lib/Debugger/SourceFile.cpp

   1 //===-- SourceFile.cpp - SourceFile implementation for the debugger -------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the SourceFile class for the LLVM debugger.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Debugger/SourceFile.h"
  15 #include "llvm/Support/MemoryBuffer.h"
  16 #include <cassert>
  17 using namespace llvm;
  18
  19 static const char EmptyFile = 0;
  20
  21 SourceFile::SourceFile(const std::string &fn, const GlobalVariable *Desc)
  22   : Filename(fn), Descriptor(Desc) {
  23   File.reset(MemoryBuffer::getFileOrSTDIN(fn));
  24
  25   // On error, return an empty buffer.
  26   if (File == 0)
  27     File.reset(MemoryBuffer::getMemBuffer(&EmptyFile, &EmptyFile));
  28 }
  29
  30 SourceFile::~SourceFile() {
  31 }
  32
  33
  34 /// calculateLineOffsets - Compute the LineOffset vector for the current file.
  35 ///
  36 void SourceFile::calculateLineOffsets() const {
  37   assert(LineOffset.empty() && "Line offsets already computed!");
  38   const char *BufPtr = File->getBufferStart();
  39   const char *FileStart = BufPtr;
  40   const char *FileEnd = File->getBufferEnd();
  41   do {
  42     LineOffset.push_back(BufPtr-FileStart);
  43
  44     // Scan until we get to a newline.
  45     while (BufPtr != FileEnd && *BufPtr != '\n' && *BufPtr != '\r')
  46       ++BufPtr;
  47
  48     if (BufPtr != FileEnd) {
  49       ++BufPtr;               // Skip over the \n or \r
  50       if (BufPtr[-1] == '\r' && BufPtr != FileEnd && BufPtr[0] == '\n')
  51         ++BufPtr;   // Skip over dos/windows style \r\n's
  52     }
  53   } while (BufPtr != FileEnd);
  54 }
  55
  56
  57 /// getSourceLine - Given a line number, return the start and end of the line
  58 /// in the file.  If the line number is invalid, or if the file could not be
  59 /// loaded, null pointers are returned for the start and end of the file. Note
  60 /// that line numbers start with 0, not 1.
  61 void SourceFile::getSourceLine(unsigned LineNo, const char *&LineStart,
  62                                const char *&LineEnd) const {
  63   LineStart = LineEnd = 0;
  64   if (LineOffset.empty()) calculateLineOffsets();
  65
  66   // Asking for an out-of-range line number?
  67   if (LineNo >= LineOffset.size()) return;
  68
  69   // Otherwise, they are asking for a valid line, which we can fulfill.
  70   LineStart = File->getBufferStart()+LineOffset[LineNo];
  71
  72   if (LineNo+1 < LineOffset.size())
  73     LineEnd = File->getBufferStart()+LineOffset[LineNo+1];
  74   else
  75     LineEnd = File->getBufferEnd();
  76
  77   // If the line ended with a newline, strip it off.
  78   while (LineEnd != LineStart && (LineEnd[-1] == '\n' || LineEnd[-1] == '\r'))
  79     --LineEnd;
  80
  81   assert(LineEnd >= LineStart && "We somehow got our pointers swizzled!");
  82 }