feat: add support of advanced functions (sqlancer#882)

src/sqlancer/stonedb/ast/StoneDBAdvancedFunction.java

@@ -0,0 +1,34 @@
+package sqlancer.stonedb.ast;
+
+import java.util.List;
+
+import sqlancer.Randomly;
+import sqlancer.common.ast.FunctionNode;
+import sqlancer.stonedb.ast.StoneDBAdvancedFunction.StoneDBAdvancedFunc;
+
+public class StoneDBAdvancedFunction extends FunctionNode<StoneDBAdvancedFunc, StoneDBExpression>
+        implements StoneDBExpression {
+
+    // https://stonedb.io/docs/SQL-reference/functions/advanced-functions
+    public enum StoneDBAdvancedFunc {
+        IFNULL(2), IF(3), NULLIF(2), BIN(1), BINARY(1), CONV(3);
+
+        private int nrArgs;
+
+        StoneDBAdvancedFunc(int nrArgs) {
+            this.nrArgs = nrArgs;
+        }
+
+        public static StoneDBAdvancedFunc getRandom() {
+            return Randomly.fromOptions(values());
+        }
+
+        public int getNrArgs() {
+            return nrArgs;
+        }
+    }
+
+    protected StoneDBAdvancedFunction(StoneDBAdvancedFunc function, List<StoneDBExpression> args) {
+        super(function, args);
+    }
+}

src/sqlancer/stonedb/gen/StoneDBExpressionGenerator.java

@@ -28,6 +28,7 @@
 import sqlancer.stonedb.StoneDBProvider.StoneDBGlobalState;
 import sqlancer.stonedb.StoneDBSchema.StoneDBColumn;
 import sqlancer.stonedb.StoneDBSchema.StoneDBDataType;
+import sqlancer.stonedb.ast.StoneDBAdvancedFunction.StoneDBAdvancedFunc;
 import sqlancer.stonedb.ast.StoneDBAggregate.StoneDBAggregateFunction;
 import sqlancer.stonedb.ast.StoneDBConstant;
 import sqlancer.stonedb.ast.StoneDBExpression;
@@ -118,6 +119,11 @@ protected Node<StoneDBExpression> generateExpression(int depth) {
             return new NewFunctionNode<>(generateExpressions(aggregateFunction.getNrArgs(), depth + 1),
                     aggregateFunction);
         }
+        if (Randomly.getBooleanWithRatherLowProbability()) {
+            StoneDBAdvancedFunc advancedFunction = StoneDBAdvancedFunc.getRandom();
+            return new NewFunctionNode<>(generateExpressions(advancedFunction.getNrArgs(), depth + 1),
+                    advancedFunction);
+        }
         List<Expression> possibleOptions = new ArrayList<>(Arrays.asList(Expression.values()));
         Expression expr = Randomly.fromList(possibleOptions);
         Operator op;