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//===--- StringSwitch.h - Switch-on-literal-string Construct --------------===/
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//===----------------------------------------------------------------------===/
///
/// \file
/// 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 "llvm/Support/Compiler.h"
#include <cassert>
#include <cstring>
#include <optional>
namespace llvm {
/// 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 {
/// The string we are matching.
const StringRef Str;
/// The pointer to the result of this switch statement, once known,
/// null before that.
std::optional<T> Result;
public:
explicit StringSwitch(StringRef S)
: Str(S), Result() { }
// StringSwitch is not copyable.
StringSwitch(const StringSwitch &) = delete;
// StringSwitch is not assignable due to 'Str' being 'const'.
void operator=(const StringSwitch &) = delete;
void operator=(StringSwitch &&other) = delete;
StringSwitch(StringSwitch &&other)
: Str(other.Str), Result(std::move(other.Result)) { }
~StringSwitch() = default;
// Case-sensitive case matchers
StringSwitch &Case(StringLiteral S, T Value) {
if (!Result && Str == S) {
Result = std::move(Value);
}
return *this;
}
StringSwitch& EndsWith(StringLiteral S, T Value) {
if (!Result && Str.ends_with(S)) {
Result = std::move(Value);
}
return *this;
}
StringSwitch& StartsWith(StringLiteral S, T Value) {
if (!Result && Str.starts_with(S)) {
Result = std::move(Value);
}
return *this;
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, T Value) {
return Case(S0, Value).Case(S1, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
T Value) {
return Case(S0, Value).Cases(S1, S2, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, T Value) {
return Case(S0, Value).Cases(S1, S2, S3, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, S5, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, StringLiteral S8,
T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, S8, Value);
}
StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, StringLiteral S8,
StringLiteral S9, T Value) {
return Case(S0, Value).Cases(S1, S2, S3, S4, S5, S6, S7, S8, S9, Value);
}
// Case-insensitive case matchers.
StringSwitch &CaseLower(StringLiteral S, T Value) {
if (!Result && Str.equals_insensitive(S))
Result = std::move(Value);
return *this;
}
StringSwitch &EndsWithLower(StringLiteral S, T Value) {
if (!Result && Str.ends_with_insensitive(S))
Result = Value;
return *this;
}
StringSwitch &StartsWithLower(StringLiteral S, T Value) {
if (!Result && Str.starts_with_insensitive(S))
Result = std::move(Value);
return *this;
}
StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, T Value) {
return CaseLower(S0, Value).CaseLower(S1, Value);
}
StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
T Value) {
return CaseLower(S0, Value).CasesLower(S1, S2, Value);
}
StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, T Value) {
return CaseLower(S0, Value).CasesLower(S1, S2, S3, Value);
}
StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, T Value) {
return CaseLower(S0, Value).CasesLower(S1, S2, S3, S4, Value);
}
[[nodiscard]] R Default(T Value) {
if (Result)
return std::move(*Result);
return Value;
}
[[nodiscard]] operator R() {
assert(Result && "Fell off the end of a string-switch");
return std::move(*Result);
}
};
} // end namespace llvm
#endif // LLVM_ADT_STRINGSWITCH_H
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