public void SelectClause_VariableAssignment()
{
using (StringReader reader = new StringReader(
@"SELECT @id = p.ProductID
FROM Production.Product p
WHERE
p.[Name] = 'Blade';" ))
using (ITSQLTokenizer tokenizer = new TSQLTokenizer(reader))
{
Assert.IsTrue(tokenizer.MoveNext());
TSQLSelectClause select = new TSQLSelectClauseParser().Parse(tokenizer);
Assert.AreEqual(6, select.Tokens.Count);
Assert.AreEqual(TSQLKeywords.FROM, tokenizer.Current.AsKeyword.Keyword);
Assert.AreEqual(1, select.Columns.Count);
TSQLSelectColumn column = select.Columns[0];
Assert.IsNull(column.ColumnAlias);
Assert.AreEqual(TSQLExpressionType.VariableAssignment, column.Expression.Type);
TSQLVariableAssignmentExpression assignmentExpression = column.Expression.AsVariableAssignment;
Assert.AreEqual("=", assignmentExpression.Operator.Text);
Assert.AreEqual("@id", assignmentExpression.Variable.Text);
TSQLColumnExpression columnExpression = assignmentExpression.ValueExpression.AsColumn;
Assert.AreEqual("p", columnExpression.TableReference.Single().AsIdentifier.Name);
Assert.AreEqual("ProductID", columnExpression.Column.Name);
}
}
public TSQLVariableAssignmentExpression Parse(
ITSQLTokenizer tokenizer,
TSQLVariableExpression variable)
{
TSQLVariableAssignmentExpression opExpression = new TSQLVariableAssignmentExpression();
opExpression.Variable = variable.Variable;
opExpression.Operator = tokenizer.Current.AsOperator;
opExpression.Tokens.AddRange(variable.Tokens);
opExpression.Tokens.Add(tokenizer.Current);
while (
tokenizer.MoveNext() &&
(
tokenizer.Current.IsWhitespace() ||
tokenizer.Current.IsComment()
))
{
opExpression.Tokens.Add(tokenizer.Current);
}
TSQLExpression rightSide = new TSQLValueExpressionParser().Parse(
tokenizer);
// TODO: add test for nested operators like below
// a + (b + (c + d))
if (
tokenizer.Current != null &&
tokenizer.Current.Type.In(
TSQLTokenType.Operator))
{
rightSide = new TSQLOperatorExpressionParser().Parse(
tokenizer,
rightSide);
}
opExpression.ValueExpression = rightSide;
opExpression.Tokens.AddRange(rightSide.Tokens);
return(opExpression);
}