//===--- SourceLoc.cpp - SourceLoc and SourceRange implementations --------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "swift/Basic/SourceLoc.h"
#include "swift/Basic/SourceManager.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"

using namespace swift;

SourceLoc SourceManager::getCodeCompletionLoc() const {
  return getLocForBufferStart(CodeCompletionBufferID)
      .getAdvancedLoc(CodeCompletionOffset);
}

unsigned SourceManager::addNewSourceBuffer(llvm::MemoryBuffer *Buffer) {
  assert(Buffer);
  auto ID = LLVMSourceMgr.AddNewSourceBuffer(Buffer, llvm::SMLoc());
  BufIdentIDMap[Buffer->getBufferIdentifier()] = ID;
  return ID;
}

unsigned SourceManager::addMemBufferCopy(llvm::MemoryBuffer *Buffer) {
  return addMemBufferCopy(Buffer->getBuffer(), Buffer->getBufferIdentifier());
}

unsigned SourceManager::addMemBufferCopy(StringRef InputData,
                                         StringRef BufIdentifier) {
  auto Buffer = llvm::MemoryBuffer::getMemBufferCopy(InputData, BufIdentifier);
  return addNewSourceBuffer(Buffer);
}

void SourceManager::openVirtualFile(SourceLoc loc, StringRef name,
                                    int lineOffset) {
  assert(!getVirtualFile(loc) && "must call closeVirtualFile first");

  CharSourceRange fullRange = getRangeForBuffer(findBufferContainingLoc(loc));
  SourceLoc end;

  auto nextRangeIter = VirtualFiles.upper_bound(loc.Value.getPointer());
  if (nextRangeIter != VirtualFiles.end() &&
      fullRange.contains(nextRangeIter->second.Range.getStart())) {
    end = nextRangeIter->second.Range.getStart();
  } else {
    end = fullRange.getEnd();
  }

  CharSourceRange range = CharSourceRange(*this, loc, end);
  VirtualFiles[end.Value.getPointer()] = { range, name, lineOffset };
}

void SourceManager::closeVirtualFile(SourceLoc end) {
  auto *virtualFile = const_cast<VirtualFile *>(getVirtualFile(end));
  assert(virtualFile && "no open virtual file for this location");
  CachedVFile = {};

  CharSourceRange oldRange = virtualFile->Range;
  virtualFile->Range = CharSourceRange(*this, virtualFile->Range.getStart(),
                                       end);
  VirtualFiles[end.Value.getPointer()] = std::move(*virtualFile);

  bool existed = VirtualFiles.erase(oldRange.getEnd().Value.getPointer());
  assert(existed);
  (void)existed;
}

const SourceManager::VirtualFile *
SourceManager::getVirtualFile(SourceLoc Loc) const {
  const char *p = Loc.Value.getPointer();

  if (CachedVFile.first == p)
    return CachedVFile.second;

  // Returns the first element that is >p.
  auto VFileIt = VirtualFiles.upper_bound(p);
  if (VFileIt != VirtualFiles.end() && VFileIt->second.Range.contains(Loc)) {
    CachedVFile = { p, &VFileIt->second };
    return CachedVFile.second;
  }

  return nullptr;
}


Optional<unsigned> SourceManager::getIDForBufferIdentifier(
    StringRef BufIdentifier) {
  auto It = BufIdentIDMap.find(BufIdentifier);
  if (It == BufIdentIDMap.end())
    return Nothing;
  return It->second;
}

const char *SourceManager::getIdentifierForBuffer(unsigned bufferID) const {
  auto *buffer = LLVMSourceMgr.getMemoryBuffer(bufferID);
  assert(buffer && "invalid buffer ID");
  return buffer->getBufferIdentifier();
}

CharSourceRange SourceManager::getRangeForBuffer(unsigned bufferID) const {
  auto *buffer = LLVMSourceMgr.getMemoryBuffer(bufferID);
  SourceLoc start{llvm::SMLoc::getFromPointer(buffer->getBufferStart())};
  return CharSourceRange(start, buffer->getBufferSize());
}

unsigned SourceManager::getLocOffsetInBuffer(SourceLoc Loc,
                                             unsigned BufferID) const {
  assert(Loc.isValid() && "location should be valid");
  auto *Buffer = LLVMSourceMgr.getMemoryBuffer(BufferID);
  assert(Loc.Value.getPointer() >= Buffer->getBuffer().begin() &&
         Loc.Value.getPointer() <= Buffer->getBuffer().end() &&
         "Location is not from the specified buffer");
  return Loc.Value.getPointer() - Buffer->getBuffer().begin();
}

unsigned SourceManager::getByteDistance(SourceLoc Start, SourceLoc End) const {
  assert(Start.isValid() && "start location should be valid");
  assert(End.isValid() && "end location should be valid");
#ifndef NDEBUG
  unsigned BufferID = findBufferContainingLoc(Start);
  auto *Buffer = LLVMSourceMgr.getMemoryBuffer(BufferID);
  assert(End.Value.getPointer() >= Buffer->getBuffer().begin() &&
         End.Value.getPointer() <= Buffer->getBuffer().end() &&
         "End location is not from the same buffer");
#endif
  // When we have a rope buffer, could be implemented in terms of
  // getLocOffsetInBuffer().
  return End.Value.getPointer() - Start.Value.getPointer();
}

StringRef SourceManager::extractText(CharSourceRange Range,
                                     Optional<unsigned> BufferID) const {
  assert(Range.isValid() && "range should be valid");

  if (!BufferID)
    BufferID = findBufferContainingLoc(Range.getStart());
  StringRef Buffer = LLVMSourceMgr.getMemoryBuffer(*BufferID)->getBuffer();
  return Buffer.substr(getLocOffsetInBuffer(Range.getStart(), *BufferID),
                       Range.getByteLength());
}

unsigned SourceManager::findBufferContainingLoc(SourceLoc Loc) const {
  assert(Loc.isValid());
  // Search the buffers back-to front, so later alias buffers are
  // visited first.
  auto less_equal = std::less_equal<const char *>();
  for (unsigned i = LLVMSourceMgr.getNumBuffers(), e = 1; i >= e; --i) {
    auto Buf = LLVMSourceMgr.getMemoryBuffer(i);
    if (less_equal(Buf->getBufferStart(), Loc.Value.getPointer()) &&
        // Use <= here so that a pointer to the null at the end of the buffer
        // is included as part of the buffer.
        less_equal(Loc.Value.getPointer(), Buf->getBufferEnd()))
      return i;
  }
  llvm_unreachable("no buffer containing location found");
}

void SourceLoc::printLineAndColumn(raw_ostream &OS,
                                   const SourceManager &SM) const {
  if (isInvalid()) {
    OS << "<invalid loc>";
    return;
  }

  auto LineAndCol = SM.getLineAndColumn(*this);
  OS << "line:" << LineAndCol.first << ':' << LineAndCol.second;
}

void SourceLoc::print(raw_ostream &OS, const SourceManager &SM,
                      unsigned &LastBufferID) const {
  if (isInvalid()) {
    OS << "<invalid loc>";
    return;
  }

  unsigned BufferID = SM.findBufferContainingLoc(*this);
  if (BufferID != LastBufferID) {
    OS << SM.getIdentifierForBuffer(BufferID);
    LastBufferID = BufferID;
  } else {
    OS << "line";
  }

  auto LineAndCol = SM.getLineAndColumn(*this, BufferID);
  OS << ':' << LineAndCol.first << ':' << LineAndCol.second;
}

void SourceLoc::dump(const SourceManager &SM) const {
  print(llvm::errs(), SM);
}

void SourceRange::print(raw_ostream &OS, const SourceManager &SM,
                        unsigned &LastBufferID, bool PrintText) const {
  OS << '[';
  Start.print(OS, SM, LastBufferID);
  OS << " - ";
  End.print(OS, SM, LastBufferID);
  OS << ']';
  
  if (Start.isInvalid() || End.isInvalid())
    return;
  
  if (PrintText) {
    OS << " RangeText=\""
       << StringRef(Start.Value.getPointer(),
                    End.Value.getPointer() - Start.Value.getPointer()+1)
       << '"';
  }
}

void SourceRange::dump(const SourceManager &SM) const {
  print(llvm::errs(), SM);
}

CharSourceRange::CharSourceRange(const SourceManager &SM, SourceLoc Start,
                                 SourceLoc End)
    : Start(Start) {
  assert(Start.isValid() == End.isValid() &&
         "Start and end should either both be valid or both be invalid!");
  if (Start.isValid())
    ByteLength = SM.getByteDistance(Start, End);
}