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![Zichang Guo](/assets/img/avatar_default.png)
Change-Id: I9efc87ca83be6272005bf395b63495a8a99e4a1f Reviewed-on: https://dart-review.googlesource.com/c/87985 Commit-Queue: Zichang Guo <zichangguo@google.com> Reviewed-by: Siva Annamalai <asiva@google.com>
307 lines
11 KiB
Dart
307 lines
11 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// part of "core_patch.dart";
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/// VM implementation of int.
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@patch
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class int {
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@patch
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const factory int.fromEnvironment(String name, {int defaultValue})
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native "Integer_fromEnvironment";
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int _bitAndFromSmi(_Smi other);
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int _bitAndFromInteger(int other);
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int _bitOrFromInteger(int other);
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int _bitXorFromInteger(int other);
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int _shrFromInteger(int other);
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int _shlFromInteger(int other);
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static int _tryParseSmi(String str, int first, int last) {
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assert(first <= last);
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var ix = first;
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var sign = 1;
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var c = str.codeUnitAt(ix);
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// Check for leading '+' or '-'.
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if ((c == 0x2b) || (c == 0x2d)) {
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ix++;
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sign = 0x2c - c; // -1 for '-', +1 for '+'.
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if (ix > last) {
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return null; // Empty.
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}
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}
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var smiLimit = is64Bit ? 18 : 9;
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if ((last - ix) >= smiLimit) {
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return null; // May not fit into a Smi.
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}
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var result = 0;
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for (int i = ix; i <= last; i++) {
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var c = 0x30 ^ str.codeUnitAt(i);
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if (9 < c) {
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return null;
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}
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result = 10 * result + c;
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}
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return sign * result;
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}
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@patch
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static int parse(String source, {int radix, int onError(String source)}) {
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if (source == null) throw new ArgumentError("The source must not be null");
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if (source.isEmpty) {
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return _throwFormatException(onError, source, 0, radix, null);
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}
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if (radix == null || radix == 10) {
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// Try parsing immediately, without trimming whitespace.
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int result = _tryParseSmi(source, 0, source.length - 1);
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if (result != null) return result;
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} else if (radix < 2 || radix > 36) {
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throw new RangeError("Radix $radix not in range 2..36");
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}
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// Split here so improve odds of parse being inlined and the checks omitted.
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return _parse(source, radix, onError);
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}
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static int _parse(_StringBase source, int radix, onError) {
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int end = source._lastNonWhitespace() + 1;
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if (end == 0) {
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return _throwFormatException(onError, source, source.length, radix, null);
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}
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int start = source._firstNonWhitespace();
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int first = source.codeUnitAt(start);
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int sign = 1;
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if (first == 0x2b /* + */ || first == 0x2d /* - */) {
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sign = 0x2c - first; // -1 if '-', +1 if '+'.
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start++;
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if (start == end) {
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return _throwFormatException(onError, source, end, radix, null);
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}
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first = source.codeUnitAt(start);
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}
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if (radix == null) {
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// check for 0x prefix.
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int index = start;
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if (first == 0x30 /* 0 */) {
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index++;
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if (index == end) return 0;
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first = source.codeUnitAt(index);
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if ((first | 0x20) == 0x78 /* x */) {
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index++;
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if (index == end) {
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return _throwFormatException(onError, source, index, null, null);
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}
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return _parseRadix(source, 16, index, end, sign, sign > 0, onError);
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}
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}
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radix = 10;
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}
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return _parseRadix(source, radix, start, end, sign, false, onError);
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}
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@patch
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static int tryParse(String source, {int radix}) {
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if (source == null) throw new ArgumentError("The source must not be null");
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if (source.isEmpty) return null;
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if (radix == null || radix == 10) {
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// Try parsing immediately, without trimming whitespace.
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int result = _tryParseSmi(source, 0, source.length - 1);
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if (result != null) return result;
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} else if (radix < 2 || radix > 36) {
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throw new RangeError("Radix $radix not in range 2..36");
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}
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try {
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return _parse(source, radix, _kNull);
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} catch (e) {
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return null;
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}
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}
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static Null _kNull(_) => null;
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static int _throwFormatException(onError, source, index, radix, message) {
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if (onError != null) return onError(source);
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if (message != null) {
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throw new FormatException(message, source, index);
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}
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if (radix == null) {
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throw new FormatException("Invalid number", source, index);
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}
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throw new FormatException("Invalid radix-$radix number", source, index);
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}
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static int _parseRadix(String source, int radix, int start, int end, int sign,
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bool allowU64, onError) {
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int tableIndex = (radix - 2) * 4 + (is64Bit ? 2 : 0);
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int blockSize = _PARSE_LIMITS[tableIndex];
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int length = end - start;
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if (length <= blockSize) {
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_Smi smi = _parseBlock(source, radix, start, end);
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if (smi == null) {
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return _throwFormatException(onError, source, start, radix, null);
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}
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return sign * smi;
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}
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// Often cheaper than: int smallBlockSize = length % blockSize;
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// because digit count generally tends towards smaller. rather
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// than larger.
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int smallBlockSize = length;
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while (smallBlockSize >= blockSize) smallBlockSize -= blockSize;
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int result = 0;
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if (smallBlockSize > 0) {
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int blockEnd = start + smallBlockSize;
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_Smi smi = _parseBlock(source, radix, start, blockEnd);
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if (smi == null) {
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return _throwFormatException(onError, source, start, radix, null);
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}
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result = sign * smi;
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start = blockEnd;
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}
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int multiplier = _PARSE_LIMITS[tableIndex + 1];
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int positiveOverflowLimit = 0;
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int negativeOverflowLimit = 0;
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tableIndex = tableIndex << 1; // pre-multiply by 2 for simpler indexing
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positiveOverflowLimit = _int64OverflowLimits[tableIndex];
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if (positiveOverflowLimit == 0) {
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positiveOverflowLimit = _initInt64OverflowLimits(tableIndex, multiplier);
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}
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negativeOverflowLimit = _int64OverflowLimits[tableIndex + 1];
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int blockEnd = start + blockSize;
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do {
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_Smi smi = _parseBlock(source, radix, start, blockEnd);
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if (smi == null) {
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return _throwFormatException(onError, source, start, radix, null);
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}
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if (result >= positiveOverflowLimit) {
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if ((result > positiveOverflowLimit) ||
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(smi > _int64OverflowLimits[tableIndex + 2])) {
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// Although the unsigned overflow limits do not depend on the
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// platform, the multiplier and block size, which are used to
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// compute it, do.
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int X = is64Bit ? 1 : 0;
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if (allowU64 &&
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!(result >= _int64UnsignedOverflowLimits[X] &&
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(result > _int64UnsignedOverflowLimits[X] ||
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smi > _int64UnsignedSmiOverflowLimits[X])) &&
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blockEnd + blockSize > end) {
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return (result * multiplier) + smi;
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}
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return _throwFormatException(onError, source, null, radix,
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"Positive input exceeds the limit of integer");
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}
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} else if (result <= negativeOverflowLimit) {
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if ((result < negativeOverflowLimit) ||
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(smi > _int64OverflowLimits[tableIndex + 3])) {
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return _throwFormatException(onError, source, null, radix,
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"Negative input exceeds the limit of integer");
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}
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}
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result = (result * multiplier) + (sign * smi);
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start = blockEnd;
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blockEnd = start + blockSize;
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} while (blockEnd <= end);
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return result;
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}
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// Parse block of digits into a Smi.
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static _Smi _parseBlock(String source, int radix, int start, int end) {
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_Smi result = 0;
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if (radix <= 10) {
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for (int i = start; i < end; i++) {
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int digit = source.codeUnitAt(i) ^ 0x30;
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if (digit >= radix) return null;
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result = radix * result + digit;
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}
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} else {
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for (int i = start; i < end; i++) {
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int char = source.codeUnitAt(i);
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int digit = char ^ 0x30;
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if (digit > 9) {
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digit = (char | 0x20) - (0x61 - 10);
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if (digit < 10 || digit >= radix) return null;
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}
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result = radix * result + digit;
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}
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}
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return result;
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}
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// For each radix, 2-36, how many digits are guaranteed to fit in a smi,
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// and magnitude of such a block (radix ** digit-count).
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// 32-bit limit/multiplier at (radix - 2)*4, 64-bit limit at (radix-2)*4+2
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static const _PARSE_LIMITS = const [
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30, 1073741824, 62, 4611686018427387904, // radix: 2
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18, 387420489, 39, 4052555153018976267,
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15, 1073741824, 30, 1152921504606846976,
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12, 244140625, 26, 1490116119384765625, // radix: 5
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11, 362797056, 23, 789730223053602816,
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10, 282475249, 22, 3909821048582988049,
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10, 1073741824, 20, 1152921504606846976,
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9, 387420489, 19, 1350851717672992089,
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9, 1000000000, 18, 1000000000000000000, // radix: 10
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8, 214358881, 17, 505447028499293771,
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8, 429981696, 17, 2218611106740436992,
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8, 815730721, 16, 665416609183179841,
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7, 105413504, 16, 2177953337809371136,
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7, 170859375, 15, 437893890380859375, // radix: 15
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7, 268435456, 15, 1152921504606846976,
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7, 410338673, 15, 2862423051509815793,
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7, 612220032, 14, 374813367582081024,
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7, 893871739, 14, 799006685782884121,
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6, 64000000, 14, 1638400000000000000, // radix: 20
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6, 85766121, 14, 3243919932521508681,
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6, 113379904, 13, 282810057883082752,
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6, 148035889, 13, 504036361936467383,
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6, 191102976, 13, 876488338465357824,
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6, 244140625, 13, 1490116119384765625, // radix: 25
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6, 308915776, 13, 2481152873203736576,
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6, 387420489, 13, 4052555153018976267,
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6, 481890304, 12, 232218265089212416,
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6, 594823321, 12, 353814783205469041,
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6, 729000000, 12, 531441000000000000, // radix: 30
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6, 887503681, 12, 787662783788549761,
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6, 1073741824, 12, 1152921504606846976,
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5, 39135393, 12, 1667889514952984961,
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5, 45435424, 12, 2386420683693101056,
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5, 52521875, 12, 3379220508056640625, // radix: 35
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5, 60466176, 11, 131621703842267136,
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];
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static const _maxInt64 = 0x7fffffffffffffff;
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static const _minInt64 = -0x8000000000000000;
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static const _int64UnsignedOverflowLimits = const [0xfffffffff, 0xf];
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static const _int64UnsignedSmiOverflowLimits = const [
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0xfffffff,
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0xfffffffffffffff
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];
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/// Calculation of the expression
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///
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/// result = (result * multiplier) + (sign * smi)
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///
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/// in `_parseRadix()` may overflow 64-bit integers. In such case,
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/// `int.parse()` should stop with an error.
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///
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/// This table is lazily filled with int64 overflow limits for result and smi.
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/// For each multiplier from `_PARSE_LIMITS[tableIndex + 1]` this table
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/// contains
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///
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/// * `[tableIndex*2]` = positive limit for result
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/// * `[tableIndex*2 + 1]` = negative limit for result
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/// * `[tableIndex*2 + 2]` = limit for smi if result is exactly at positive limit
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/// * `[tableIndex*2 + 3]` = limit for smi if result is exactly at negative limit
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static final Int64List _int64OverflowLimits =
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new Int64List(_PARSE_LIMITS.length * 2);
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static int _initInt64OverflowLimits(int tableIndex, int multiplier) {
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_int64OverflowLimits[tableIndex] = _maxInt64 ~/ multiplier;
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_int64OverflowLimits[tableIndex + 1] = _minInt64 ~/ multiplier;
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_int64OverflowLimits[tableIndex + 2] = _maxInt64.remainder(multiplier);
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_int64OverflowLimits[tableIndex + 3] = -(_minInt64.remainder(multiplier));
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return _int64OverflowLimits[tableIndex];
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}
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}
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