static IList <Expr> RestructAsSqlSelect(IList <Expr> lst)
{
var seq = lst[0] as SequenceExpr;
if (seq == null)
{
return(lst);
}
var ref0 = (seq.args.Count > 0) ? seq.args[0] as ReferenceExpr : null;
if (ref0 == null || string.Compare(ref0.name, "SELECT", StringComparison.InvariantCultureIgnoreCase) != 0)
{
return(lst);
}
string sectionName = null;
string sectionPartialName = string.Empty;
var res = new List <Expr>(lst.Count);
var sectionItems = new List <Expr>(lst.Count);
foreach (var item in lst)
{
var se = item as SequenceExpr;
if (se == null)
{
se = new SequenceExpr(item);
}
var argItems = new List <Expr>();
foreach (var exprArg in se.args)
{
var expr = exprArg;
var r = expr as ReferenceExpr;
CallExpr ce = null;
if (r == null)
{
ce = expr as CallExpr;
if (ce != null && ce.funcName.Length > 0)
{
r = new ReferenceExpr(ce.funcName);
}
}
if (r != null)
{
var s = r.name.ToUpperInvariant();
switch (s)
{
case "SELECT":
case "FROM":
case "WHERE":
case "BY":
case "USING":
if (argItems.Count > 0)
{
moveArgsToSection(sectionName, sectionItems, argItems);
}
if (sectionName != null)
{
var after = new SqlSectionExpr(sectionName, sectionItems.ToArray()).Postprocess();
if (after == null)
{
return(null);
}
res.Add(after);
}
else if (sectionItems.Count > 0)
{
res.AddRange(sectionItems);
}
sectionItems.Clear();
if (s == "BY")
{
sectionName = sectionPartialName + ' ' + s;
sectionPartialName = string.Empty;
}
else
{
System.Diagnostics.Trace.Assert(sectionPartialName.Length == 0, "Unknown SQL clause");
sectionName = s;
}
break;
case "JOIN":
{
System.Diagnostics.Trace.Assert(argItems.Count > 0, "No expressions before JOIN");
var ae = AliasExpr.AsAlias(argItems);
if (ae != null)
{
argItems.Clear();
argItems.Add(ae);
}
if (sectionPartialName.Length > 0)
{
argItems.Add(new ReferenceExpr(sectionPartialName));
}
argItems.Add(new ReferenceExpr(s));
if (ae == null)
{
var tmp = new SequenceExpr(argItems.ToArray());
argItems.Clear();
argItems.Add(tmp);
}
sectionPartialName = string.Empty;
}
break;
case "ON":
{
int i = argItems.Count - 1;
var subseq = new List <Expr>();
while (i >= 0)
{
var exp = argItems[i];
var re = exp as ReferenceExpr;
if (re != null && re.name == "JOIN")
{
break;
}
argItems.RemoveAt(i);
i--;
subseq.Insert(0, exp);
}
if (subseq.Count > 0)
{
argItems.Add((Expr)AliasExpr.AsAlias(subseq) ?? new SequenceExpr(subseq));
}
argItems.Add(new ReferenceExpr(s));
}
break;
case "ORDER":
case "GROUP":
case "INNER":
case "OUTER":
case "LEFT":
case "RIGHT":
case "CROSS":
case "FULL":
if (sectionPartialName.Length == 0)
{
sectionPartialName = s;
}
else
{
sectionPartialName += ' ' + s;
}
break;
default:
if (ce == null)
{
argItems.Add(r);
}
r = null;
break;
}
if (ce == null)
{
continue;
}
if (r != null)
{
expr = new CallExpr(string.Empty, ce.args);
ce = null;
}
}
if (ce != null && ce.funcName == string.Empty)
{
// no need to modify possible aliases in nested queries
var items = RestructAsSqlSelect(ce.args);
if (items != ce.args)
{
argItems.Add(CallExpr.Eval(new SequenceExpr(items)));
}
}
else
{
argItems.Add(expr);
}
}
moveArgsToSection(sectionName, sectionItems, argItems);
}
if (sectionName != null)
{
var after = new SqlSectionExpr(sectionName, sectionItems.ToArray()).Postprocess();
if (after == null)
{
return(null);
}
res.Add(after);
}
else if (sectionItems.Count > 0)
{
res.AddRange(sectionItems);
}
return(res.ToArray());
}