//'DROP TABLE' NAME;
private Query ParseDrop(RQ q)
{
if (!q.IsNext(tokens["drop"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["table"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["name"]))
{
return(null);
}
string table = q.Pop().value;
DropTableQuery dt = new DropTableQuery();
dt.name = table;
return(dt);
}
//(expression ( 'AND' | 'OR' ) expression) | ('NOT' expression) | (term);
private Expression ParseExpression(RQ q)
{
Expression left = null;
if (q.IsNext(tokens["not"]))
{
q.Pop();
NotExpression n = new NotExpression();
n.exp = ParseExpression(q);
if (n.exp == null)
{
return(null);
}
left = n;
}
else
{
left = ParseTerm(q);
}
BooleanExpression b = new BooleanExpression();
if (q.IsNext(tokens["and"]) || q.IsNext(tokens["or"]))
{
b.or = q.Pop().value.ToLower() == "or";
Expression right = null;
if (q.IsNext(tokens["not"]))
{
q.Pop();
NotExpression n = new NotExpression();
n.exp = ParseExpression(q);
if (n.exp == null)
{
return(null);
}
right = n;
}
else
{
right = ParseTerm(q);
}
if (right == null || left == null)
{
return(null);
}
b.left = left;
b.right = right;
return(b);
}
else
{
return(left);
}
return(null);
}
//literal | ( '(' exp ')' );
private Expression ParseValue(RQ q)
{
if (q.IsNext(tokens["open"]))
{
q.Pop();
Expression exp = ParseExpression(q);
if (exp == null)
{
throw new ParseException("No expression in brackets");
}
if (q.IsNext(tokens["close"]))
{
q.Pop();
return(exp);
}
return(null);
}
return(ParseLiteral(q));
}
//INTEGER | FLOAT | BOOLEAN | STRING | NAME | PARAM;
private Expression ParseLiteral(RQ q)
{
if (q.IsNext(tokens["name"]))
{
RowValueExpression rv = new RowValueExpression();
rv.row = q.Pop().value;
return(rv);
}
if (q.IsNext(tokens["int"]) || q.IsNext(tokens["float"]) || q.IsNext(tokens["bool"]))
{
ValueExpression v = new ValueExpression();
v.value = q.Pop().value;
return(v);
}
if (q.IsNext(tokens["param"]))
{
ValueExpression v = new ValueExpression();
v.value = q.Peek().value;
v.parameterId = int.Parse(v.value.Remove(0, 1));
return(v);
}
if (q.IsNext(tokens["string"]))
{
ValueExpression v = new ValueExpression();
v.value = q.Peek().value.Remove(0, 1);
v.value = v.value.Remove(v.value.Length - 1);
q.Pop();
return(v);
}
return(null);
}
//'CREATE TABLE' NAME '(' (NAME NAME (',' NAME NAME)*)? ')';
private Query ParseCreate(RQ q)
{
if (!q.IsNext(tokens["create"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["table"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["name"]))
{
return(null);
}
string table = q.Pop().value;
if (!q.IsNext(tokens["open"]))
{
return(null);
}
q.Pop();
List <string> elems = new List <string>();
//Column list
while (q.IsNext(tokens["name"]))
{
string name = q.Pop().value;
elems.Add(name);
if (!q.IsNext(tokens["comma"]))
{
break;
}
q.Pop();
}
if (!q.IsNext(tokens["close"]))
{
return(null);
}
q.Pop();
CreateTableQuery ct = new CreateTableQuery();
ct.name = table;
ct.columns = elems.ToArray();
return(ct);
}
//'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);
}
//NAME | NAME JOIN SOURCE
private TableSource ParseSource(RQ q)
{
if (!q.IsNext(tokens["name"]))
{
return(null);
}
string left = q.Pop().value;
if (!q.IsNext(tokens["join"]))
{
RawSource r = new RawSource();
r.table = left;
return(r);
}
q.Pop();
TableSource right = ParseSource(q);
JoinSource j = new JoinSource();
j.left = left;
j.right = right;
return(j);
}
//value | (value ('>' | <' | '=') value);
private Expression ParseTerm(RQ q)
{
Expression left = ParseValue(q);
if (!q.IsNext(tokens["compare"]))
{
return(left);
}
string comp = q.Pop().value;
Expression right = ParseValue(q);
if (left == null || right == null)
{
return(null);
}
CompareExpression c = new CompareExpression();
c.left = left;
c.right = right;
c.op = comp;
return(c);
}
//'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);
}
//'INSERT INTO' NAME ('(' NAME (',' NAME)* ')') 'VALUES' expression (',' expression)*;
private Query ParseInsert(RQ q)
{
if (!q.IsNext(tokens["insert"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["into"]))
{
return(null);
}
q.Pop();
TableSource source = ParseSource(q);
if (!q.IsNext(tokens["open"]))
{
return(null);
}
q.Pop();
List <string> names = new List <string>();
while (q.IsNext(tokens["name"]))
{
string name = q.Pop().value;
names.Add(name);
if (!q.IsNext(tokens["comma"]))
{
break;
}
q.Pop();
}
if (!q.IsNext(tokens["close"]))
{
return(null);
}
q.Pop();
if (!q.IsNext(tokens["values"]))
{
return(null);
}
q.Pop();
List <Expression> ex = new List <Expression>();
while (true)
{
Expression e = ParseExpression(q);
if (e == null)
{
break;
}
ex.Add(e);
if (!q.IsNext(tokens["comma"]))
{
break;
}
q.Pop();
}
InsertIntoQuery ii = new InsertIntoQuery();
ii.exp = ex.ToArray();
ii.fields = names.ToArray();
ii.source = source;
return(ii);
}
//'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);
}