public static CodePoint Decode(ArrayAccessor buffer, Index index)
{
var i = index.index;
uint x = buffer[i++];
uint code = 0;
switch (index.count)
{
case 1:
return new CodePoint(x);
case 2:
code = x & 0b1_1111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return new CodePoint(code);
case 3:
code = x & 0b1111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return new CodePoint(code);
case 4:
code = x & 0b0111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return new CodePoint(code);
default:
throw new IndexOutOfRangeException();
}
}
public static CodePoint Decode(ArrayAccessor buffer, Index index)
{
var i = index.index;
uint x = buffer[i++];
uint code = 0;
switch (index.count)
{
case 1:
return(new CodePoint(x));
case 2:
code = x & 0b1_1111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return(new CodePoint(code));
case 3:
code = x & 0b1111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return(new CodePoint(code));
case 4:
code = x & 0b0111;
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[i++] & 0b0011_1111);
return(new CodePoint(code));
default:
throw new IndexOutOfRangeException();
}
}
public static int GetLength(ArrayAccessor buffer)
{
var count = 0;
for (int i = 0; i < buffer.Length; i++)
{
var x = buffer[i];
if ((x & 0b1100_0000) != 0b1000_0000)
count++;
}
return count;
}
public static int GetLength(ArrayAccessor buffer)
{
var count = 0;
for (int i = 0; i < buffer.Length; i++)
{
var x = buffer[i];
if ((x & 0b1100_0000) != 0b1000_0000)
{
count++;
}
}
return(count);
}
public static (CodePoint cp, byte count) TryDecode(ArrayAccessor buffer, int index)
{
if (index >= buffer.Length)
{
return(Constants.End);
}
uint code = buffer[index];
if (code < 0b1100_0000)
{
// ASCII 文字
return(new CodePoint(code), 1);
}
if (code < 0b1110_0000)
{
// 2バイト文字
if (index + 1 >= buffer.Length)
{
return(Constants.End);
}
code &= 0b1_1111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return(new CodePoint(code), 2);
}
if (code < 0b1111_0000)
{
// 3バイト文字
if (index + 2 >= buffer.Length)
{
return(Constants.End);
}
code &= 0b1111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return(new CodePoint(code), 3);
}
// 4バイト文字
if (index + 3 >= buffer.Length)
{
return(Constants.End);
}
code &= 0b0111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return(new CodePoint(code), 4);
}
public static byte TyrGetCount(ArrayAccessor buffer, int index)
{
if (index >= buffer.Length) return Constants.InvalidCount;
uint x = buffer[index];
var byteCount =
(x < 0b1100_0000U) ? (byte)1 :
(x < 0b1110_0000U) ? (byte)2 :
(x < 0b1111_0000U) ? (byte)3 :
(byte)4;
if (index + byteCount > buffer.Length) return Constants.InvalidCount;
return byteCount;
}
private static bool TryNext(ArrayAccessor buffer, ref int index, ref uint code)
{
if (index >= buffer.Length)
{
return(false);
}
var c = buffer[index++];
if ((c & 0b1100_0000) != 0b1000_0000)
{
return(false);
}
code = (code << 6) | (uint)(c & 0b0011_1111);
return(true);
}
public static byte TyrGetCount(ArrayAccessor buffer, int index)
{
if (index >= buffer.Length)
{
return(Constants.InvalidCount);
}
uint x = buffer[index];
var byteCount =
(x < 0b1100_0000U) ? (byte)1 :
(x < 0b1110_0000U) ? (byte)2 :
(x < 0b1111_0000U) ? (byte)3 :
(byte)4;
if (index + byteCount > buffer.Length)
{
return(Constants.InvalidCount);
}
return(byteCount);
}
public static (CodePoint cp, byte count) TryDecode(ArrayAccessor buffer, int index)
{
if (index >= buffer.Length) return Constants.End;
uint code = buffer[index];
if (code < 0b1100_0000)
{
// ASCII 文字
return (new CodePoint(code), 1);
}
if (code < 0b1110_0000)
{
// 2バイト文字
if (index + 1 >= buffer.Length) return Constants.End;
code &= 0b1_1111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return (new CodePoint(code), 2);
}
if (code < 0b1111_0000)
{
// 3バイト文字
if (index + 2 >= buffer.Length) return Constants.End;
code &= 0b1111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return (new CodePoint(code), 3);
}
// 4バイト文字
if (index + 3 >= buffer.Length) return Constants.End;
code &= 0b0111;
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
code = (code << 6) | (uint)(buffer[++index] & 0b0011_1111);
return (new CodePoint(code), 4);
}
public IndexEnumerable(ArrayAccessor buffer)
{
_buffer = buffer;
_i = default(Index);
}
public StringEnumerator(ArrayAccessor buffer)
{
_buffer = buffer;
_index = default(Index);
Current = default(CodePoint);
}
public String(byte[] encodedBytes)
{
_buffer = new ArrayAccessor(encodedBytes);
}
private static bool TryNext(ArrayAccessor buffer, ref int index, ref uint code)
{
if (index >= buffer.Length) return false;
var c = buffer[index++];
if ((c & 0b1100_0000) != 0b1000_0000) return false;
code = (code << 6) | (uint)(c & 0b0011_1111);
return true;
}