//===--- StringView.h -------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//
// This file contains a limited version of LLVM's StringView class.  It is
// copied here so that LLVMDemangle need not take a dependency on LLVMSupport.
//===----------------------------------------------------------------------===//

#ifndef LLVM_DEMANGLE_STRINGVIEW_H
#define LLVM_DEMANGLE_STRINGVIEW_H

#include <algorithm>

class StringView {
  const char *First;
  const char *Last;

public:
  template <size_t N>
  StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
  StringView(const char *First_, const char *Last_)
      : First(First_), Last(Last_) {}
  StringView() : First(nullptr), Last(nullptr) {}

  StringView substr(size_t From, size_t To) {
    if (To >= size())
      To = size() - 1;
    if (From >= size())
      From = size() - 1;
    return StringView(First + From, First + To);
  }

  StringView dropFront(size_t N) const {
    if (N >= size())
      N = size() - 1;
    return StringView(First + N, Last);
  }

  bool startsWith(StringView Str) const {
    if (Str.size() > size())
      return false;
    return std::equal(Str.begin(), Str.end(), begin());
  }

  const char &operator[](size_t Idx) const { return *(begin() + Idx); }

  const char *begin() const { return First; }
  const char *end() const { return Last; }
  size_t size() const { return static_cast<size_t>(Last - First); }
  bool empty() const { return First == Last; }
};

inline bool operator==(const StringView &LHS, const StringView &RHS) {
  return LHS.size() == RHS.size() &&
         std::equal(LHS.begin(), LHS.end(), RHS.begin());
}

#endif