, length), dest.length - start)
Expand Down Expand Up @@ -895,6 +946,67 @@ object ByteString {
}
}

override def lastIndexOf[B >: Byte](elem: B, end: Int): Int = {
if (end < 0) -1
else {
val byteStringsLast = bytestrings.size - 1

@tailrec
def find(bsIdx: Int, relativeIndex: Int, len: Int): Int = {
if (bsIdx < 0) -1
else {
val bs = bytestrings(bsIdx)
val bsStartIndex = len - bs.length

if (relativeIndex < bsStartIndex || bs.isEmpty) {
if (bsIdx == 0) -1
else find(bsIdx - 1, relativeIndex, bsStartIndex)
} else {
val subIndexOf = bs.lastIndexOf(elem, relativeIndex)
if (subIndexOf < 0) {
if (bsIdx == 0) -1
else find(bsIdx - 1, relativeIndex, bsStartIndex)
} else subIndexOf + bsStartIndex
}
}
}

find(byteStringsLast, math.min(end, length), length)
}
}

override def lastIndexOf(elem: Byte, end: Int): Int = {
if (end < 0) -1
else {
if (end < 0) -1
else {
val byteStringsLast = bytestrings.size - 1

@tailrec
def find(bsIdx: Int, relativeIndex: Int, len: Int): Int = {
if (bsIdx < 0) -1
else {
val bs = bytestrings(bsIdx)
val bsStartIndex = len - bs.length

if (relativeIndex < bsStartIndex || bs.isEmpty) {
if (bsIdx == 0) -1
else find(bsIdx - 1, relativeIndex, bsStartIndex)
} else {
val subIndexOf = bs.lastIndexOf(elem, relativeIndex)
if (subIndexOf < 0) {
if (bsIdx == 0) -1
else find(bsIdx - 1, relativeIndex, bsStartIndex)
} else subIndexOf + bsStartIndex
}
}
}

find(byteStringsLast, math.min(end, length), length)
}
}
}

override def copyToArray[B >: Byte](dest: Array[B], start: Int, len: Int): Int = {
if (bytestrings.size == 1) bytestrings.head.copyToArray(dest, start, len)
else {
Expand Down Expand Up @@ -1056,6 +1168,31 @@ sealed abstract class ByteString
*/
def indexOf(elem: Byte): Int = indexOf(elem, 0)

/**
* Finds index of last occurrence of some byte in this ByteString before or at some end index.
*
* Similar to lastIndexOf, but it avoids boxing if the value is already a byte.
*
* @param elem the element value to search for.
* @param end the end index
* @return the index `<= end` of the last element of this ByteString that is equal (as determined by `==`)
* to `elem`, or `-1`, if none exists.
* @since 2.0.0
*/
def lastIndexOf(elem: Byte, end: Int): Int = lastIndexOf[Byte](elem, end)

/**
* Finds index of last occurrence of some byte in this ByteString.
*
* Similar to lastIndexOf, but it avoids boxing if the value is already a byte.
*
* @param elem the element value to search for.
* @return the index of the last element of this ByteString that is equal (as determined by `==`)
* to `elem`, or `-1`, if none exists.
* @since 2.0.0
*/
def lastIndexOf(elem: Byte): Int = lastIndexOf(elem, length - 1)

override def contains[B >: Byte](elem: B): Boolean = indexOf(elem, 0) != -1

/**
Expand Down