void StmtList(out StmtList/*!*/ stmtList) {
Contract.Ensures(Contract.ValueAtReturn(out stmtList) != null); List<BigBlock/*!*/> bigblocks = new List<BigBlock/*!*/>();
/* built-up state for the current BigBlock: */
IToken startToken = null; string currentLabel = null;
List<Cmd> cs = null; /* invariant: startToken != null ==> cs != null */
/* temporary variables: */
IToken label; Cmd c; BigBlock b;
StructuredCmd ec = null; StructuredCmd/*!*/ ecn;
TransferCmd tc = null; TransferCmd/*!*/ tcn;
while (StartOf(7)) {
if (StartOf(8)) {
LabelOrCmd(out c, out label);
if (c != null) {
// LabelOrCmd read a Cmd
Contract.Assert(label == null);
if (startToken == null) { startToken = c.tok; cs = new List<Cmd>(); }
Contract.Assert(cs != null);
cs.Add(c);
} else {
// LabelOrCmd read a label
Contract.Assert(label != null);
if (startToken != null) {
Contract.Assert(cs != null);
// dump the built-up state into a BigBlock
b = new BigBlock(startToken, currentLabel, cs, null, null);
bigblocks.Add(b);
cs = null;
}
startToken = label;
currentLabel = label.val;
cs = new List<Cmd>();
}
} else if (la.kind == 41 || la.kind == 43 || la.kind == 46) {
StructuredCmd(out ecn);
ec = ecn;
if (startToken == null) { startToken = ec.tok; cs = new List<Cmd>(); }
Contract.Assert(cs != null);
b = new BigBlock(startToken, currentLabel, cs, ec, null);
bigblocks.Add(b);
startToken = null; currentLabel = null; cs = null;
} else {
TransferCmd(out tcn);
tc = tcn;
if (startToken == null) { startToken = tc.tok; cs = new List<Cmd>(); }
Contract.Assert(cs != null);
b = new BigBlock(startToken, currentLabel, cs, null, tc);
bigblocks.Add(b);
startToken = null; currentLabel = null; cs = null;
}
}
Expect(29);
IToken/*!*/ endCurly = t;
if (startToken == null && bigblocks.Count == 0) {
startToken = t; cs = new List<Cmd>();
}
if (startToken != null) {
Contract.Assert(cs != null);
b = new BigBlock(startToken, currentLabel, cs, null, null);
bigblocks.Add(b);
}
stmtList = new StmtList(bigblocks, endCurly);
}
TransferCmd GotoSuccessor(IToken tok, BigBlock b)
{
Contract.Requires(b != null);
Contract.Requires(tok != null);
Contract.Ensures(Contract.Result<TransferCmd>() != null);
if (b.successorBigBlock != null) {
return new GotoCmd(tok, new List<String> { b.successorBigBlock.LabelName });
} else {
return new ReturnCmd(tok);
}
}
void RecordSuccessors(StmtList stmtList, BigBlock successor)
{
Contract.Requires(stmtList != null);
for (int i = stmtList.BigBlocks.Count; 0 <= --i; ) {
BigBlock big = stmtList.BigBlocks[i];
big.successorBigBlock = successor;
if (big.ec is WhileCmd) {
WhileCmd wcmd = (WhileCmd)big.ec;
RecordSuccessors(wcmd.Body, successor);
} else {
for (IfCmd ifcmd = big.ec as IfCmd; ifcmd != null; ifcmd = ifcmd.elseIf) {
RecordSuccessors(ifcmd.thn, successor);
if (ifcmd.elseBlock != null) {
RecordSuccessors(ifcmd.elseBlock, successor);
}
}
}
successor = big;
}
}
void CheckLegalLabels(StmtList stmtList, StmtList parentContext, BigBlock parentBigBlock)
{
Contract.Requires(stmtList != null);
Contract.Requires((parentContext == null) == (parentBigBlock == null));
Contract.Requires(stmtList.ParentContext == null); // it hasn't been set yet
//modifies stmtList.*;
Contract.Ensures(stmtList.ParentContext == parentContext);
stmtList.ParentContext = parentContext;
stmtList.ParentBigBlock = parentBigBlock;
// record the labels declared in this StmtList
foreach (BigBlock b in stmtList.BigBlocks) {
if (b.LabelName != null) {
string n = b.LabelName;
if (n.StartsWith(prefix)) {
if (prefix.Length < n.Length && n[prefix.Length] == '0') {
prefix += "1";
} else {
prefix += "0";
}
}
stmtList.Labels.Add(b.LabelName);
}
}
// check that labels in this and nested StmtList's are legal
foreach (BigBlock b in stmtList.BigBlocks) {
// goto's must reference blocks in enclosing blocks
if (b.tc is GotoCmd) {
GotoCmd g = (GotoCmd)b.tc;
foreach (string/*!*/ lbl in cce.NonNull(g.labelNames)) {
Contract.Assert(lbl != null);
/*
bool found = false;
for (StmtList sl = stmtList; sl != null; sl = sl.ParentContext) {
if (sl.Labels.Contains(lbl)) {
found = true;
break;
}
}
if (!found) {
this.errorHandler.SemErr(g.tok, "Error: goto label '" + lbl + "' is undefined or out of reach");
}
*/
if (!allLabels.Contains(lbl)) {
this.errorHandler.SemErr(g.tok, "Error: goto label '" + lbl + "' is undefined");
}
}
}
// break labels must refer to an enclosing while statement
else if (b.ec is BreakCmd) {
BreakCmd bcmd = (BreakCmd)b.ec;
Contract.Assert(bcmd.BreakEnclosure == null); // it hasn't been initialized yet
bool found = false;
for (StmtList sl = stmtList; sl.ParentBigBlock != null; sl = sl.ParentContext) {
cce.LoopInvariant(sl != null);
BigBlock bb = sl.ParentBigBlock;
if (bcmd.Label == null) {
// a label-less break statement breaks out of the innermost enclosing while statement
if (bb.ec is WhileCmd) {
bcmd.BreakEnclosure = bb;
found = true;
break;
}
} else if (bcmd.Label == bb.LabelName) {
// a break statement with a label can break out of both if statements and while statements
if (bb.simpleCmds.Count == 0) {
// this is a good target: the label refers to the if/while statement
bcmd.BreakEnclosure = bb;
} else {
// the label of bb refers to the first statement of bb, which in which case is a simple statement, not an if/while statement
this.errorHandler.SemErr(bcmd.tok, "Error: break label '" + bcmd.Label + "' must designate an enclosing statement");
}
found = true; // don't look any further, since we've found a matching label
break;
}
}
if (!found) {
if (bcmd.Label == null) {
this.errorHandler.SemErr(bcmd.tok, "Error: break statement is not inside a loop");
} else {
this.errorHandler.SemErr(bcmd.tok, "Error: break label '" + bcmd.Label + "' must designate an enclosing statement");
}
}
}
// recurse
else if (b.ec is WhileCmd) {
WhileCmd wcmd = (WhileCmd)b.ec;
CheckLegalLabels(wcmd.Body, stmtList, b);
} else {
for (IfCmd ifcmd = b.ec as IfCmd; ifcmd != null; ifcmd = ifcmd.elseIf) {
CheckLegalLabels(ifcmd.thn, stmtList, b);
if (ifcmd.elseBlock != null) {
CheckLegalLabels(ifcmd.elseBlock, stmtList, b);
}
}
}
}
}
