void ASTVisitor.Accept(NodeWhile value)
{
Accept(value);
}
internal void Accept(NodeWhile expr)
{
var isResultRequired = expr.isResultRequired;
var hasEl = expr.fail != null;
var condition = expr.condition;
uint initFailLoc = 0, initPassLoc = 0, start, failLoc;
// Disable scopes, we'll do them ourselves
if (expr.pass is NodeBlock)
(expr.pass as NodeBlock).createScope = false;
if (expr.fail != null && expr.fail is NodeBlock)
(expr.fail as NodeBlock).createScope = false;
expr.pass.isResultRequired = isResultRequired;
expr.pass.inTailPosition = expr.inTailPosition;
builder.StartScope();
if (hasEl)
{
expr.fail.isResultRequired = isResultRequired;
expr.fail.inTailPosition = expr.inTailPosition;
// initial if
condition.Visit(this);
initFailLoc = builder.InsnCount;
if (expr.not)
builder.OpJumpT(0);
else builder.OpJumpF(0);
}
// while loop
if (isResultRequired)
builder.OpList(0);
if (hasEl)
initPassLoc = builder.OpJump(0);
//*/ Handle cont
if (isResultRequired)
builder.OpJump(builder.InsnCount + 2);
builder.StartFlowBlock(expr.label);
if (isResultRequired)
builder.OpPop(false);
// END Handle cont */
start = builder.InsnCount;
{
condition.Visit(this);
failLoc = builder.InsnCount;
if (expr.not)
builder.OpJumpT(0);
else builder.OpJumpF(0);
}
if (hasEl)
builder.SetOpC(initPassLoc, builder.InsnCount);
if (isResultRequired)
builder.OpDup();
expr.pass.Visit(this);
if (isResultRequired)
{
builder.OpOIStore("+");
builder.OpPop();
}
builder.OpJump(start);
//*/ Handle break
if (isResultRequired)
builder.OpJump(builder.InsnCount + 2);
builder.EndFlowBlock();
if (isResultRequired)
builder.OpPop(false);
// END Handle break */
builder.EndScope();
builder.SetOpC(failLoc, builder.InsnCount);
uint finalFailLoc = builder.OpJump(0);
// el
if (hasEl)
{
builder.SetOpC(initFailLoc, builder.InsnCount);
builder.StartScope();
expr.fail.Visit(this);
builder.EndScope();
}
builder.SetOpC(finalFailLoc, builder.InsnCount);
}
private Node ParseWhile()
{
var expr = new NodeWhile(Location);
Advance();
// while not (condition) is allowed and handled specially.
if (Check(NOT))
{
expr.not = true;
Advance();
}
if (Check(COLON))
{
Advance();
ExpectIdentifier(out expr.label, "Expected an identifier for loop label.");
}
// Conditions must be in braces ()
Expect(OPEN_BRACE, "An open brace ('(') is expected to start the condition of a 'while' expression.");
if (!TokensRemain)
{
log.Error(expr.location, "Expected expression for 'while' condition, but the end of the file was reached.");
return expr;
}
expr.condition = Expression();
Expect(CLOSE_BRACE, "A close brace (')') is expected to end the condition of a 'while' expression.");
// Get the body:
if (!TokensRemain)
{
log.Error(expr.location, "Expected expression for 'while' block, but the end of the file was reached.");
return expr;
}
expr.pass = Expression();
// Check for an 'el' (fail) condition
if (Check(EL))
{
Advance();
expr.fail = Expression();
}
return expr;
}