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rune.jai
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rune.jai
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/*
* This source is adapted from the utf-8 library by Rob Pike and Ken Thompson.
* Copyright (c) 2002 by Lucent Technologies.
* Permission to use, copy, modify, and distribute this software for any
* purpose without fee is hereby granted, provided that this entire notice
* is included in all copies of any software which is or includes a copy
* or modification of this software and in all copies of the supporting
* documentation for such software.
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
*/
#scope_module
// @ToDo: Why is this signed!?
Rune :: s32;
UTFmax :: 4; /* maximum bytes per rune */
Runesync :: 0x80; /* cannot represent part of a UTF sequence (<) */
Runeself :: 0x80; /* rune and UTF sequences are the same (<) */
Runeerror :: 0xFFFD; /* decoding error in UTF */
Runemax : s32 : 0x10FFFF; /* maximum rune value */
// @ToDo: Move to unicode module?
rune_from_string :: (str: string) -> Rune, len: int {
/*
* one character sequence
* 00000-0007F => T1
*/
c: s32 = str[0];
if c < Tx {
return c, 1;
}
/*
* two character sequence
* 0080-07FF => T2 Tx
*/
if str.count < 2 return Runeerror, 0;
c1 := cast(s32)(str[1]) ^ Tx;
if c1 & Testx return Runeerror, 0;
if c < T3 {
if c < T2 return Runeerror, 0;
result := ((c << Bitx) | c1) & Rune2;
if result <= Rune1 return Runeerror, 0;
return result, 2;
}
/*
* three character sequence
* 0800-FFFF => T3 Tx Tx
*/
if str.count < 3 return Runeerror, 0;
c2 := cast(s32)(str[2]) ^ Tx;
if c2 & Testx return Runeerror, 0;
if c < T4 {
result := ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
if result <= Rune2 return Runeerror, 0;
return result, 3;
}
/*
* four character sequence (21-bit value)
* 10000-1FFFFF => T4 Tx Tx Tx
*/
if str.count < 4 return Runeerror, 0;
c3 := cast(s32)(str[3]) ^ Tx;
if c3 & Testx return Runeerror, 0;
if c < T5 {
result := ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
if result <= Rune3 return Runeerror, 0;
return result, 4;
}
return Runeerror, 0;
}
bytes_from_rune :: (rune: Rune) -> [UTFmax] u8, len: int {
/* Runes are signed, so convert to unsigned for range check. */
c := cast(u32)rune;
result: [UTFmax] u8;
/*
* one character sequence
* 00000-0007F => 00-7F
*/
if c <= Rune1 {
result[0] = cast(u8) c;
return result, 1;
}
/*
* two character sequence
* 0080-07FF => T2 Tx
*/
if c <= Rune2 {
result[0] = T2 | cast(u8)(c >> (1*Bitx));
result[1] = Tx | cast(u8)(c & Maskx);
return result, 2;
}
/*
* If the Rune is out of range, convert it to the error rune.
* Do this test here because the error rune encodes to three bytes.
* Doing it earlier would duplicate work, since an out of range
* Rune wouldn't have fit in one or two bytes.
*/
if c > cast(u32)Runemax {
c = Runeerror;
}
/*
* three character sequence
* 0800-FFFF => T3 Tx Tx
*/
if c <= Rune3 {
result[0] = T3 | cast(u8)(c >> (2*Bitx));
result[1] = Tx | cast(u8)((c >> (1*Bitx)) & Maskx);
result[2] = Tx | cast(u8)(c & Maskx);
return result, 3;
}
/*
* four character sequence (21-bit value)
* 10000-1FFFFF => T4 Tx Tx Tx
*/
result[0] = T4 | cast(u8)(c >> (3*Bitx));
result[1] = Tx | cast(u8)((c >> (2*Bitx)) & Maskx);
result[2] = Tx | cast(u8)((c >> (1*Bitx)) & Maskx);
result[3] = Tx | cast(u8)(c & Maskx);
return result, 4;
}
string_from_runes :: (runes: [] Rune) -> string {
builder: String_Builder;
defer free_buffers(*builder);
for runes {
bytes, len := bytes_from_rune(it);
append(*builder, bytes.data, len);
}
return builder_to_string(*builder);
}
#scope_file
Bit1 :: 7;
Bitx :: 6;
Bit2 :: 5;
Bit3 :: 4;
Bit4 :: 3;
Bit5 :: 2;
T1 : u8 : 0b0000_0000;
Tx : u8 : 0b1000_0000;
T2 : u8 : 0b1100_0000;
T3 : u8 : 0b1110_0000;
T4 : u8 : 0b1111_0000;
T5 : u8 : 0b1111_1000;
Rune1 :: 0b0000_0000_0111_1111;
Rune2 :: 0b0000_0111_1111_1111;
Rune3 :: 0b1111_1111_1111_1111;
Rune4 :: 0b0001_1111_1111_1111_1111_1111;
Maskx : u8 : 0b0011_1111;
Testx : u8 : 0b1100_0000;