[Issue 10472] lastIndexOf(string, string) does not find single character string at beginning of string

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=10472



--- Comment #1 from monarchdodra at gmail.com 2013-06-25 05:00:57 PDT ---
The problem is this condition:

----
if (cast(dchar)(cast(Char)c) == c)
----

This is basically saying "if the code_point_ representation fits in a singe
code_unit_, then we look at the code_units_". This is wrong, since for UTF8
characters with code_point_s in the 0x80 0xFF range will "fit" in a single
code_unit_, but actually have a dual code_unit_ representation. In particular:

ö is represented by \00F6, which fits in a single code unit, yet, when encoded
into UTF8 take up two: "0xC3 0xB6"

The correct question is:
if (codeLength!Char(c) == 1)

Or, if you want to tweak a little, since you don't need the *actual*
codeLength:

----
        static if      (Char.sizeof == 1) immutable fits = c <=   0x7F;
        else static if (Char.sizeof == 2) immutable fits = c <= 0xFFFF;
        else immutable fits = true;

        if (fits)
        {
            ...
----

------------------
BTW, implementation wise, I do believe a simple foreach_reverse is more
efficient, because it pops *as* it decodes. The for loop needs to stride
backwards (again) after a call to "back" ("back" strides backwards already)).

            foreach_reverse (i, dchar c2 ; s)
            {
                if ( c2 == c)
                    return i;
            }

and

            immutable c1 = std.uni.toLower(c);
            foreach_reverse (i, dchar c2 ; s)
            {
                if ( std.uni.toLower(c2) == c1)
                    return i;
            }

In any case, it is much simpler.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------