public override Expression VisitMethodCall(MethodCall call)
{
MemberBinding mb = call.Callee as MemberBinding;
if (mb == null)
{
return(call);
}
Method calledMethod = mb.BoundMember as Method;
if (calledMethod == null)
{
return(call);
}
Method template = calledMethod.Template;
if (contractNodes.IsOldMethod(template))
{
OldExpression oe = new OldExpression(ExtractOldExpression(call));
oe.Type = call.Type;
return(oe);
}
if (contractNodes.IsValueAtReturnMethod(template))
{
return(new AddressDereference(call.Operands[0], calledMethod.TemplateArguments[0], call.SourceContext));
}
if (contractNodes.IsResultMethod(template))
{
// check if we are in an Task returning method
if (this.declaringMethod != null && this.declaringMethod.ReturnType != null)
{
var rt = this.declaringMethod.ReturnType;
var templ = rt.Template;
if (templ != null && templ.Name.Name == "Task`1" && rt.TemplateArguments != null &&
rt.TemplateArguments.Count == 1)
{
var targ = rt.TemplateArguments[0];
if (calledMethod.TemplateArguments[0] == targ)
{
// use of ReturnValue<T>() instead of ReturnValue<Task<T>>().Result
var retExp = new ReturnValue(rt, call.SourceContext);
var resultProp = rt.GetProperty(Identifier.For("Result"));
if (resultProp != null && resultProp.Getter != null)
{
return(new MethodCall(new MemberBinding(retExp, resultProp.Getter), new ExpressionList()));
}
}
}
}
return(new ReturnValue(calledMethod.ReturnType, call.SourceContext));
}
return(base.VisitMethodCall(call));
}
/// <summary>
/// Performs a bunch of transformations that the basic Extractor doesn't seem to do:
/// - Turns calls to Old contract method into OldExpressions
/// - Turns references to "result" into ResultExpressions
/// -
/// </summary>
public override Expression VisitMethodCall(MethodCall call)
{
MemberBinding mb = call.Callee as MemberBinding;
if (mb == null)
{
return(call);
}
Method calledMethod = mb.BoundMember as Method;
if (calledMethod == null)
{
return(call);
}
Method template = calledMethod.Template;
if (contractNodes.IsOldMethod(template))
{
Expression result = base.VisitMethodCall(call);
call = result as MethodCall;
if (call == null)
{
return(result);
}
result = new OldExpression(call.Operands[0]);
result.Type = call.Type;
return(result);
}
if (contractNodes.IsValueAtReturnMethod(template))
{
return(new AddressDereference(call.Operands[0], calledMethod.TemplateArguments[0], call.SourceContext));
}
if (calledMethod.Parameters != null)
{
if (calledMethod.Parameters.Count == 0)
{
if (contractNodes.IsResultMethod(template))
{
return(new ReturnValue(calledMethod.ReturnType, call.SourceContext));
}
}
else if (insideInvariant &&
contractNodes.IsInvariantMethod(calledMethod))
{
Expression condition = call.Operands[0];
condition.SourceContext = call.SourceContext;
return(VisitExpression(condition));
}
}
return(base.VisitMethodCall(call));
}
private Local GetLocalForOldExpression(OldExpression oldExpression)
{
Contract.Requires(oldExpression != null);
string localName = BestGuessForLocalName(oldExpression);
return(new Local(Identifier.For("Contract.Old(" + localName + ")"), oldExpression.Type));
}
public override Expression VisitParameter(Parameter parameter)
{
if (parameter == null) return null;
var oe = new OldExpression(parameter);
oe.Type = parameter.Type;
return oe;
}
public override Expression VisitOldExpression(OldExpression oldExpression)
{
//Debug.Assert(false, "old was not substituted");
TypeNode returnType = oldExpression.Type;
if (returnType.IsValueType)
return new Literal(0, returnType);
return new Literal(null, returnType);
}
public override Expression VisitOldExpression(OldExpression oldExpression)
{
//Debug.Assert(false, "old was not substituted");
TypeNode returnType = oldExpression.Type;
if (returnType.IsValueType)
{
return(new Literal(0, returnType));
}
return(new Literal(null, returnType));
}
public override Expression VisitMethodCall(MethodCall call)
{
MemberBinding mb = call.Callee as MemberBinding;
if (mb == null) return call;
Method calledMethod = mb.BoundMember as Method;
if (calledMethod == null) return call;
Method template = calledMethod.Template;
if (contractNodes.IsOldMethod(template))
{
OldExpression oe = new OldExpression(ExtractOldExpression(call));
oe.Type = call.Type;
return oe;
}
if (contractNodes.IsValueAtReturnMethod(template))
{
return new AddressDereference(call.Operands[0], calledMethod.TemplateArguments[0], call.SourceContext);
}
if (contractNodes.IsResultMethod(template))
{
// check if we are in an Task returning method
if (this.declaringMethod != null && this.declaringMethod.ReturnType != null)
{
var rt = this.declaringMethod.ReturnType;
var templ = rt.Template;
if (templ != null && templ.Name.Name == "Task`1" && rt.TemplateArguments != null &&
rt.TemplateArguments.Count == 1)
{
var targ = rt.TemplateArguments[0];
if (calledMethod.TemplateArguments[0] == targ)
{
// use of ReturnValue<T>() instead of ReturnValue<Task<T>>().Result
var retExp = new ReturnValue(rt, call.SourceContext);
var resultProp = rt.GetProperty(Identifier.For("Result"));
if (resultProp != null && resultProp.Getter != null)
{
return new MethodCall(new MemberBinding(retExp, resultProp.Getter), new ExpressionList());
}
}
}
}
return new ReturnValue(calledMethod.ReturnType, call.SourceContext);
}
return base.VisitMethodCall(call);
}
public override Expression VisitParameter(Parameter parameter)
{
if (parameter == null)
{
return(null);
}
var oe = new OldExpression(parameter);
oe.Type = parameter.Type;
return(oe);
}
/// <summary>
/// Checks for errors before applying a rule.
/// </summary>
/// <param name="node">The node instance to check.</param>
/// <param name="dataList">Optional data collected during inspection of sources.</param>
/// <param name="data">Private data to give to Apply() upon return.</param>
/// <returns>True if an error occured.</returns>
public override bool CheckConsistency(IOldExpression node, IDictionary <ISourceTemplate, object> dataList, out object data)
{
data = null;
bool Success = true;
Success &= OldExpression.ResolveCompilerReferences(node, ErrorList, out ResolvedExpression ResolvedExpression);
if (Success)
{
data = ResolvedExpression;
}
return(Success);
}
public override Expression VisitOldExpression(OldExpression oldExpression)
{
if (oldExpression == null || oldExpression.expression == null)
{
return(null);
}
if (this._string == null)
{
this._string = new StringBuilder();
}
this._string.Append("\\old(");
this.VisitExpression(oldExpression.expression);
this._string.Append(")");
return(oldExpression);
}
private string BestGuessForLocalName(OldExpression oldExpression)
{
Contract.Requires(oldExpression != null);
MemberBinding mb = oldExpression.expression as MemberBinding;
if (mb != null)
{
return(mb.BoundMember.Name.Name);
}
MethodCall mc = oldExpression.expression as MethodCall;
if (mc != null)
{
mb = mc.Callee as MemberBinding;
if (mb != null)
{
Method calledMethod = mb.BoundMember as Method;
if (calledMethod != null && calledMethod.IsPropertyGetter)
{
Property prop = calledMethod.DeclaringMember as Property;
if (prop != null)
{
return(prop.Name.Name);
}
return(mb.BoundMember.Name.Name);
}
return(mb.BoundMember.Name.Name);
}
}
Parameter p = oldExpression.expression as Parameter;
if (p != null)
{
return(p.Name.Name);
}
// Didn't find something good to use for the name, so just make it unique.
var x = this.counter.ToString();
this.counter++;
return(x);
}
private string BestGuessForLocalName(OldExpression oldExpression) {
Contract.Requires(oldExpression != null);
MemberBinding mb = oldExpression.expression as MemberBinding;
if (mb != null) {
return mb.BoundMember.Name.Name;
}
MethodCall mc = oldExpression.expression as MethodCall;
if (mc != null) {
mb = mc.Callee as MemberBinding;
if (mb != null) {
Method calledMethod = mb.BoundMember as Method;
if (calledMethod != null && calledMethod.IsPropertyGetter) {
Property prop = calledMethod.DeclaringMember as Property;
if (prop != null)
return prop.Name.Name;
else
return mb.BoundMember.Name.Name;
} else {
return mb.BoundMember.Name.Name;
}
}
}
Parameter p = oldExpression.expression as Parameter;
if (p != null) {
return p.Name.Name;
}
// Didn't find something good to use for the name, so just make it unique.
var x = this.counter.ToString();
this.counter++;
return x;
}
public override Expression VisitOldExpression(OldExpression oldExpression) {
// no point descending down into any old expressions
return oldExpression;
}
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 EventingVisitor(Action<OldExpression> visitOldExpression) { VisitedOldExpression += visitOldExpression; } public event Action<OldExpression> VisitedOldExpression; public override Expression VisitOldExpression(OldExpression oldExpression) { if (VisitedOldExpression != null) VisitedOldExpression(oldExpression); return base.VisitOldExpression(oldExpression); }
public virtual void VisitOldExpression(OldExpression oldExpression)
{
if (oldExpression == null) return;
this.VisitExpression(oldExpression.expression);
}
private static string oldExpression2str(OldExpression oe)
{
StringBuilder sb = new StringBuilder();
sb.Append(oldExpression2str(oe.NodeType));
sb.Append("(");
sb.Append(expression2str(oe.expression));
sb.Append(")");
return sb.ToString();
}
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);
}
}
private Local GetLocalForOldExpression(OldExpression oldExpression) {
Contract.Requires(oldExpression != null);
string localName = BestGuessForLocalName(oldExpression);
return new Local(Identifier.For("Contract.Old(" + localName + ")"), oldExpression.Type);
}
public override Expression VisitOldExpression(OldExpression old){
if (old == null) return null;
old.expression = this.VisitExpression(old.expression);
if (old.expression == null) return null;
old.Type = old.expression.Type;
return old;
}
public override void VisitOldExpression(OldExpression oldExpression)
{
this.errorHandler(new Error(1023, "OldValue() can be used only in Ensures.", lastSC));
}
public override Expression VisitOldExpression(OldExpression oldExpression)
{
// no point descending down into any old expressions
return(oldExpression);
}
// TODO: allow arr[i][x][j], where i,j are quantified variables, and x is not
// TODO: multidimensional array...
public override Expression VisitIndexer(Indexer indexer) {
//^ assert this.dependents.Contains(indexer)
bool operandsDependentOnQuantifiedVar = false;
foreach (Expression e1 in indexer.Operands) {
if (this.dependents.ContainsKey(e1)) {
operandsDependentOnQuantifiedVar = true;
break;
}
}
bool objectDependentOnQuantifiedVar = this.dependents.ContainsKey(indexer.Object);
if (operandsDependentOnQuantifiedVar) {
this.currentIndexLevel ++;
Expression newArr = this.VisitExpression(indexer.Object);
OldExpression olde = newArr as OldExpression;
if (olde == null && !objectDependentOnQuantifiedVar) {
// If this is an array expression that does not depend on any of the quantified vars
// create an old expression
olde = new OldExpression(newArr);
}
if (olde != null) {
olde.ShallowCopyUptoDimension = this.currentIndexLevel;
indexer.Object = olde;
} else {
indexer.Object = newArr;
}
this.currentIndexLevel --;
indexer.Operands = this.VisitExpressionList(indexer.Operands);
return indexer;
}
return base.VisitIndexer(indexer);
}
private Expression ParseIndexerCallOrSelector(Expression expression, TokenSet followers){
TokenSet followersOrContinuers = followers|Token.LeftBracket|Token.LeftParenthesis|Token.Dot;
for(;;){
switch (this.currentToken){
case Token.LeftBracket:
SourceContext lbCtx = this.scanner.CurrentSourceContext;
this.GetNextToken();
if (this.insideModifiesClause && this.currentToken == Token.Multiply){
// Handle code such as
//
// modifies myArray[*];
//
// which means that the method may modify all elements of myArray.
int savedStartPos = this.scanner.startPos;
int savedEndPos = this.scanner.endPos;
this.GetNextToken();
if (this.currentToken == Token.RightBracket){
SourceContext sctxt = this.scanner.CurrentSourceContext;
sctxt.StartPos = lbCtx.StartPos;
this.GetNextToken();
return new ModifiesArrayClause(expression, sctxt);
}
this.scanner.startPos = savedStartPos;
this.scanner.endPos = savedEndPos;
}
int endCol;
ExpressionList indices = this.ParseIndexList(followersOrContinuers, lbCtx, out endCol);
Indexer indexer = new Indexer(expression, indices);
indexer.SourceContext = expression.SourceContext;
indexer.SourceContext.EndPos = endCol;
indexer.ArgumentListIsIncomplete = this.scanner.GetChar(endCol-1) != ']';
expression = indexer;
break;
case Token.LessThan:
SourceContext ltCtx = this.scanner.CurrentSourceContext;
ScannerState ss = this.scanner.state;
int arity;
TypeNodeList typeArguments = this.ParseTypeArguments(true, false, followers|Token.LeftParenthesis, out endCol, out arity);
if (typeArguments == null || (typeArguments.Count > 1 && Parser.TypeArgumentListNonFollower[this.currentToken])) {
this.scanner.endPos = ltCtx.StartPos;
this.scanner.state = ss;
this.currentToken = Token.None;
this.GetNextToken();
return expression;
}
TemplateInstance instance = new TemplateInstance(expression, typeArguments);
instance.TypeArgumentExpressions = typeArguments == null ? null : typeArguments.Clone();
instance.SourceContext = expression.SourceContext;
instance.SourceContext.EndPos = endCol;
expression = instance;
break;
case Token.LeftParenthesis:
SourceContext lpCtx = this.scanner.CurrentSourceContext;
this.GetNextToken();
ExpressionList arguments = this.ParseArgumentList(followersOrContinuers, lpCtx, out endCol);
if (expression == null) return null;
if (expression is Identifier && arguments.Count == 1 && ((Identifier)expression).Name == "old" && InEnsuresContext){
OldExpression old = new OldExpression(arguments[0]);
typeArguments = null;
old.SourceContext = expression.SourceContext;
old.SourceContext.EndPos = endCol;
expression = old;
break;
}
if (expression is TemplateInstance)
((TemplateInstance)expression).IsMethodTemplate = true;
MethodCall mcall = new MethodCall(expression, arguments);
typeArguments = null;
mcall.GiveErrorIfSpecialNameMethod = true;
mcall.SourceContext = expression.SourceContext;
mcall.SourceContext.EndPos = endCol;
mcall.ArgumentListIsIncomplete = this.scanner.GetChar(endCol-1) != ')';
expression = mcall;
break;
case Token.LeftBrace:
if (this.compatibilityOn || this.scanner.TokenIsFirstAfterLineBreak) goto default;
Expression quant = this.ParseComprehension(followers);
if (quant == null) { break; }
Block argBlock = new Block(new StatementList(new ExpressionStatement(quant)),quant.SourceContext,
this.insideCheckedBlock, this.insideUncheckedBlock, this.inUnsafeCode);
argBlock.IsUnsafe = this.inUnsafeCode;
argBlock.SourceContext = quant.SourceContext;
ExpressionList arguments2 = new ExpressionList(new AnonymousNestedFunction(new ParameterList(0), argBlock, quant.SourceContext));
MethodCall mcall2 = new MethodCall(expression, arguments2);
typeArguments = null;
mcall2.GiveErrorIfSpecialNameMethod = true;
mcall2.SourceContext = expression.SourceContext;
mcall2.SourceContext.EndPos = this.scanner.endPos;
expression = mcall2;
break;
case Token.Dot:
expression = this.ParseQualifiedIdentifier(expression, followersOrContinuers);
break;
case Token.RealLiteral:
string tokStr = this.scanner.GetTokenSource();
if (this.insideModifiesClause && tokStr == ".0") {
// this case is here only for parsing ".0" while parsing a modifies clause
// e.g., "modifies this.0;"
this.GetNextToken(); // eat the ".0"
return new ModifiesNothingClause(expression, this.scanner.CurrentSourceContext);
} else {
return expression;
}
case Token.Arrow:
if (!this.allowUnsafeCode){
this.HandleError(Error.IllegalUnsafe);
this.allowUnsafeCode = true;
}
this.currentToken = Token.Dot;
AddressDereference ad = new AddressDereference();
ad.Address = expression;
ad.ExplicitOperator = AddressDereference.ExplicitOp.Arrow;
ad.SourceContext = expression.SourceContext;
expression = this.ParseQualifiedIdentifier(ad, followersOrContinuers);
break;
default:
return expression;
}
}
}
public override Expression VisitOldExpression(OldExpression oldExp) {
Expression/*?*/ transformedExpression = oldExp;
if (this.toplevelOldExpression == null) {
this.toplevelOldExpression = oldExp;
this.collectSubExpsDependentOnQuantifiedVars(oldExp);
transformedExpression = this.markOldSubExps(oldExp);
}
if (transformedExpression != oldExp) {
// if we are not at the toplevel, or the transformed top level is not the old expression,
// which means the old operator has been pushed down using the distribution law.
Expression result = this.VisitExpression(transformedExpression);
if (this.toplevelOldExpression == oldExp) {
// leave top level old expression
this.toplevelOldExpression = null;
this.subExpsDependentOnQuantifiedVars = null;
}
return result;
} else {
OldExpression oldExpression = transformedExpression as OldExpression;
//^ assert oldExpression != null;
TypeNode t = oldExpression.Type;
Reference rt = t as Reference;
Expression e = oldExpression.expression;
if (rt != null) {
e = new AddressDereference(e, rt.ElementType, e.SourceContext);
}
string oldName = e.SourceContext.SourceText != null && e.SourceContext.SourceText.Length > 0
? "old(" + e.SourceContext.SourceText + ")" : "$SSold" + e.UniqueKey;
Local l = new Local(Identifier.For(oldName), e.Type);
#region Add local to method's local list so it gets the right debug scope
// Since the scope of the "old" local is the entire method body, it suffices
// to add it to the method's local list. Because of how that is processed in Writer,
// that means the local's scope will be the entire method body.
if (this.currentMethod.LocalList == null) {
this.currentMethod.LocalList = new LocalList();
}
this.currentMethod.LocalList.Add(l);
#endregion
// normalize the old expression itself
e = this.VisitExpression(e);
Statement a = this.initializeOldExp(l, e, oldExpression.ShallowCopyUptoDimension);
this.currentContractPrelude.Statements.Add(a);
this.currentContractPrelude.HasLocals = true;
if (this.toplevelOldExpression == oldExpression) {
this.toplevelOldExpression = null;
this.subExpsDependentOnQuantifiedVars = null;
}
if (rt != null)
return new UnaryExpression(l, NodeType.AddressOf, t, e.SourceContext);
else
return l;
}
}
void Factor(Expression target, out Expression e) {
e = null;
Member m;
ExpressionList es; Expression p;
Expression p1; Expression p2;
TypeNode t1;
/*Identifier blockVarId;*/
MemberBinding mb;
switch (la.kind) {
case 2: case 3: case 4: case 70: case 71: case 72: case 73: case 74: case 75: {
Literal(out e);
break;
}
case 27: case 30: case 55: {
Local(out p);
e = p;
break;
}
case 1: case 6: case 7: case 8: case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: case 17: case 18: case 19: case 20: case 21: case 25: case 26: case 28: case 35: {
MemberRef(out m);
Debug.Assert(m != null); e = new MemberBinding(target,m);
if (la.kind == 49) {
ArgExprs(out es);
Method meth = (Method)m;
if ( ! meth.IsVirtual){
e = new MethodCall(e, es, NodeType.Call);
}else{
e = new MethodCall(e, es, NodeType.Callvirt); /*dangerous*/
}
e.Type = meth.ReturnType;
}
break;
}
case 54: {
BlockVar(out mb);
Debug.Assert(target == null);
e = mb;
Debug.Assert(e != null); // block variable not found
break;
}
case 5: {
Get();
Expect(38);
Expect(22);
Expr(out e);
OldExpression oe = new OldExpression(e);
oe.Type = e.Type;
e = oe;
Expect(24);
break;
}
case 22: {
Get();
Expr(out e);
Expect(24);
break;
}
case 39: {
Get();
Expect(22);
Expr(out p);
Expect(23);
PType(out t1);
Expect(24);
e = new BinaryExpression(p,new Literal(t1,SystemTypes.Type),NodeType.ExplicitCoercion);
e.Type = t1;
break;
}
case 40: {
Get();
Expect(22);
Expr(out p);
Expect(23);
PType(out t1);
Expect(24);
e = new BinaryExpression(p,new Literal(t1,SystemTypes.Type),NodeType.Is);
e.Type = SystemTypes.Boolean;
break;
}
case 41: {
Get();
Expect(22);
Expr(out p);
Expect(23);
PType(out t1);
Expect(24);
e = new BinaryExpression(p,new Literal(t1,SystemTypes.Type),NodeType.Castclass);
e.Type = t1;
break;
}
case 42: {
Get();
Expect(22);
PType(out t1);
Expect(24);
e = new UnaryExpression(new Literal(t1, SystemTypes.Type), NodeType.Typeof, OptionalModifier.For(SystemTypes.NonNullType, SystemTypes.Type));
break;
}
case 43: {
Get();
Expect(22);
Expr(out p);
Expect(23);
Expr(out p1);
Expect(23);
Expr(out p2);
Expect(23);
PType(out t1);
Expect(24);
e = new TernaryExpression(p,p1,p2,NodeType.Conditional,t1);
break;
}
case 44: {
Get();
Expect(22);
Expr(out p);
Expect(23);
PType(out t1);
Expect(24);
e = new BinaryExpression(p,new MemberBinding(null,t1),NodeType.Box);
e.Type = SystemTypes.Object;
break;
}
case 45: {
Get();
Expect(22);
Expr(out p);
Expect(23);
PType(out t1);
Expect(24);
e = new BinaryExpression(p,new MemberBinding(null,t1),NodeType.Unbox);
e.Type = t1.GetReferenceType();
break;
}
case 46: {
Get();
Expect(22);
Expr(out p);
Expect(24);
e = new UnaryExpression(p, NodeType.RefAddress, p.Type);
break;
}
case 57: case 58: case 59: case 60: case 61: case 62: case 63: case 64: {
Quantifier(out e);
break;
}
case 65: {
TrueComprehension(out e);
break;
}
case 47: {
Get();
if (la.kind == 48 || la.kind == 51 || la.kind == 52) {
if (la.kind == 48) {
Get();
Expect(22);
PType(out t1);
Expect(24);
Expect(49);
Expr(out p);
Expect(50);
TypeNode newType = p.Type.GetReferenceType();
e = new UnaryExpression(p,NodeType.AddressOf,newType);
} else if (la.kind == 51) {
Get();
Expect(49);
Expr(out p);
Expect(50);
Reference r = (Reference) p.Type;
if (r != null)
e = new AddressDereference(p,r.ElementType);
else
e = new AddressDereference(p, SystemTypes.UInt8);
} else {
TypeNode tt1 = null, tt2 = null, tt3 = null;
Get();
Expect(22);
PType(out tt1);
Expect(23);
PType(out tt2);
Expect(24);
Expect(49);
Expr(out p);
Expect(23);
PType(out tt3);
Expect(50);
e = new BinaryExpression(p, new Literal(tt3, SystemTypes.Type), NodeType.Isinst); e.Type = tt3;
}
} else if (la.kind == 53) {
TypeNode tt1 = null, tt2 = null, tt3 = null;
Get();
Expect(22);
PType(out tt1);
Expect(23);
PType(out tt2);
Expect(24);
Expect(49);
Expr(out p);
Expect(23);
PType(out tt3);
Expect(50);
e = new BinaryExpression(p, new Literal(tt3, SystemTypes.Type), NodeType.Isinst); e.Type = tt3;
} else if (StartOf(2)) {
OperatorNode(out p);
e = p;
} else SynErr(111);
break;
}
default: SynErr(112); break;
}
}
public virtual Expression VisitOldExpression(OldExpression oldExpression1, OldExpression oldExpression2) {
if (oldExpression1 == null) return null;
if (oldExpression2 == null)
oldExpression1.expression = this.VisitExpression(oldExpression1.expression, null);
else
oldExpression1.expression = this.VisitExpression(oldExpression1.expression, oldExpression2.expression);
return oldExpression1;
}
public override Expression VisitOldExpression(OldExpression oldExpression) {
if (oldExpression == null) return null;
if (insidePureContract && insideEnsures)
this.HandleError(oldExpression, Error.OldExprInPureEnsures);
return base.VisitOldExpression(oldExpression);
}
public override Expression VisitOldExpression(OldExpression oldExpression) {
if (oldExpression == null) return null;
return base.VisitOldExpression((OldExpression)oldExpression.Clone());
}
public virtual Expression VisitOldExpression (OldExpression oldExpression) {
if (oldExpression == null) return null;
oldExpression.expression = this.VisitExpression(oldExpression.expression);
return oldExpression;
}
public override Expression VisitOldExpression(OldExpression oldExpression) {
if (oldExpression == null || oldExpression.expression == null) return null;
if (this._string == null){ this._string = new StringBuilder(); }
this._string.Append("\\old(");
this.VisitExpression(oldExpression.expression);
this._string.Append(")");
return oldExpression;
}
public override void VisitOldExpression(OldExpression oldExpression)
{
if (oldExpression == null) return;
// Make sure the argument to Old() isn't just a literal.
if (oldExpression.expression is Literal)
this.HandleError(1000, "Literal expression in Old expression.");
base.VisitOldExpression(oldExpression);
}
/// <summary>
/// Performs a bunch of transformations that the basic Extractor doesn't seem to do:
/// - Turns calls to Old contract method into OldExpressions
/// - Turns references to "result" into ResultExpressions
/// -
/// </summary>
public override Expression VisitMethodCall(MethodCall call)
{
MemberBinding mb = call.Callee as MemberBinding;
if (mb == null) return call;
Method calledMethod = mb.BoundMember as Method;
if (calledMethod == null) return call;
Method template = calledMethod.Template;
if (contractNodes.IsOldMethod(template))
{
Expression result = base.VisitMethodCall(call);
call = result as MethodCall;
if (call == null) return result;
result = new OldExpression(call.Operands[0]);
result.Type = call.Type;
return result;
}
if (contractNodes.IsValueAtReturnMethod(template))
{
return new AddressDereference(call.Operands[0], calledMethod.TemplateArguments[0], call.SourceContext);
}
if (calledMethod.Parameters != null)
{
if (calledMethod.Parameters.Count == 0)
{
if (contractNodes.IsResultMethod(template))
{
return new ReturnValue(calledMethod.ReturnType, call.SourceContext);
}
}
else if (insideInvariant &&
contractNodes.IsInvariantMethod(calledMethod))
{
Expression condition = call.Operands[0];
condition.SourceContext = call.SourceContext;
return VisitExpression(condition);
}
}
return base.VisitMethodCall(call);
}
