ENH: Added application DGraph in Utility directory.

This application expect a DGraph input file and output the corresponding
topological order or a description of the discovered cycle if any.

The format of the file should be the following:
<#vertices> <#edges>
<from> <to>
<from> <to>
<from> <to>
<from> <to>
...

<#vertices> and <#edges> should integer
<from> <to> could be any label.

Utilities/DGraph/CMakeLists.txt

@@ -0,0 +1,30 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
+
+FOREACH(policy CMP0003)
+  IF(POLICY ${policy})
+    CMAKE_POLICY(SET ${policy} NEW)
+  ENDIF()
+ENDFOREACH()
+
+PROJECT(DGraph)
+
+SET(CTK_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../)
+
+# QT is required
+INCLUDE(${CTK_SOURCE_DIR}/CMake/ctkMacroSetupQt.cmake)
+ctkMacroSetupQt()
+
+INCLUDE_DIRECTORIES(
+  ${CMAKE_CURRENT_SOURCE_DIR}
+  ${CTK_SOURCE_DIR}/Libs/Core
+  )
+
+# Add excutable
+ADD_EXECUTABLE(${PROJECT_NAME}
+  DGraph.cxx
+  ${CTK_SOURCE_DIR}/Libs/Core/ctkDependencyGraph.h
+  ${CTK_SOURCE_DIR}/Libs/Core/ctkDependencyGraph.cxx)
+  
+TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${QT_LIBRARIES} )
+
+  

Utilities/DGraph/DGraph.cxx

@@ -0,0 +1,212 @@
+
+// QT includes
+#include <QFile>
+#include <QTextStream>
+#include <QRegExp>
+#include <QStringList>
+#include <QDebug>
+
+// CTK includes
+#include <ctkDependencyGraph.h>
+
+// STD includes
+#include <cstdlib>
+#include <iostream>
+
+//----------------------------------------------------------------------------
+QString help(const QString& progName)
+{
+  QString msg = "Usage: %1 <graphfile>";
+  return msg.arg(progName);
+}
+
+//----------------------------------------------------------------------------
+void displayError(const QString& progName, const QString& msg)
+{
+  std::cerr << QString("%1\n%2\n%3\n").arg(progName).
+                                       arg(msg).
+                                       arg(help(progName)).toStdString();
+}
+
+//----------------------------------------------------------------------------
+int getOrGenerateId(QHash<int, QString>& vertexIdToLabel,
+                    QHash<QString, int>& vertexLabelToId,
+                    const QString& label)
+{
+  // If needed, generate vertex id
+  int vertexId = -1;
+  if (!vertexLabelToId.keys().contains(label))
+    {
+    vertexId = vertexLabelToId.keys().size() + 1;
+    vertexLabelToId[label] = vertexId;
+    vertexIdToLabel[vertexId] = label;
+    }
+  else
+    {
+    vertexId = vertexLabelToId[label];
+    }
+  return vertexId; 
+}
+
+//----------------------------------------------------------------------------
+int main(int argc, char** argv)
+{
+  bool verbose = false;
+  
+  // a graph file is expected
+  if (argc < 2)
+    {
+    displayError(argv[0], QLatin1String("Missing one argument"));
+    return EXIT_FAILURE;
+    }
+    
+  QString filepath = QString::fromLatin1(argv[1]);
+  if (!QFile::exists(filepath))
+    {
+    displayError(argv[0], QString("File '%1' doesn't exists !").arg(filepath));
+    return EXIT_FAILURE;
+    }
+
+  QFile data(filepath);
+  if (!data.open(QFile::ReadOnly))
+    {
+    displayError(argv[0], QString("Failed to open file '%1' !").arg(filepath));
+    return EXIT_FAILURE; 
+    }
+    
+  QTextStream in(&data);
+  QString header = in.readLine();
+  if (header.isNull())
+    {
+    displayError(argv[0], QString("Failed to read Header line in file '%1' !").arg(filepath));
+    return EXIT_FAILURE;
+    }
+
+  // Regular expression to extract two integers
+  QRegExp twoint_re("^([0-9]+)\\s+([0-9]+)");
+  
+  // Extract numberOfVertices and numberOfEdges
+  int pos = twoint_re.indexIn(header.trimmed());
+  if (pos != 0)
+    {
+    displayError(argv[0], QString("Error in file '%1' - First line should look like: <#Vertices> <#Edges>")
+      .arg(filepath));
+    return EXIT_FAILURE;
+    }
+  QStringList list = twoint_re.capturedTexts();
+  Q_ASSERT(list.size() == 3);
+
+  int numberOfVertices = list[1].toInt();
+  int numberOfEdges = list[2].toInt();
+
+  if (verbose)
+    {
+    qDebug() << "#Vertices:" << numberOfVertices << "#Edges:" << numberOfEdges;
+    }
+
+  // Init
+  ctkDependencyGraph mygraph(numberOfVertices, numberOfEdges);
+  mygraph.setVerbose(verbose);
+
+  // Map between vertex label and vertex id
+  QHash<int, QString> vertexIdToLabel;
+  QHash<QString, int> vertexLabelToId;
+  
+  // Regular expression to extract two label
+  QRegExp twolabel_re("^(.+)\\s+(.+)");
+  
+  // Read vertex connection
+  int lineNumber = 2;
+  QString line = in.readLine();
+  do
+    {
+    // Skip empty line or commented line
+    if (line.isEmpty() || line.startsWith("#"))
+      {
+      continue;
+      }
+
+    // Extract vertex points
+    
+    int pos = twolabel_re.indexIn(line.trimmed());
+    if (pos != 0)
+      {
+      displayError(argv[0], QString("Error in file '%1' - line:%2 - Expected format is: <label> <label>")
+        .arg(filepath).arg(lineNumber));
+      return EXIT_FAILURE;
+      }
+    lineNumber++;
+
+    QStringList list = twolabel_re.capturedTexts();
+    Q_ASSERT(list.size() == 3);
+
+    int from = getOrGenerateId(vertexIdToLabel, vertexLabelToId, list[1]);
+    int to = getOrGenerateId(vertexIdToLabel, vertexLabelToId, list[2]);
+
+    // Insert edge
+    mygraph.insertEdge(from, to);
+
+    line = in.readLine();
+    }
+  while (!line.isNull());
+
+  if (verbose)
+    {
+    mygraph.printGraph();
+    qDebug() << "> Check for cycle ...";
+    }
+   
+  mygraph.checkForCycle();
+  
+  if (mygraph.cycleDetected())
+    {
+    std::cerr << "Cycle detected !" << std::endl;
+    QList<int> path; 
+    mygraph.findPath(mygraph.cycleOrigin(), mygraph.cycleEnd(), path);
+    
+    for(int i = 0; i < path.size(); ++i)
+      {
+      std::cerr << vertexIdToLabel[path[i]].toStdString();
+      if (i != path.size() - 1)
+        {
+        std::cerr << " -> ";
+        }
+      }
+    std::cerr << std::endl;
+    
+    path.clear();
+    mygraph.findPath(mygraph.cycleEnd(), mygraph.cycleOrigin(), path);
+
+    for(int i = 0; i < path.size(); ++i)
+      {
+      std::cerr << vertexIdToLabel[path[i]].toStdString();
+      if (i != path.size() - 1)
+        {
+        std::cerr << " -> ";
+        }
+      }
+    std::cerr << std::endl;
+    
+    return EXIT_FAILURE;
+    }
+
+  if (verbose)
+    {
+    qDebug() << "> Topological order ...";
+    }
+  QList<int> out;
+  if (mygraph.topologicalSort(out))
+    {
+    for(int i=out.size() - 1; i >= 0; --i)
+      {
+      std::cout << vertexIdToLabel[out[i]].toStdString();
+      if (i != 0)
+        {
+        std::cout << " ";
+        }
+      }
+    std::cout << std::endl;
+    }
+    
+  return EXIT_SUCCESS;
+}