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Merge pull request #2986 from andralex/master

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skipOver: no unnecessary decoding
This commit is contained in:
Walter Bright 2015-02-16 18:19:11 -08:00
commit dd00f64095
1 changed files with 37 additions and 2 deletions
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39
std/algorithm/searching.d
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@ -2850,11 +2850,39 @@ true if the initial segment of $(D r1) matches $(D r2), and $(D r1) has been
advanced to the point past this segment; otherwise false, and $(D r1) is left
in its original position.
*/
bool skipOver(alias pred = "a == b", R1, R2)(ref R1 r1, R2 r2)
bool skipOver(R1, R2)(ref R1 r1, R2 r2)
if (isForwardRange!R1 && isInputRange!R2
&& is(typeof(r1.front == r2.front)))
{
static if (is(typeof(r1[0 .. $] == r2) : bool)
&& is(typeof(r2.length > r1.length) : bool)
&& is(typeof(r1 = r1[r2.length .. $])))
{
if (r2.length > r1.length || r1[0 .. r2.length] != r2)
{
return false;
}
r1 = r1[r2.length .. $];
return true;
}
else
{
return skipOver!((a, b) => a == b)(r1, r2);
}
}
/// Ditto
bool skipOver(alias pred, R1, R2)(ref R1 r1, R2 r2)
if (is(typeof(binaryFun!pred(r1.front, r2.front))) &&
isForwardRange!R1 &&
isInputRange!R2)
{
static if (hasLength!R1 && hasLength!R2)
{
// Shortcut opportunity!
if (r2.length > r1.length)
return false;
}
auto r = r1.save;
while (!r2.empty && !r.empty && binaryFun!pred(r.front, r2.front))
{
@ -2901,7 +2929,14 @@ true if the first element matches the given element according to the given
predicate, and the range has been advanced by one element; otherwise false, and
the range is left untouched.
*/
bool skipOver(alias pred = "a == b", R, E)(ref R r, E e)
bool skipOver(R, E)(ref R r, E e)
if (isInputRange!R && is(typeof(r.front == e) : bool))
{
return skipOver!((a, b) => a == b)(r, e);
}
/// Ditto
bool skipOver(alias pred, R, E)(ref R r, E e)
if (is(typeof(binaryFun!pred(r.front, e))) && isInputRange!R)
{
if (r.empty || !binaryFun!pred(r.front, e))