Performance of map!()

[Chris via Digitalmars-d]

On Friday, 24 April 2015 at 10:53:04 UTC, John Colvin wrote:
> On Friday, 24 April 2015 at 10:22:05 UTC, Chris wrote:
>> I replaced a range that was similar to map with map and the 
>> performance dropped by ~0.5 msec.
>>
>> The range I used previously is based on Adam's D Cookbook. It 
>> is consistently faster than map.
>>
>> private struct Transformer(alias agent, R) if (isInputRange!R) 
>> {
>>
>>  private R r;
>>  this (R r) {
>>    this.r = r;
>>  }
>>
>>  static if (isInfinite!R) {
>>    enum bool empty = false;
>>  }
>>  else {
>>    @property bool empty() {
>>      return r.empty;
>>    }
>>  }
>>
>>  void popFront() {
>>    r.popFront();
>>
>>  }
>>  @property ref auto front() {
>>    return agent(r.front);
>>  }
>>
>>  static if (isForwardRange!R) {
>>    @property auto save() {
>>      return Transformer!(agent, R)(r.save);
>>    }
>>  }
>>
>>  static if (isBidirectionalRange!R) {
>>    @property auto back() {
>>      return agent(r.back);
>>    }
>>    void popBack() {
>>      r.popBack();
>>    }
>>  }
>>
>>  static if (isRandomAccessRange!R) {
>>    auto opIndex(size_t i) {
>>      return agent(r[i]);
>>    }
>>  }
>>
>>  static if (hasLength!R) {
>>    @property auto length() {
>>      return r.length;
>>    }
>>  }
>> }
>
> Compiler? Compiler flags?

dmd v2.067.0

dub --build=release (-release -inline -O -boundscheck=off)