private SqlString AppendWhere(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.WhereIndex > -1 &&
(clauses & Clauses.Where) == Clauses.Where)
{
// Remove the WHERE keyword and the subsequent space
var startIndex = segmentPositions.WhereIndex + 6;
var length = commandText.Length - startIndex;
if (segmentPositions.GroupByIndex > -1)
{
// Remove the space before the GROUP BY keyword
length = segmentPositions.GroupByIndex - startIndex;
}
else if (segmentPositions.OrderByIndex > -1)
{
// Remove the space before the ORDER BY keyword
length = segmentPositions.OrderByIndex - startIndex;
}
var segment = commandText.Substring(startIndex, length).Trim();
this.Where = segment;
}
return(this);
}
internal static SegmentPositions GetSegmentPositions(string commandText)
{
var segmentPositions = new SegmentPositions(
commandText.IndexOf(" FROM", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" WHERE", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" GROUP BY", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" ORDER BY", 0, commandText.Length, StringComparison.OrdinalIgnoreCase));
return(segmentPositions);
}
private void AppendOrderBy(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.OrderByIndex > -1 &&
(clauses & Clauses.OrderBy) == Clauses.OrderBy)
{
// Remove the ORDER BY keyword and the subsequent space
int startIndex = segmentPositions.OrderByIndex + 10;
int length = commandText.Length - startIndex;
string segment = commandText.Substring(startIndex, length).Trim();
OrderBy = segment;
}
}
private SqlString AppendOrderBy(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.OrderByIndex > -1 &&
(clauses & Clauses.OrderBy) == Clauses.OrderBy)
{
// Remove the ORDER BY keyword and the subsequent space
var startIndex = segmentPositions.OrderByIndex + 10;
var length = commandText.Length - startIndex;
var segment = commandText.Substring(startIndex, length).Trim();
this.OrderBy = segment;
}
return(this);
}
private SqlString AppendSelect(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.FromIndex > -1 &&
(clauses & Clauses.Select) == Clauses.Select)
{
// Remove the SELECT keyword and the subsequent space
var startIndex = 7;
// Remove the space before the FROM keyword
var length = segmentPositions.FromIndex - startIndex;
var segment = commandText.Substring(startIndex, length).Trim();
this.Select = segment;
}
return(this);
}
private SqlString AppendGroupBy(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.GroupByIndex > -1 &&
(clauses & Clauses.GroupBy) == Clauses.GroupBy)
{
// Remove the GROUP BY keyword and the subsequent space
int startIndex = segmentPositions.GroupByIndex + 10;
int length = commandText.Length - startIndex;
if (segmentPositions.OrderByIndex > -1)
{
// Remove the space before the ORDER BY keyword
length = segmentPositions.OrderByIndex - startIndex;
}
string segment = commandText.Substring(startIndex, length).Trim();
GroupBy = segment;
}
return(this);
}
/// <summary>
/// Parses the specified command text into a SqlString instance populating the specified <see cref="Clauses"/> if
/// present in the command text.
/// </summary>
/// <param name="commandText">The SQL command text.</param>
/// <param name="clauses">The clauses to include in the SqlString.</param>
/// <returns>An SqlString instance populating the specified <see cref="Clauses"/> if present in the command text.</returns>
public static SqlString Parse(string commandText, Clauses clauses)
{
if (string.IsNullOrEmpty(commandText))
{
return(new SqlString());
}
if (commandText.Contains(Environment.NewLine))
{
commandText = commandText.Replace(Environment.NewLine, " ");
}
var segmentPositions = SegmentPositions.GetSegmentPositions(commandText);
var sqlString = new SqlString();
sqlString.AppendSelect(commandText, clauses, segmentPositions)
.AppendFrom(commandText, clauses, segmentPositions)
.AppendWhere(commandText, clauses, segmentPositions)
.AppendGroupBy(commandText, clauses, segmentPositions)
.AppendOrderBy(commandText, clauses, segmentPositions);
return(sqlString);
}
internal static SegmentPositions GetSegmentPositions(string commandText)
{
var segmentPositions = new SegmentPositions(
commandText.IndexOf(" FROM", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" WHERE", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" GROUP BY", 0, commandText.Length, StringComparison.OrdinalIgnoreCase),
commandText.IndexOf(" ORDER BY", 0, commandText.Length, StringComparison.OrdinalIgnoreCase));
return segmentPositions;
}
private SqlString AppendWhere(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.WhereIndex > -1
&& (clauses & Clauses.Where) == Clauses.Where)
{
// Remove the WHERE keyword and the subsequent space
var startIndex = segmentPositions.WhereIndex + 6;
var length = commandText.Length - startIndex;
if (segmentPositions.GroupByIndex > -1)
{
// Remove the space before the GROUP BY keyword
length = segmentPositions.GroupByIndex - startIndex;
}
else if (segmentPositions.OrderByIndex > -1)
{
// Remove the space before the ORDER BY keyword
length = segmentPositions.OrderByIndex - startIndex;
}
var segment = commandText.Substring(startIndex, length).Trim();
this.Where = segment;
}
return this;
}
private SqlString AppendSelect(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.FromIndex > -1
&& (clauses & Clauses.Select) == Clauses.Select)
{
// Remove the SELECT keyword and the subsequent space
var startIndex = 7;
// Remove the space before the FROM keyword
var length = segmentPositions.FromIndex - startIndex;
var segment = commandText.Substring(startIndex, length).Trim();
this.Select = segment;
}
return this;
}
private SqlString AppendOrderBy(string commandText, Clauses clauses, SegmentPositions segmentPositions)
{
if (segmentPositions.OrderByIndex > -1
&& (clauses & Clauses.OrderBy) == Clauses.OrderBy)
{
// Remove the ORDER BY keyword and the subsequent space
var startIndex = segmentPositions.OrderByIndex + 10;
var length = commandText.Length - startIndex;
var segment = commandText.Substring(startIndex, length).Trim();
this.OrderBy = segment;
}
return this;
}
