lib/Debugger/SourceFile.cpp

   1 //===-- SourceFile.cpp - SourceFile implementation for the debugger -------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source 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 <cassert>
  16
  17 using namespace llvm;
  18
  19 /// readFile - Load Filename
  20 ///
  21 void SourceFile::readFile() {
  22   File.map();
  23 }
  24
  25 /// calculateLineOffsets - Compute the LineOffset vector for the current file.
  26 ///
  27 void SourceFile::calculateLineOffsets() const {
  28   assert(LineOffset.empty() && "Line offsets already computed!");
  29   const char *BufPtr = File.charBase();
  30   const char *FileStart = BufPtr;
  31   const char *FileEnd = FileStart + File.size();
  32   do {
  33     LineOffset.push_back(BufPtr-FileStart);
  34
  35     // Scan until we get to a newline.
  36     while (BufPtr != FileEnd && *BufPtr != '\n' && *BufPtr != '\r')
  37       ++BufPtr;
  38
  39     if (BufPtr != FileEnd) {
  40       ++BufPtr;               // Skip over the \n or \r
  41       if (BufPtr[-1] == '\r' && BufPtr != FileEnd && BufPtr[0] == '\n')
  42         ++BufPtr;   // Skip over dos/windows style \r\n's
  43     }
  44   } while (BufPtr != FileEnd);
  45 }
  46
  47
  48 /// getSourceLine - Given a line number, return the start and end of the line
  49 /// in the file.  If the line number is invalid, or if the file could not be
  50 /// loaded, null pointers are returned for the start and end of the file. Note
  51 /// that line numbers start with 0, not 1.
  52 void SourceFile::getSourceLine(unsigned LineNo, const char *&LineStart,
  53                                const char *&LineEnd) const {
  54   LineStart = LineEnd = 0;
  55   if (!File.isMapped()) return;  // Couldn't load file, return null pointers
  56   if (LineOffset.empty()) calculateLineOffsets();
  57
  58   // Asking for an out-of-range line number?
  59   if (LineNo >= LineOffset.size()) return;
  60
  61   // Otherwise, they are asking for a valid line, which we can fulfill.
  62   LineStart = File.charBase()+LineOffset[LineNo];
  63
  64   if (LineNo+1 < LineOffset.size())
  65     LineEnd = File.charBase()+LineOffset[LineNo+1];
  66   else
  67     LineEnd = File.charBase() + File.size();
  68
  69   // If the line ended with a newline, strip it off.
  70   while (LineEnd != LineStart && (LineEnd[-1] == '\n' || LineEnd[-1] == '\r'))
  71     --LineEnd;
  72
  73   assert(LineEnd >= LineStart && "We somehow got our pointers swizzled!");
  74 }