[Issue 10868] New: std.string.translate should take an optional buffer

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=10868

           Summary: std.string.translate should take an optional buffer
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: andrej.mitrovich at gmail.com
        ReportedBy: andrej.mitrovich at gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich at gmail.com> 2013-08-21 18:46:42 PDT ---
translate is useful for interfacing with other languages that require special
string literal escaping rules (e.g. Tcl), however these escaped strings
themselves typically have to be wrapped in some outer block.

Currently translate doesn't allow a user-provided buffer, leading to writing
inefficient code like this:

-----
import std.array;
import std.string;

void main()
{
    string[dchar] table = ['{' : `\{`, '}' : `\}`];
    string input = `{ foobar }`;

    // multiple allocation
    auto res = format(`"%s"`, input.translate(table));

    assert(res == `"\{ foobar \}"`);
}
-----

A more efficient approach is to allow passing a custom buffer to translate:

-----
import std.array;
import std.string;

void main()
{
    string[dchar] table = ['{' : `\{`, '}' : `\}`];
    auto buffer = appender!(dchar[])();

    buffer ~= '{';
    string input = `{ foobar }`;
    input.translate(table, null, buffer);
    buffer ~= '}';
    assert(buffer.data == `"\{ foobar \}"`);
}
-----

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