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Optimize InetAddresses.hextetsToIPv6String to avoid unnecessary allocations during hex conversion. #8588

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Optimize InetAddresses.hextetsToIPv6String to avoid unnecessary allocations during hex conversion. #8588

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22 changes: 21 additions & 1 deletion android/guava/src/com/google/common/net/InetAddresses.java
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Original file line number Diff line number Diff line change
Expand Up @@ -532,6 +532,26 @@ private static void compressLongestRunOfZeroes(int[] hextets) {
}
}

private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();

private static void appendHex(StringBuilder sb, int val) {
if (val < 16) {
sb.append(HEX_DIGITS[val]);
} else if (val < 256) {
sb.append(HEX_DIGITS[val >> 4]);
sb.append(HEX_DIGITS[val & 0xF]);
} else if (val < 4096) {
sb.append(HEX_DIGITS[val >> 8]);
sb.append(HEX_DIGITS[(val >> 4) & 0xF]);
sb.append(HEX_DIGITS[val & 0xF]);
} else {
sb.append(HEX_DIGITS[val >> 12]);
sb.append(HEX_DIGITS[(val >> 8) & 0xF]);
sb.append(HEX_DIGITS[(val >> 4) & 0xF]);
sb.append(HEX_DIGITS[val & 0xF]);
}
}

/**
* Convert a list of hextets into a human-readable IPv6 address.
*
Expand All @@ -553,7 +573,7 @@ private static String hextetsToIPv6String(int[] hextets) {
if (lastWasNumber) {
buf.append(':');
}
buf.append(Integer.toHexString(hextets[i]));
appendHex(buf, hextets[i]);
} else {
if (i == 0 || lastWasNumber) {
buf.append("::");
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22 changes: 21 additions & 1 deletion guava/src/com/google/common/net/InetAddresses.java
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Original file line number Diff line number Diff line change
Expand Up @@ -532,6 +532,26 @@ private static void compressLongestRunOfZeroes(int[] hextets) {
}
}

private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();

private static void appendHex(StringBuilder sb, int val) {
if (val < 16) {
sb.append(HEX_DIGITS[val]);
} else if (val < 256) {
sb.append(HEX_DIGITS[val >> 4]);
sb.append(HEX_DIGITS[val & 0xF]);
} else if (val < 4096) {
sb.append(HEX_DIGITS[val >> 8]);
sb.append(HEX_DIGITS[(val >> 4) & 0xF]);
sb.append(HEX_DIGITS[val & 0xF]);
} else {
sb.append(HEX_DIGITS[val >> 12]);
sb.append(HEX_DIGITS[(val >> 8) & 0xF]);
sb.append(HEX_DIGITS[(val >> 4) & 0xF]);
sb.append(HEX_DIGITS[val & 0xF]);
}
}

/**
* Convert a list of hextets into a human-readable IPv6 address.
*
Expand All @@ -553,7 +573,7 @@ private static String hextetsToIPv6String(int[] hextets) {
if (lastWasNumber) {
buf.append(':');
}
buf.append(Integer.toHexString(hextets[i]));
appendHex(buf, hextets[i]);
} else {
if (i == 0 || lastWasNumber) {
buf.append("::");
Expand Down
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