public override Expression VisitOldExpression(OldExpression oldExpression) {
if (this.topLevelClosureClass != null) {
#region In Closure ==> Create a field
// Since we're within a closure, we can't create a local to hold the value of the old expression
// but instead have to create a field for it. That field can be a member of the top-level
// closure class since nothing mentioned in the old expression (except possibly for the
// bound variables of enclosing quantifications) should be anything captured from
// an inner anonymous delegate.
// BUT, first we have to know if the old expression depends on any of the bound
// variables of the closures in which it is located. If not, then we can implement
// it as a scalar and just generate the assignment "closure_class.field := e" for
// "Old(e)" to take a snapshot of e's value in the prestate. If it does depend on
// any of the bound variables, then we need to generate a set of for-loops that
// compute the indices and values of e for each tuple of indices so it can be retrieved
// (given the indices) in the post-state.
CollectBoundVariables cbv = new CollectBoundVariables(this.stackOfBoundVariables);
cbv.VisitExpression(oldExpression.expression);
SubstituteClosureClassWithinOldExpressions subst =
new SubstituteClosureClassWithinOldExpressions(this.closureLocals);
Expression e = subst.VisitExpression(oldExpression.expression);
if (cbv.FoundVariables.Count == 0) {
#region Use a scalar for the old variable
Local closureLocal;
if (!this.closureLocals.TryGetValue(this.topLevelClosureClass, out closureLocal))
{
Contract.Assume(false, "can't find closure local!");
}
#region Define a scalar
var clTemplate = HelperMethods.Unspecialize(this.topLevelClosureClass);
Field f = new Field(clTemplate,
null,
FieldFlags.CompilerControlled | FieldFlags.Public,
Identifier.For("_old" + oldExpression.expression.UniqueKey.ToString()), // unique name for this old expr.
oldExpression.Type,
null);
clTemplate.Members.Add(f);
// now produce properly instantiated field
f = (Field)Rewriter.GetMemberInstanceReference(f, this.topLevelClosureClass);
#endregion
#region Generate code to store value in prestate
this.prestateValuesOfOldExpressions.Statements.Add(new AssignmentStatement(new MemberBinding(closureLocal, f), e));
#endregion
#region Return expression to be used in poststate
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. This will be this.up.f where "up" is the field C#
// generated to point to the instance of the top-level closure class.
if (this.PointerToTopLevelClosureClass == null) {
// then the old expression occurs in the top-level closure class. Just return "this.f"
// where "this" refers to the top-level closure class.
return new MemberBinding(new This(this.currentClosureClass), f);
} else {
return new MemberBinding(
new MemberBinding(new This(this.currentClosureClass), this.PointerToTopLevelClosureClass),
f);
}
#endregion
#endregion
} else {
// the Old expression *does* depend upon at least one of the bound variable
// in a ForAll or Exists expression
#region Use an indexed variable for the old variable
TypeNode oldVariableTypeDomain;
#region Decide if domain is one-dimensional or not
bool oneDimensional = cbv.FoundVariables.Count == 1 && cbv.FoundVariables[0].Type.IsValueType;
if (oneDimensional) {
// a one-dimensional old-expression can use the index variable directly
oldVariableTypeDomain = cbv.FoundVariables[0].Type;
} else {
oldVariableTypeDomain = SystemTypes.GenericList.GetTemplateInstance(this.module, SystemTypes.Int32);
}
#endregion
TypeNode oldVariableTypeRange = oldExpression.Type;
TypeNode oldVariableType = SystemTypes.GenericDictionary.GetTemplateInstance(this.module, oldVariableTypeDomain, oldVariableTypeRange);
Local closureLocal;
if (!this.closureLocals.TryGetValue(this.topLevelClosureClass, out closureLocal))
{
Contract.Assume(false, "can't find closure local");
}
#region Define an indexed variable
var clTemplate = HelperMethods.Unspecialize(this.topLevelClosureClass);
Field f = new Field(clTemplate,
null,
FieldFlags.CompilerControlled | FieldFlags.Assembly, // can't be private or protected because it needs to be accessed from inner (closure) classes that don't inherit from the class this field is added to.
Identifier.For("_old" + oldExpression.expression.UniqueKey.ToString()), // unique name for this old expr.
oldVariableType,
null);
clTemplate.Members.Add(f);
// instantiate f
f = (Field)Rewriter.GetMemberInstanceReference(f, closureLocal.Type);
#endregion
#region Generate code to initialize the indexed variable
Statement init = new AssignmentStatement(
new MemberBinding(closureLocal, f),
new Construct(new MemberBinding(null, oldVariableType.GetConstructor()), null));
this.prestateValuesOfOldExpressions.Statements.Add(init);
#endregion
#region Generate code to store values in prestate
#region Create assignment: this.closure.f[i,j,k,...] = e;
Method setItem = oldVariableType.GetMethod(Identifier.For("set_Item"), oldVariableTypeDomain, oldVariableTypeRange);
Expression index;
if (oneDimensional) {
index = cbv.FoundVariables[0];
} else {
//InstanceInitializer ctor =
// ContractNodes.TupleClass.GetConstructor(SystemTypes.Int32.GetArrayType(1));
//Expression index = new Construct(new MemberBinding(null,ctor),new ExpressionList(
index = Literal.Null;
}
MethodCall mc = new MethodCall(new MemberBinding(new MemberBinding(closureLocal, f), setItem),
new ExpressionList(index, e));
Statement stat = new ExpressionStatement(mc);
#endregion
List<Local> locals = new List<Local>(this.stackOfBoundVariables.Count);
TrivialHashtable paramMap = new TrivialHashtable();
#region Generate a local for each bound variable to use in for-loop
foreach (Variable v in this.stackOfBoundVariables) {
Local l = new Local(Identifier.Empty, v.Type);
paramMap[v.UniqueKey] = l;
locals.Add(l);
}
#endregion
#region Substitute locals for bound variables in old expression *AND* in inner loop bounds
SubstituteParameters sps = new SubstituteParameters(paramMap, this.stackOfBoundVariables);
sps.Visit(stat);
#endregion
#region Create nested for-loops around assignment
// keep track of when the first variable is used (from innermost to outermost)
// as soon as the first one is needed because the old expression depends on it,
// then keep all enclosing loops. It would be possible to keep only those where
// the necessary loops have loop bounds that depend on an enclosing loop, but I
// haven't calculated that, so just keep them all. For instance, if the old expression
// depends on j and the loops are "for i,0,n" and inside that "for j,0,i", then need
// both loops. If the inner loop bounds were 0 and n, then wouldn't need the outer
// loop.
bool usedAVariable = false;
for (int i = this.stackOfBoundVariables.Count - 1; 0 <= i; i--) {
if (!usedAVariable
&& !cbv.FoundVariables.Contains(this.stackOfBoundVariables[i])) continue;
usedAVariable = true;
Expression lowerBound = new Duplicator(this.module, this.currentClosureClass).VisitExpression(
this.stackOfMethods[i].Operands[0]);
lowerBound = subst.VisitExpression(lowerBound);
lowerBound = sps.VisitExpression(lowerBound);
Expression upperBound = new Duplicator(this.module, this.currentClosureClass).VisitExpression(
this.stackOfMethods[i].Operands[1]);
upperBound = subst.VisitExpression(upperBound);
upperBound = sps.VisitExpression(upperBound);
stat = RewriteHelper.GenerateForLoop(locals[i], lowerBound, upperBound, stat);
}
#endregion
this.prestateValuesOfOldExpressions.Statements.Add(stat);
#endregion
#region Return expression to be used in poststate
Method getItem = oldVariableType.GetMethod(Identifier.For("get_Item"), oldVariableTypeDomain);
if (oneDimensional) {
index = cbv.FoundReferences[0];
} else {
//InstanceInitializer ctor =
// ContractNodes.TupleClass.GetConstructor(SystemTypes.Int32.GetArrayType(1));
//Expression index = new Construct(new MemberBinding(null,ctor),new ExpressionList(
index = Literal.Null;
}
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. This will be this.up.f[i,j,k,...] where "up" is the field C#
// generated to point to the instance of the top-level closure class.
MemberBinding thisDotF;
if (this.PointerToTopLevelClosureClass == null) {
// then the old expression occurs in the top-level closure class. Just return "this.f"
// where "this" refers to the top-level closure class.
Contract.Assume(f != null);
thisDotF = new MemberBinding(new This(clTemplate), HelperMethods.Unspecialize(f));
} else {
thisDotF = new MemberBinding(
new MemberBinding(new This(clTemplate), this.PointerToTopLevelClosureClass),
f);
}
return new MethodCall(new MemberBinding(thisDotF, getItem), new ExpressionList(index));
#endregion
#endregion
}
#endregion
} else {
#region Not in closure ==> Create a local variable
Local l = GetLocalForOldExpression(oldExpression);
#region Make sure local can be seen in the debugger (for the entire method, unfortunately)
if (currentMethod.LocalList == null) {
currentMethod.LocalList = new LocalList();
}
currentMethod.LocalList.Add(l);
currentMethod.Body.HasLocals = true;
#endregion
this.prestateValuesOfOldExpressions.Statements.Add(
new AssignmentStatement(l, oldExpression.expression));
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. When we're not in a closure, this is just the local
// itself.
return l;
#endregion
}
}
public override Expression VisitOldExpression(OldExpression oldExpression)
{
if (this.topLevelClosureClass != null)
{
// In Closure ==> Create a field
// Since we're within a closure, we can't create a local to hold the value of the old expression
// but instead have to create a field for it. That field can be a member of the top-level
// closure class since nothing mentioned in the old expression (except possibly for the
// bound variables of enclosing quantifications) should be anything captured from
// an inner anonymous delegate.
// BUT, first we have to know if the old expression depends on any of the bound
// variables of the closures in which it is located. If not, then we can implement
// it as a scalar and just generate the assignment "closure_class.field := e" for
// "Old(e)" to take a snapshot of e's value in the prestate. If it does depend on
// any of the bound variables, then we need to generate a set of for-loops that
// compute the indices and values of e for each tuple of indices so it can be retrieved
// (given the indices) in the post-state.
CollectBoundVariables cbv = new CollectBoundVariables(this.stackOfBoundVariables);
cbv.VisitExpression(oldExpression.expression);
SubstituteClosureClassWithinOldExpressions subst = new SubstituteClosureClassWithinOldExpressions(this.closureLocals);
Expression e = subst.VisitExpression(oldExpression.expression);
if (cbv.FoundVariables.Count == 0)
{
// Use a scalar for the old variable
Local closureLocal;
if (!this.closureLocals.TryGetValue(this.topLevelClosureClass, out closureLocal))
{
Contract.Assume(false, "can't find closure local!");
}
// Define a scalar
var clTemplate = HelperMethods.Unspecialize(this.topLevelClosureClass);
Field f = new Field(clTemplate,
null,
FieldFlags.CompilerControlled | FieldFlags.Public,
Identifier.For("_old" + oldExpression.expression.UniqueKey.ToString()),
// unique name for this old expr.
oldExpression.Type,
null);
clTemplate.Members.Add(f);
// now produce properly instantiated field
f = (Field)Rewriter.GetMemberInstanceReference(f, this.topLevelClosureClass);
// Generate code to store value in prestate
this.prestateValuesOfOldExpressions.Statements.Add(
new AssignmentStatement(new MemberBinding(closureLocal, f), e));
// Return expression to be used in poststate
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. This will be this.up.f where "up" is the field C#
// generated to point to the instance of the top-level closure class.
if (this.PointerToTopLevelClosureClass == null)
{
// then the old expression occurs in the top-level closure class. Just return "this.f"
// where "this" refers to the top-level closure class.
return(new MemberBinding(new This(this.currentClosureClass), f));
}
else
{
return(new MemberBinding(
new MemberBinding(new This(this.currentClosureClass), this.PointerToTopLevelClosureClass),
f));
}
}
else
{
// the Old expression *does* depend upon at least one of the bound variable
// in a ForAll or Exists expression
// Use an indexed variable for the old variable
TypeNode oldVariableTypeDomain;
// Decide if domain is one-dimensional or not
bool oneDimensional = cbv.FoundVariables.Count == 1 && cbv.FoundVariables[0].Type.IsValueType;
if (oneDimensional)
{
// a one-dimensional old-expression can use the index variable directly
oldVariableTypeDomain = cbv.FoundVariables[0].Type;
}
else
{
oldVariableTypeDomain = SystemTypes.GenericList.GetTemplateInstance(this.module,
SystemTypes.Int32);
}
TypeNode oldVariableTypeRange = oldExpression.Type;
TypeNode oldVariableType = SystemTypes.GenericDictionary.GetTemplateInstance(this.module,
oldVariableTypeDomain, oldVariableTypeRange);
Local closureLocal;
if (!this.closureLocals.TryGetValue(this.topLevelClosureClass, out closureLocal))
{
Contract.Assume(false, "can't find closure local");
}
// Define an indexed variable
var clTemplate = HelperMethods.Unspecialize(this.topLevelClosureClass);
Field f = new Field(clTemplate,
null,
FieldFlags.CompilerControlled | FieldFlags.Assembly,
// can't be private or protected because it needs to be accessed from inner (closure) classes that don't inherit from the class this field is added to.
Identifier.For("_old" + oldExpression.expression.UniqueKey.ToString()),
// unique name for this old expr.
oldVariableType,
null);
clTemplate.Members.Add(f);
// instantiate f
f = (Field)Rewriter.GetMemberInstanceReference(f, closureLocal.Type);
// Generate code to initialize the indexed variable
Statement init = new AssignmentStatement(
new MemberBinding(closureLocal, f),
new Construct(new MemberBinding(null, oldVariableType.GetConstructor()), null));
this.prestateValuesOfOldExpressions.Statements.Add(init);
// Generate code to store values in prestate
// Create assignment: this.closure.f[i,j,k,...] = e;
Method setItem = oldVariableType.GetMethod(Identifier.For("set_Item"), oldVariableTypeDomain, oldVariableTypeRange);
Expression index;
if (oneDimensional)
{
index = cbv.FoundVariables[0];
}
else
{
//InstanceInitializer ctor =
// ContractNodes.TupleClass.GetConstructor(SystemTypes.Int32.GetArrayType(1));
//Expression index = new Construct(new MemberBinding(null,ctor),new ExpressionList(
index = Literal.Null;
}
MethodCall mc = new MethodCall(new MemberBinding(new MemberBinding(closureLocal, f), setItem),
new ExpressionList(index, e));
Statement stat = new ExpressionStatement(mc);
List <Local> locals = new List <Local>(this.stackOfBoundVariables.Count);
TrivialHashtable paramMap = new TrivialHashtable();
// Generate a local for each bound variable to use in for-loop
foreach (Variable v in this.stackOfBoundVariables)
{
Local l = new Local(Identifier.Empty, v.Type);
paramMap[v.UniqueKey] = l;
locals.Add(l);
}
// Substitute locals for bound variables in old expression *AND* in inner loop bounds
SubstituteParameters sps = new SubstituteParameters(paramMap, this.stackOfBoundVariables);
sps.Visit(stat);
// Create nested for-loops around assignment
// keep track of when the first variable is used (from innermost to outermost)
// as soon as the first one is needed because the old expression depends on it,
// then keep all enclosing loops. It would be possible to keep only those where
// the necessary loops have loop bounds that depend on an enclosing loop, but I
// haven't calculated that, so just keep them all. For instance, if the old expression
// depends on j and the loops are "for i,0,n" and inside that "for j,0,i", then need
// both loops. If the inner loop bounds were 0 and n, then wouldn't need the outer
// loop.
bool usedAVariable = false;
for (int i = this.stackOfBoundVariables.Count - 1; 0 <= i; i--)
{
if (!usedAVariable &&
!cbv.FoundVariables.Contains(this.stackOfBoundVariables[i]))
{
continue;
}
usedAVariable = true;
Expression lowerBound = new Duplicator(this.module, this.currentClosureClass).VisitExpression(
this.stackOfMethods[i].Operands[0]);
lowerBound = subst.VisitExpression(lowerBound);
lowerBound = sps.VisitExpression(lowerBound);
Expression upperBound = new Duplicator(this.module, this.currentClosureClass).VisitExpression(
this.stackOfMethods[i].Operands[1]);
upperBound = subst.VisitExpression(upperBound);
upperBound = sps.VisitExpression(upperBound);
stat = RewriteHelper.GenerateForLoop(locals[i], lowerBound, upperBound, stat);
}
this.prestateValuesOfOldExpressions.Statements.Add(stat);
// Return expression to be used in poststate
Method getItem = oldVariableType.GetMethod(Identifier.For("get_Item"), oldVariableTypeDomain);
if (oneDimensional)
{
index = cbv.FoundReferences[0];
}
else
{
//InstanceInitializer ctor =
// ContractNodes.TupleClass.GetConstructor(SystemTypes.Int32.GetArrayType(1));
//Expression index = new Construct(new MemberBinding(null,ctor),new ExpressionList(
index = Literal.Null;
}
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. This will be this.up.f[i,j,k,...] where "up" is the field C#
// generated to point to the instance of the top-level closure class.
MemberBinding thisDotF;
if (this.PointerToTopLevelClosureClass == null)
{
// then the old expression occurs in the top-level closure class. Just return "this.f"
// where "this" refers to the top-level closure class.
Contract.Assume(f != null);
thisDotF = new MemberBinding(new This(clTemplate), HelperMethods.Unspecialize(f));
}
else
{
thisDotF = new MemberBinding(
new MemberBinding(new This(clTemplate), this.PointerToTopLevelClosureClass),
f);
}
return(new MethodCall(new MemberBinding(thisDotF, getItem), new ExpressionList(index)));
}
}
else
{
// Not in closure ==> Create a local variable
Local l = GetLocalForOldExpression(oldExpression);
// Make sure local can be seen in the debugger (for the entire method, unfortunately)
if (currentMethod.LocalList == null)
{
currentMethod.LocalList = new LocalList();
}
currentMethod.LocalList.Add(l);
currentMethod.Body.HasLocals = true;
this.prestateValuesOfOldExpressions.Statements.Add(new AssignmentStatement(l, oldExpression.expression));
// Return an expression that will evaluate in the poststate to the value of the old
// expression in the prestate. When we're not in a closure, this is just the local
// itself.
return(l);
}
}
