ctfe library

[Don]

Ellery Newcomer wrote:
> Are there any good libraries for ctfe/code generation?
> 
> I don't know, things like parsing support for compile time strings, 
> string formatting, type <-> string
> 
> My project seems to be growing ctfe, and it's all horribly hacky and 
> ugly code.

I've found that the function below improves things immensely. I might 
propose it for std.metastrings in the next Phobos release.

===============

/** Escape any quotes and backslashes inside the given string,
  * prefixing them with the given escape sequence. Use `\` to escape
  * once, `\\\` to escape twice.
  */
string enquote(string instr, string escape = `\`)
{
     // This function is critical for compilation speed.
     // Need to minimise the number of allocations.
     // It's worth using copy-on-write even for CTFE.

     for(int i = 0; i < instr.length; ++i)
     {
         if (instr[i] == '"' || instr[i] == '\\')
         {
             string str = instr[0..i] ~ escape;
             int m = i;
             foreach(int k, char c; instr[i+1..$])
             {
                 if (c=='"' || c=='\\')
                 {
                     str ~= instr[m..i+1+k] ~ escape;
                     m = i+k+1;
                 }
             }
             return str ~ instr[m..$];
         }
     }
     return instr;
}

unittest {
     assert(enquote(`"a\"`)==`\"a\\\"`);
     assert(enquote(`abc`)==`abc`);
}