ASCII optimizations for isPrintableValidUTF8.
This commit is contained in:
Ferdinand Majerech
parent
1c0702f3cd
commit
7409f3bbd9
|
|
@ -736,20 +736,110 @@ auto toUTF8(ubyte[] input, const UTFEncoding encoding) @safe pure nothrow
|
|||
return result;
|
||||
}
|
||||
|
||||
/// Determine if all characters (code points, not bytes) in a string are printable,
|
||||
/// except for one or more trailing zeroes.
|
||||
///
|
||||
/// Params:
|
||||
///
|
||||
/// chars =
|
||||
bool isPrintableValidUTF8(const char[] chars) @safe pure nothrow @nogc
|
||||
/// Determine if all characters (code points, not bytes) in a string are printable.
|
||||
bool isPrintableValidUTF8(const char[] chars) @trusted pure nothrow @nogc
|
||||
{
|
||||
for(size_t b = 0; b < chars.length;)
|
||||
// This is oversized (only 128 entries are necessary) simply because having 256
|
||||
// entries improves performance... for some reason (alignment?)
|
||||
bool[256] printable = [false, false, false, false, false, false, false, false,
|
||||
false, true, true, false, false, true, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
true, true, true, true, true, true, true, true,
|
||||
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false,
|
||||
false, false, false, false, false, false, false, false];
|
||||
|
||||
for(size_t index = 0; index < chars.length;)
|
||||
{
|
||||
const dchar c = chars[b] < 0x80 ? chars[b++] : decodeValidUTF8NoGC(chars, b);
|
||||
if(!((c == 0x09 || c == 0x0A || c == 0x0D || c == 0x85) ||
|
||||
(c >= 0x20 && c <= 0x7E) ||
|
||||
(c >= 0xA0 && c <= '\uD7FF') ||
|
||||
// Fast path for ASCII.
|
||||
// Both this while() block and the if() block below it are optimized, unrolled
|
||||
// versions of the for() block below them; the while()/if() block could be
|
||||
// removed without affecting logic, but both help increase performance.
|
||||
size_t asciiCount = countASCII(chars[index .. $]);
|
||||
// 8 ASCII iterations unrolled, looping while there are at most 8 ASCII chars.
|
||||
while(asciiCount > 8)
|
||||
{
|
||||
const dchar b0 = chars[index];
|
||||
const dchar b1 = chars[index + 1];
|
||||
const dchar b2 = chars[index + 2];
|
||||
const dchar b3 = chars[index + 3];
|
||||
const dchar b4 = chars[index + 4];
|
||||
const dchar b5 = chars[index + 5];
|
||||
const dchar b6 = chars[index + 6];
|
||||
const dchar b7 = chars[index + 7];
|
||||
|
||||
index += 8;
|
||||
asciiCount -= 8;
|
||||
|
||||
const all = printable[b0] & printable[b1] & printable[b2] & printable[b3] &
|
||||
printable[b4] & printable[b5] & printable[b6] & printable[b1];
|
||||
if(!all)
|
||||
{
|
||||
return false;
|
||||
}
|
||||
}
|
||||
// 4 ASCII iterations unrolled
|
||||
if(asciiCount > 4)
|
||||
{
|
||||
const char b0 = chars[index];
|
||||
const char b1 = chars[index + 1];
|
||||
const char b2 = chars[index + 2];
|
||||
const char b3 = chars[index + 3];
|
||||
|
||||
index += 4;
|
||||
asciiCount -= 4;
|
||||
|
||||
if(!printable[b0]) { return false; }
|
||||
if(!printable[b1]) { return false; }
|
||||
if(!printable[b2]) { return false; }
|
||||
if(!printable[b3]) { return false; }
|
||||
}
|
||||
// Any remaining ASCII chars. This is really the only code needed to handle
|
||||
// ASCII, the above if() and while() blocks are just an optimization.
|
||||
for(; asciiCount > 0; --asciiCount)
|
||||
{
|
||||
const char b = chars[index];
|
||||
++index;
|
||||
if(b >= 0x20) { continue; }
|
||||
if(printable[b]) { continue; }
|
||||
return false;
|
||||
}
|
||||
|
||||
if(index == chars.length) { break; }
|
||||
|
||||
// Not ASCII, need to decode.
|
||||
const dchar c = decodeValidUTF8NoGC(chars, index);
|
||||
// We now c is not ASCII, so only check for printable non-ASCII chars.
|
||||
if(!(c == 0x85 || (c >= 0xA0 && c <= '\uD7FF') ||
|
||||
(c >= '\uE000' && c <= '\uFFFD')))
|
||||
{
|
||||
return false;
|
||||
|
|
|
|||
Loading…
Reference in a new issue