libs/cassowary/ClBug2.cc

   1 /* $Id$
   2
   3 From: "Anthony Beurive'" <beurive@labri.u-bordeaux.fr>
   4 Subject: cassowary
   5 To: gjb@cs.washington.edu
   6 Date: Tue, 9 Mar 1999 12:42:24 +0100 (CET)
   7
   8 I believe there's a bug in cassowary.  It seems to be related to the
   9 previous one I encountered a while ago, concerning the removal of
  10 constraints.
  11
  12 The three following examples may help you to track the bug, I hope.
  13
  14 --------------------------------------------------------------------------------
  15 #include "Cl.h"
  16
  17 void main()
  18 {
  19   ClSimplexSolver *solver = new ClSimplexSolver();
  20   ClVariable *var = new ClVariable();
  21   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),1.0);
  22
  23   solver->AddConstraint(*stcn);
  24   cout << *solver;
  25   solver->RemoveConstraint(*stcn);
  26   cout << *solver;
  27 }
  28 --------------------------------------------------------------------------------
  29 This works fine.
  30
  31
  32 Now, the factor of the stay constraint is changed.
  33 --------------------------------------------------------------------------------
  34 #include "Cl.h"
  35
  36 void main()
  37 {
  38   ClSimplexSolver *solver = new ClSimplexSolver();
  39   ClVariable *var = new ClVariable();
  40   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),2.0);
  41
  42   solver->AddConstraint(*stcn);
  43   cout << *solver;
  44   solver->RemoveConstraint(*stcn);
  45   cout << *solver;
  46 }
  47 --------------------------------------------------------------------------------
  48 The result is:
  49 test2: ClSimplexSolver.cc:1199: void ClSimplexSolver::Optimize(class ClVariable): Assertion \
  50 `pzRow != __null' failed.
  51 Aborted
  52
  53
  54 Now, the solver is created after the variable.
  55 --------------------------------------------------------------------------------
  56 #include "Cl.h"
  57
  58 void main()
  59 {
  60   ClVariable *var = new ClVariable();
  61   ClSimplexSolver *solver = new ClSimplexSolver();
  62   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),2.0);
  63
  64   solver->AddConstraint(*stcn);
  65   cout << *solver;
  66   solver->RemoveConstraint(*stcn);
  67   cout << *solver;
  68 }
  69 --------------------------------------------------------------------------------
  70 This works again.
  71
  72
  73 Can you reproduce the same results?  Maybe the cause is my c++
  74 compiler (egcs-2.90.29 980515 (egcs-1.0.3 release)).  I don't know.
  75
  76 */
  77
  78 #include <cassowary/Cl.h>
  79
  80 void foo1()
  81 {
  82   ClSimplexSolver *solver = new ClSimplexSolver();
  83   ClVariable *var = new ClVariable();
  84   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),1.0);
  85
  86   solver->AddConstraint(*stcn);
  87   cout << *solver;
  88   solver->RemoveConstraint(*stcn);
  89   cout << *solver;
  90 }
  91
  92
  93 void foo2()
  94 {
  95   ClSimplexSolver *solver = new ClSimplexSolver();
  96   ClVariable *var = new ClVariable();
  97   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),2.0);
  98
  99   solver->AddConstraint(*stcn);
 100   cout << *solver;
 101   solver->RemoveConstraint(*stcn);
 102   cout << *solver;
 103 }
 104
 105
 106 void foo3()
 107 {
 108   ClVariable *var = new ClVariable();
 109   ClSimplexSolver *solver = new ClSimplexSolver();
 110   ClStayConstraint *stcn = new ClStayConstraint(*var,ClsWeak(),2.0);
 111
 112   solver->AddConstraint(*stcn);
 113   cout << *solver;
 114   solver->RemoveConstraint(*stcn);
 115   cout << *solver;
 116 }
 117
 118
 119 int main()
 120 {
 121   cerr << "Test1: " << endl;
 122   foo1();
 123
 124   cerr << "\nTest2: " << endl;
 125   foo2();
 126
 127   cerr << "\nTest3: " << endl;
 128   foo3();
 129
 130 }