Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===--- 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.endswith(S)) {

      Result = std::move(Value);

    }

    return *this;

  }

  StringSwitch& StartsWith(StringLiteral S, T Value) {

    if (!Result && Str.startswith(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.endswith_insensitive(S))

      Result = Value;

    return *this;

  }

  StringSwitch &StartsWithLower(StringLiteral S, T Value) {

    if (!Result && Str.startswith_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