Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/772#discussion_r39946230
--- Diff:
tajo-plan/src/main/java/org/apache/tajo/plan/expr/AlgebraicUtil.java ---
@@ -493,4 +497,190 @@ public Object visitTimeLiteral(Object ctx,
Stack<Expr> stack, TimeLiteral expr)
return super.visitTimeLiteral(ctx, stack, expr);
}
}
+
+ /**
+ * Find the top expr matched to type from the given expr
+ *
+ * @param expr start expr
+ * @param type to find
+ * @return a found expr
+ */
+ public static <T extends Expr> T findTopExpr(Expr expr, OpType type)
throws TajoException {
+ Preconditions.checkNotNull(expr);
+ Preconditions.checkNotNull(type);
+
+ ExprFinder finder = new ExprFinder(type);
+ finder.visit(null, new Stack<Expr>(), expr);
+
+ if (finder.getFoundExprs().size() == 0) {
+ return null;
+ }
+ return (T) finder.getFoundExprs().get(0);
+ }
+
+ private static class ExprFinder extends SimpleAlgebraVisitor<Object,
Expr> {
+ private List<Expr> list = new ArrayList<Expr>();
+ private final OpType[] tofind;
+ private boolean topmost = false;
+ private boolean finished = false;
+
+ public ExprFinder(OpType... type) {
+
+ this.tofind = type;
+ }
+
+ public ExprFinder(OpType[] type, boolean topmost) {
+ this(type);
+ this.topmost = topmost;
+ }
+
+ @Override
+ public Expr visit(Object ctx, Stack<Expr> stack, Expr expr) throws
TajoException {
+ if (!finished) {
+ for (OpType type : tofind) {
+ if (expr.getType() == type) {
+ list.add(expr);
+ }
+ if (topmost && list.size() > 0) {
+ finished = true;
+ }
+ }
+ }
+ return super.visit(ctx, stack, expr);
+ }
+
+ public List<Expr> getFoundExprs() {
+ return list;
+ }
+
+ }
+
+ public static Expr[] toConjunctiveNormalFormArray(Expr expr) {
+ List<Expr> list = new ArrayList<Expr>();
+ toConjunctiveNormalFormArrayRecursive(expr, list);
+ return list.toArray(new Expr[list.size()]);
+ }
+
+ private static void toConjunctiveNormalFormArrayRecursive(Expr node,
List<Expr> found) {
+ if (node.getType() == OpType.And) {
+ toConjunctiveNormalFormArrayRecursive(((BinaryOperator)
node).getLeft(), found);
+ toConjunctiveNormalFormArrayRecursive(((BinaryOperator)
node).getRight(), found);
+ } else {
+ found.add(node);
+ }
+ }
+
+ /**
+ * It finds unique columns from a Expr.
+ */
+ public static LinkedHashSet<ColumnReferenceExpr>
findUniqueColumnReferences(Expr expr) throws TajoException {
+ UniqueColumnReferenceFinder finder = new UniqueColumnReferenceFinder();
+ finder.visit(null, new Stack<Expr>(), expr);
+ return finder.getColumnRefs();
+ }
+
+ private static class UniqueColumnReferenceFinder extends
SimpleAlgebraVisitor<Object, Expr> {
+ private LinkedHashSet<ColumnReferenceExpr> columnSet =
Sets.newLinkedHashSet();
+ private ColumnReferenceExpr field = null;
+
+ @Override
+ public Expr visit(Object ctx, Stack<Expr> stack, Expr expr) throws
TajoException {
+ if (expr.getType() == OpType.Column) {
+ field = (ColumnReferenceExpr) expr;
+ columnSet.add(field);
+ }
+ return super.visit(ctx, stack, expr);
+ }
+
+ public LinkedHashSet<ColumnReferenceExpr> getColumnRefs() {
+ return this.columnSet;
+ }
+
+ }
+
+ /**
+ * Build Exprs for all columns with a list of filter conditions.
+ *
+ * For example, consider you have a partitioned table for three columns
(i.e., col1, col2, col3).
+ * Then, this methods will create three Exprs for (col1), (col2), (col3).
+ *
+ * Assume that an user gives a condition WHERE col1 ='A' and col3 = 'C'.
+ * There is no filter condition corresponding to col2.
+ * Then, the path filter conditions are corresponding to the followings:
+ *
+ * The first Expr: col1 = 'A'
+ * The second Expr: col2 IS NOT NULL
+ * The third Expr: col3 = 'C'
+ *
+ * 'IS NOT NULL' predicate is always true against the partition path.
+ *
+ *
+ * @param partitionColumns
+ * @param conjunctiveForms
+ * @return
+ */
+ public static Expr[] getAccumulatedFiltersByExpr(String tableName,
--- End diff --
Method name is not intuitive. This method just rearrange the order of cnfs.
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