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BitString.cs
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1198 lines (1196 loc) · 48.9 KB
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// NpgsqlTypes\ArrayHandling.cs
//
// Author:
// Jon Hanna. (jon@hackcraft.net)
//
// Copyright (C) 2008 The Npgsql Development Team
// npgsql-general@gborg.postgresql.org
// http://gborg.postgresql.org/project/npgsql/projdisplay.php
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace NpgsqlTypes
{
/// <summary>
/// <para>Implements a bit string; a collection of zero or more bits which can each be 1 or 0.</para>
/// <para>BitString's behave as a list of bools, though like most strings and unlike most collections the position
/// tends to be of as much significance as the value.</para>
/// <para>BitStrings are often used as masks, and are commonly cast to and from other values.</para>
/// </summary>
public struct BitString : IList<bool>, IEquatable<BitString>, IComparable<BitString>, IComparable, IFormattable, IConvertible
{
/// <summary>
/// Represents the empty string.
/// </summary>
public static readonly BitString Empty = new BitString(new List<uint>(0), 0);
private readonly List<uint> _chunks;
private readonly int _lastChunkLen;
/// <summary>
/// Create a BitString from an enumeration of boolean values. The BitString will contain
/// those booleans in the order they came in.
/// </summary>
/// <param name="bits">The boolean values.</param>
public BitString(IEnumerable<bool> bits)
{
_chunks = new List<uint>();
int curChunkLen = 0;
uint curChunk = 0;
foreach(bool bit in bits)
{
curChunk = (curChunk << 1) | (bit ? 1u : 0u);
if(++curChunkLen == 32)
{
_chunks.Add(curChunk);
curChunk = 0;
curChunkLen = 0;
}
}
if(curChunkLen != 0)
_chunks.Add(curChunk << -curChunkLen);
_lastChunkLen = curChunkLen;
}
//Used for optimised internal creation. The last chunk must be zero'd at bits less significant than lastChunkLen or comparisons will fail.
private BitString(List<uint> chunks, int lastChunkLen)
{
_chunks = chunks;
_lastChunkLen = lastChunkLen;
}
/// <summary>
/// Creates a BitString filled with a given number of true or false values.
/// </summary>
/// <param name="value">The value to fill the string with.</param>
/// <param name="count">The number of bits to fill.</param>
public BitString(bool value, int count)
{
if(value)
{
_chunks = new List<uint>((count + 31) / 32);
for(int i = 0; i < count / 32; ++i)
_chunks.Add(0xFFFFFFFFu);
_chunks.Add(0xFFFFFFFFu << - count);
}
else
_chunks = new List<uint>(new uint[(count + 31) / 32]);
_lastChunkLen = count % 32;
}
/// <summary>
/// Creats a bitstring from a <see cref="System.String">string</see>.
/// <param name="str">The <see cref="System.String">string to copy from</see>.</param>
/// <seealso cref="Npgsql.BitString.Parse(System.String)"/>
/// </summary>
public BitString(string str)
{
BitString fromParse = Parse(str);
_chunks = fromParse._chunks;
_lastChunkLen = fromParse._lastChunkLen;
}
/// <summary>
/// Creates a single-bit element from a boolean value.
/// </summary>
/// <param name="boolean">The <see cref="System.Boolean">bool</see> value which determines whether
/// the bit is 1 or 0.</param>
public BitString(bool boolean)
:this(boolean, 1){}
/// <summary>
/// Creates a bitstring from an unsigned integer value. The string will be the shortest required to
/// contain the integer (e.g. 1 bit for 0 or 1, 2 for 2 or 3, 3 for 4-7, and so on).
/// </summary>
/// <param name="integer">The <see cref="System.UInt32">integer</see>.</param>
/// <remarks>This method is not CLS Compliant, and may not be available to some languages.</remarks>
[CLSCompliant(false)]
public BitString(uint integer)
{
int bitCount = 32;
while(bitCount >= 1 && (integer & 0x80000000u) == 0)
{
integer <<= 1;
--bitCount;
}
_chunks = new List<uint>(1);
_chunks.Add(integer);
_lastChunkLen = bitCount;
}
/// <summary>
/// Creates a bitstring from an integer value. The string will be the shortest required to
/// contain the integer (e.g. 1 bit for 0 or 1, 2 for 2 or 3, 3 for 4-7, and so on).
/// </summary>
/// <param name="integer">The <see cref="System.Int32">integer</see>.</param>
public BitString(int integer)
:this((uint)integer){}
private IEnumerable<uint> AllChunksButLast
{
get
{
if(_chunks.Count > 1)
return _chunks.GetRange(1, _chunks.Count - 1);
else
return new uint[]{};
}
}
private IEnumerable<uint> EnumChunks(bool includeLast)
{
return includeLast ? _chunks : AllChunksButLast;
}
/// <summary>
/// The length of the string.
/// </summary>
public int Length
{
get
{
return (_chunks.Count - (_lastChunkLen == 0 ? 0 : 1)) * 32 + _lastChunkLen;
}
}
/// <summary>
/// Retrieves the value of the bit at the given index.
/// </summary>
public bool this[int index]
{
get
{
if(index < 0 || index >= Length)
throw new ArgumentOutOfRangeException();
return (_chunks[index / 32] & (1 << (31 - index % 32))) != 0;
}
}
bool IList<bool>.this[int idx]
{
get
{
return this[idx];
}
set
{
throw new NotSupportedException();
}
}
int ICollection<bool>.Count
{
get
{
return Length;
}
}
bool ICollection<bool>.IsReadOnly
{
get
{
return true;
}
}
/// <summary>
/// Finds the first instance of a given value
/// </summary>
/// <param name="item">The value - whether true or false - to search for.</param>
/// <returns>The index of the value found, or -1 if none are present.</returns>
public int IndexOf(bool item)
{
if(item)
{
for(int chunkCount = 0; chunkCount != _chunks.Count; ++chunkCount)
{
if(_chunks[chunkCount] != 0)
{
uint chunk = _chunks[chunkCount];
for(int i = 0; i != 32; ++i)
{
if((chunkCount & (0x80000000u >> i)) != 0)
{
return chunkCount * 32 + i;
}
}
}
}
}
else
{
for(int chunkCount = 0; chunkCount != _chunks.Count; ++chunkCount)
{
if(_chunks[chunkCount] != 0xFFFFFFFFu)
{
uint chunk = _chunks[chunkCount];
for(int i = 0; i != 32; ++i)
{
if((~chunkCount & (0x80000000u >> i)) != 0)
{
int ret = chunkCount * 32 + i;
return ret < Length ? ret : -1;
}
}
}
}
}
return -1;
}
void IList<bool>.Insert(int index, bool item)
{
throw new NotSupportedException();
}
void IList<bool>.RemoveAt(int index)
{
throw new NotSupportedException();
}
void ICollection<bool>.Add(bool item)
{
throw new NotSupportedException();
}
void ICollection<bool>.Clear()
{
throw new NotSupportedException();
}
/// <summary>
/// True if there is at least one bit with the value looked for.
/// </summary>
/// <param name="item">The value - true or false - to detect.</param>
/// <returns>True if at least one bit was the same as item, false otherwise.</returns>
public bool Contains(bool item)
{
foreach(uint chunk in EnumChunks(item))//because last chunk is zero-filled in unused portion, it is safe to check it if searching for true
if(item && (chunk != 0) || !item && chunk != 0xFFFFFFFFu)
return true;
return !item && (_chunks[_chunks.Count - 1] & (0xFFFFFFFFu >> _lastChunkLen)) != 0;
}
/// <summary>
/// Copies the bitstring to an array of bools.
/// </summary>
/// <param name="array">The <see cref="System.Boolean">boolean</see> array to copy to.</param>
/// <param name="arrayIndex">The index in the array to start copying from.</param>
public void CopyTo(bool[] array, int arrayIndex)
{
if(array == null)
throw new ArgumentNullException();
if(arrayIndex < 0)
throw new ArgumentOutOfRangeException();
if(array.Rank != 1
|| arrayIndex >= array.Length
|| arrayIndex + Length > array.Length)
throw new ArgumentException();
foreach(bool bit in this)
array[arrayIndex++] = bit;
}
bool ICollection<bool>.Remove(bool item)
{
throw new NotSupportedException();
}
/// <summary>
/// Returns an enumerator that enumerates through the string.
/// </summary>
/// <returns>The enumerator.</returns>
public IEnumerator<bool> GetEnumerator()
{
if(_chunks.Count != 0)
{
foreach(uint chunk in EnumChunks(_lastChunkLen == 0))
for(int i = 31; i != -1; --i)
yield return (chunk & (1u << i)) != 0;
uint lastChunk = _chunks[_chunks.Count - 1];
for(int i = 31; i != 31 - _lastChunkLen; --i)
yield return (lastChunk & (1u << i)) != 0;
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
/// <summary>
/// Creats a bitstring by concatenating another onto this one.
/// </summary>
/// <param name="append">The string to append to this one.</param>
/// <returns>The combined strings.</returns>
public BitString Concat(BitString append)
{
if(Length == 0)
return append;
else if(append.Length == 0)
return this;
else if(_lastChunkLen == 0)//Not only more efficient case with special handling, but also reasonably likely to appear in real use quite often.
{
List<uint> chunks = new List<uint>(_chunks);//Note that this copies, doesn't share.
chunks.AddRange(append._chunks);
return new BitString(chunks, append._lastChunkLen);
}
else
{
List<uint> chunks = new List<uint>(AllChunksButLast);
chunks.Add(_chunks[_chunks.Count - 1] | (append._chunks[0] >> _lastChunkLen));
for(int idx = 1; idx != append._chunks.Count; ++idx)
{
chunks.Add((append._chunks[idx - 1] << -_lastChunkLen) | (append._chunks[idx] >> _lastChunkLen));
}
chunks.Add(append._chunks[append._chunks.Count - 1] << -_lastChunkLen);
while(chunks.Count > (Length + append.Length + 31) / 32)
chunks.RemoveAt(chunks.Count - 1);
return new BitString(chunks, (_lastChunkLen + append._lastChunkLen) % 32);
}
}
/// <summary>
/// Returns a substring of this string.
/// </summary>
/// <param name="start">The position to start from, must be between 0 and the length of the string.</param>
/// <param name="length">The length of the string to return, must be greater than zero, and may not be
/// so large that the start + length exceeds the bounds of this instance.</param>
/// <returns>The Bitstring identified</returns>
public BitString Substring(int start, int length)
{
if(start < 0 || length < 0 || start + length > Length)
throw new ArgumentOutOfRangeException();
else if(length == 0)
return Empty;
else if(start == 0 && length == Length)
return this;
else if(start % 32 == 0)
{
List<uint> chunks = _chunks.GetRange(start / 32, (length + 31) / 32);
if(length % 32 != 0)
chunks[chunks.Count - 1] = chunks[chunks.Count -1] & (0xFFFFFFFFu << -length);
return new BitString(chunks, length % 32);
}
else
{
List<uint> chunks = new List<uint>();
for(int i = start / 32 + 1; i < (start + length) / 32 + 1; ++i)
chunks.Add((_chunks[i - 1] << start) | (_chunks[i] >> -start));
if(length % 32 != 0 && chunks.Count < length / 32 + 1)
chunks.Add((_chunks[(start + length - 1) / 32] << start) & (0xFFFFFFFFu << -length));
return new BitString(chunks, length % 32);
}
}
/// <summary>
/// Returns a substring of this string.
/// </summary>
/// <param name="start">The position to start from, must be between 0 and the length of the string,
/// the rest of the string is returned.</param>
/// <returns>The Bitstring identified</returns>
public BitString Substring(int start)
{
return Substring(start, Length - start);
}
/// <summary>
/// A logical and between this string and another. The two strings must be the same length.
/// </summary>
/// <param name="operand">Another BitString to AND with this one.</param>
/// <returns>A bitstring with 1 where both BitStrings had 1 and 0 otherwise.</returns>
public BitString And(BitString operand)
{
if(_lastChunkLen != operand._lastChunkLen || _chunks.Count != operand._chunks.Count)
throw new ArgumentException("Cannot AND bitstrings of different sizes");
List<uint> chunks = new List<uint>(_chunks.Count);
for(int i = 0; i != _chunks.Count; ++i)
chunks.Add(_chunks[i] & operand._chunks[i]);
return new BitString(chunks, _lastChunkLen);
}
/// <summary>
/// A logical or between this string and another. The two strings must be the same length.
/// </summary>
/// <param name="operand">Another BitString to OR with this one.</param>
/// <returns>A bitstring with 1 where either BitString had 1 and 0 otherwise.</returns>
public BitString Or(BitString operand)
{
if(_lastChunkLen != operand._lastChunkLen || _chunks.Count != operand._chunks.Count)
throw new ArgumentException("Cannot OR bitstrings of different sizes");
List<uint> chunks = new List<uint>(_chunks.Count);
for(int i = 0; i != _chunks.Count; ++i)
chunks.Add(_chunks[i] | operand._chunks[i]);
return new BitString(chunks, _lastChunkLen);
}
/// <summary>
/// A logical xor between this string and another. The two strings must be the same length.
/// </summary>
/// <param name="operand">Another BitString to XOR with this one.</param>
/// <returns>A bitstring with 1 where one BitStrings and the other had 0,
/// and 0 where they both had 1 or both had 0.</returns>
public BitString Xor(BitString operand)
{
if(_lastChunkLen != operand._lastChunkLen || _chunks.Count != operand._chunks.Count)
throw new ArgumentException("Cannot XOR bitstrings of different sizes");
List<uint> chunks = new List<uint>(_chunks.Count);
for(int i = 0; i != _chunks.Count; ++i)
chunks.Add(_chunks[i] ^ operand._chunks[i]);
return new BitString(chunks, _lastChunkLen);
}
/// <summary>
/// A bitstring that is the logical inverse of this one.
/// </summary>
/// <returns>A bitstring of the same length as this with 1 where this has 0 and vice-versa.</returns>
public BitString Not()
{
List<uint> chunks = new List<uint>(_chunks.Count);
foreach(uint chunk in _chunks)
chunks.Add(~chunk);
chunks[chunks.Count - 1] = chunks[chunks.Count - 1] & (0xFFFFFFFFu << -_lastChunkLen);
return new BitString(chunks, _lastChunkLen);
}
/// <summary>
/// Shifts the string operand bits to the left, filling with zeros to produce a
/// string of the same length.
/// </summary>
/// <param name="operand">The number of bits to shift to the left.</param>
/// <returns>A left-shifted bitstring.</returns>
/// <remarks><para>The behaviour of LShift is closer to what one would expect from dealing
/// with PostgreSQL bit-strings than in using the same operations on integers in .NET</para>
/// <para>In particular, negative operands result in a right-shift, and operands greater than
/// the length of the string will shift it entirely, resulting in a zero-filled string.</para>
/// </remarks>
public BitString LShift(int operand)
{
if(_chunks.Count == 0)
return Empty;
else if(operand < 0)
return RShift(-operand);
else if(operand == 0)
return this;
else if(operand >= Length)
return new BitString(false, Length);
else if(operand % 32 == 0)
{
List<uint> chunks = _chunks.GetRange(operand / 32, (Length - operand) / 32);
chunks.AddRange(new uint[_chunks.Count - chunks.Count]);
return new BitString(chunks, _lastChunkLen);
}
else
{
List<uint> chunks = new List<uint>();
for(int idx = (operand + 31) / 32; idx != _chunks.Count; ++idx)
chunks.Add((_chunks[idx - 1] << operand) | (_chunks[idx] >> -operand));
chunks.Add(_chunks[_chunks.Count - 1] << operand);
chunks.AddRange(new uint[_chunks.Count - chunks.Count]);
return new BitString(chunks, _lastChunkLen);
}
}
/// <summary>
/// Shifts the string operand bits to the right, filling with zeros to produce a
/// string of the same length.
/// </summary>
/// <param name="operand">The number of bits to shift to the right.</param>
/// <returns>A right-shifted bitstring.</returns>
/// <remarks><para>The behaviour of RShift is closer to what one would expect from dealing
/// with PostgreSQL bit-strings than in using the same operations on integers in .NET</para>
/// <para>In particular, negative operands result in a left-shift, and operands greater than
/// the length of the string will shift it entirely, resulting in a zero-filled string. It also performs
/// a logical shift, rather than an arithmetic shift, so it always sets the vacated bit positions to zero
/// (like PostgreSQL and like .NET for unsigned integers but not for signed integers).</para>
/// </remarks>
public BitString RShift(int operand)
{
if(_chunks.Count == 0)
return Empty;
else if(operand < 0)
return LShift(-operand);
else if(operand == 0)
return this;
else if(operand >= Length)
return new BitString(false, Length);
else if(operand % 32 == 0)
{
List<uint> chunks = _chunks.GetRange(0, _chunks.Count - operand / 32);
chunks.InsertRange(0, new uint[_chunks.Count - chunks.Count]);
return new BitString(chunks, _lastChunkLen);
}
else
{
List<uint> chunks = new List<uint>();
chunks.Add(_chunks[0] >> operand);
for(int idx = 0; idx != (_chunks.Count - operand /32) - 1; ++idx)
chunks.Add((_chunks[idx] << -operand) | (_chunks[idx + 1] >> operand));
chunks.InsertRange(0, new uint[_chunks.Count - chunks.Count]);
return new BitString(chunks, _lastChunkLen);
}
}
/// <summary>
/// Returns true if the this string is identical to the argument passed.
/// </summary>
public bool Equals(BitString other)
{
if(null == (object)other)
return false;
if(ReferenceEquals(_chunks, other._chunks))//short cut on shallow copies
return true;
if(_lastChunkLen != other._lastChunkLen || _chunks.Count != other._chunks.Count)
return false;
for(int i = 0; i != _chunks.Count; ++i)
if(_chunks[i] != other._chunks[i])
return false;
return true;
}
/// <summary>
/// Compares two strings. Strings are compared as strings, so while 0 being less than 1 will
/// mean a comparison between two strings of the same size is the same as treating them as numbers,
/// in the case of two strings of differing lengths the comparison starts at the right-most (most significant)
/// bit, and if all bits of the shorter string are exhausted without finding a comparison, then the larger
/// string is deemed to be greater than the shorter (0010 is greater than 0001 but less than 00100).
/// </summary>
/// <param name="other">Another string to compare with this one.</param>
/// <returns>A value if the two strings are identical, an integer less
/// than zero if this is less than the argument, and an integer greater
/// than zero otherwise.</returns>
public int CompareTo(BitString other)
{
if(null == (object)other)
return 1;
int endAt = Math.Min(_chunks.Count, other._chunks.Count);
int cmp = 0;
for(int i = 0; i != endAt; ++i)
if((cmp = _chunks[i].CompareTo(other._chunks[i])) != 0)
return cmp;
return _lastChunkLen.CompareTo(other._lastChunkLen);
}
/// <summary>
/// Compares the string with another object.
/// </summary>
/// <param name="obj">The object to compare with.</param>
/// <returns>If the object is null then this string is considered greater. If the object is another BitString
/// then they are compared as in <see cref="CompareTo(Npgsql.BitString)">the explicit comparison for BitStrings</see>
/// in any other case a <see cref="System.ArgumentException"/> is thrown.</returns>
public int CompareTo(object obj)
{
if(null == obj)
return 1;
if(!(obj is BitString))
throw new ArgumentException();
return CompareTo((BitString)obj);
}
/// <summary>
/// Compares this BitString with an object for equality.
/// </summary>
public override bool Equals(object obj)
{
return obj is BitString && Equals((BitString)obj);
}
/// <summary>
/// Returns a code for use in hashing operations.
/// </summary>
public override int GetHashCode()
{
int ret = _lastChunkLen;
//The ideal amount to shift each value is one that would evenly spread it throughout
//the resultant bytes. Using the current result % 32 is essentially using a random value
//but one that will be the same on subsequent calls.
foreach(uint chunk in _chunks)
ret ^= Npgsql.PGUtil.RotateShift((int)chunk, ret % 32);
return ret;
}
private StringBuilder BFormatString()
{
StringBuilder sb = new StringBuilder();
foreach(bool bit in this)
sb.Append(bit ? '1' : '0');
return sb;
}
private StringBuilder XFormatString(bool upperCase, bool ignoreTrailingBits)
{
if(!ignoreTrailingBits && _lastChunkLen % 4 != 0)
throw new FormatException();
StringBuilder sb = new StringBuilder();
foreach(int chunk in _chunks)
sb.Append(chunk.ToString(upperCase ? "X8" : "x8"));
if(_lastChunkLen != 0)
sb.Length -= (32 - _lastChunkLen + 3) / 4;
return sb;
}
private static StringBuilder ZeroPad(StringBuilder str, int padTo)
{
int padBy = padTo - str.Length;
while(padBy-- > 0)
str.Insert(0, '0');
return str;
}
/// <summary>
/// Returns a string representation of the BitString.
/// </summary>
/// <param name="format">
/// A string which can contain a letter and optionally a number which sets a minimum size for the string
/// returned. In each case using the lower-case form of the letter will result in a lower-case string
/// being returned.
/// <list type="table">
/// <item>
/// <term>B</term>
/// <description>A string of 1s and 0s.</description>
/// </item>
/// <item>
/// <term>X</term>
/// <description>An hexadecimal string (will result in an error unless the string's length is divisible by 4).</description>
/// </item>
/// <item>
/// <term>G</term>
/// <description>A string of 1s and 0s in single-quotes preceded by 'B' (Postgres bit string literal syntax).</description>
/// </item>
/// <term>Y</term>
/// <description>An hexadecimal string in single-quotes preceded by 'X' (Postgres bit literal syntax, will result in an error unless the string's length is divisible by 4.</description>
/// </list>
/// <term>C</term>
/// <description>The format produced by format-string "Y" if legal, otherwise that produced by format-string "G".</description>
/// <term>E</term>
/// <description>The most compact safe representation for Postgres. If single bit will be either a 0 or a 1. Otherwise if it
/// can be that produce by format string "Y" it will, otherwise if there are less than 9bits in length it will be that
/// produced by format-string "G". For longer strings that cannot be represented in hexadecimal it will be a string
/// representing the first part of the string in format "Y" followed by the PostgreSQL concatenation operator, followed
/// by the final bits in the format "G". E.g. "X'13DCE'||B'110'"</description>
/// If format is empty or null, it is treated as if "B" had been passed (the default repreesentation, and that
/// generally used by PostgreSQL for display).
/// </param>
/// <returns>The formatted string.</returns>
public string ToString(string format)
{
format = string.IsNullOrEmpty(format) ? "B" : format.Trim();
int padTo = int.Parse("0" + format.Substring(1));
switch(format[0])
{
case 'b': case 'B':
return ZeroPad(BFormatString(), padTo).ToString();
case 'x':
return ZeroPad(XFormatString(false, false), padTo).ToString();
case 'X':
return ZeroPad(XFormatString(true, false), padTo).ToString();
case 'g':
return ZeroPad(BFormatString(), padTo).Insert(0, "b'").Append('\'').ToString();
case 'G':
return ZeroPad(BFormatString(), padTo).Insert(0, "B'").Append('\'').ToString();
case 'y':
return ZeroPad(XFormatString(false, false), padTo).Insert(0, "x'").Append('\'').ToString();
case 'Y':
return ZeroPad(XFormatString(true, false), padTo).Insert(0, "X'").Append('\'').ToString();
case 'c':
return ToString((_lastChunkLen %4 == 0 ? "y" : "g") + padTo.ToString());
case 'C':
return ToString((_lastChunkLen %4 == 0 ? "Y" : "G") + padTo.ToString());
case 'e':
return ToString("E" + padTo.ToString()).ToLowerInvariant();
case 'E':
if(_lastChunkLen == 1 && _chunks.Count == 1)
return (_chunks[0] & 0x80000000u) == 0 ? "0" : "1";//both safe in this case for all lengths, and allows for some backwards compatibility from threating bit(1) as if it were boolean.
else if(_lastChunkLen % 4 == 0)
return ToString("Y" + padTo.ToString());
else if(Length < 9)
return ToString("G" + padTo.ToString());
else
{
StringBuilder sb = XFormatString(true, true).Insert(0, "X'");
sb.Append("\'||B\'");
uint lastNibble = _chunks[_chunks.Count - 1] << (_lastChunkLen / 4 * 4);
for(int i = 0; i < _lastChunkLen % 4; ++i)
{
uint mask = 0x80000000u >> i;
sb.Append((lastNibble & mask) != 0 ? '1' : '0');
}
return sb.Append('\'').ToString();
}
default:
throw new FormatException();
}
}
/// <summary>
/// Returns a string representation for the Bitstring
/// </summary>
/// <returns>A string containing '0' and '1' characters.</returns>
public override string ToString()
{
return ToString("B");
}
/// <summary>
/// Returns the same string as <see cref="ToString(System.String)"/>. formatProvider is ignored.
/// </summary>
public string ToString(string format, IFormatProvider formatProvider)
{
return ToString(format);
}
private static IEnumerable<bool> ReadBinary(TextReader tr)
{
for(;;)
switch(tr.Peek())
{
case -1: case (int)'\'':
yield break;
case (int)'0':
tr.Read();
yield return false;
break;
case (int)'1':
tr.Read();
yield return true;
break;
default:
throw new FormatException();
}
}
private static IEnumerable<uint> ReadHexNibbles(TextReader tr)
{
for(;;)
switch(tr.Peek())
{
case -1: case (int)'\'':
yield break;
case (int)'0': case (int)'1': case (int)'2': case (int)'3':
case (int)'4': case (int)'5': case (int)'6': case (int)'7':
case (int)'8': case (int)'9':
yield return (uint)tr.Read() - '0';
break;
case (int)'a': case (int)'b': case (int)'c': case (int)'d':
case (int)'e': case (int)'f':
yield return (uint)tr.Read() - 'a' + 10;
break;
case (int)'A': case (int)'B': case (int)'C': case (int)'D':
case (int)'E': case (int)'F':
yield return (uint)tr.Read() - 'A' + 10;
break;
default:
throw new FormatException();
}
}
private static BitString Parse(TextReader tr)
{
List<BitString> parts = new List<BitString>();
for(;;)
switch(tr.Peek())
{
case (int)'0': case (int)'1':
parts.Add(new BitString(ReadBinary(tr)));
break;
case (int)'x': case (int)'X':
tr.Read();
if(tr.Read() != (int)'\'')
throw new FormatException();
int nibbleCount = 0;
uint currentChunk = 0;
List<uint> chunks = new List<uint>();
foreach(uint nibble in ReadHexNibbles(tr))
{
currentChunk = currentChunk << 4 | nibble;
if(++nibbleCount == 8)
{
chunks.Add(currentChunk);
nibbleCount = 0;
}
}
if(nibbleCount != 0)
chunks.Add(currentChunk << 32 - nibbleCount * 4);
parts.Add(new BitString(chunks, nibbleCount * 4));
break;
case (int)'\'': case (int)'b': case (int)'B': case (int)'|':
case (int)' ': case (int)'\n': case (int)'\r': case '\t':
tr.Read();
break;
case -1:
switch(parts.Count)
{
case 0:
return Empty;
case 1:
return parts[0];
default:
BitString accum = parts[0];
for(int i = 1; i != parts.Count; ++i)
accum = accum.Concat(parts[i]);
return accum;
}
default:
throw new FormatException();
}
}
/// <summary>
/// Parses a string to produce a BitString. Most formats that can be produced by
/// <see cref="ToString(System.String)"/> can be accepted, but hexadecimal
/// can be interpreted with the preceding X' to mark the following characters as
/// being hexadecimal rather than binary.
/// </summary>
public static BitString Parse(string text)
{
using(StringReader sr = new StringReader(text))
return Parse(sr);
}
/// <summary>
/// Performs a logical AND on the two operands.
/// </summary>
public static BitString operator&(BitString x, BitString y)
{
return x.And(y);
}
/// <summary>
/// Performs a logcial OR on the two operands.
/// </summary>
public static BitString operator|(BitString x, BitString y)
{
return x.Or(y);
}
/// <summary>
/// Perofrms a logical EXCLUSIVE-OR on the two operands
/// </summary>
public static BitString operator^(BitString x, BitString y)
{
return x.Xor(y);
}
/// <summary>
/// Performs a logical NOT on the operand.
/// </summary>
public static BitString operator~(BitString x)
{
return x.Not();
}
/// <summary>
/// Concatenates the operands.
/// </summary>
public static BitString operator+(BitString x, BitString y)
{
return x.Concat(y);
}
/// <summary>
/// Left-shifts the string BitString.
/// </summary>
public static BitString operator<<(BitString bs, int shift)
{
return bs.LShift(shift);
}
/// <summary>
/// Right-shifts the string BitString.
/// </summary>
public static BitString operator>>(BitString bs, int shift)
{
return bs.RShift(shift);
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator==(BitString x, BitString y)
{
return x.Equals(y);
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator!=(BitString x, BitString y)
{
return !x.Equals(y);
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator<(BitString x, BitString y)
{
return x.CompareTo(y) < 0;
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator>(BitString x, BitString y)
{
return x.CompareTo(y) > 0;
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator<=(BitString x, BitString y)
{
return x.CompareTo(y) <= 0;
}
/// <summary>
/// Compares the two operands.
/// </summary>
public static bool operator>=(BitString x, BitString y)
{
return x.CompareTo(y) >= 0;
}
public TypeCode GetTypeCode()
{
return TypeCode.Object;
}
public bool ToBoolean()
{
if(Length != 1)
throw new InvalidCastException();
return _chunks[0] != 0;
}
public bool ToBoolean(IFormatProvider provider)
{
return ToBoolean();
}
char IConvertible.ToChar(IFormatProvider provider)
{
//To a char in what character encoding?
//If we insist on UTF-8 as a reasonable choice for most modern code, what
//do we do with surrogate pairs?
//
//In all, there's no single reasonable approach to this.
throw new NotSupportedException();
}
[CLSCompliant(false)]
public sbyte ToSByte()
{
return (sbyte)ToByte();
}
[CLSCompliant(false)]
public sbyte ToSByte(IFormatProvider provider)
{
return ToSByte();
}
public byte ToByte()
{
if(_lastChunkLen > 8)
throw new InvalidCastException();
return (byte)(ToUInt32() & 0x000000FFu);
}
public byte ToByte(IFormatProvider provider)
{
return ToByte();
}
public short ToInt16()
{
return (short)ToUInt16();
}
public short ToInt16(IFormatProvider provider)
{
return ToInt16();
}
[CLSCompliant(false)]
public ushort ToUInt16()
{
if(_lastChunkLen > 16)
throw new InvalidCastException();
return (ushort)(ToUInt32() & 0x0000FFFFu);
}
[CLSCompliant(false)]
public ushort ToUInt16(IFormatProvider provider)
{
return ToUInt16();
}
public int ToInt32()
{
return (int)ToUInt32();
}
public int ToInt32(IFormatProvider provider)
{
return ToInt32();
}
[CLSCompliant(false)]
public uint ToUInt32()
{
switch(_chunks.Count)
{
case 0:
return 0;
case 1:
return _chunks[0] >> - _lastChunkLen;
default:
throw new InvalidCastException();
}
}
[CLSCompliant(false)]
public uint ToUInt32(IFormatProvider provider)
{
return ToUInt32();
}