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8357289: Break down the String constructor into smaller methods
Reviewed-by: liach, rriggs
This commit is contained in:
Shaojin Wen
parent
ecd2d83096
commit
839cede1a4
@ -553,135 +553,125 @@ public final class String
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* disambiguate it against other similar methods of this class.
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*/
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private String(Charset charset, byte[] bytes, int offset, int length) {
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String str;
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if (length == 0) {
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this.value = "".value;
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this.coder = "".coder;
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str = "";
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} else if (charset == UTF_8.INSTANCE) {
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if (COMPACT_STRINGS) {
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int dp = StringCoding.countPositives(bytes, offset, length);
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if (dp == length) {
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this.value = Arrays.copyOfRange(bytes, offset, offset + length);
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this.coder = LATIN1;
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return;
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str = utf8(bytes, offset, length);
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} else if (charset == ISO_8859_1.INSTANCE) {
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str = iso88591(bytes, offset, length);
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} else if (charset == US_ASCII.INSTANCE) {
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str = ascii(bytes, offset, length);
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} else {
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str = decode(charset, bytes, offset, length);
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}
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this(str);
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}
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private static String utf8(byte[] bytes, int offset, int length) {
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if (COMPACT_STRINGS) {
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int dp = StringCoding.countPositives(bytes, offset, length);
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if (dp == length) {
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return new String(Arrays.copyOfRange(bytes, offset, offset + length), LATIN1);
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}
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// Decode with a stable copy, to be the result if the decoded length is the same
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byte[] latin1 = Arrays.copyOfRange(bytes, offset, offset + length);
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int sp = dp; // first dp bytes are already in the copy
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while (sp < length) {
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int b1 = latin1[sp++];
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if (b1 >= 0) {
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latin1[dp++] = (byte) b1;
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continue;
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}
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// Decode with a stable copy, to be the result if the decoded length is the same
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byte[] latin1 = Arrays.copyOfRange(bytes, offset, offset + length);
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int sp = dp; // first dp bytes are already in the copy
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while (sp < length) {
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int b1 = latin1[sp++];
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if (b1 >= 0) {
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latin1[dp++] = (byte)b1;
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if ((b1 & 0xfe) == 0xc2 && sp < length) { // b1 either 0xc2 or 0xc3
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int b2 = latin1[sp];
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if (b2 < -64) { // continuation bytes are always negative values in the range -128 to -65
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latin1[dp++] = (byte) decode2(b1, b2);
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sp++;
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continue;
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}
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if ((b1 & 0xfe) == 0xc2 && sp < length) { // b1 either 0xc2 or 0xc3
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int b2 = latin1[sp];
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if (b2 < -64) { // continuation bytes are always negative values in the range -128 to -65
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latin1[dp++] = (byte)decode2(b1, b2);
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sp++;
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continue;
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}
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}
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// anything not a latin1, including the REPL
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// we have to go with the utf16
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sp--;
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break;
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}
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if (sp == length) {
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if (dp != latin1.length) {
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latin1 = Arrays.copyOf(latin1, dp);
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}
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this.value = latin1;
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this.coder = LATIN1;
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return;
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}
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byte[] utf16 = StringUTF16.newBytesFor(length);
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StringLatin1.inflate(latin1, 0, utf16, 0, dp);
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dp = decodeUTF8_UTF16(latin1, sp, length, utf16, dp, true);
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if (dp != length) {
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utf16 = Arrays.copyOf(utf16, dp << 1);
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}
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this.value = utf16;
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this.coder = UTF16;
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} else { // !COMPACT_STRINGS
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byte[] dst = StringUTF16.newBytesFor(length);
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int dp = decodeUTF8_UTF16(bytes, offset, offset + length, dst, 0, true);
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if (dp != length) {
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dst = Arrays.copyOf(dst, dp << 1);
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}
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this.value = dst;
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this.coder = UTF16;
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// anything not a latin1, including the REPL
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// we have to go with the utf16
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sp--;
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break;
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}
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} else if (charset == ISO_8859_1.INSTANCE) {
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if (COMPACT_STRINGS) {
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this.value = Arrays.copyOfRange(bytes, offset, offset + length);
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this.coder = LATIN1;
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} else {
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this.value = StringLatin1.inflate(bytes, offset, length);
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this.coder = UTF16;
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}
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} else if (charset == US_ASCII.INSTANCE) {
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if (COMPACT_STRINGS && !StringCoding.hasNegatives(bytes, offset, length)) {
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this.value = Arrays.copyOfRange(bytes, offset, offset + length);
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this.coder = LATIN1;
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} else {
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byte[] dst = StringUTF16.newBytesFor(length);
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int dp = 0;
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while (dp < length) {
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int b = bytes[offset++];
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StringUTF16.putChar(dst, dp++, (b >= 0) ? (char) b : REPL);
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if (sp == length) {
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if (dp != latin1.length) {
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latin1 = Arrays.copyOf(latin1, dp);
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}
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this.value = dst;
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this.coder = UTF16;
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return new String(latin1, LATIN1);
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}
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} else {
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// (1)We never cache the "external" cs, the only benefit of creating
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// an additional StringDe/Encoder object to wrap it is to share the
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// de/encode() method. These SD/E objects are short-lived, the young-gen
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// gc should be able to take care of them well. But the best approach
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// is still not to generate them if not really necessary.
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// (2)The defensive copy of the input byte/char[] has a big performance
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// impact, as well as the outgoing result byte/char[]. Need to do the
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// optimization check of (sm==null && classLoader0==null) for both.
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CharsetDecoder cd = charset.newDecoder();
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// ArrayDecoder fastpaths
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if (cd instanceof ArrayDecoder ad) {
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// ascii
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if (ad.isASCIICompatible() && !StringCoding.hasNegatives(bytes, offset, length)) {
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if (COMPACT_STRINGS) {
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this.value = Arrays.copyOfRange(bytes, offset, offset + length);
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this.coder = LATIN1;
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return;
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}
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this.value = StringLatin1.inflate(bytes, offset, length);
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this.coder = UTF16;
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return;
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}
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byte[] utf16 = StringUTF16.newBytesFor(length);
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StringLatin1.inflate(latin1, 0, utf16, 0, dp);
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dp = decodeUTF8_UTF16(latin1, sp, length, utf16, dp, true);
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if (dp != length) {
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utf16 = Arrays.copyOf(utf16, dp << 1);
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}
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return new String(utf16, UTF16);
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} else { // !COMPACT_STRINGS
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byte[] dst = StringUTF16.newBytesFor(length);
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int dp = decodeUTF8_UTF16(bytes, offset, offset + length, dst, 0, true);
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if (dp != length) {
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dst = Arrays.copyOf(dst, dp << 1);
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}
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return new String(dst, UTF16);
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}
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}
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private static String iso88591(byte[] bytes, int offset, int length) {
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if (COMPACT_STRINGS) {
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return new String(Arrays.copyOfRange(bytes, offset, offset + length), LATIN1);
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} else {
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return new String(StringLatin1.inflate(bytes, offset, length), UTF16);
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}
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}
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private static String ascii(byte[] bytes, int offset, int length) {
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if (COMPACT_STRINGS && !StringCoding.hasNegatives(bytes, offset, length)) {
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return new String(Arrays.copyOfRange(bytes, offset, offset + length), LATIN1);
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} else {
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byte[] dst = StringUTF16.newBytesFor(length);
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int dp = 0;
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while (dp < length) {
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int b = bytes[offset++];
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StringUTF16.putChar(dst, dp++, (b >= 0) ? (char) b : REPL);
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}
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return new String(dst, UTF16);
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}
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}
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private static String decode(Charset charset, byte[] bytes, int offset, int length) {
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// (1)We never cache the "external" cs, the only benefit of creating
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// an additional StringDe/Encoder object to wrap it is to share the
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// de/encode() method. These SD/E objects are short-lived, the young-gen
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// gc should be able to take care of them well. But the best approach
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// is still not to generate them if not really necessary.
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// (2)The defensive copy of the input byte/char[] has a big performance
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// impact, as well as the outgoing result byte/char[]. Need to do the
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// optimization check of (sm==null && classLoader0==null) for both.
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CharsetDecoder cd = charset.newDecoder();
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// ArrayDecoder fastpaths
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if (cd instanceof ArrayDecoder ad) {
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// ascii
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if (ad.isASCIICompatible() && !StringCoding.hasNegatives(bytes, offset, length)) {
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return iso88591(bytes, offset, length);
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} else {
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// fastpath for always Latin1 decodable single byte
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if (COMPACT_STRINGS && ad.isLatin1Decodable()) {
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byte[] dst = new byte[length];
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ad.decodeToLatin1(bytes, offset, length, dst);
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this.value = dst;
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this.coder = LATIN1;
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return;
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return new String(dst, LATIN1);
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} else {
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int en = scale(length, cd.maxCharsPerByte());
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cd.onMalformedInput(CodingErrorAction.REPLACE)
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.onUnmappableCharacter(CodingErrorAction.REPLACE);
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char[] ca = new char[en];
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int clen = ad.decode(bytes, offset, length, ca);
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return new String(ca, 0, clen, null);
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}
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int en = scale(length, cd.maxCharsPerByte());
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cd.onMalformedInput(CodingErrorAction.REPLACE)
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.onUnmappableCharacter(CodingErrorAction.REPLACE);
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char[] ca = new char[en];
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int clen = ad.decode(bytes, offset, length, ca);
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if (COMPACT_STRINGS) {
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byte[] val = StringUTF16.compress(ca, 0, clen);;
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this.coder = StringUTF16.coderFromArrayLen(val, clen);
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this.value = val;
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return;
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}
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coder = UTF16;
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value = StringUTF16.toBytes(ca, 0, clen);
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return;
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}
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} else {
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// decode using CharsetDecoder
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int en = scale(length, cd.maxCharsPerByte());
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cd.onMalformedInput(CodingErrorAction.REPLACE)
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@ -694,14 +684,7 @@ public final class String
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// Substitution is enabled, so this shouldn't happen
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throw new Error(x);
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}
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if (COMPACT_STRINGS) {
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byte[] val = StringUTF16.compress(ca, 0, caLen);
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this.coder = StringUTF16.coderFromArrayLen(val, caLen);
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this.value = val;
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return;
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}
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coder = UTF16;
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value = StringUTF16.toBytes(ca, 0, caLen);
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return new String(ca, 0, caLen, null);
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}
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}
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