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more improvements in cout/countUntil

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monarch dodra 2012-11-19 12:06:09 +01:00 • committed by unknown
parent 1b7db2de5e
commit 3dffa6c475
1 changed files with 42 additions and 12 deletions
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50
std/algorithm.d
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@ -4019,12 +4019,23 @@ ptrdiff_t countUntil(alias pred = "a == b", R1, R2)(R1 haystack, R2 needle)
if (isForwardRange!R1 && isForwardRange!R2 &&
is(typeof(binaryFun!pred(haystack.front, needle.front)) : bool))
{
//Note: This implementation does take narrow strings into consideration
typeof(return) result;
for (; !haystack.empty; ++result, haystack.popFront())
if (startsWith!pred(haystack.save, needle.save)) return result;
static if (hasLength!R1) //Note: String don't have length
{
//Delegate to find. Find is very efficient
//We save haystack, but we don't care for needle
auto r2 = find!pred(haystack.save, needle);
if (!r2.empty) return cast(typeof(return)) (haystack.length - r2.length);
}
else
{
//Default case, slower route doing startsWith iteration
for (; !haystack.empty; ++result, haystack.popFront())
if (startsWith!pred(haystack.save, needle.save)) return result;
}
static if (isInfinite!R1) assert(0); // @@@8804@@@
//Because of @@@8804@@@: Avoids both "unreachable code" or "no return statement"
static if (isInfinite!R1) assert(0);
else return -1;
}
/// ditto
@ -4069,6 +4080,8 @@ ptrdiff_t countUntil(alias pred, R)(R haystack)
typeof(return) i;
static if (isRandomAccessRange!R)
{
//Optimized RA implementation. Since we want to count *and* iterate at
//the same time, it is more efficient this way.
static if (hasLength!R)
{
auto len = cast(typeof(return)) haystack.length;
@ -4081,13 +4094,25 @@ ptrdiff_t countUntil(alias pred, R)(R haystack)
if (unaryFun!pred(haystack[i])) return i;
}
}
else //everything else (including narrow strings)
else static if (hasLength!R)
{
for ( ; !haystack.empty; ++i, haystack.popFront())
if (unaryFun!pred(haystack.front)) return i;
//For those odd ranges that have a length, but aren't RA.
//It is faster to quick find, and then compare the lengths
auto r2 = find!pred(haystack.save);
if (!r2.empty) return cast(typeof(return)) (haystack.length - r2.length);
}
else //Everything else
{
alias ElementType!R T; //For narrow strings forces dchar iteration
foreach (T elem; haystack)
{
if (unaryFun!pred(elem)) return i;
++i;
}
}
static if (isInfinite!R) assert(0); // @@@8804@@@
//Because of @@@8804@@@: Avoids both "unreachable code" or "no return statement"
static if (isInfinite!R) assert(0);
else return -1;
}
@ -5045,11 +5070,16 @@ size_t count(alias pred = "a == b", R1, R2)(R1 haystack, R2 needle)
{
enforce(!needle.empty, "Cannot count occurrences of an empty range");
static if (isInfinite!R2)
{
//Note: This is the special case of looking for an infinite inside a finite...
//"How many instances of the Fibonacci sequence can you count in [1, 2, 3]?" - "None."
return 0;
}
else
{
size_t result;
for (; findSkip!pred(haystack, needle.save); ++result)
//Note: haystack is not saved, because findskip is designed to modify it
for ( ; findSkip!pred(haystack, needle.save) ; ++result)
{}
return result;
}
@ -5069,7 +5099,7 @@ size_t count(alias pred = "true", R)(R haystack)
is(typeof(unaryFun!pred(haystack.front)) : bool))
{
size_t result;
alias ElementType!R T; //For narrow strings
alias ElementType!R T; //For narrow strings forces dchar iteration
foreach (T elem; haystack)
if (unaryFun!pred(elem)) ++result;
return result;