public virtual ISqlNode VisitCase(SqlCaseNode n)
{
var input = Visit(n.InputExpression);
var whens = VisitTypedNodeList(n.WhenExpressions);
var e = Visit(n.ElseExpression);
return(n.Update(input, whens, e));
}
public override ISqlNode VisitCase(SqlCaseNode n)
{
_result.AssertIsScalarExpression(n, nameof(n.InputExpression), n.InputExpression);
if (n.ElseExpression != null)
{
_result.AssertIsScalarExpression(n, nameof(n.ElseExpression), n.ElseExpression);
}
return(base.VisitCase(n));
}
private ISqlNode ParseCaseExpression(ITokenizer t)
{
// "CASE" <Expression>? <When>+ <Else>? "END"
var caseToken = t.Expect(SqlTokenType.Keyword, "CASE");
var caseNode = new SqlCaseNode
{
Location = caseToken.Location
};
if (!t.Peek().IsKeyword("WHEN"))
{
caseNode.InputExpression = ParseScalarExpression(t);
}
while (true)
{
var lookahead = t.Peek();
if (lookahead.IsKeyword("END"))
{
t.GetNext();
return(caseNode);
}
if (lookahead.IsKeyword("ELSE"))
{
t.GetNext();
caseNode.ElseExpression = ParseScalarExpression(t);
t.Expect(SqlTokenType.Keyword, "END");
return(caseNode);
}
if (lookahead.IsKeyword("WHEN"))
{
var whenNode = t.GetNext();
var condition = ParseBooleanExpression(t);
t.Expect(SqlTokenType.Keyword, "THEN");
var result = ParseScalarExpression(t);
caseNode.WhenExpressions.Add(new SqlCaseWhenNode
{
Location = whenNode.Location,
Condition = condition,
Result = result
});
continue;
}
throw ParsingException.CouldNotParseRule(nameof(ParseCaseExpression), lookahead);
}
}
public ISqlNode VisitCase(SqlCaseNode n)
{
Append("CASE ");
Visit(n.InputExpression);
IncreaseIndent();
foreach (var when in n.WhenExpressions)
{
AppendLineAndIndent();
Visit(when);
}
if (n.ElseExpression != null)
{
AppendLineAndIndent();
Append("ELSE ");
Visit(n.ElseExpression);
}
DecreaseIndent();
AppendLineAndIndent();
Append("END");
return(n);
}
