Add Expression.getSubexpression() and getSubexpressionCount()

h2/src/main/org/h2/command/dml/Query.java

@@ -12,19 +12,14 @@ import java.util.List;
 import org.h2.api.ErrorCode;
 import org.h2.command.Prepared;
 import org.h2.engine.Database;
-import org.h2.engine.Session;
 import org.h2.engine.Mode.ModeEnum;
+import org.h2.engine.Session;
 import org.h2.expression.Alias;
-import org.h2.expression.Comparison;
-import org.h2.expression.ConditionAndOr;
-import org.h2.expression.ConditionNot;
 import org.h2.expression.Expression;
 import org.h2.expression.ExpressionColumn;
 import org.h2.expression.ExpressionVisitor;
 import org.h2.expression.Function;
-import org.h2.expression.Operation;
 import org.h2.expression.Parameter;
-import org.h2.expression.UnaryOperation;
 import org.h2.expression.ValueExpression;
 import org.h2.message.DbException;
 import org.h2.result.ResultInterface;
@@ -530,6 +525,7 @@ public abstract class Query extends Prepared {
      */
     private static boolean checkOrderOther(Session session, Expression expr, ArrayList<String> expressionSQL) {
         if (expr.isConstant()) {
+            // ValueExpression or other
             return true;
         }
         String exprSQL = expr.getSQL();
@@ -538,42 +534,20 @@ public abstract class Query extends Prepared {
                 return true;
             }
         }
-        if (expr instanceof Function) {
-            Function function = (Function) expr;
-            if (!function.isDeterministic()) {
+        int count = expr.getSubexpressionCount();
+        if (expr instanceof Function ? !((Function) expr).isDeterministic() : count <= 0) {
+            // If expression is a non-deterministic function or expression is an
+            // ExpressionColumn, Parameter, SequenceValue or has other
+            // unsupported type without subexpressions
             return false;
         }
-            for (Expression e : function.getArgs()) {
-                if (!checkOrderOther(session, e, expressionSQL)) {
+        for (int i = 0; i < count; i++) {
+            if (!checkOrderOther(session, expr.getSubexpression(i), expressionSQL)) {
                 return false;
             }
         }
         return true;
     }
-        if (expr instanceof Operation) {
-            Operation operation = (Operation) expr;
-            Expression right = operation.getRightSubExpression();
-            return checkOrderOther(session, operation.getLeftSubExpression(), expressionSQL)
-                    && (right == null || checkOrderOther(session, right, expressionSQL));
-        }
-        if (expr instanceof UnaryOperation) {
-            return checkOrderOther(session, ((UnaryOperation) expr).getSubExpression(), expressionSQL);
-        }
-        if (expr instanceof ConditionAndOr) {
-            ConditionAndOr condition = (ConditionAndOr) expr;
-            return checkOrderOther(session, condition.getLeftSubExpression(), expressionSQL)
-                    && checkOrderOther(session, condition.getRightSubExpression(), expressionSQL);
-        }
-        if (expr instanceof ConditionNot) {
-            return checkOrderOther(session, ((ConditionNot) expr).getSubCondition(), expressionSQL);
-        }
-        if (expr instanceof Comparison) {
-            Comparison condition = (Comparison) expr;
-            return checkOrderOther(session, condition.getLeftSubExpression(), expressionSQL)
-                    && checkOrderOther(session, condition.getRightSubExpression(), expressionSQL);
-        }
-        return false;
-    }
 
     /**
      * Create a {@link SortOrder} object given the list of {@link SelectOrderBy}

h2/src/main/org/h2/expression/Comparison.java

@@ -587,22 +587,24 @@ public class Comparison extends Condition {
         return null;
     }
 
-    /**
-     * Get the left sub-expression of this condition.
-     *
-     * @return the left sub-expression
-     */
-    public Expression getLeftSubExpression() {
-        return left;
+    @Override
+    public int getSubexpressionCount() {
+        return compareType == IS_NULL || compareType == IS_NOT_NULL ? 1 : 2;
     }
 
-    /**
-     * Get the right sub-expression of this condition.
-     *
-     * @return the right sub-expression
-     */
-    public Expression getRightSubExpression() {
+    @Override
+    public Expression getSubexpression(int index) {
+        switch (index) {
+        case 0:
+            return left;
+        case 1:
+            if (compareType != IS_NULL && compareType != IS_NOT_NULL) {
                 return right;
             }
+            //$FALL-THROUGH$
+        default:
+            throw new IndexOutOfBoundsException();
+        }
+    }
 
 }

h2/src/main/org/h2/expression/ConditionAndOr.java

@@ -283,22 +283,21 @@ public class ConditionAndOr extends Condition {
         return left.getCost() + right.getCost();
     }
 
-    /**
-     * Get the left sub-expression of this condition.
-     *
-     * @return the left sub-expression
-     */
-    public Expression getLeftSubExpression() {
-        return left;
+    @Override
+    public int getSubexpressionCount() {
+        return 2;
     }
 
-    /**
-     * Get the right sub-expression of this condition.
-     *
-     * @return the right sub-expression
-     */
-    public Expression getRightSubExpression() {
+    @Override
+    public Expression getSubexpression(int index) {
+        switch (index) {
+        case 0:
+            return left;
+        case 1:
             return right;
+        default:
+            throw new IndexOutOfBoundsException();
+        }
     }
 
 }

h2/src/main/org/h2/expression/ConditionNot.java

@@ -98,13 +98,17 @@ public class ConditionNot extends Condition {
         return condition.getCost();
     }
 
-    /**
-     * Get the sub-expression of this condition.
-     *
-     * @return the sub-expression
-     */
-    public Expression getSubCondition() {
+    @Override
+    public int getSubexpressionCount() {
+        return 1;
+    }
+
+    @Override
+    public Expression getSubexpression(int index) {
+        if (index == 0) {
             return condition;
         }
+        throw new IndexOutOfBoundsException();
+    }
 
 }

h2/src/main/org/h2/expression/Expression.java

@@ -357,4 +357,24 @@ public abstract class Expression {
         }
     }
 
+    /**
+     * Returns count of subexpressions.
+     *
+     * @return count of subexpressions
+     */
+    public int getSubexpressionCount() {
+        return 0;
+    }
+
+    /**
+     * Returns subexpression with specified index.
+     *
+     * @param index 0-based index
+     * @return subexpression with specified index
+     * @throws IndexOutOfBoundsException if specified index is not valid
+     */
+    public Expression getSubexpression(int index) {
+        throw new IndexOutOfBoundsException();
+    }
+
 }

h2/src/main/org/h2/expression/Function.java

@@ -2710,4 +2710,14 @@ public class Function extends Expression implements FunctionCall {
         return info.type == NEXTVAL;
     }
 
+    @Override
+    public int getSubexpressionCount() {
+        return args.length;
+    }
+
+    @Override
+    public Expression getSubexpression(int index) {
+        return args[index];
+    }
+
 }

h2/src/main/org/h2/expression/Operation.java

@@ -451,22 +451,21 @@ public class Operation extends Expression {
         return left.getCost() + right.getCost() + 1;
     }
 
-    /**
-     * Get the left sub-expression of this operation.
-     *
-     * @return the left sub-expression
-     */
-    public Expression getLeftSubExpression() {
-        return left;
+    @Override
+    public int getSubexpressionCount() {
+        return 2;
     }
 
-    /**
-     * Get the right sub-expression of this operation.
-     *
-     * @return the right sub-expression
-     */
-    public Expression getRightSubExpression() {
+    @Override
+    public Expression getSubexpression(int index) {
+        switch (index) {
+        case 0:
+            return left;
+        case 1:
             return right;
+        default:
+            throw new IndexOutOfBoundsException();
+        }
     }
 
 }

h2/src/main/org/h2/expression/UnaryOperation.java

@@ -96,13 +96,17 @@ public class UnaryOperation extends Expression {
         return arg.getCost() + 1;
     }
 
-    /**
-     * Get the sub-expression of this operation.
-     *
-     * @return the sub-expression
-     */
-    public Expression getSubExpression() {
+    @Override
+    public int getSubexpressionCount() {
+        return 1;
+    }
+
+    @Override
+    public Expression getSubexpression(int index) {
+        if (index == 0) {
             return arg;
         }
+        throw new IndexOutOfBoundsException();
+    }
 
 }

h2/src/main/org/h2/fulltext/FullText.java

@@ -669,19 +669,17 @@ public class FullText {
             ArrayList<String> data, Expression expr) {
         if (expr instanceof ConditionAndOr) {
             ConditionAndOr and = (ConditionAndOr) expr;
-            Expression left = and.getLeftSubExpression();
-            Expression right = and.getRightSubExpression();
-            addColumnData(columns, data, left);
-            addColumnData(columns, data, right);
+            addColumnData(columns, data, and.getSubexpression(0));
+            addColumnData(columns, data, and.getSubexpression(1));
         } else {
             Comparison comp = (Comparison) expr;
-            ExpressionColumn ec = (ExpressionColumn) comp.getLeftSubExpression();
-            ValueExpression ev = (ValueExpression) comp.getRightSubExpression();
+            ExpressionColumn ec = (ExpressionColumn) comp.getSubexpression(0);
             String columnName = ec.getColumnName();
             columns.add(columnName);
-            if (ev == null) {
+            if (expr.getSubexpressionCount() == 1) {
                 data.add(null);
             } else {
+                ValueExpression ev = (ValueExpression) comp.getSubexpression(1);
                 data.add(ev.getValue(null).getString());
             }
         }

h2/src/test/org/h2/test/scripts/distinct.sql

@@ -66,6 +66,9 @@ SELECT DISTINCT NAME, ID + 1 FROM TEST ORDER BY UPPER(NAME) || (ID + 1);
 SELECT DISTINCT ID FROM TEST ORDER BY NAME;
 > exception ORDER_BY_NOT_IN_RESULT
 
+SELECT DISTINCT ID FROM TEST ORDER BY UPPER(NAME);
+> exception ORDER_BY_NOT_IN_RESULT
+
 SELECT DISTINCT ID FROM TEST ORDER BY CURRENT_TIMESTAMP;
 > exception ORDER_BY_NOT_IN_RESULT
 

h2/src/tools/org/h2/build/doc/dictionary.txt

@@ -789,4 +789,4 @@ inconsistencies discover eliminated violates tweaks postpone leftovers
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 converging smth rng curs casts unmapping unmapper
-immediate hhmmss scheduled hhmm prematurely postponed arranges
+immediate hhmmss scheduled hhmm prematurely postponed arranges subexpression subexpressions