//'DELETE FROM' NAME ('WHERE' expression)?
private Query ParseDelete(RQ q)
{
if (!q.IsNext(tokens["delete"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["from"]))
{
return(null);
}
q.Pop();
TableSource source = ParseSource(q);
DeleteFromQuery df = new DeleteFromQuery();
df.table = source;
df.eval = new TrueExpression();
if (q.IsNext(tokens["where"]))
{
q.Pop();
Expression e = ParseExpression(q);
if (e == null)
{
e = new TrueExpression();
}
else
{
df.eval = e;
}
}
return(df);
}
//'UPDATE' NAME 'SET' (NAME '=' expression) (',' NAME '=' expression)* ('WHERE' expression)?
private Query ParseUpdate(RQ q)
{
if (!q.IsNext(tokens["update"]))
{
return(null);
}
q.Pop();
TableSource s = ParseSource(q);
if (!q.IsNext(tokens["set"]))
{
return(null);
}
q.Pop();
List <string> fields = new List <string>();
List <Expression> values = new List <Expression>();
while (true)
{
if (!q.IsNext(tokens["name"]))
{
break;
}
string field = q.Pop().value;
if (!q.IsNext(tokens["compare"]))
{
break;
}
string op = q.Peek().value;
if (op != "=")
{
break;
}
q.Pop();
Expression e2 = ParseExpression(q);
fields.Add(field);
values.Add(e2);
if (!q.IsNext(tokens["comma"]))
{
break;
}
}
if (!q.IsNext(tokens["where"]))
{
return(null);
}
q.Pop();
Expression e = ParseExpression(q);
if (e == null)
{
e = new TrueExpression();
}
UpdateQuery u = new UpdateQuery();
u.table = s;
u.fields = fields.ToArray();
u.values = values.ToArray();
u.exp = e;
return(u);
}
//'SELECT' ('*' | (NAME (',' NAME)*)) 'FROM' table (WHERE expression)?;
private Query ParseSelect(RQ q)
{
if (!q.IsNext(tokens["select"]))
{
return(null);
}
q.Pop();
SelectFromQuery sf = new SelectFromQuery();
if (q.IsNext(tokens["*"]))
{
sf.all = true;
q.Pop();
}
else
{
List <string> names = new List <string>();
while (true)
{
if (!q.IsNext(tokens["name"]))
{
break;
}
string name = q.Pop().value;
names.Add(name);
if (!q.IsNext(tokens["comma"]))
{
break;
}
q.Pop();
}
sf.fields = names.ToArray();
}
if (!q.IsNext(tokens["from"]))
{
return(null);
}
q.Pop();
TableSource source = ParseSource(q);
if (!q.IsNext(tokens["where"]))
{
return(null);
}
q.Pop();
Expression e = ParseExpression(q);
if (e == null)
{
e = new TrueExpression();
}
sf.source = source;
sf.expr = e;
return(sf);
}