public Expr BuildExpressionTree(string text)
{
var tokenList = new List <TokenInfo>();
int tokenListNumber = 0;
// 1. read all tokens and build initial tree by Parens
using (TextReader sr = new StringReader(text))
{
var t = new SqlTokenizer(sr, _resolver);
var current = t.Token;
var openParenStack = new List <int>();
while (current != Token.EOF)
{
tokenList.Add(t.Info);
// read expression
if (current == Token.OpenParens)
{
openParenStack.Add(tokenListNumber);
}
if (current == Token.CloseParens)
{
if (openParenStack.Count < 1)
{
throw new Exception($"Cannot find open parens for close parens ')'");
}
var openParensIndex = openParenStack.Last();
openParenStack.RemoveAt(openParenStack.Count - 1);
//var sb = new StringBuilder();
var expr = new List <TokenInfo>();
for (int i = openParensIndex + 1; i <= tokenListNumber; i++)
{
var ti = tokenList[i];
//sb.Append($"{ti.Field}{ti.Param}{ti.Operator}{ti.Number}{ti.StringLiteral}");
if (ti != null && ti.Token != Token.CloseParens)
{
expr.Add(ti);
tokenList[i] = null;
}
//if(ti?.Token == Token.CloseParens)
//{
// tokenList[i] = null;
//}
}
tokenList[openParensIndex] = new TokenInfo {
Token = Token.ParensExpression, Expression = expr
};
tokenList[tokenListNumber] = null;
}
// next
t.NextToken();
current = t.Token;
tokenListNumber++;
}
tokenList = tokenList.Where(x => x != null && x.Token != Token.CloseParens).ToList();
}
if (!tokenList.Any())
{
return(new Expr {
Type = ExprType.None
});
}
// 2. Apply logical operators in order : = AND OR
var prioDict = _resolver.GetPriorityOperators();
var min = prioDict.Keys.Min();
var max = prioDict.Keys.Max();
for (int i = min; i <= max; i++)
{
ApplyOperators(tokenList, prioDict[i]);
}
var sb = new StringBuilder();
PrintExpressions(tokenList, sb);
Console.WriteLine(sb.ToString());
var mainExpr = new Expr {
Type = ExprType.Expr
};
BuildTree(tokenList, mainExpr);
return(mainExpr);
}
