DirectXShaderCompiler/tools/clang/lib/Basic/VersionTuple.cpp

//===- VersionTuple.cpp - Version Number Handling ---------------*- C++ -*-===//
//
//                     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 VersionTuple class, which represents a version in
// the form major[.minor[.subminor]].
//
//===----------------------------------------------------------------------===//

#include "clang/Basic/VersionTuple.h"
#include "llvm/Support/raw_ostream.h"
//                                                                           //
///////////////////////////////////////////////////////////////////////////////
using namespace clang;

std::string VersionTuple::getAsString() const {
  std::string Result;
  {
    llvm::raw_string_ostream Out(Result);
    Out << *this;
  }
  return Result;
}

raw_ostream& clang::operator<<(raw_ostream &Out, 
                                     const VersionTuple &V) {
  Out << V.getMajor();
  if (Optional<unsigned> Minor = V.getMinor())
    Out << (V.usesUnderscores() ? '_' : '.') << *Minor;
  if (Optional<unsigned> Subminor = V.getSubminor())
    Out << (V.usesUnderscores() ? '_' : '.') << *Subminor;
  if (Optional<unsigned> Build = V.getBuild())
    Out << (V.usesUnderscores() ? '_' : '.') << *Build;
  return Out;
}

static bool parseInt(StringRef &input, unsigned &value) {
  assert(value == 0);
  if (input.empty()) return true;

  char next = input[0];
  input = input.substr(1);
  if (next < '0' || next > '9') return true;
  value = (unsigned) (next - '0');

  while (!input.empty()) {
    next = input[0];
    if (next < '0' || next > '9') return false;
    input = input.substr(1);
    value = value * 10 + (unsigned) (next - '0');
  }

  return false;
}

bool VersionTuple::tryParse(StringRef input) {
  unsigned major = 0, minor = 0, micro = 0, build = 0;

  // Parse the major version, [0-9]+
  if (parseInt(input, major)) return true;

  if (input.empty()) {
    *this = VersionTuple(major);
    return false;
  }

  // If we're not done, parse the minor version, \.[0-9]+
  if (input[0] != '.') return true;
  input = input.substr(1);
  if (parseInt(input, minor)) return true;

  if (input.empty()) {
    *this = VersionTuple(major, minor);
    return false;
  }

  // If we're not done, parse the micro version, \.[0-9]+
  if (input[0] != '.') return true;
  input = input.substr(1);
  if (parseInt(input, micro)) return true;

  if (input.empty()) {
    *this = VersionTuple(major, minor, micro);
    return false;
  }

  // If we're not done, parse the micro version, \.[0-9]+
  if (input[0] != '.') return true;
  input = input.substr(1);
  if (parseInt(input, build)) return true;

  // If we have characters left over, it's an error.
  if (!input.empty()) return true;

  *this = VersionTuple(major, minor, micro, build);
  return false;
}