private bool ParseIfStatement(TokenReader reader, out Statement statement)
{
Token start = reader.Peek();
statement = null;
if (!this.Expect(reader, Keyword.If))
{
return false;
}
IfStatement ifStatement = new IfStatement(start);
Expression condition = null;
if (!this.ParseExpression(reader, out condition))
{
return false;
}
ifStatement.Condition = condition;
if (!this.Expect(reader, Keyword.Then))
{
return false;
}
Statement trueStatement = null;
if (!this.ParseStatement(reader, out trueStatement))
{
return false;
}
ifStatement.TrueStatement = trueStatement;
Token tok = reader.Peek();
if (tok.Is(Keyword.Else))
{
reader.Read();
Statement falseStatement = null;
if (!this.ParseStatement(reader, out falseStatement))
{
return false;
}
ifStatement.FalseStatement = falseStatement;
}
statement = ifStatement;
return true;
}
private bool TryEmitIfStatement(IfStatement ifStatement, CompilerContext context, Scope scope, MethodImpl method)
{
TypeDefinition conditionType = null;
if (!this.TryEmitExpression(ifStatement.Condition, context, scope, method, out conditionType))
{
return false;
}
if (!this.ValidateConditionType(ifStatement.Condition, conditionType))
{
return false;
}
string elseLabel = null;
if (ifStatement.FalseStatement != null)
{
elseLabel = method.Module.GetNextJumpLabel();
}
string endLabel = method.Module.GetNextJumpLabel();
if (elseLabel == null)
{
elseLabel = endLabel;
}
method.Statements.Add(new AsmStatement { Instruction = "test al,al" });
method.Statements.Add(new AsmStatement { Instruction = "jz " + elseLabel });
if (!this.TryEmitStatement(ifStatement.TrueStatement, context, scope, method))
{
return false;
}
if (ifStatement.FalseStatement != null)
{
method.Statements.Add(new AsmStatement { Instruction = "jmp " + endLabel });
method.Statements.Add(new AsmStatement { Instruction = "nop", Label = elseLabel });
if (!this.TryEmitStatement(ifStatement.FalseStatement, context, scope, method))
{
return false;
}
}
method.Statements.Add(new AsmStatement { Instruction = "nop", Label = endLabel });
return true;
}