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//===--- 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()
// statements 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)
/// .Case("violet", Violet)
/// .Default(UnknownColor);
/// \endcode
template<typename T>
class StringSwitch {
/// \brief The string we are matching.
StringRef Str;
/// \brief The result of this switch statement, once known.
T Result;
/// \brief Set true when the result of this switch is already known; in this
/// case, Result is valid.
bool ResultKnown;
public:
explicit StringSwitch(StringRef Str)
: Str(Str), ResultKnown(false) { }
template<unsigned N>
StringSwitch& Case(const char (&S)[N], const T& Value) {
if (!ResultKnown && N-1 == Str.size() &&
(std::memcmp(S, Str.data(), N-1) == 0)) {
Result = Value;
ResultKnown = true;
}
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);
}
T Default(const T& Value) {
if (ResultKnown)
return Result;
return Value;
}
operator T() {
assert(ResultKnown && "Fell off the end of a string-switch");
return Result;
}
};
} // end namespace llvm
#endif // LLVM_ADT_STRINGSWITCH_H
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