public static Express Parse(char[] sql, int beginIndex, int endIndex)
{
List <Word> wordList = Parser.GetWordList(sql, beginIndex, endIndex);
List <Word> opList = new List <Word>();
Operator op1 = null;
Operator op2 = null;
foreach (Word w in wordList)
{
if (w.type != WordType.NonWrapped)
{
continue;
}
if (op1 == null)
{
op1 = GetOperator(sql, w.iLeft, w.iRight);
}
else
{
op2 = GetOperator(sql, w.iLeft, w.iRight);
if (op2 != null && op2.Priority <= op1.Priority)
{
op1 = op2;
}
}
}
if (op1 == null)
{
//StrSpan s = StrUtil.Trim(sql, beginIndex, endIndex, Parser._whiteSpaces);
//if ( s.isEmpty )
//{
// throw new Exception()
//}
Content content = Parser.GetContent(sql, beginIndex, endIndex);
if (content.isEmpty)
{
return(null);
//throw new Exception("语法错误， 表达式 不能为空 。 在 第 " + content.iLeft + " 个字符 \"" + sql[content.iLeft] + "\" 。");
}
if (content.type == ContentType.String)
{
return(new StringExpress(sql, content));
}
if (content.type == ContentType.Number)
{
return(new NumberExpress(sql, content));
}
if (content.type == ContentType.Column)
{
return(new ColumnExpress(sql, content));
}
return(Parse(sql, content.iLeft, content.iRight));
//throw new Exception("缺少 运算符 。在 第 " + word.iLeft + " 个字符 \"" + sql[word.iLeft] + "\" 和 第 " + word.iLeft + " 个字符 \"" + sql[word.iRight] + "\" 之间 。");
}
Express express1 = null;
Express express2 = null;
if (op1.iLeft > beginIndex)
{
express1 = Parse(sql, beginIndex, op1.iLeft - 1);
}
if (op1.iRight < endIndex)
{
express2 = Parse(sql, op1.iRight + 1, endIndex);
}
Express express = new OperatorExpress(op1, express1, express2);
return(express);
}