[llvm-commits] PATCH: Additional SmallString methods

David Blaikie dblaikie at gmail.com
Fri Jan 20 12:24:51 PST 2012

If we just made these free functions taking StringRef would that be
easier/more reusable? (& then relying on the conversion operator Jim

I'd say it's a preferable design anyway (see the GoTW post on the
problems of the monolithic design of std::basic_string
http://www.gotw.ca/gotw/084.htm )

On Thu, Jan 19, 2012 at 11:42 PM, Talin <viridia at gmail.com> 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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