private static void ExtractColumnOrAliasNames(SqlString select, out List <SqlString> columnsOrAliases,
out Dictionary <SqlString, SqlString> aliasToColumn)
{
columnsOrAliases = new List <SqlString>();
aliasToColumn = new Dictionary <SqlString, SqlString>();
IList <string> tokens = new QuotedAndParenthesisStringTokenizer(select.ToString()).GetTokens();
int index = 0;
while (index < tokens.Count)
{
string token = tokens[index];
index += 1;
if ("select".Equals(token, StringComparison.InvariantCultureIgnoreCase))
{
continue;
}
if ("distinct".Equals(token, StringComparison.InvariantCultureIgnoreCase))
{
continue;
}
if ("," == token)
{
continue;
}
if ("from".Equals(token, StringComparison.InvariantCultureIgnoreCase))
{
break;
}
//handle composite expressions like 2 * 4 as foo
while (index < tokens.Count && "as".Equals(tokens[index], StringComparison.InvariantCultureIgnoreCase) == false &&
"," != tokens[index])
{
token = token + " " + tokens[index];
index += 1;
}
string alias = token;
bool isFunctionCallOrQuotedString = token.Contains("'") || token.Contains("(");
// this is heuristic guess, if the expression contains ' or (, it is probably
// not appropriate to just slice parts off of it
if (isFunctionCallOrQuotedString == false)
{
int dot = token.IndexOf('.');
if (dot != -1)
{
alias = token.Substring(dot + 1);
}
}
// notice! we are checking here the existence of "as" "alias", two
// tokens from the current one
if (index + 1 < tokens.Count && "as".Equals(tokens[index], StringComparison.InvariantCultureIgnoreCase))
{
alias = tokens[index + 1];
index += 2; //skip the "as" and the alias \
}
columnsOrAliases.Add(new SqlString(alias));
aliasToColumn[SqlString.Parse(alias)] = SqlString.Parse(token);
}
}
private static void ExtractColumnOrAliasNames(SqlString select, out List <SqlString> columnsOrAliases,
out Dictionary <SqlString, SqlString> aliasToColumn)
{
columnsOrAliases = new List <SqlString>();
aliasToColumn = new Dictionary <SqlString, SqlString>();
IList <SqlString> tokens = new QuotedAndParenthesisStringTokenizer(select).GetTokens();
int index = 0;
while (index < tokens.Count)
{
SqlString token = tokens[index];
int nextTokenIndex = index += 1;
if (token.StartsWithCaseInsensitive("select"))
{
continue;
}
if (token.StartsWithCaseInsensitive("distinct"))
{
continue;
}
if (token.StartsWithCaseInsensitive(","))
{
continue;
}
if (token.StartsWithCaseInsensitive("from"))
{
break;
}
// handle composite expressions like "2 * 4 as foo"
while ((nextTokenIndex < tokens.Count) && (tokens[nextTokenIndex].StartsWithCaseInsensitive("as") == false && tokens[nextTokenIndex].StartsWithCaseInsensitive(",") == false))
{
SqlString nextToken = tokens[nextTokenIndex];
token = token.Append(nextToken);
nextTokenIndex = index += 1;
}
// if there is no alias, the token and the alias will be the same
SqlString alias = token;
bool isFunctionCallOrQuotedString = token.IndexOfCaseInsensitive("'") >= 0 || token.IndexOfCaseInsensitive("(") >= 0;
// this is heuristic guess, if the expression contains ' or (, it is probably
// not appropriate to just slice parts off of it
if (isFunctionCallOrQuotedString == false)
{
// its a simple column reference, so lets set the alias to the
// column name minus the table qualifier if it exists
int dot = token.IndexOfCaseInsensitive(".");
if (dot != -1)
{
alias = token.Substring(dot + 1);
}
}
// notice! we are checking here the existence of "as" "alias", two
// tokens from the current one
if (nextTokenIndex + 1 < tokens.Count)
{
SqlString nextToken = tokens[nextTokenIndex];
if (nextToken.IndexOfCaseInsensitive("as") >= 0)
{
SqlString tokenAfterNext = tokens[nextTokenIndex + 1];
alias = tokenAfterNext;
index += 2; //skip the "as" and the alias
}
}
columnsOrAliases.Add(alias);
aliasToColumn[alias] = token;
}
}
