[llvm-commits] PATCH: Additional SmallString methods

[Talin]

On Fri, Jan 20, 2012 at 12:17 PM, Jim Grosbach <grosbach at apple.com> wrote:

> Hi Talin,
>
> There's already a conversion operator to StringRef. Does that not handle
> things for you?
>
>   // Implicit conversion to StringRef.
>
>   operator StringRef() const { return str(); }
>

This works when passing a SmallString as an argument, but not when calling
members of SmallString. Currently you'd have to say something like
theString.str().find(...). Now, admittedly it's only 6 extra characters,
but I think it does make the code a little less readable.


>  -j
> On Jan 19, 2012, at 11:42 PM, Talin wrote:
>
> This patch adds many convenience methods to class SmallString:
>
>    - void assign(unsigned NumElts, char Elt);
>    - void assign(in_iter S, in_iter E);
>    - void assign(StringRef RHS);
>    - void assign(const SmallVectorImpl<char> &RHS);
>    - void append(in_iter S, in_iter E);
>    - void append(StringRef RHS);
>    - void append(const SmallVectorImpl<char> &RHS);
>    - bool equals(StringRef RHS) const;
>    - bool equals_lower(StringRef RHS) const;
>    - int compare(StringRef RHS) const;
>    - int compare_lower(StringRef RHS) const;
>    - int compare_numeric(StringRef RHS) const;
>    - bool startswith(StringRef Prefix) const;
>    - bool endswith(StringRef Suffix) const;
>    - size_t find(char C, size_t From = 0) const;
>    - size_t find(StringRef Str, size_t From = 0) const;
>    - size_t rfind(char C, size_t From = StringRef::npos) const;
>    - size_t rfind(StringRef Str) const;
>    - size_t find_first_of(char C, size_t From = 0) const;
>    - size_t find_first_of(StringRef Chars, size_t From = 0) const;
>    - size_t find_first_not_of(char C, size_t From = 0) const;
>    - size_t find_first_not_of(StringRef Chars, size_t From = 0) const;
>    - size_t find_last_of(char C, size_t From = StringRef::npos) const;
>    - size_t find_last_of(StringRef Chars, size_t From = StringRef::npos)
>    const;
>    - size_t count(char C) const;
>    - size_t count(StringRef Str) const;
>    - StringRef substr(size_t Start, size_t N = StringRef::npos) const;
>    - StringRef slice(size_t Start, size_t End) const;
>
> Most of the methods are taken directly from StringRef (find_x, compare_x,
> substr, and so on). My motivation for adding these methods is that often I
> find myself working with a SmallString instead of a StringRef, and it would
> be nice to call substr() for example directly without having to convert to
> a StringRef. Internally, of course, the methods simply convert the
> SmallString to a StringRef (which is extremely cheap), and then call the
> corresponding StringRef method. Doing it this way minimizes template
> expansion, since StringRef is a non-template class.
>
> The 'assign' and 'append' methods are taken from standard STL, with
> additional overloads that are convenient for strings. For example, assign()
> now allows assigning to a SmallString from an iterator pair, which was not
> supported before.
>
> (Note: I thought about adding support for assign/append/construct from an
> ArrayRef<char>, but that would add an additional include file dependency.)
>
> This patch also includes many additions to the unit tests for SmallString,
> as well as some minor typographical cleanups in the comments in
> SmallString.h.
>
> --
> -- Talin
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>
>


-- 
-- Talin
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