/// <summary>
/// Evaluates the expression and reduces to a constant expression,
/// whose value is then returned.
/// </summary>
/// <param name="expression">The expression to evaluate.</param>
/// <param name="context">The context used to evaluate the expression.</param>
/// <returns>
/// Returns a <see cref="Field"/> is the result of the
/// <see cref="SqlExpression.Evaluate(Deveel.Data.Sql.Expressions.EvaluateContext)"/>
/// is a <see cref="SqlConstantExpression"/>.
/// </returns>
/// <exception cref="InvalidOperationException">
/// If the expression could not be evaluated or if the result of the
/// evaluation is not a <see cref="SqlConstantExpression"/>.
/// </exception>
/// <seealso cref="SqlExpression.Evaluate(Deveel.Data.Sql.Expressions.EvaluateContext)"/>
/// <seealso cref="SqlConstantExpression"/>
/// <seealso cref="SqlConstantExpression.Value"/>
public static Field EvaluateToConstant(this SqlExpression expression, EvaluateContext context)
{
var evalExp = expression.Evaluate(context);
if (evalExp == null)
{
throw new InvalidOperationException();
}
var constantExp = evalExp as SqlConstantExpression;
if (constantExp == null)
{
throw new InvalidOperationException();
}
return(constantExp.Value);
}
public void BetweenDates()
{
const string sql = "TODATE('2001-02-12') BETWEEN TODATE('2000-01-20') AND TODATE('2003-01-01')";
SqlExpression expression = null;
Assert.DoesNotThrow(() => expression = SqlExpression.Parse(sql));
Assert.IsNotNull(expression);
Assert.IsInstanceOf <SqlBinaryExpression>(expression);
Assert.AreEqual(SqlExpressionType.And, expression.ExpressionType);
SqlExpression resultExpression = null;
Assert.DoesNotThrow(() => resultExpression = expression.Evaluate());
Assert.IsNotNull(resultExpression);
Assert.AreEqual(SqlExpressionType.Constant, resultExpression.ExpressionType);
var value = ((SqlConstantExpression)resultExpression).Value;
Assert.IsInstanceOf <BooleanType>(value.Type);
Assert.AreEqual(SqlBoolean.True, (SqlBoolean)value.Value);
}
public void BetweenNumerics()
{
const string sql = "22 BETWEEN 10 AND 54";
SqlExpression expression = null;
Assert.DoesNotThrow(() => expression = SqlExpression.Parse(sql));
Assert.IsNotNull(expression);
Assert.IsInstanceOf <SqlBinaryExpression>(expression);
Assert.AreEqual(SqlExpressionType.And, expression.ExpressionType);
SqlExpression resultExpression = null;
Assert.DoesNotThrow(() => resultExpression = expression.Evaluate());
Assert.IsNotNull(resultExpression);
Assert.AreEqual(SqlExpressionType.Constant, resultExpression.ExpressionType);
var value = ((SqlConstantExpression)resultExpression).Value;
Assert.IsInstanceOf <BooleanType>(value.Type);
Assert.AreEqual(SqlBoolean.True, (SqlBoolean)value.Value);
}
public void DateSmallerThanOtherDate()
{
const string text = "TODATE('2013-03-01') < TODATE('2013-05-02')";
SqlExpression expression = null;
Assert.DoesNotThrow(() => expression = SqlExpression.Parse(text));
Assert.IsNotNull(expression);
Assert.IsInstanceOf <SqlBinaryExpression>(expression);
SqlExpression evaluated = null;
Assert.DoesNotThrow(() => evaluated = expression.Evaluate());
Assert.IsNotNull(evaluated);
Assert.IsInstanceOf <SqlConstantExpression>(evaluated);
var value = ((SqlConstantExpression)evaluated).Value;
Assert.IsInstanceOf <SqlBoolean>(value.Value);
Assert.AreEqual(SqlBoolean.True, value.Value);
}
public static ITable ExhaustiveSelect(this ITable table, IQueryContext context, SqlExpression expression)
{
var result = table;
// Exit early if there's nothing in the table to select from
int rowCount = table.RowCount;
if (rowCount > 0) {
var tableResolver = table.GetVariableResolver();
List<int> selectedSet = new List<int>(rowCount);
foreach (var row in table) {
int rowIndex = row.RowId.RowNumber;
var rowResolver = tableResolver.ForRow(rowIndex);
// Resolve expression into a constant.
var exp = expression.Evaluate(context, rowResolver);
if (exp.ExpressionType != SqlExpressionType.Constant)
throw new NotSupportedException();
var value = ((SqlConstantExpression) exp).Value;
// If resolved to true then include in the selected set.
if (!value.IsNull && value.Type is BooleanType &&
value == true) {
selectedSet.Add(rowIndex);
}
}
result = new VirtualTable(table, selectedSet); ;
}
return result;
}
public static ITable SimpleSelect(this ITable table, IQueryContext context, ObjectName columnName, SqlExpressionType op, SqlExpression exp)
{
// Find the row with the name given in the condition.
int column = table.FindColumn(columnName);
if (column == -1)
throw new ArgumentException(String.Format("Unable to find the column {0} in the condition.", columnName.Name));
// If we are doing a sub-query search
if (op.IsSubQuery()) {
// We can only handle constant expressions in the RHS expression, and
// we must assume that the RHS is a Expression[] array.
if (exp.ExpressionType != SqlExpressionType.Constant &&
exp.ExpressionType != SqlExpressionType.Tuple)
throw new ArgumentException();
IEnumerable<SqlExpression> list;
if (exp.ExpressionType == SqlExpressionType.Constant) {
var tob = ((SqlConstantExpression) exp).Value;
if (tob.Type is ArrayType) {
var array = (SqlArray) tob.Value;
list = array;
} else {
throw new Exception("Error with format or RHS expression.");
}
} else {
list = ((SqlTupleExpression) exp).Expressions;
}
// Construct a temporary table with a single column that we are
// comparing to.
var col = table.TableInfo[column];
var ttable = TemporaryTable.SingleColumnTable(table.DatabaseContext, col.ColumnName, col.ColumnType);
foreach (var expression in list) {
var rowNum = ttable.NewRow();
var evalExp = (SqlConstantExpression)expression.Evaluate(context, null, null);
ttable.SetValue(rowNum, 0, evalExp.Value);
}
ttable.BuildIndexes();
// Perform the any/all sub-query on the constant table.
return table.SelectAnyAllNonCorrelated(new[] { columnName }, op, ttable);
}
{
if (!exp.IsConstant())
throw new ArgumentException("The search expression is not constant.");
var evalExp = exp.Evaluate(context, null);
if (evalExp.ExpressionType != SqlExpressionType.Constant)
throw new InvalidOperationException();
var value = ((SqlConstantExpression) evalExp).Value;
IEnumerable<int> rows;
if (op == SqlExpressionType.Like ||
op == SqlExpressionType.NotLike
/* TODO: ||
op.IsOfType(BinaryOperatorType.Regex)*/) {
/*
TODO:
if (op.IsOfType(BinaryOperatorType.Regex)) {
rows = SelectFromRegex(column, op, value);
} else {
*/
rows = table.SelectFromPattern(column, op, value);
} else {
// Is the column we are searching on indexable?
var colInfo = table.TableInfo[column];
if (!colInfo.IsIndexable)
throw new InvalidOperationException(String.Format("Column {0} os type {1} cannot be searched.", colInfo.ColumnName,
colInfo.ColumnType));
rows = table.SelectRows(column, op, value);
}
return new VirtualTable(table, rows.ToArray()) {SortColumn = column};
}
}
private DataObject Evaluate(SqlExpression expression, IQueryContext queryContext)
{
var ignoreCase = queryContext.IgnoreIdentifiersCase();
// Resolve any variables to the table_def for this expression.
expression = Table.TableInfo.ResolveColumns(ignoreCase, expression);
// Get the variable resolver and evaluate over this data.
IVariableResolver vresolver = VariableResolver;
var reduced = expression.Evaluate(queryContext, vresolver, null);
if (reduced.ExpressionType != SqlExpressionType.Constant)
throw new InvalidOperationException("The DEFAULT expression of the column cannot be reduced to a constant");
return ((SqlConstantExpression) reduced).Value;
}
