public override RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
BlockExpression be = otherwise.Condition as BlockExpression;
if (be != null && be.Type == SystemTypes.Void) // then it was put here by the extractor?
{
Expression e = DecompileBooleanExpression(be);
Debug.Assert(e != null);
TernaryExpression te = e as TernaryExpression;
Debug.Assert(te != null);
e = this.HackyMungeForTernaryExpressions(te);
e.Type = SystemTypes.Boolean;
te = e as TernaryExpression;
if (te != null && Literal.IsNullLiteral(te.Operand2))
{
return(new RequiresOtherwise(te.Operand1, new Construct(new MemberBinding(null, SystemTypes.Exception.GetConstructor()), null)));
}
else
{
return(otherwise);
}
}
else
{
return(otherwise);
}
}
public override void VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
if (otherwise.SourceConditionText != null)
{
return;
}
ExtractSourceTextFromLegacyRequires(otherwise);
}
public override void VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
seenDup = false;
base.VisitRequiresOtherwise(otherwise);
}
private bool ExtractFromClump(StatementList contractClump, Method method, GatherLocals gatherLocals,
RequiresList Preconditions, EnsuresList Postconditions, RequiresList validations,
EnsuresList modelPostconditions, SourceContext defaultContext, Method originalMethod,
Block contractInitializer, ref HelperMethods.StackDepthTracker dupStackTracker)
{
// set the state so that the contract clump is used for extraction (as opposed to the method body as it used to)
StatementList stmts = contractClump;
int beginning = 0;
int n = stmts.Count;
int seginning = HelperMethods.FindNextRealStatement(((Block) stmts[beginning]).Statements, 0);
bool endContractFound = false;
bool postConditionFound = false;
SourceContext currentSourceContext;
for (int i = beginning; i < n; i++)
{
Block b = (Block) stmts[i];
if (b == null) continue;
for (int j = 0, m = b.Statements == null ? 0 : b.Statements.Count; j < m; j++)
{
if (dupStackTracker.IsValid && dupStackTracker.Depth >= 0)
{
b.Statements[j] = dupStackTracker.Visit(b.Statements[j]);
}
Statement s = b.Statements[j];
if (s == null) continue;
Block currentClump;
Throw t = null;
t = s as Throw;
Method calledMethod = HelperMethods.IsMethodCall(s);
if ((t != null ||
(calledMethod != null &&
calledMethod.DeclaringType != null &&
calledMethod.DeclaringType != this.contractNodes.ContractClass &&
HelperMethods.IsVoidType(calledMethod.ReturnType) &&
!this.contractNodes.IsContractOrValidatorOrAbbreviatorMethod(calledMethod))))
{
// Treat throw statements as (part of) a precondition
// don't accept "throw ..." unless it comes in the "precondition section"
// then treat the current clump as a precondition, but need to massage it a bit:
// all branches to the block just after the throw should be modified to be branches to
// a new manufactured block that sets a fresh local to "true". The
// throw itself should be changed to set the same local to "false". That way the
// clump can be treated as the value of precondition (because the branch polarity has
// already been negated as part of the code gen).
// This test was supposed to be a sanity check that the current block contained
// only "throw ..." or else "nop; throw ...". But I've also seen "ThrowHelper.Throw(...); nop",
// so I'm just going to comment this out for now.
//if (!((m == 1 && j == 0) || (m == 2 && j == 1))) {
// Preconditions = new RequiresList();
// Postconditions = new EnsuresList();
// return; // throw new ExtractorException();
//}
Expression exception;
// The clump being extracted may contain code/blocks that represent (part of)
// the expression that is being thrown (if the original throw expression had
// control flow in it from boolean expressions and/or ternary expressions).
b.Statements[j] = null; // wipe out throw statement
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
int currentClumpLength = i - beginning + 1;
// there better be a next block because that must have been the target for all of the branches
// that didn't cause the throw to happen
if (!(i < n - 1))
{
this.HandleError(method, 1027, "Malformed contract.", s.SourceContext);
return false;
}
Block nextBlock = (Block) stmts[i + 1]; // cast succeeds because body is clump
Local valueOfPrecondition = new Local(Identifier.For("_preConditionHolds"), SystemTypes.Boolean);
Block preconditionHolds = new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.True)));
ReplaceBranchTarget rbt = new ReplaceBranchTarget(nextBlock, preconditionHolds);
rbt.VisitBlock(currentClump);
int ILOffset;
CountPopExpressions cpe = new CountPopExpressions();
currentSourceContext = s.SourceContext;
cpe.Visit(s);
if (0 < cpe.PopOccurrences)
{
// then there is a set of blocks that represent the exception: the Reader
// was not able to decompile it back into an expression. Extract the set
// from the current clump and make it into a block expression
// Find the last block that has a branch to "preconditionHolds". After that are all of the blocks
// that represent the evaluation of the exception
int branchBlockIndex = currentClumpLength - 2;
// can't be the current block: that has the throw in it
while (0 <= branchBlockIndex)
{
Block possibleBranchBlock = currentClump.Statements[branchBlockIndex] as Block;
Branch br = possibleBranchBlock.Statements[possibleBranchBlock.Statements.Count - 1] as Branch;
if (br != null && br.Target == preconditionHolds)
{
break;
}
branchBlockIndex--;
}
if (branchBlockIndex < 0)
{
this.HandleError(method, 1028, "Malformed exception constructor in contract.", defaultContext);
return false;
}
Block exceptionBlock =
new Block(HelperMethods.ExtractClump(currentClump.Statements, branchBlockIndex + 1, 0,
currentClumpLength - 1,
((Block) currentClump.Statements[currentClumpLength - 1]).Statements.Count - 1));
exceptionBlock.Statements.Add(new ExpressionStatement(t.Expression));
SourceContext sctx = ((Block) exceptionBlock.Statements[0]).Statements[0].SourceContext;
if (sctx.IsValid)
{
currentSourceContext = sctx;
}
else
{
SourceContext tmp;
bool foundContext = HelperMethods.GetLastSourceContext(exceptionBlock.Statements, out tmp);
if (foundContext)
currentSourceContext = tmp;
}
if (!CheckClump(method, gatherLocals, currentSourceContext, exceptionBlock)) return false;
exception = new BlockExpression(exceptionBlock, SystemTypes.Exception);
ILOffset = t.ILOffset;
}
else
{
currentSourceContext = s.SourceContext;
if (t != null)
{
// then the statement is "throw ..."
exception = t.Expression;
ILOffset = t.ILOffset;
}
else
{
ExpressionStatement throwHelperCall = s as ExpressionStatement;
Debug.Assert(throwHelperCall != null);
exception = throwHelperCall.Expression;
ILOffset = s.ILOffset;
}
exception.SourceContext = currentSourceContext;
SourceContext tmp;
bool foundContext = HelperMethods.GetLastSourceContext(currentClump.Statements, out tmp);
if (foundContext)
currentSourceContext = tmp;
}
Block returnValueOfPrecondition = new Block(new StatementList(new ExpressionStatement(valueOfPrecondition)));
Statement extraAssumeFalse = this.ExtraAssumeFalseOnThrow();
Block preconditionFails =
new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.False),
extraAssumeFalse, new Branch(null, returnValueOfPrecondition, true, false, false)));
//Block preconditionFails = new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.False), new Branch(null, returnValueOfPrecondition, true, false, false)));
currentClump.Statements.Add(preconditionFails); // replace throw statement
currentClump.Statements.Add(preconditionHolds);
currentClump.Statements.Add(returnValueOfPrecondition);
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump)) return false;
BlockExpression be = new BlockExpression(currentClump, SystemTypes.Boolean);
be.SourceContext = currentSourceContext;
var ro = new RequiresOtherwise(be, exception);
ro.ILOffset = ILOffset;
ro.SourceContext = currentSourceContext;
if (postConditionFound)
{
HandleError(originalMethod, 1013, "Precondition found after postcondition.", currentSourceContext);
return false;
}
validations.Add(ro);
var req = new RequiresPlain(be, FindExceptionThrown.Find(exception));
req.IsFromValidation = true;
req.ILOffset = ro.ILOffset;
req.SourceContext = ro.SourceContext;
Preconditions.Add(req);
}
else
{
if (contractNodes.IsContractMethod(calledMethod))
{
// Treat calls to contract methods
if (endContractFound)
{
HandleError(originalMethod, 1012, "Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
if (contractNodes.IsEndContract(calledMethod))
{
endContractFound = true;
continue;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
Expression arg = mc.Operands[0];
arg.SourceContext = s.SourceContext;
MethodContractElement mce;
currentSourceContext = s.SourceContext;
Expression condition;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
condition = arg;
}
else
{
b.Statements[j] = new ExpressionStatement(arg);
// construct a clump from
// methodBody.Statements[beginning].Statements[seginning] to
// methodBody.Statements[i].Statements[j]
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(currentClump, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump))
return false;
BlockExpression be = new BlockExpression(currentClump);
condition = be;
}
condition.SourceContext = currentSourceContext;
if (contractNodes.IsPlainPrecondition(calledMethod))
{
var req = new RequiresPlain(condition);
contractNodes.IsRequiresWithException(calledMethod, out req.ExceptionType);
mce = req;
}
else if (this.contractNodes.IsPostcondition(calledMethod))
{
mce = new EnsuresNormal(condition);
}
else if (contractNodes.IsExceptionalPostcondition(calledMethod))
{
EnsuresExceptional ee = new EnsuresExceptional(condition);
// Extract the type of exception.
ee.Type = calledMethod.TemplateArguments[0];
mce = ee;
}
else
{
throw new InvalidOperationException("Cannot recognize contract method");
}
mce.SourceContext = currentSourceContext;
mce.ILOffset = mc.ILOffset;
if (1 < mc.Operands.Count)
{
var candidate = SanitizeUserMessage(method, mc.Operands[1], currentSourceContext);
mce.UserMessage = candidate;
}
if (2 < mc.Operands.Count)
{
Literal lit = mc.Operands[2] as Literal;
if (lit != null)
{
mce.SourceConditionText = lit;
}
}
// determine Model status
mce.UsesModels = CodeInspector.UsesModel(mce.Assertion, this.contractNodes);
// Check context rules
switch (mce.NodeType)
{
case NodeType.RequiresPlain:
if (postConditionFound)
{
this.HandleError(originalMethod, 1014, "Precondition found after postcondition.", currentSourceContext);
return false;
}
if (mce.UsesModels)
{
this.HandleError(originalMethod, 1073, "Preconditions may not refer to model members.", currentSourceContext);
return false;
}
var rp = (RequiresPlain) mce;
Preconditions.Add(rp);
validations.Add(rp); // also add to the internal validation list
break;
// TODO: check visibility of post conditions based on visibility of possible implementation
case NodeType.EnsuresNormal:
case NodeType.EnsuresExceptional:
Ensures ensures = (Ensures) mce;
if (mce.UsesModels)
{
if (this.IncludeModels)
{
modelPostconditions.Add(ensures);
}
}
else
{
Postconditions.Add(ensures);
}
postConditionFound = true;
break;
}
}
else if (ContractNodes.IsValidatorMethod(calledMethod))
{
// Treat calls to Contract validators
if (endContractFound)
{
this.HandleError(originalMethod, 1012,
"Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
var memberBinding = (MemberBinding) mc.Callee;
currentSourceContext = s.SourceContext;
Statement validation;
Block validationPrefix;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
validation = s;
validationPrefix = null;
}
else
{
// The clump may contain multiple statements ending in the validator call.
// to extract the code as Requires<E>, we need to keep the statements preceeding
// the validator call, as they may contain local initialization etc. These should go
// into the first Requires<E> that the validator expands to. This way, if there are
// no Requires<E> expanded from the validator, then the statements can be omitted.
// At the same time, the statements won't be duplicated when validations are emitted.
//
// If the validator call contains any pops, then the extraction must fail saying it
// is too complicated.
// must null out statement with call before extract clump
b.Statements[j] = null; // we have a copy in mc, s
validationPrefix = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(validationPrefix, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (CountPopExpressions.Count(mc) > 0)
{
this.HandleError(method, 1071,
"Arguments to contract validator call are too complicated. Please simplify.",
currentSourceContext);
return false;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, validationPrefix))
return false;
validation = new Block(new StatementList(validationPrefix, s));
validation.SourceContext = currentSourceContext;
}
var ro = new RequiresOtherwise(null, new BlockExpression(new Block(new StatementList(validation))));
validations.Add(ro);
CopyValidatorContracts(
method, calledMethod, memberBinding.TargetObject, mc.Operands,
Preconditions, currentSourceContext, validationPrefix);
}
else if (ContractNodes.IsAbbreviatorMethod(calledMethod))
{
// Treat calls to Contract abbreviators
if (endContractFound)
{
this.HandleError(originalMethod, 1012, "Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
var memberBinding = (MemberBinding) mc.Callee;
currentSourceContext = s.SourceContext;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
// nothing to do. All is in the call and its arguments
}
else
{
// The clump may contain multiple statements ending in the abbreviator call.
// We need to keep the statements preceeding the abbreviator call and add them to the
// contract initializer block. The reason we cannot add them to the first expansion contract
// of the abbreviator is that the abbreviator may give rise to closure initialization which will
// be hoisted into the closure initializer block. This closure initializer may refer to the
// locals initialized by the present statement sequence, so it must precede it.
//
// If the abbreviator call contains any pops, then the extraction must fail saying it
// is too complicated.
// grab prefix of clump minus last call statement.
// must null out current call statement before we extract clump (ow. it stays in body)
b.Statements[j] = null;
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(currentClump, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (CountPopExpressions.Count(mc) > 0)
{
this.HandleError(method, 1070,
"Arguments to contract abbreviator call are too complicated. Please simplify.",
currentSourceContext);
return false;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump))
return false;
if (HelperMethods.IsNonTrivial(currentClump))
{
contractInitializer.Statements.Add(currentClump);
}
}
CopyAbbreviatorContracts(method, calledMethod, memberBinding.TargetObject, mc.Operands,
Preconditions, Postconditions, currentSourceContext, validations, contractInitializer);
}
else
{
// important to continue here and accumulate blocks/statements for next contract!
if (i == beginning && j == seginning && s.NodeType == NodeType.Nop)
{
// nop following contract is often associated with previous code, so skip it
seginning = j + 1;
}
continue;
}
}
// Re-initialize current state after contract has been found
beginning = i;
seginning = j + 1;
//seginning = HelperMethods.FindNextRealStatement(((Block)stmts[i]).Statements, j + 1);
if (seginning < 0) seginning = 0;
//b = (Block)stmts[i]; // IMPORTANT! Need this to keep "b" in sync
}
}
if (this.verbose)
{
Console.WriteLine("\tNumber of Preconditions: " + Preconditions.Count);
Console.WriteLine("\tNumber of Postconditions: " + Postconditions.Count);
}
return true;
}
public virtual RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise) {
if (otherwise == null) return null;
otherwise.Condition = this.VisitExpression(otherwise.Condition);
otherwise.ThrowException = this.VisitExpression(otherwise.ThrowException);
return otherwise;
}
public override RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise) {
if (otherwise == null) return null;
if (otherwise.ThrowException != null) {
otherwise.ThrowException = this.VisitExpression(otherwise.ThrowException);
}
if (otherwise.ThrowException != null && otherwise.ThrowException.Type != null) {
TypeNode ot = otherwise.ThrowException.Type;
if (otherwise.ThrowException.NodeType != NodeType.Literal && !this.typeSystem.IsNonNullType(ot)) {
this.HandleError(otherwise, Error.OtherwiseExpressionMustBeNonNull);
return null;
}
ot = this.typeSystem.Unwrap(ot);
if (otherwise.ThrowException.NodeType == NodeType.Literal) {
if (ot != SystemTypes.Type) {
this.HandleError(otherwise, Error.OtherwiseExpressionMustBeType);
return null;
}
ot = ((Literal)otherwise.ThrowException).Value as TypeNode;
}
if (!this.isCompilingAContractAssembly) {
if (this.GetTypeView(ot).IsAssignableTo(SystemTypes.ICheckedException)) {
this.HandleError(otherwise, Error.CheckedExceptionInRequiresOtherwiseClause);
return null;
} else if (!this.GetTypeView(ot).IsAssignableTo(SystemTypes.Exception)) {
this.HandleError(otherwise, Error.BadExceptionType);
return null;
}
}
}
otherwise.Condition = this.VisitBooleanExpression(otherwise.Condition);
return otherwise;
}
private Statement GenerateValidationCode(RequiresOtherwise ro)
{
if (ro.Condition == null)
{
// just a validation code block
BlockExpression be = (BlockExpression)ro.ThrowException;
return be.Block;
}
// make an if-then for it so the exception doesn't get evaluated if the condition is true
Block b = new Block(new StatementList());
Block afterIf = new Block(new StatementList());
b.Statements.Add(new Branch(ro.Condition, afterIf));
// add call to RaiseContractFailedEvent method
ExpressionList elist = new ExpressionList();
elist.Add(this.runtimeContracts.PreconditionKind);
if (ro.UserMessage != null)
elist.Add(ro.UserMessage);
else
elist.Add(Literal.Null);
if (ro.SourceConditionText != null)
{
elist.Add(ro.SourceConditionText);
}
else
{
elist.Add(Literal.Null);
}
elist.Add(Literal.Null); // exception arg
if (this.runtimeContracts.AssertOnFailure)
{
var messageLocal = new Local(SystemTypes.String);
b.Statements.Add(new AssignmentStatement(messageLocal, new MethodCall(new MemberBinding(null, this.runtimeContracts.RaiseFailureEventMethod), elist)));
// if we should assert and the msgLocal is non-null, then assert
var assertMethod = RuntimeContractMethods.GetSystemDiagnosticsAssertMethod();
if (assertMethod != null)
{
var skipAssert = new Block();
b.Statements.Add(new Branch(new UnaryExpression(messageLocal, NodeType.LogicalNot), skipAssert));
// emit assert call
ExpressionList assertelist = new ExpressionList();
assertelist.Add(Literal.False);
assertelist.Add(messageLocal);
b.Statements.Add(new ExpressionStatement(new MethodCall(new MemberBinding(null, assertMethod), assertelist)));
b.Statements.Add(skipAssert);
}
}
else
{
b.Statements.Add(new ExpressionStatement(new UnaryExpression(new MethodCall(new MemberBinding(null, this.runtimeContracts.RaiseFailureEventMethod), elist), NodeType.Pop)));
}
// need to check whether it was "throw ..." in the original source or else "ThrowHelper.Throw(...)"
if (HelperMethods.IsVoidType(ro.ThrowException.Type))
{
// then it is a call to a throw helper method
b.Statements.Add(new ExpressionStatement(ro.ThrowException));
}
else
{
b.Statements.Add(new Throw(ro.ThrowException, ro.ThrowException.SourceContext));
}
b.Statements.Add(afterIf);
return b;
}
public virtual void VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
if (otherwise == null) return;
this.VisitExpression(otherwise.Condition);
this.VisitExpression(otherwise.ThrowException);
}
public virtual RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise1, RequiresOtherwise otherwise2) {
if (otherwise1 == null) return null;
if (otherwise2 == null) {
otherwise1.Condition = this.VisitExpression(otherwise1.Condition, null);
otherwise1.ThrowException = this.VisitExpression(otherwise1.ThrowException, null);
}else{
otherwise1.Condition = this.VisitExpression(otherwise1.Condition, otherwise2.Condition);
otherwise1.ThrowException = this.VisitExpression(otherwise1.ThrowException, otherwise2.ThrowException);
}
return otherwise1;
}
public override RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
if (otherwise == null) return null;
return base.VisitRequiresOtherwise((RequiresOtherwise)otherwise.Clone());
}
private void ParseMethodContract(Method m, TokenSet followers, ref bool swallowedSemicolonAlready){
bool savedParsingStatement = this.parsingStatement;
if (this.currentToken != Token.EndOfFile) this.parsingStatement = true;
if (!swallowedSemicolonAlready) m.SourceContext.EndPos = this.scanner.endPos;
MethodContract mc = new MethodContract(m);
SourceContext initialSourceContext = this.scanner.CurrentSourceContext;
while ( Parser.ContractStart[this.currentToken] ) {
SourceContext ctx = this.scanner.CurrentSourceContext;
Node n = null;
int finalPos = 0;
switch ( this.currentToken ) {
case Token.Requires: {
this.GetNextToken();
if (this.currentToken == Token.LeftBrace){
this.HandleError(Error.ExpectedExpression);
break; // without this, the left bracket gets parsed as an anonymous nested function
}
Expression e = this.ParseExpression(followers|ContractStart|Token.Otherwise);
if (mc.Requires == null) mc.Requires = new RequiresList();
if (this.currentToken != Token.Otherwise) {
Requires r = new RequiresPlain(e);
n = r;
mc.Requires.Add(r);
}else {
this.Skip(Token.Otherwise);
Expression e2 = this.ParseExpression(followers|ContractStart);
Requires r = new RequiresOtherwise(e,e2);
n = r;
mc.Requires.Add(r);
}
finalPos = this.scanner.CurrentSourceContext.EndPos;
swallowedSemicolonAlready= (this.currentToken == Token.Semicolon);
this.SkipSemiColon(followers|ContractStart);
break;
}
case Token.Modifies: {
// modifies expressions have their source context set here within this
// case, so don't use the variable "n" to hold on to the AST otherwise
// it will have the wrong source context set for it at the end of the switch
// statement
n = null;
this.insideModifiesClause = true;
list : {
this.GetNextToken(); // Token.Modifies or Token.Comma
SourceContext sctx = this.scanner.CurrentSourceContext;
Expression e = this.ParseExpression(followers | ContractStart | Token.Comma);
if (mc.Modifies == null) mc.Modifies = new ExpressionList();
if (e != null) { // REVIEW: does this just silently miss errors?
sctx.EndPos = e.SourceContext.EndPos;
ModifiesClause modClause = e as ModifiesClause;
if (modClause != null) {
e.SourceContext = sctx;
}
else {
e = new UnaryExpression(e, NodeType.RefAddress, sctx);
}
mc.Modifies.Add(e);
}
if (this.currentToken == Token.Comma)
goto list;
}
swallowedSemicolonAlready= (this.currentToken == Token.Semicolon);
finalPos = this.scanner.CurrentSourceContext.EndPos;
this.SkipSemiColon(followers|ContractStart);
this.insideModifiesClause = false;
break;
}
case Token.Ensures: {
InEnsuresContext = true;
this.GetNextToken();
if (this.currentToken == Token.LeftBrace){
this.HandleError(Error.ExpectedExpression);
break; // without this, the left bracket gets parsed as an anonymous nested function
}
Expression e = this.ParseExpression(followers|ContractStart);
if (mc.Ensures == null) mc.Ensures = new EnsuresList();
EnsuresNormal en = new EnsuresNormal(e);
n = en;
mc.Ensures.Add(en);
finalPos = this.scanner.CurrentSourceContext.EndPos;
swallowedSemicolonAlready= (this.currentToken == Token.Semicolon);
this.SkipSemiColon(followers|ContractStart);
InEnsuresContext = false;
break;
}
case Token.Throws: {
this.GetNextToken();
// throws (E1) ensures P;
// throws (E1 e) ensures P;
// throws E1 ensures P;
// throws E1, E2, ...;
// Note, for constuctors, only the last of these forms is allowed.
if (mc.Ensures == null) {
mc.Ensures = new EnsuresList();
// Note, this list may be left empty in case of parsing errors below.
}
EnsuresExceptional exc = new EnsuresExceptional();
exc.SourceContext = this.scanner.CurrentSourceContext;
bool hasLeftParen = false;
if (this.currentToken == Token.LeftParenthesis) {
hasLeftParen = true;
this.Skip(Token.LeftParenthesis);
}
exc.Type = exc.TypeExpression = this.ParseTypeExpression(Identifier.Empty, followers|Token.Identifier|Token.RightParenthesis|ContractStart);
if (hasLeftParen && Parser.IdentifierOrNonReservedKeyword[this.currentToken]) {
exc.Variable = this.scanner.GetIdentifier();
exc.Variable.Type = exc.Type;
this.GetNextToken();
}else{
exc.Variable = null; // need to be able to distinguish whether the source contains a variable or not
}
if (hasLeftParen) {
this.Skip(Token.RightParenthesis);
}
if (hasLeftParen || this.currentToken == Token.Ensures) {
// throws (E1) ensures P;
// throws (E1 e) ensures P;
// throws E1 ensures P;
SourceContext ctxEnsures = this.scanner.CurrentSourceContext;
this.Skip(Token.Ensures);
InEnsuresContext = true;
Expression ens = this.ParseExpression(followers|ContractStart);
InEnsuresContext = false;
// Do the constructor check now. This is rather late, since the whole throws...ensures
// has now been parsed, but this may lead to better parse-error recovery.
if (m is InstanceInitializer) {
this.HandleError(ctxEnsures, Error.ThrowsEnsuresOnConstructor);
// ignore what was parsed
exc.PostCondition = new Literal(true, null, ctx);
}else{
exc.PostCondition = ens;
}
mc.Ensures.Add(exc);
}else{
// throws E1, E2, ...;
// exc.PostCondition = new Literal(true, null, ctx);
mc.Ensures.Add(exc);
while (this.currentToken == Token.Comma) {
this.GetNextToken();
exc = new EnsuresExceptional();
exc.SourceContext = this.scanner.CurrentSourceContext;
exc.Type = exc.TypeExpression = this.ParseTypeExpression(Identifier.Empty, followers|Token.Comma|ContractStart);
exc.Variable = new Local(TypeExpressionFor("System", "Exception"));
exc.Variable.SourceContext = ctx;
exc.PostCondition = new Literal(true, null, ctx);
mc.Ensures.Add(exc);
}
}
finalPos = this.scanner.CurrentSourceContext.EndPos;
swallowedSemicolonAlready= (this.currentToken == Token.Semicolon);
this.SkipSemiColon(followers|ContractStart);
n = exc;
break;
}
}
if (n != null) {
n.SourceContext= ctx;
n.SourceContext.EndPos = finalPos ;
}
m.SourceContext.EndPos = finalPos;
}
// What error to generate here?
if (!followers[this.currentToken])
this.SkipTo(followers);
if (initialSourceContext.EndPos != this.scanner.CurrentSourceContext.EndPos) {
// then a contract really was parsed
m.Contract = mc;
}
if (this.currentToken != Token.EndOfFile) this.parsingStatement = savedParsingStatement;
}
// Instead of overriding VisitRequiresPlain or VisitRequiresOtherwise, just process the list.
// Almost all of the code is the same for both plain and otherwise requires.
// This could be done by overriding VisitRequires -- but would depend upon introducing
// a VisitRequires method in StandardVisitor.
public override RequiresList VisitRequiresList(RequiresList Requires){
// add a default precondition here and not earlier in the pipeline so it doesn't confuse
// the contract inheritance checks.
// REVIEW: probably better to add it earlier and have a HasCompilerGeneratedSignature on it
// so it can be ignored in the inheritance checks.
bool addDefaultPrecondition =
this.currentMethod != null
&& !this.currentMethod.IsStatic
&& !this.currentMethod.IsAbstract
&& this.currentMethod.Body != null && this.currentMethod.Body.Statements != null
&& !(this.currentMethod.HasCompilerGeneratedSignature && !this.currentMethod.Name.Name.StartsWith("get_") && !this.currentMethod.Name.Name.StartsWith("set_"))
&& this.currentMethod.NodeType != NodeType.InstanceInitializer
&& this.currentMethod.NodeType != NodeType.StaticInitializer
&& (this.currentType != null && this.currentType.Contract != null && this.currentType.Contract.FramePropertyGetter != null)
&& this.currentMethod.GetAttribute(SystemTypes.NoDefaultContractAttribute) == null
;
RequiresList newRequires = new RequiresList();
if (addDefaultPrecondition){
Method frameGetter = this.currentType.Contract.FramePropertyGetter;
Method m = null;
// We used to use "get_CanStartWriting" for non-virtual methods. But Rustan and I decided
// that it should be fine to use the transitive one for all methods. It is more liberal
// but still prevents re-entrance into a method in a frame that is exposed.
m = SystemTypes.Guard.GetMethod(Identifier.For("get_CanStartWritingTransitively"), null);
// default precondition is (as normalized IR):
// requires this.get_FrameGuard().get_CanStartWriting(); if it is a non-virtual method
// requires this.get_FrameGuard().get_CanStartWritingTransitively(); if it is a virtual method
if (frameGetter != null && m != null){
SourceContext sc = this.currentMethod.Name.SourceContext;
MethodCall getFrameGuard = new MethodCall(new MemberBinding(this.currentThisParameter, frameGetter), null, NodeType.MethodCall, SystemTypes.Guard, sc);
Requires r = new RequiresOtherwise(
new MethodCall(
new MemberBinding(getFrameGuard,m),
null,
NodeType.MethodCall,
SystemTypes.Boolean),
new Construct(new MemberBinding(null, SystemTypes.RequiresException.GetConstructor(SystemTypes.String)), new ExpressionList(new Literal("The target object of this call must be exposable.", SystemTypes.String)), SystemTypes.RequiresException)
);
r.SourceContext = sc;
newRequires.Add(r);
}
}
if ((this.currentMethod.IsPublic || this.currentMethod.IsFamilyOrAssembly) &&
!(this.currentCompilation != null && this.currentCompilation.CompilerParameters != null &&
((CompilerOptions)this.currentCompilation.CompilerParameters).DisableNullParameterValidation)){
ParameterList parameters = this.currentMethod.Parameters;
for (int i = 0, n = parameters == null ? 0 : parameters.Count; i < n; i++){
Parameter parameter = parameters[i];
if (parameter != null && !parameter.IsOut && this.typeSystem.IsNonNullType(parameter.Type)){
RequiresOtherwise r;
Reference rtype = parameter.Type as Reference;
if (rtype == null) {
TypeNode parameterType = TypeNode.StripModifier(parameter.Type, SystemTypes.NonNullType);
Expression e = null;
if (this.useGenerics && (parameterType is TypeParameter || parameterType is ClassParameter)) {
e = new BinaryExpression(parameter, new MemberBinding(null, parameterType), NodeType.Box, SystemTypes.Object, parameter.SourceContext);
} else {
e = new ParameterBinding(parameter, parameter.SourceContext);
}
r =
new RequiresOtherwise(
new BinaryExpression(e, new Literal(null, TypeNode.StripModifiers(parameter.Type)), NodeType.Ne, SystemTypes.Boolean, parameter.SourceContext),
new Construct(new MemberBinding(null, SystemTypes.ArgumentNullException.GetConstructor(SystemTypes.String)), new ExpressionList(new Literal(parameter.Name.Name, SystemTypes.String)), SystemTypes.ArgumentNullException));
}
else {
// have to perform deref
r =
new RequiresOtherwise(
new BinaryExpression(new AddressDereference(new ParameterBinding(parameter, parameter.SourceContext), rtype.ElementType), new Literal(null, TypeNode.StripModifiers(rtype.ElementType)), NodeType.Ne, SystemTypes.Boolean, parameter.SourceContext),
new Construct(new MemberBinding(null, SystemTypes.ArgumentNullException.GetConstructor(SystemTypes.String)), new ExpressionList(new Literal(parameter.Name.Name, SystemTypes.String)), SystemTypes.ArgumentNullException));
}
r.SourceContext = parameter.SourceContext;
newRequires.Add(r);
}
}
}
for (int i = 0, n = Requires == null ? 0 : Requires.Count; i < n; i++){
newRequires.Add(Requires[i]);
}
if (newRequires.Count == 0)
return Requires;
Block preConditionBlock = new Block(new StatementList());
preConditionBlock.HasLocals = true;
for (int i = 0, n = newRequires.Count; i < n; i++)
{
Requires r = newRequires[i];
if (r == null) continue;
if (r.Condition == null) continue;
// Code generation for preconditions needs to be such that the
// data flow analysis will "see" the consequences. If the value
// of the precondition is assigned to a local, then the information
// is lost.
//
// try {
// if re goto pre_i_holds;
// }
// catch { throw new ErrorDuringPreConditionEvaluation(...); }
// throw new PreConditionException(...);
// pre_i_holds: nop
bool noAllocationAllowed = this.currentMethod.GetAttribute(SystemTypes.BartokNoHeapAllocationAttribute) != null;
Local exceptionDuringPreCondition = new Local(Identifier.For("SS$exceptionDuringPreCondition" + i),SystemTypes.Exception);
Local exceptionDuringPreCondition3 = new Local(Identifier.For("SS$objectExceptionDuringPreCondition" + i),SystemTypes.Object);
Expression cond = r.Condition;
string condition = cond != null && cond.SourceContext.SourceText != null && cond.SourceContext.SourceText.Length > 0 ?
cond.SourceContext.SourceText : "<unknown condition>";
Expression ec2;
Expression ec3;
if (noAllocationAllowed) {
ec2 = ec3 = new MemberBinding(null, SystemTypes.PreAllocatedExceptions.GetField(Identifier.For("InvalidContract")));
}
else {
MemberBinding excBinding2 = new MemberBinding(null, SystemTypes.InvalidContractException.GetConstructor(SystemTypes.String, SystemTypes.Exception));
MemberBinding excBinding3 = new MemberBinding(null, SystemTypes.InvalidContractException.GetConstructor(SystemTypes.String));
string msg2 = "Exception occurred during evaluation of precondition '" + condition + "' in method '" + currentMethod.FullName + "'";
ec2 = new Construct(excBinding2, new ExpressionList(new Literal(msg2, SystemTypes.String), exceptionDuringPreCondition));
ec3 = new Construct(excBinding3, new ExpressionList(new Literal(msg2, SystemTypes.String)));
}
#region If the precondition fails, throw an exception
Expression throwExpression = null;
#region Create the expression to throw. Deal with different subtypes of Requires
if (noAllocationAllowed) {
throwExpression = new MemberBinding(null, SystemTypes.PreAllocatedExceptions.GetField(Identifier.For("Requires")));
}
else {
if (r is RequiresPlain) {
MemberBinding excBinding = new MemberBinding(null, SystemTypes.RequiresException.GetConstructor(SystemTypes.String));
Construct ec = new Construct(excBinding, new ExpressionList());
string msg = "Precondition '" + condition + "' violated from method '" + currentMethod.FullName + "'";
ec.Operands.Add(new Literal(msg, SystemTypes.String));
throwExpression = ec;
}
else if (r is RequiresOtherwise) {
RequiresOtherwise otherwise = (RequiresOtherwise)r;
if (otherwise.ThrowException is Literal) {
// it was "requires P otherwise E" where E is a type name of an exception class
Literal l = (Literal)otherwise.ThrowException;
Class exceptionClass = (Class)l.Value;
MemberBinding excBinding = new MemberBinding(null, this.GetTypeView(exceptionClass).GetConstructor());
// what to do if there is no nullary constructor? I guess that should have been checked in the context checker
Construct ec = new Construct(excBinding, new ExpressionList());
throwExpression = ec;
}
else {
// it was "requires P otherwise new E(...)" (or some other expression whose value is an exception)
throwExpression = this.VisitExpression(otherwise.ThrowException);
}
}
else {
Debug.Assert(false, "Expecting only RequiresOtherwise and RequiresPlain as subtypes of Requires");
}
}
#endregion
Throw t = new Throw(throwExpression,r.SourceContext);
#endregion
Block pre_i_holds = new Block();
//CatchList cl = new CatchList(2);
//cl.Add(new Catch(new Block(new StatementList(new Throw(ec2,r.Condition.SourceContext))),exceptionDuringPreCondition,SystemTypes.Exception));
//cl.Add(new Catch(new Block(new StatementList(new Throw(ec3,r.Condition.SourceContext))),exceptionDuringPreCondition3,SystemTypes.Object));
//Try tryPre = new Try(new Block(new StatementList(new If(r.Condition,new Block(new StatementList(new Branch(null,pre_i_holds))),null))),cl,null,null,null);
//preConditionBlock.Statements.Add(tryPre);
preConditionBlock.Statements.Add(new If(r.Condition,new Block(new StatementList(new Branch(null,pre_i_holds))),null));
preConditionBlock.Statements.Add(t);
preConditionBlock.Statements.Add(pre_i_holds);
}
preConditionBlock = this.VisitBlock(preConditionBlock);
this.currentContractPrelude.Statements.Add(preConditionBlock);
return Requires;
}
public override RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
if (otherwise == null) return null;
RequiresOtherwise dup = (RequiresOtherwise)this.DuplicateFor[otherwise.UniqueKey];
if (dup != null) return dup;
this.DuplicateFor[otherwise.UniqueKey] = dup = (RequiresOtherwise)otherwise.Clone();
return base.VisitRequiresOtherwise(dup);
}
public override void VisitRequiresOtherwise(RequiresOtherwise otherwise)
{
seenDup = false;
seenConstructArray = false;
base.VisitRequiresOtherwise(otherwise);
}
public EventingVisitor(Action<RequiresOtherwise> visitRequiresOtherwise) { VisitedRequiresOtherwise += visitRequiresOtherwise; } public event Action<RequiresOtherwise> VisitedRequiresOtherwise; public override RequiresOtherwise VisitRequiresOtherwise(RequiresOtherwise otherwise) { if (VisitedRequiresOtherwise != null) VisitedRequiresOtherwise(otherwise); return base.VisitRequiresOtherwise(otherwise); }
