static string Compile(IEnumerable <Token> tokens, IFunctionCallRewriter rewriter)
{
using var token = tokens.GetEnumerator();
return(Function(null));
string Function(string name)
{
var expression = new StringBuilder();
var lastIdentier = (string)null;
var args = (ImmutableArray <string> .Builder)null;
void PushArg(string arg)
{
args ??= ImmutableArray.CreateBuilder <string>();
args.Add(arg);
}
while (token.TryRead(out var t))
{
switch (t.Type)
{
case nameof(TOKEN_ID):
case nameof(TOKEN_LEFT):
case nameof(TOKEN_RIGHT):
case nameof(TOKEN_NULLIF):
{
lastIdentier = t.Text;
break;
}
case "(":
{
expression.Append(Function(Reset(ref lastIdentier)?.Trim()));
break;
}
case ")":
{
if (name is null) // just a parenthesized expression
{
return("(" + expression.Append(lastIdentier).Append(t.Text));
}
var arg = (expression + lastIdentier).Trim();
if (arg.Length > 0)
{
PushArg(arg);
}
return(rewriter.Rewrite(new FunctionCall(TransactSql.DequoteQuoutedIdentifier(name), args?.ToImmutable() ?? ImmutableArray <string> .Empty)));
}
case ",":
{
PushArg((expression + Reset(ref lastIdentier)).Trim());
expression.Clear();
break;
}
case nameof(LEX_WHITE):
{
if (lastIdentier is null)
{
expression.Append(" ");
}
else
{
lastIdentier += " ";
}
break;
}
case nameof(LEX_END_OF_LINE_COMMENT):
{
expression.Append("/*")
.Append(t.Text.Substring(2).TrimEnd('\r'))
.Append(" */");
break;
}
case nameof(TOKEN_CONVERT):
case nameof(TOKEN_TRY_CONVERT):
{
// These should have been caught out during parsing so arriving
// here is considered an internal implementation error.
throw new Exception("Internal error due to forbidden use of native function call: " + t.Text);
}
default:
{
expression.Append(Reset(ref lastIdentier)).Append(t.Text);
break;
}
}
}
return(expression.Append(lastIdentier).ToString());
}
}
public static string Compile(Expression expression, IFunctionCallRewriter rewriter)
{
return(Compile(expression.Tokens, rewriter ?? FunctionCallRewriter.PassThru));
ArgCount(this IFunctionCallRewriter rewriter, int minArgCount, int maxArgCount) => Create(call =>
ArgCount(this IFunctionCallRewriter rewriter, int argCount) => rewriter.ArgCount(argCount, argCount);
public static IFunctionCallRewriter Rename(this IFunctionCallRewriter rewriter, string name) => Create(call => rewriter.Rewrite(call.WithName(name)));
public DelegatingFunction(string name, IFunctionCallRewriter rewriter)
{
_rewriter = rewriter;
Name = name;
}
