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llvm-mirror/include/llvm/ADT/StringSwitch.h
Alexis Hunt 068811ea03 Finish full attribute class emission for clang.
For more information, see the accompanying clang patch.

llvm-svn: 111454
2010-08-18 23:23:09 +00:00

127 lines
3.8 KiB
C++

//===--- StringSwitch.h - Switch-on-literal-string Construct --------------===/
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//===----------------------------------------------------------------------===/
//
// This file implements the StringSwitch template, which mimics a switch()
// statement whose cases are string literals.
//
//===----------------------------------------------------------------------===/
#ifndef LLVM_ADT_STRINGSWITCH_H
#define LLVM_ADT_STRINGSWITCH_H
#include "llvm/ADT/StringRef.h"
#include <cassert>
#include <cstring>
namespace llvm {
/// \brief A switch()-like statement whose cases are string literals.
///
/// The StringSwitch class is a simple form of a switch() statement that
/// determines whether the given string matches one of the given string
/// literals. The template type parameter \p T is the type of the value that
/// will be returned from the string-switch expression. For example,
/// the following code switches on the name of a color in \c argv[i]:
///
/// \code
/// Color color = StringSwitch<Color>(argv[i])
/// .Case("red", Red)
/// .Case("orange", Orange)
/// .Case("yellow", Yellow)
/// .Case("green", Green)
/// .Case("blue", Blue)
/// .Case("indigo", Indigo)
/// .Cases("violet", "purple", Violet)
/// .Default(UnknownColor);
/// \endcode
template<typename T, typename R = T>
class StringSwitch {
/// \brief The string we are matching.
StringRef Str;
/// \brief The pointer to the result of this switch statement, once known,
/// null before that.
const T *Result;
public:
explicit StringSwitch(StringRef Str)
: Str(Str), Result(0) { }
template<unsigned N>
StringSwitch& Case(const char (&S)[N], const T& Value) {
if (!Result && N-1 == Str.size() &&
(std::memcmp(S, Str.data(), N-1) == 0)) {
Result = &Value;
}
return *this;
}
template<unsigned N>
StringSwitch& EndsWith(const char (&S)[N], const T &Value) {
if (!Result && Str.size() >= N-1 &&
std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0) {
Result = &Value;
}
return *this;
}
template<unsigned N>
StringSwitch& StartsWith(const char (&S)[N], const T &Value) {
if (!Result && Str.size() >= N-1 &&
std::memcmp(S, Str.data(), N-1) == 0) {
Result = &Value;
}
return *this;
}
template<unsigned N0, unsigned N1>
StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
const T& Value) {
return Case(S0, Value).Case(S1, Value);
}
template<unsigned N0, unsigned N1, unsigned N2>
StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
const char (&S2)[N2], const T& Value) {
return Case(S0, Value).Case(S1, Value).Case(S2, Value);
}
template<unsigned N0, unsigned N1, unsigned N2, unsigned N3>
StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
const char (&S2)[N2], const char (&S3)[N3],
const T& Value) {
return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value);
}
template<unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4>
StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
const char (&S2)[N2], const char (&S3)[N3],
const char (&S4)[N4], const T& Value) {
return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value)
.Case(S4, Value);
}
R Default(const T& Value) const {
if (Result)
return *Result;
return Value;
}
operator R() const {
assert(Result && "Fell off the end of a string-switch");
return *Result;
}
};
} // end namespace llvm
#endif // LLVM_ADT_STRINGSWITCH_H