/// <summary>
/// Loop over all branches, trying to locate one that is equal to the given opcode
/// If the branch is a branch itself, perform the locate recursively.
/// </summary>
/// <param name="opcode"></param>
/// <returns></returns>
internal override Opcode Locate(Opcode opcode)
{
Fx.Assert(!opcode.TestFlag(OpcodeFlags.Branch), "");
for (int i = 0, count = this.branches.Count; i < count; ++i)
{
Opcode branch = this.branches[i];
if (branch.TestFlag(OpcodeFlags.Branch))
{
// The branch is itself a branch. Since branch opcodes serve as branches in the exection
// path for a query, but don't comprise one of the opcodes used to actually perform it, we
// recursively try to locate an equivalent opcode inside the branch
Opcode subBranch = branch.Locate(opcode);
if (null != subBranch)
{
return(subBranch);
}
}
else if (branch.Equals(opcode))
{
return(branch);
}
}
return(null);
}
void AddAlwaysBranch(QueryBranch literalBranch, Opcode next)
{
if (OpcodeID.Branch == next.ID)
{
BranchOpcode opcode = (BranchOpcode)next;
OpcodeList branches = opcode.Branches;
for (int i = 0; i < branches.Count; ++i)
{
Opcode branch = branches[i];
if (this.IsAlwaysBranch(branch))
{
this.AlwaysBranches.AddInOrder(new QueryBranch(branch, literalBranch.ID));
}
else
{
branch.Flags |= OpcodeFlags.NoContextCopy;
}
}
}
else
{
Fx.Assert(!next.TestFlag(OpcodeFlags.Branch), "");
if (this.IsAlwaysBranch(next))
{
this.AlwaysBranches.AddInOrder(new QueryBranch(next, literalBranch.ID));
}
else
{
next.Flags |= OpcodeFlags.NoContextCopy;
}
}
}
private void InvokeMultiMatch(ProcessingContext context)
{
int counterMarker = context.Processor.CounterMarker;
BranchContext context2 = new BranchContext(context);
int count = this.resultTable.Count;
int num3 = 0;
while (num3 < count)
{
ProcessingContext context3;
QueryBranchResult result = this.resultTable[num3];
QueryBranch branch = result.Branch;
Opcode next = branch.Branch.Next;
if (next.TestFlag(OpcodeFlags.NoContextCopy))
{
context3 = context;
}
else
{
context3 = context2.Create();
}
this.InitResults(context3);
context3.Values[context3.TopArg[result.ValIndex]].Boolean = true;
while (++num3 < count)
{
result = this.resultTable[num3];
if (branch.ID != result.Branch.ID)
{
break;
}
context3.Values[context3.TopArg[result.ValIndex]].Boolean = true;
}
try
{
context3.EvalCodeBlock(next);
}
catch (XPathNavigatorException exception)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(exception.Process(next));
}
catch (NavigatorInvalidBodyAccessException exception2)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(exception2.Process(next));
}
context.Processor.CounterMarker = counterMarker;
}
context2.Release();
}
internal QueryBranch GetBranch(Opcode op)
{
if (op.TestFlag(OpcodeFlags.Literal))
{
LiteralRelationOpcode opcode = this.ValidateOpcode(op);
if (opcode != null)
{
QueryBranch branch = this.branchIndex[opcode.Literal];
if ((branch != null) && (branch.Branch.ID == op.ID))
{
return(branch);
}
}
}
return(null);
}
internal QueryBranch GetBranch(Opcode op)
{
if (op.TestFlag(OpcodeFlags.Literal))
{
LiteralRelationOpcode relOp = this.ValidateOpcode(op);
if (null != relOp)
{
QueryBranch branch = this.branchIndex[relOp.Literal];
if (null != branch && branch.Branch.ID == op.ID)
{
return(branch);
}
}
}
return(null);
}
private bool IsAlwaysBranch(Opcode next)
{
JumpIfOpcode opcode = next as JumpIfOpcode;
if (opcode != null)
{
if (opcode.Test)
{
Opcode opcode3;
Opcode jump = opcode.Jump;
if (jump == null)
{
return(false);
}
if (jump.TestFlag(OpcodeFlags.Branch))
{
OpcodeList branches = ((BranchOpcode)jump).Branches;
for (int i = 0; i < branches.Count; i++)
{
opcode3 = branches[i].Next;
if ((opcode3 != null) && !opcode3.TestFlag(OpcodeFlags.Result))
{
return(true);
}
}
return(false);
}
opcode3 = opcode.Jump.Next;
if ((opcode3 != null) && opcode3.TestFlag(OpcodeFlags.Result))
{
return(false);
}
}
return(true);
}
if (OpcodeID.BlockEnd == next.ID)
{
return(!next.Next.TestFlag(OpcodeFlags.Result));
}
return(!next.TestFlag(OpcodeFlags.Result));
}
internal override Opcode Locate(Opcode opcode)
{
int num = 0;
int count = this.branches.Count;
while (num < count)
{
Opcode opcode2 = this.branches[num];
if (opcode2.TestFlag(OpcodeFlags.Branch))
{
Opcode opcode3 = opcode2.Locate(opcode);
if (opcode3 != null)
{
return(opcode3);
}
}
else if (opcode2.Equals(opcode))
{
return(opcode2);
}
num++;
}
return(null);
}
private bool IsAlwaysBranch(Opcode next)
{
JumpIfOpcode opcode = next as JumpIfOpcode;
if (opcode != null)
{
if (opcode.Test)
{
Opcode opcode3;
Opcode jump = opcode.Jump;
if (jump == null)
{
return false;
}
if (jump.TestFlag(OpcodeFlags.Branch))
{
OpcodeList branches = ((BranchOpcode) jump).Branches;
for (int i = 0; i < branches.Count; i++)
{
opcode3 = branches[i].Next;
if ((opcode3 != null) && !opcode3.TestFlag(OpcodeFlags.Result))
{
return true;
}
}
return false;
}
opcode3 = opcode.Jump.Next;
if ((opcode3 != null) && opcode3.TestFlag(OpcodeFlags.Result))
{
return false;
}
}
return true;
}
if (OpcodeID.BlockEnd == next.ID)
{
return !next.Next.TestFlag(OpcodeFlags.Result);
}
return !next.TestFlag(OpcodeFlags.Result);
}
internal QueryBranch GetBranch(Opcode op)
{
if (op.TestFlag(OpcodeFlags.Literal))
{
LiteralRelationOpcode opcode = this.ValidateOpcode(op);
if (opcode != null)
{
QueryBranch branch = this.branchIndex[opcode.Literal];
if ((branch != null) && (branch.Branch.ID == op.ID))
{
return branch;
}
}
}
return null;
}
bool IsAlwaysBranch(Opcode next)
{
Fx.Assert(null != next, "");
// Opcodes subsequent to matching literals must obviously be branched to.
// The question is whether we should branch to the opcodes following those literals that do *not* match.
// Naturally, the answer depends on the sort of opcode that succeeds the literal.
//
// If the literal is within a boolean conjunction, the succeeding opcode will either be a JumpIfNot
// Or a BlockEnd.
//
// -If the JumpIfNot is multiway, then always evaluate if it contains ANY non-result only opcodes.
// -If JumpIfNot(False) -i.e. AND - only evaluate if the opcode succeeding the jump is NOT a result opcode.
// -If JumpIfNot(True) - i.e. OR - always evaluate
//
// -If BlockEnd - evaluate only if not followed by a result
//
// When branching for matching literals, we push trues onto the ValueStack corresponding to the items that
// matched. When branching for non-matching literals, we push ALL FALSE values... and then eval.
// is it a the termination of a conditional?
JumpIfOpcode jump = next as JumpIfOpcode;
if (null != jump)
{
// Is the conditional JumpIfNot(False) = i.e. OR?
if (!jump.Test)
{
return(true);
}
// Does the conditional actually jump to anything? Should never be the case, but paranoia demands..
Opcode jumpTo = jump.Jump;
if (null == jumpTo)
{
return(false);
}
// Lets see where the jump will take us
Opcode postJump;
if (jumpTo.TestFlag(OpcodeFlags.Branch))
{
// Multiway jump
OpcodeList branches = ((BranchOpcode)jumpTo).Branches;
for (int i = 0; i < branches.Count; ++i)
{
postJump = branches[i].Next;
if (null != postJump && !postJump.TestFlag(OpcodeFlags.Result))
{
// There is at least one jump here that leads to a non-result.
// For now, this dooms everybody to being branched to, whether or not their respective literals
// matched
return(true);
}
}
return(false);
}
// single jump
postJump = jump.Jump.Next;
if (null != postJump && postJump.TestFlag(OpcodeFlags.Result))
{
return(false);
}
return(true);
}
// If the next opcode is a BlockEnd, then only bother processing if what follows the block is not a result
if (OpcodeID.BlockEnd == next.ID)
{
Fx.Assert(null != next.Next, "");
return(!next.Next.TestFlag(OpcodeFlags.Result));
}
// The literal is not inside a boolean conjunction
// If the literal is not followed by a result, then we must do further processing after the branch
return(!next.TestFlag(OpcodeFlags.Result));
}
void InvokeMultiMatch(ProcessingContext context)
{
int marker = context.Processor.CounterMarker;
BranchContext branchContext = new BranchContext(context); // struct. quick.
int resultTableCount = this.resultTable.Count;
for (int i = 0; i < resultTableCount;)
{
QueryBranchResult result = this.resultTable[i];
QueryBranch branch = result.Branch;
// Branches can arbitrarily alter context stacks, rendering them unuseable to other branches.
// Therefore, before following a branch, we have to clone the context. Cloning is relatively efficient because
// can avoid allocating memory in most cases. We cannot, unfortunately, avoid Array copies.
//
// Optimization:
// We can avoid cloning altogether when we can predict that the branch does NOT tamper with the stack,
// or does so in a predictable way. If we are sure that we can restore the stack easily after the branch
// completes, we have no reason to copy the stack.
ProcessingContext newContext;
Opcode nextOpcode = branch.Branch.Next;
if (nextOpcode.TestFlag(OpcodeFlags.NoContextCopy))
{
newContext = context;
}
else
{
newContext = branchContext.Create();
}
this.InitResults(newContext);
//
// Matches are sorted by their branch ID.
// It is very possible that the a literal matches multiple times, especially when the value being
// compared is a sequence. A literal may match multiple items in a single sequence
// OR multiple items in multiple sequences. If there were 4 context sequences, the literal may have
// matched one item each in 3 of them. The branchID for that literal will be present 3 times in the
// resultTable.
// Sorting the matches groups them by their branch Ids. We only want to take the branch ONCE, so now we
// iterate over all the duplicate matches..
// result.ValIndex will give us the index of the value that was matched. Thus if the 3rd sequence
// matched, ValIndex == 2 (0 based)
newContext.Values[newContext.TopArg[result.ValIndex]].Boolean = true;
while (++i < resultTableCount)
{
result = this.resultTable[i];
if (branch.ID == result.Branch.ID)
{
newContext.Values[newContext.TopArg[result.ValIndex]].Boolean = true;
}
else
{
break;
}
}
try
{
newContext.EvalCodeBlock(nextOpcode);
}
catch (XPathNavigatorException e)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(e.Process(nextOpcode));
}
catch (NavigatorInvalidBodyAccessException e)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(e.Process(nextOpcode));
}
context.Processor.CounterMarker = marker;
}
branchContext.Release();
}
