Re: lower case only first letter of word

[Ali Çehreli via Digitalmars-d-learn]

On 12/05/2017 11:41 AM, kdevel wrote:
On Tuesday, 5 December 2017 at 17:25:57 UTC, Steven Schveighoffer wrote:

But one cannot use the return value of lowerCaseFirst as argument for 
foo(string). Only the use as argument to writeln seems to work.

That's how ranges work. LowerCaseFirst produces dchar elements one at a 
time. An easy way of getting a string out of it is calling 
std.conv.text, which converts all those dchars to a series of UTF-8 chars.

Note, .text below is an expensive call because it allocates a new 
string. You may want to cache its result first if you need the result 
more than once:

    auto lowered = lowerCaseFirst("HELLO").text;
    foo(lowered);

This works:

import std.range;

struct LowerCaseFirst(R) // if(isSomeString!R)
{
   R src;
   bool notFirst; // terrible name, but I want default false
   dchar front() {
      import std.uni: toLower;
      return notFirst ? src.front : src.front.toLower;
   }
   void popFront() { notFirst = true; src.popFront; }
   bool empty() { return src.empty; }
}

auto lowerCaseFirst(R)(R r)
{
   return LowerCaseFirst!R(r);
}

void foo(string s) {
    import std.stdio;
    writefln("good old string: %s", s);
}

void main() {
    import std.conv;
    foo(lowerCaseFirst("HELLO").text);
}

Ali