Refactor the linear programming class to use a minimal solver interface class and implement the interface for lp_solve. As a result lp_solve is not visible to the outside any more. This interface could be used to use other solvers as well. Rename operator constants to no clash with lp_solve constants.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@39829 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/libs/linprog/LinearSpec.h

@@ -22,11 +22,41 @@
 #include "Summand.h"
 #include "Variable.h"
 
-#include "lp_lib.h"
-
 
 namespace LinearProgramming {
 
+class SolverInterface {
+public:
+	virtual						~SolverInterface() {}
+
+	virtual ResultType			Solve(VariableList& variables) = 0;
+	virtual double				GetObjectiveValue() = 0;
+
+	virtual	bool				AddVariable() = 0;
+	virtual	bool				RemoveVariable(int variable) = 0;
+	virtual	bool				SetVariableRange(int variable, double min,
+									double max) = 0;
+
+	virtual	bool				AddConstraint(int nElements,
+									double* coefficients, int* variableIndices,
+									OperatorType op, double rightSide) = 0;
+	virtual	bool				RemoveConstraint(int constraint) = 0;
+	virtual	bool				SetLeftSide(int constraint, int nElements,
+									double* coefficients,
+									int* variableIndices) = 0;
+	virtual	bool				SetRightSide(int constraint, double value) = 0;
+	virtual	bool				SetOperator(int constraint,
+									OperatorType op) = 0;
+
+	virtual bool				SetObjectiveFunction(int nElements,
+									double* coefficients,
+									int* variableIndices) = 0;
+	virtual bool				SetOptimization(OptimizationType value) = 0;
+
+	virtual bool				SaveModel(const char* fileName) = 0;
+};
+
+
 /*!
  * Specification of a linear programming problem.
  */
@@ -40,8 +70,7 @@ public:
 			bool				RemoveVariable(Variable* variable,
 									bool deleteVariable = true);
 			int32				IndexOf(const Variable* variable) const;
-			bool				SetRange(Variable* variable, double min,
-									double max);
+			bool				UpdateRange(Variable* variable);
 
 			bool				AddConstraint(Constraint* constraint);
 			bool				RemoveConstraint(Constraint* constraint,
@@ -97,7 +126,7 @@ public:
 			void				UpdateObjectiveFunction();
 
 			ResultType			Solve();
-			void				Save(const char* fileName);
+			bool				Save(const char* fileName);
 
 			int32				CountColumns() const;
 			OptimizationType	Optimization() const;
@@ -125,12 +154,8 @@ private:
 									OperatorType op, double rightSide,
 									double penaltyNeg, double penaltyPos);
 
-			ResultType			_Presolve();
-			void				_RemovePresolved();
-
-			lprec*				fLpPresolved;
 			OptimizationType	fOptimization;
-			lprec*				fLP;
+
 			SummandList*		fObjFunction;
 			VariableList		fVariables;
 			ConstraintList		fConstraints;
@@ -138,6 +163,7 @@ private:
 			double 				fObjectiveValue;
 			double 				fSolvingTime;
 
+			SolverInterface*	fSolver;
 };
 
 }	// namespace LinearProgramming

headers/libs/linprog/OperatorType.h

@@ -14,7 +14,9 @@ namespace LinearProgramming {
  * Possible operators for linear constraints.
  */
 enum OperatorType {
-	EQ, LE, GE
+	kEQ,
+	kLE,
+	kGE
 };
 
 }	// namespace LinearProgramming

src/add-ons/decorators/SATDecorator/SATWindow.cpp

@@ -19,6 +19,7 @@
 
 
 using namespace BPrivate;
+using namespace LinearProgramming;
 
 
 const uint32 kExtentPenalty = 10;
@@ -163,27 +164,27 @@ GroupCookie::Init(SATGroup* group, WindowArea* area)
 
 	// create constraints
 	BRect frame = fSATWindow->CompleteWindowFrame();
-	fLeftConstraint = linearSpec->AddConstraint(1.0, fLeftBorder,
-		OperatorType(EQ), frame.left, 1, 1);
-	fTopConstraint  = linearSpec->AddConstraint(1.0, fTopBorder,
-		OperatorType(EQ), frame.top, 1, 1);
+	fLeftConstraint = linearSpec->AddConstraint(1.0, fLeftBorder, kEQ,
+		frame.left, 1, 1);
+	fTopConstraint  = linearSpec->AddConstraint(1.0, fTopBorder, kEQ,
+		frame.top, 1, 1);
 
 	int32 minWidth, maxWidth, minHeight, maxHeight;
 	fSATWindow->GetSizeLimits(&minWidth, &maxWidth, &minHeight,
 		&maxHeight);
 	fMinWidthConstraint = linearSpec->AddConstraint(1.0, fRightBorder, -1.0,
-		fLeftBorder, OperatorType(GE), minWidth);
+		fLeftBorder, kGE, minWidth);
 	fMinHeightConstraint = linearSpec->AddConstraint(1.0, fBottomBorder, -1.0,
-		fTopBorder, OperatorType(GE), minHeight);
+		fTopBorder, kGE, minHeight);
 
 	// The width and height constraints have higher penalties than the
 	// position constraints (left, top), so a window will keep its size
 	// unless explicitly resized.
 	fWidthConstraint = linearSpec->AddConstraint(-1.0, fLeftBorder, 1.0,
-		fRightBorder, OperatorType(EQ), frame.Width(), kExtentPenalty,
+		fRightBorder, kEQ, frame.Width(), kExtentPenalty,
 		kExtentPenalty);
 	fHeightConstraint = linearSpec->AddConstraint(-1.0, fTopBorder, 1.0,
-		fBottomBorder, OperatorType(EQ), frame.Height(), kExtentPenalty,
+		fBottomBorder, kEQ, frame.Height(), kExtentPenalty,
 		kExtentPenalty);
 
 	if (!fLeftConstraint || !fTopConstraint || !fMinWidthConstraint

src/add-ons/decorators/SATDecorator/StackAndTile.h

@@ -20,7 +20,7 @@
 #include "WindowList.h"
 
 
-//#define DEBUG_STACK_AND_TILE
+#define DEBUG_STACK_AND_TILE
 
 #ifdef DEBUG_STACK_AND_TILE
 #	define STRACE_SAT(x...) debug_printf("SAT: "x)

src/libs/alm/ALMLayout.cpp

@@ -17,6 +17,9 @@
 #include "ResultType.h"
 
 
+using namespace LinearProgramming;
+
+
 const BSize kUnsetSize(B_SIZE_UNSET, B_SIZE_UNSET);
 const BSize kMinSize(0, 0);
 const BSize kMaxSize(B_SIZE_UNLIMITED, B_SIZE_UNLIMITED);

src/libs/alm/Area.cpp

@@ -20,6 +20,7 @@
 #include "ALMLayout.h"
 
 
+using namespace LinearProgramming;
 using namespace std;
 
 
@@ -361,7 +362,7 @@ Area::SetContentAspectRatio(double ratio)
 		fContentAspectRatioC = NULL;
 	} else if (fContentAspectRatioC == NULL) {
 		fContentAspectRatioC = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight,
-			ratio, fTop, -ratio, fBottom, OperatorType(EQ), 0.0);
+			ratio, fTop, -ratio, fBottom, kEQ, 0.0);
 		fConstraints.AddItem(fContentAspectRatioC);
 	} else {
 		fContentAspectRatioC->SetLeftSide(-1.0, fLeft, 1.0, fRight, ratio,
@@ -513,7 +514,7 @@ Constraint*
 Area::SetWidthAs(Area* area, float factor)
 {
 	return fLS->AddConstraint(-1.0, fLeft, 1.0, fRight, factor, area->Left(),
-		-factor, area->Right(), OperatorType(EQ), 0.0);
+		-factor, area->Right(), kEQ, 0.0);
 }
 
 
@@ -528,7 +529,7 @@ Constraint*
 Area::SetHeightAs(Area* area, float factor)
 {
 	return fLS->AddConstraint(-1.0, fTop, 1.0, fBottom, factor, area->Top(),
-		-factor, area->Bottom(), OperatorType(EQ), 0.0);
+		-factor, area->Bottom(), kEQ, 0.0);
 }
 
 
@@ -614,20 +615,18 @@ Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom,
 	// adds the two essential constraints of the area that make sure that the
 	// left x-tab is really to the left of the right x-tab, and the top y-tab
 	// really above the bottom y-tab
-	fMinContentWidth = ls->AddConstraint(-1.0, fLeft, 1.0, fRight,
-		OperatorType(GE), 0);
-	fMinContentHeight = ls->AddConstraint(-1.0, fTop, 1.0, fBottom,
-		OperatorType(GE), 0);
+	fMinContentWidth = ls->AddConstraint(-1.0, fLeft, 1.0, fRight, kGE, 0);
+	fMinContentHeight = ls->AddConstraint(-1.0, fTop, 1.0, fBottom, kGE, 0);
 
 	fConstraints.AddItem(fMinContentWidth);
 	fConstraints.AddItem(fMinContentHeight);
 
 	fPreferredContentWidth = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight, -1.0,
-		fScaleWidth, OperatorType(EQ), 0, fShrinkPenalties.Width(),
+		fScaleWidth, kEQ, 0, fShrinkPenalties.Width(),
 		fGrowPenalties.Width());
 
 	fPreferredContentHeight = fLS->AddConstraint(-1.0, fTop, 1.0, fBottom, -1.0,
-		fScaleHeight, OperatorType(EQ), 0, fShrinkPenalties.Height(),
+		fScaleHeight, kEQ, 0, fShrinkPenalties.Height(),
 		fGrowPenalties.Height());
 
 	fConstraints.AddItem(fPreferredContentWidth);
@@ -694,7 +693,7 @@ Area::_UpdateMaxSizeConstraint(BSize max)
 	if (alignment.Vertical() == B_ALIGN_USE_FULL_HEIGHT) {
 		if (fMaxContentHeight == NULL) {
 			fMaxContentHeight = fLS->AddConstraint(-1.0, fTop, 1.0, fBottom,
-				OperatorType(LE), max.Height());
+				kLE, max.Height());
 			fConstraints.AddItem(fMaxContentHeight);
 		} else
 			fMaxContentHeight->SetRightSide(max.Height());
@@ -707,8 +706,8 @@ Area::_UpdateMaxSizeConstraint(BSize max)
 
 	if (alignment.Horizontal() == B_ALIGN_USE_FULL_WIDTH) {
 		if (fMaxContentWidth == NULL) {
-			fMaxContentWidth = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight,
-				OperatorType(LE), max.Width());
+			fMaxContentWidth = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight, kLE,
+				max.Width());
 			fConstraints.AddItem(fMaxContentWidth);
 		} else
 			fMaxContentWidth->SetRightSide(max.Width());

src/libs/alm/Column.cpp

@@ -13,6 +13,9 @@
 #include "Tab.h"
 
 
+using namespace LinearProgramming;
+
+
 /**
  * The left boundary of the column.
  */
@@ -156,7 +159,7 @@ Column::HasSameWidthAs(Column* column)
 {
 	Constraint* constraint = fLS->AddConstraint(
 		-1.0, Left(), 1.0, Right(), 1.0, column->Left(), -1.0, column->Right(),
-		OperatorType(EQ), 0.0);
+		kEQ, 0.0);
 	fConstraints.AddItem(constraint);
 	return constraint;
 }

src/libs/alm/Row.cpp

@@ -14,7 +14,10 @@
 
 #include <SupportDefs.h>
 
-	
+
+using namespace LinearProgramming;
+
+
 /**
  * The top boundary of the row.
  */
@@ -159,8 +162,8 @@ Constraint*
 Row::HasSameHeightAs(Row* row)
 {
 	Constraint* constraint = fLS->AddConstraint(
-		-1.0, Top(), 1.0, Bottom(), 1.0, row->Top(), -1.0, row->Bottom(),
-		OperatorType(EQ), 0.0);
+		-1.0, Top(), 1.0, Bottom(), 1.0, row->Top(), -1.0, row->Bottom(), kEQ,
+		0.0);
 	fConstraints.AddItem(constraint);
 	return constraint;
 }

src/libs/linprog/Constraint.cpp

@@ -9,6 +9,7 @@
 #include "Constraint.h"
 
 #include <new>
+#include <stdio.h>
 
 #include "LinearSpec.h"
 #include "Variable.h"
@@ -321,11 +322,11 @@ Constraint::WriteXML(BFile* file)
 	file->Write(buffer, sprintf(buffer, "\t\t</leftside>\n"));
 
 	const char* op = "??";
-	if (fOp == OperatorType(EQ))
+	if (fOp == kEQ)
 		op = "EQ";
-	else if (fOp == OperatorType(LE))
+	else if (fOp == kLE)
 		op = "LE";
-	else if (fOp == OperatorType(GE))
+	else if (fOp == kGE)
 		op = "GE";
 
 	file->Write(buffer, sprintf(buffer, "\t\t<op>%s</op>\n", op));
@@ -406,9 +407,9 @@ Constraint::GetString(BString& string) const
 			s->Var()->GetString(string);
 			string << " ";
 		}
-		string << ((fOp == OperatorType(EQ)) ? "== "
-			: (fOp == OperatorType(GE)) ? ">= "
-			: (fOp == OperatorType(LE)) ? "<= "
+		string << ((fOp == kEQ) ? "== "
+			: (fOp == kGE) ? ">= "
+			: (fOp == kLE) ? "<= "
 			: "?? ");
 		string << (float)fRightSide;
 		string << " PenaltyPos=" << (float)PenaltyPos();

src/libs/linprog/Jamfile

@@ -8,6 +8,7 @@ UsePrivateHeaders shared ;
 StaticLibrary liblinprog.a : 
 	Constraint.cpp
 	LinearSpec.cpp
+	LPSolveInterface.cpp
 	Summand.cpp
 	PenaltyFunction.cpp
 	Variable.cpp

src/libs/linprog/LPSolveInterface.cpp

@@ -0,0 +1,225 @@
+#include "LPSolveInterface.h"
+
+
+using namespace LinearProgramming;
+
+
+LPSolveInterface::LPSolveInterface()
+	:
+	fLpPresolved(NULL),
+	fLP(NULL)
+{
+	fLP = make_lp(0, 0);
+	if (fLP == NULL)
+		printf("Couldn't construct a new model.");
+
+	// minimize the objective functions, this is the default of lp_solve so we
+	// don't have to do it here:
+	// set_minim(fLP);
+
+	set_verbose(fLP, 1);
+}
+
+
+LPSolveInterface::~LPSolveInterface()
+{
+	_RemovePresolved();
+	delete_lp(fLP);
+}
+
+
+ResultType
+LPSolveInterface::Solve(VariableList& variables)
+{
+	if (fLpPresolved != NULL)
+		return _Presolve(variables);
+
+	ResultType result = (ResultType)solve(fLP);
+
+	if (result == OPTIMAL) {
+		int32 size = variables.CountItems();
+		double x[size];
+		if (!get_variables(fLP, &x[0]))
+			printf("Error in get_variables.\n");
+
+		for (int32 i = 0; i < size; i++)
+			variables.ItemAt(i)->SetValue(x[i]);
+	}
+	return result;
+}
+
+
+double
+LPSolveInterface::GetObjectiveValue()
+{
+	if (fLpPresolved)
+		return get_objective(fLpPresolved);
+	return get_objective(fLP);
+}
+
+
+bool
+LPSolveInterface::AddVariable()
+{
+	double d = 0;
+	int i = 0;
+	if (!add_columnex(fLP, 0, &d, &i))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::RemoveVariable(int variable)
+{
+	if (!del_column(fLP, variable))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetVariableRange(int variable, double min, double max)
+{
+	if (!set_bounds(fLP, variable, min, max))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::AddConstraint(int nElements, double* coefficients,
+	int* variableIndices, OperatorType op, double rightSide)
+{
+	if (!add_constraintex(fLP, nElements, coefficients, variableIndices,
+		(op == kEQ ? EQ : (op == kGE) ? GE : LE), rightSide)) {
+		return false;
+	}
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::RemoveConstraint(int constraint)
+{
+	if (!del_constraint(fLP, constraint))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetLeftSide(int constraint, int nElements,
+	double* coefficients, int* variableIndices)
+{
+	if (!set_rowex(fLP, constraint, nElements, coefficients, variableIndices))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetRightSide(int constraint, double value)
+{
+	if (!set_rh(fLP, constraint, value))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetOperator(int constraint, OperatorType op)
+{
+	if (!set_constr_type(fLP, constraint, op == kEQ) ? EQ : (op == kGE) ? GE
+		: LE) {
+		return false;
+	}
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetObjectiveFunction(int nElements, double* coefficients,
+	int* variableIndices)
+{
+	if (!set_obj_fnex(fLP, nElements, coefficients, variableIndices))
+		return false;
+	_RemovePresolved();
+	return true;
+}
+
+
+bool
+LPSolveInterface::SetOptimization(OptimizationType value)
+{
+	if (value == LinearProgramming::MINIMIZE)
+		set_minim(fLP);
+	else
+		set_maxim(fLP);
+	return true;
+}
+
+
+bool
+LPSolveInterface::SaveModel(const char* fileName)
+{
+	// TODO: Constness should be fixed in liblpsolve API.
+	if (!write_lp(fLP, const_cast<char*>(fileName)))
+		return false;
+	return true;
+}
+
+
+/**
+ * Remove a cached presolved model, if existent.
+ * This is automatically done each time after the model has been changed,
+ * to avoid an old cached presolved model getting out of sync.
+ */
+void
+LPSolveInterface::_RemovePresolved()
+{
+	if (fLpPresolved == NULL)
+		return;
+	delete_lp(fLpPresolved);
+	fLpPresolved = NULL;
+}
+
+
+/**
+ * Creates and caches a simplified version of the linear programming problem,
+ * where redundant rows, columns and constraints are removed,
+ * if it has not been created before.
+ * Then, the simplified problem is solved.
+ *
+ * @return the result of the solving attempt
+ */
+ResultType
+LPSolveInterface::_Presolve(VariableList& variables)
+{
+	if (fLpPresolved == NULL) {
+		fLpPresolved = copy_lp(fLP);
+		set_presolve(fLpPresolved, PRESOLVE_ROWS | PRESOLVE_COLS
+			| PRESOLVE_LINDEP, get_presolveloops(fLpPresolved));
+	}
+
+	ResultType result = (ResultType)solve(fLpPresolved);
+
+	if (result == OPTIMAL) {
+		int32 size = variables.CountItems();
+		for (int32 i = 0; i < size; i++) {
+			Variable* current = variables.ItemAt(i);
+			current->SetValue(get_var_primalresult(fLpPresolved,
+				get_Norig_rows(fLpPresolved) + current->Index()));
+		}
+	}
+
+	return result;
+}

src/libs/linprog/LPSolveInterface.h

@@ -0,0 +1,49 @@
+#ifndef LP_SOLVE_INTERFACE_H
+#define LP_SOLVE_INTERFACE_H
+
+
+#include "LinearSpec.h"
+
+#include "lp_lib.h"
+
+
+class LPSolveInterface : public LinearProgramming::SolverInterface {
+public:
+								LPSolveInterface();
+								~LPSolveInterface();
+
+			ResultType			Solve(VariableList& variables);
+			double				GetObjectiveValue();
+
+			bool				AddVariable();
+			bool				RemoveVariable(int variable);
+			bool				SetVariableRange(int variable, double min,
+									double max);
+
+			bool				AddConstraint(int nElements,
+									double* coefficients, int* variableIndices,
+									OperatorType op, double rightSide);
+			bool				RemoveConstraint(int constraint);
+			bool				SetLeftSide(int constraint, int nElements,
+									double* coefficients, int* variableIndices);
+			bool				SetRightSide(int constraint, double value);
+			bool				SetOperator(int constraint,
+									OperatorType op);
+
+			bool				SetObjectiveFunction(int nElements,
+									double* coefficients,
+									int* variableIndices);
+			bool				SetOptimization(OptimizationType value);
+
+			bool				SaveModel(const char* fileName);
+
+private:
+			ResultType			_Presolve(VariableList& variables);
+			void				_RemovePresolved();
+
+			lprec*				fLpPresolved;
+			lprec*				fLP;
+};
+
+
+#endif // LP_SOLVE_INTERFACE_H

src/libs/linprog/LinearSpec.cpp

@@ -9,6 +9,9 @@
 #include "LinearSpec.h"
 
 #include <new>
+#include <stdio.h>
+
+#include "LPSolveInterface.h"
 
 
 /**
@@ -17,22 +20,13 @@
  */
 LinearSpec::LinearSpec()
 	:
-	fLpPresolved(NULL),
 	fOptimization(MINIMIZE),
 	fObjFunction(new(std::nothrow) SummandList()),
 	fResult(ERROR),
 	fObjectiveValue(NAN),
 	fSolvingTime(NAN)
 {
-	fLP = make_lp(0, 0);
-	if (fLP == NULL)
-		printf("Couldn't construct a new model.");
-
-	// minimize the objective functions, this is the default of lp_solve so we
-	// don't have to do it here:
-	// set_minim(fLP);
-
-	set_verbose(fLP, 1);
+	fSolver = new LPSolveInterface;
 }
 
 
@@ -43,7 +37,6 @@ LinearSpec::LinearSpec()
  */
 LinearSpec::~LinearSpec()
 {
-	_RemovePresolved();
 	for (int32 i = 0; i < fConstraints.CountItems(); i++)
 		delete (Constraint*)fConstraints.ItemAt(i);
 	for (int32 i = 0; i < fObjFunction->CountItems(); i++)
@@ -51,9 +44,8 @@ LinearSpec::~LinearSpec()
 	while (fVariables.CountItems() > 0)
 		RemoveVariable(fVariables.ItemAt(0));
 
-	delete_lp(fLP);
-
 	delete fObjFunction;
+	delete fSolver;
 }
 
 
@@ -83,17 +75,14 @@ LinearSpec::AddVariable(Variable* variable)
 	if (variable->IsValid())
 		return false;
 
-	double d = 0;
-	int i = 0;
-
 	if (!fVariables.AddItem(variable))
 		return false;
-	if (add_columnex(fLP, 0, &d, &i) == 0) {
+	if (!fSolver->AddVariable()) {
 		fVariables.RemoveItem(variable);
 		return false;
 	}
 
-	if (!SetRange(variable, variable->Min(), variable->Max())) {
+	if (!UpdateRange(variable)) {
 		RemoveVariable(variable, false);
 		return false;
 	}
@@ -110,7 +99,7 @@ LinearSpec::RemoveVariable(Variable* variable, bool deleteVariable)
 	if (index < 0)
 		return false;
 
-	if (!del_column(fLP, index))
+	if (!fSolver->RemoveVariable(index))
 		return false;
 	fVariables.RemoveItemAt(index - 1);
 	variable->fIsValid = false;
@@ -156,9 +145,12 @@ LinearSpec::IndexOf(const Variable* variable) const
 
 
 bool
-LinearSpec::SetRange(Variable* variable, double min, double max)
+LinearSpec::UpdateRange(Variable* variable)
 {
-	return set_bounds(fLP, IndexOf(variable), min, max);
+	if (!fSolver->SetVariableRange(IndexOf(variable), variable->Min(),
+		variable->Max()))
+		return false;
+	return true;
 }
 
 
@@ -180,7 +172,7 @@ LinearSpec::AddConstraint(Constraint* constraint)
 		varIndexes[nCoefficient] = s->Var()->Index();
 	}
 
-	if (penaltyNeg != INFINITY && penaltyNeg != 0. && op != OperatorType(LE)) {
+	if (penaltyNeg != INFINITY && penaltyNeg != 0. && op != LE) {
 		constraint->fDNegObjSummand
 			= new(std::nothrow) Summand(constraint->PenaltyNeg(),
 				AddVariable());
@@ -190,7 +182,7 @@ LinearSpec::AddConstraint(Constraint* constraint)
 		nCoefficient++;
 	}
 
-	if (penaltyPos != INFINITY && penaltyPos != 0. && op != OperatorType(GE)) {
+	if (penaltyPos != INFINITY && penaltyPos != 0. && op != GE) {
 		constraint->fDPosObjSummand
 			= new(std::nothrow) Summand(constraint->PenaltyPos(),
 				AddVariable());
@@ -200,10 +192,10 @@ LinearSpec::AddConstraint(Constraint* constraint)
 		nCoefficient++;
 	}
 
-	if (!add_constraintex(fLP, nCoefficient, &coeffs[0], &varIndexes[0],
-			(op == OperatorType(EQ) ? EQ : (op == OperatorType(GE)) ? GE
-				: LE), rightSide))
+	if (!fSolver->AddConstraint(nCoefficient, &coeffs[0], &varIndexes[0], op,
+		rightSide)) {
 		return false;
+	}
 
 	UpdateObjectiveFunction();
 	fConstraints.AddItem(constraint);
@@ -228,7 +220,7 @@ LinearSpec::RemoveConstraint(Constraint* constraint, bool deleteConstraint)
 		constraint->fDPosObjSummand = NULL;
 	}
 
-	del_constraint(fLP, constraint->Index());
+	fSolver->RemoveConstraint(constraint->Index());
 	fConstraints.RemoveItem(constraint);
 	constraint->fIsValid = false;
 
@@ -268,12 +260,11 @@ LinearSpec::UpdateLeftSide(Constraint* constraint)
 		i++;
 	}
 
-	if (!set_rowex(fLP, constraint->Index(), i, &coeffs[0],
+	if (!fSolver->SetLeftSide(constraint->Index(), i, &coeffs[0],
 		&varIndexes[0]))
 		return false;
 
 	UpdateObjectiveFunction();
-	_RemovePresolved();
 	return true;
 }
 
@@ -281,10 +272,8 @@ LinearSpec::UpdateLeftSide(Constraint* constraint)
 bool
 LinearSpec::UpdateRightSide(Constraint* constraint)
 {
-	if (!set_rh(fLP, constraint->Index(), constraint->RightSide()))
+	if (!fSolver->SetRightSide(constraint->Index(), constraint->RightSide()))
 		return false;
-
-	_RemovePresolved();
 	return true;
 }
 
@@ -292,13 +281,8 @@ LinearSpec::UpdateRightSide(Constraint* constraint)
 bool
 LinearSpec::UpdateOperator(Constraint* constraint)
 {
-	OperatorType op = constraint->Op();
-	if (!set_constr_type(fLP, constraint->Index(),
-		(op == OperatorType(EQ)) ? EQ : (op == OperatorType(GE)) ? GE
-			: LE))
+	if (!fSolver->SetOperator(constraint->Index(), constraint->Op()))
 		return false;
-
-	_RemovePresolved();
 	return true;
 }
 
@@ -613,10 +597,8 @@ LinearSpec::UpdateObjectiveFunction()
 		varIndexes[i] = current->Var()->Index();
 	}
 
-	if (!set_obj_fnex(fLP, size, &coeffs[0], &varIndexes[0]))
+	if (!fSolver->SetObjectiveFunction(size, &coeffs[0], &varIndexes[0]))
 		printf("Error in set_obj_fnex.\n");
-
-	_RemovePresolved();
 }
 
 
@@ -652,65 +634,10 @@ LinearSpec::_AddConstraint(SummandList* leftSide, OperatorType op,
 		delete constraint;
 		return NULL;
 	}
-	_RemovePresolved();
 	return constraint;
 }
 
 
-/**
- * Remove a cached presolved model, if existent.
- * This is automatically done each time after the model has been changed,
- * to avoid an old cached presolved model getting out of sync.
- */
-void
-LinearSpec::_RemovePresolved()
-{
-	if (fLpPresolved == NULL)
-		return;
-	delete_lp(fLpPresolved);
-	fLpPresolved = NULL;
-}
-
-
-/**
- * Creates and caches a simplified version of the linear programming problem,
- * where redundant rows, columns and constraints are removed,
- * if it has not been created before.
- * Then, the simplified problem is solved.
- *
- * @return the result of the solving attempt
- */
-ResultType
-LinearSpec::_Presolve()
-{
-	bigtime_t start, end;
-	start = system_time();
-
-	if (fLpPresolved == NULL) {
-		fLpPresolved = copy_lp(fLP);
-		set_presolve(fLpPresolved, PRESOLVE_ROWS | PRESOLVE_COLS
-			| PRESOLVE_LINDEP, get_presolveloops(fLpPresolved));
-	}
-
-	fResult = (ResultType)solve(fLpPresolved);
-	fObjectiveValue = get_objective(fLpPresolved);
-
-	if (fResult == OPTIMAL) {
-		int32 size = fVariables.CountItems();
-		for (int32 i = 0; i < size; i++) {
-			Variable* current = (Variable*)fVariables.ItemAt(i);
-			current->SetValue(get_var_primalresult(fLpPresolved,
-					get_Norig_rows(fLpPresolved) + current->Index()));
-		}
-	}
-
-	end = system_time();
-	fSolvingTime = (end - start) / 1000.0;
-
-	return fResult;
-}
-
-
 /**
  * Tries to solve the linear programming problem.
  * If a cached simplified version of the problem exists, it is used instead.
@@ -720,27 +647,11 @@ LinearSpec::_Presolve()
 ResultType
 LinearSpec::Solve()
 {
-	if (fLpPresolved != NULL)
-		return _Presolve();
-
 	bigtime_t start, end;
 	start = system_time();
 
-	fResult = (ResultType)solve(fLP);
-	fObjectiveValue = get_objective(fLP);
-
-	if (fResult == OPTIMAL) {
-		int32 size = fVariables.CountItems();
-		double x[size];
-		if (!get_variables(fLP, &x[0]))
-			printf("Error in get_variables.\n");
-
-		int32 i = 0;
-		while (i < size) {
-			((Variable*)fVariables.ItemAt(i))->SetValue(x[i]);
-			i++;
-		}
-	}
+	fResult = fSolver->Solve(fVariables);
+	fObjectiveValue = fSolver->GetObjectiveValue();
 
 	end = system_time();
 	fSolvingTime = (end - start) / 1000.0;
@@ -755,11 +666,10 @@ LinearSpec::Solve()
  *
  * @param fname	the file name
  */
-void
+bool
 LinearSpec::Save(const char* fileName)
 {
-	// TODO: Constness should be fixed in liblpsolve API.
-	write_lp(fLP, const_cast<char*>(fileName));
+	return fSolver->SaveModel(fileName) == B_OK;
 }
 
 
@@ -786,10 +696,7 @@ void
 LinearSpec::SetOptimization(OptimizationType value)
 {
 	fOptimization = value;
-	if (fOptimization == MINIMIZE)
-		set_minim(fLP);
-	else
-		set_maxim(fLP);
+	fSolver->SetOptimization(value);
 }
 
 

src/libs/linprog/PenaltyFunction.cpp

@@ -4,12 +4,16 @@
  * Distributed under the terms of the MIT License.
  */
 
+
 #include "PenaltyFunction.h"
+
+#include <stdio.h>
+
 #include "Constraint.h"
-#include "Summand.h"
-#include "OperatorType.h"
-#include "Variable.h"
 #include "LinearSpec.h"
+#include "OperatorType.h"
+#include "Summand.h"
+#include "Variable.h"
 
 
 /**
@@ -34,14 +38,14 @@ PenaltyFunction::PenaltyFunction(LinearSpec* ls, Variable* var, BList* xs, BList
 	fConstraints = new BList(sizeGs + 1);
 	fObjFunctionSummands = new BList(sizeGs);
 		
-	fConstraints->AddItem(ls->AddConstraint(1.0, var, OperatorType(EQ), 
+	fConstraints->AddItem(ls->AddConstraint(1.0, var, kEQ, 
 		*(double*)(xs->ItemAt(0)), -*(double*)(gs->ItemAt(0)), 
 		*(double*)(gs->ItemAt(1))));
 	
 	for (int32 i = 1; i < sizeGs; i++) {
 		Variable* dPos = ls->AddVariable();
 			
-		fConstraints->AddItem(ls->AddConstraint(1.0, var, -1.0, dPos, OperatorType(LE), 
+		fConstraints->AddItem(ls->AddConstraint(1.0, var, -1.0, dPos, kLE, 
 			*(double*)(xs->ItemAt(i))));
 		
 		Summand* objSummand =  new Summand(*(double*)(gs->ItemAt(i + 1)) - *(double*)(gs->ItemAt(i)), dPos);

src/libs/linprog/Variable.cpp

@@ -135,7 +135,7 @@ Variable::SetRange(double min, double max)
 
 	fMin = min;
 	fMax = max;
-	fLS->SetRange(this, fMin, fMax);
+	fLS->UpdateRange(this);
 }
 
 
@@ -196,7 +196,7 @@ Variable::IsEqual(Variable* var)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(1.0, this, -1.0, var, OperatorType(EQ), 0.0);
+	return fLS->AddConstraint(1.0, this, -1.0, var, kEQ, 0.0);
 }
 
 
@@ -212,7 +212,7 @@ Variable::IsSmallerOrEqual(Variable* var)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(1.0, this, -1.0, var, OperatorType(LE), 0.0);
+	return fLS->AddConstraint(1.0, this, -1.0, var, kLE, 0.0);
 }
 
 
@@ -228,7 +228,7 @@ Variable::IsGreaterOrEqual(Variable* var)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(-1.0, var, 1.0, this, OperatorType(GE), 0.0);
+	return fLS->AddConstraint(-1.0, var, 1.0, this, kGE, 0.0);
 }
 
 
@@ -238,7 +238,7 @@ Variable::IsEqual(Variable* var, double penaltyNeg, double penaltyPos)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(1.0, this, -1.0, var, OperatorType(EQ), 0.0,
+	return fLS->AddConstraint(1.0, this, -1.0, var, kEQ, 0.0,
 		penaltyNeg, penaltyPos);
 }
 
@@ -249,8 +249,8 @@ Variable::IsSmallerOrEqual(Variable* var, double penaltyNeg, double penaltyPos)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(1.0, this, -1.0, var, OperatorType(LE), 0.0,
-		penaltyNeg, penaltyPos);
+	return fLS->AddConstraint(1.0, this, -1.0, var, kLE, 0.0, penaltyNeg,
+		penaltyPos);
 }
 
 
@@ -260,8 +260,8 @@ Variable::IsGreaterOrEqual(Variable* var, double penaltyNeg, double penaltyPos)
 	if (!fIsValid)
 		return NULL;
 
-	return fLS->AddConstraint(-1.0, var, 1.0, this, OperatorType(GE), 0.0,
-		penaltyNeg, penaltyPos);
+	return fLS->AddConstraint(-1.0, var, 1.0, this, kGE, 0.0, penaltyNeg,
+		penaltyPos);
 }