/*
Derby - Class org.apache.derby.impl.sql.compile.ConditionalNode
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to you under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package org.apache.derby.impl.sql.compile;
import org.apache.derby.iapi.services.compiler.MethodBuilder;
import org.apache.derby.iapi.services.monitor.Monitor;
import org.apache.derby.iapi.services.sanity.SanityManager;
import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.sql.dictionary.DataDictionary;
import org.apache.derby.iapi.types.TypeId;
import org.apache.derby.iapi.types.BooleanDataValue;
import org.apache.derby.iapi.types.DataTypeDescriptor;
import org.apache.derby.iapi.types.DataValueFactory;
import org.apache.derby.iapi.reference.SQLState;
import org.apache.derby.iapi.types.DataValueDescriptor;
import org.apache.derby.iapi.types.TypeId;
import org.apache.derby.iapi.services.loader.ClassInspector;
import org.apache.derby.impl.sql.compile.ExpressionClassBuilder;
import org.apache.derby.iapi.sql.compile.Visitable;
import org.apache.derby.iapi.sql.compile.Visitor;
import org.apache.derby.iapi.sql.compile.C_NodeTypes;
import org.apache.derby.iapi.reference.ClassName;
import org.apache.derby.iapi.util.JBitSet;
import org.apache.derby.iapi.services.classfile.VMOpcode;
import java.util.Vector;
/**
* A ConditionalNode represents an if/then/else operator with a single
* boolean expression on the "left" of the operator and a list of expressions on
* the "right". This is used to represent the java conditional (aka immediate if).
*
*/
public class ConditionalNode extends ValueNode
{
ValueNode testCondition;
ValueNodeList thenElseList;
//true means we are here for NULLIF(V1,V2), false means we are here for following
//CASE WHEN BooleanExpression THEN thenExpression ELSE elseExpression END
boolean thisIsNullIfNode;
/**
* Initializer for a ConditionalNode
*
* @param testCondition The boolean test condition
* @param thenElseList ValueNodeList with then and else expressions
*/
public void init(Object testCondition, Object thenElseList, Object thisIsNullIfNode)
{
this.testCondition = (ValueNode) testCondition;
this.thenElseList = (ValueNodeList) thenElseList;
this.thisIsNullIfNode = ((Boolean) thisIsNullIfNode).booleanValue();
}
/**
* Prints the sub-nodes of this object. See QueryTreeNode.java for
* how tree printing is supposed to work.
*
* @param depth The depth of this node in the tree
*/
public void printSubNodes(int depth)
{
if (SanityManager.DEBUG)
{
super.printSubNodes(depth);
if (testCondition != null)
{
printLabel(depth, "testCondition: ");
testCondition.treePrint(depth + 1);
}
if (thenElseList != null)
{
printLabel(depth, "thenElseList: ");
thenElseList.treePrint(depth + 1);
}
}
}
/**
* Checks if the provided node is a CastNode.
*
* @param node The node to check.
* @return True if this node is a CastNode, false otherwise.
*/
private boolean isCastNode(ValueNode node) {
if (node.getNodeType() == C_NodeTypes.CAST_NODE)
return true;
else
return false;
}
/**
* Checks if the provided CastNode is cast to a SQL CHAR type.
*
* @param node The CastNode to check.
* @return True if this CastNode's target type is CHAR,
* false otherwise.
* @throws StandardException
*/
private boolean isCastToChar(ValueNode node) throws StandardException {
if (node.getTypeServices().getTypeName().equals(TypeId.CHAR_NAME))
return true;
else
return false;
}
/**
* Checks to see if the provided node represents
* a parsing of an SQL NULL.
*
* @param node The node to check.
* @return True if this node represents a SQL NULL, false otherwise.
*/
private boolean isNullNode(ValueNode node) {
if (isCastNode(node) &&
(((CastNode)node).castOperand instanceof UntypedNullConstantNode))
return true;
else
return false;
}
/**
* Checks to see if the provided node represents
* a ConditionalNode.
*
* @param node The node to check.
* @return True if this node is a CondtionalNode, false otherwise.
*/
private boolean isConditionalNode(ValueNode node) {
if (node.getNodeType() == C_NodeTypes.CONDITIONAL_NODE)
return true;
else
return false;
}
/**
* Checks to see if oldType should be casted to the newType.
* Returns TRUE if the two DataTypeDescriptors have different
* TypeID's or if the oldType is NULL. Returns FALSE if the newType is
* NULL or if the two Types are identical.
*
* @param newType The type to cast oldType to if they're different.
* @param oldType The type that should be casted to the newType if
* they're different.
* @return False if the newType is null or they have the same
* TypeId, true otherwise.
*/
private boolean shouldCast(DataTypeDescriptor newType,
DataTypeDescriptor oldType) throws StandardException
{
if ((newType != null) &&
((oldType == null) ||
(!oldType.getTypeId().equals(newType.getTypeId()))))
return true;
else
return false;
}
/**
* This method is a 'prebind.' We need to determine what the types of
* the nodes are going to be before we can set all the SQLParsed NULL's
* to the appropriate type. After we bind, however, we want to ignore
* the SQLParsed NULL's which will be bound to CHAR. Also, we might
* have to delve into the CASE Expression tree.
*
* @param thenElseList The thenElseList (recursive method)
* @param fromList The fromList (required for Column References).
*
* @exception StandardException Thrown on error.
*/
private DataTypeDescriptor findType(ValueNodeList thenElseList,
FromList fromList) throws StandardException
{
/* We need to "prebind" because we want the Types. Provide
* dummy SubqueryList and AggreateList (we don't care)
*/
ValueNode thenNode =
((ValueNode)thenElseList.elementAt(0)).bindExpression(
fromList, new SubqueryList(), new Vector());
ValueNode elseNode =
((ValueNode)thenElseList.elementAt(1)).bindExpression(
fromList, new SubqueryList(), new Vector());
DataTypeDescriptor thenType = thenNode.getTypeServices();
DataTypeDescriptor elseType = elseNode.getTypeServices();
DataTypeDescriptor theType = null;
/* If it's not a Cast Node or a Conditional Node, then we'll
* use this type.
*/
if ((thenType != null) && !isCastNode(thenNode)
&& !isConditionalNode(thenNode))
{
return thenType;
}
/* If it's not cast to CHAR it isn't a SQL parsed NULL, so
* we can use it.
*/
if (isCastNode(thenNode) && !isCastToChar(thenNode))
return thenNode.getTypeServices();
/* If we get here, we can't use the THEN node type, so we'll
* use the ELSE node type
*/
if ((elseType != null) && !isCastNode(elseNode)
&& !isConditionalNode(elseNode))
{
return elseType;
}
if (isCastNode(elseNode) && !isCastToChar(elseNode))
return elseNode.getTypeServices();
/* If we get here, it means that we've got a conditional and a
* SQL parsed NULL or two conditionals.
*/
if (isConditionalNode(thenNode))
{
theType =
findType(((ConditionalNode)thenNode).thenElseList, fromList);
}
if (theType != null) return theType;
// Two conditionals and the first one was all SQL parsed NULLS.
if (isConditionalNode(elseNode))
{
theType =
findType(((ConditionalNode)elseNode).thenElseList, fromList);
}
if (theType != null) return theType;
return null;
}
/**
* This recursive method will hunt through the ValueNodeList thenElseList
* looking for SQL NULL's. If it finds any, it casts them to the provided
* castType.
*
* @param thenElseList The thenElseList to update.
* @param castType The type to cast SQL parsed NULL's too.
*
* @exception StandardException Thrown on error.
*/
private void recastNullNodes(ValueNodeList thenElseList,
DataTypeDescriptor castType)
throws StandardException {
// Don't do anything if we couldn't find a castType.
if (castType == null) return;
ValueNode thenNode = (ValueNode)thenElseList.elementAt(0);
ValueNode elseNode = (ValueNode)thenElseList.elementAt(1);
// first check if the "then" node is NULL
if (isNullNode(thenNode) &&
shouldCast(castType, thenNode.getTypeServices()))
{
thenElseList.setElementAt(recastNullNode(thenNode, castType), 0);
// otherwise recurse on thenNode, but only if it's a conditional
} else if (isConditionalNode(thenNode)) {
recastNullNodes(((ConditionalNode)thenNode).thenElseList,
castType);
}
// lastly, check if the "else" node is NULL
if (isNullNode(elseNode) &&
shouldCast(castType, elseNode.getTypeServices()))
{
thenElseList.setElementAt(recastNullNode(elseNode, castType), 1);
// otherwise recurse on elseNode, but only if it's a conditional
} else if (isConditionalNode(elseNode)) {
recastNullNodes(((ConditionalNode)elseNode).thenElseList,
castType);
}
}
/**
* recastNullNode casts the nodeToCast node to the typeToUse.
*
* recastNullNode is called by recastNullNodes. It is called when the
* nodeToCast is an UntypedNullConstantNode that's been cast by the
* SQLParser to a CHAR. The node needs to be recasted to the same type
* of the other nodes in order to prevent the type compatibility error
* 42X89 from occuring. SQL Standard requires that:
*
* VALUES CASE WHEN 1=2 THEN 3 ELSE NULL END
*
* returns NULL and not an error message.
*
* @param nodeToCast The node that represents a SQL NULL value.
* @param typeToUse The type which the nodeToCast should be
* recasted too.
*
* @exception StandardException Thrown on error.
*/
private QueryTreeNode recastNullNode(ValueNode nodeToCast,
DataTypeDescriptor typeToUse) throws StandardException
{
QueryTreeNode cast = getNodeFactory().getNode(
C_NodeTypes.CAST_NODE,
((CastNode)nodeToCast).castOperand,
typeToUse,
getContextManager());
return cast;
}
/**
* Bind this expression. This means binding the sub-expressions,
* as well as figuring out what the return type is for this expression.
*
* @param fromList The FROM list for the query this
* expression is in, for binding columns.
* @param subqueryList The subquery list being built as we find SubqueryNodes
* @param aggregateVector The aggregate vector being built as we find AggregateNodes
*
* @return The new top of the expression tree.
*
* @exception StandardException Thrown on error
*/
public ValueNode bindExpression(FromList fromList, SubqueryList subqueryList,
Vector aggregateVector)
throws StandardException
{
testCondition = testCondition.bindExpression(fromList,
subqueryList,
aggregateVector);
if (thisIsNullIfNode) {
//for NULLIF(V1,V2), parser binds thenElseList.elementAt(0) to untyped NULL
//At bind phase, we should bind it to the type of V1 since now we know the
//type of V1
BinaryComparisonOperatorNode bcon = (BinaryComparisonOperatorNode)testCondition;
/*
* NULLIF(V1,V2) is equivalent to:
*
* CASE WHEN V1=V2 THEN NULL ELSE V1 END
*
* The untyped NULL should have a data type descriptor
* that allows its value to be nullable.
*/
QueryTreeNode cast = getNodeFactory().getNode(
C_NodeTypes.CAST_NODE,
thenElseList.elementAt(0),
bcon.getLeftOperand().getTypeServices().getNullabilityType(true),
getContextManager());
thenElseList.setElementAt(cast,0);
} else {
recastNullNodes(thenElseList, findType(thenElseList, fromList));
}
thenElseList.bindExpression(fromList,
subqueryList,
aggregateVector);
// Can't get the then and else expressions until after they've been bound
ValueNode thenExpression = (ValueNode) thenElseList.elementAt(0);
ValueNode elseExpression = (ValueNode) thenElseList.elementAt(1);
/* testCondition must be a boolean expression.
* If it is a ? parameter on the left, then set type to boolean,
* otherwise verify that the result type is boolean.
*/
if (testCondition.requiresTypeFromContext())
{
testCondition.setType(
new DataTypeDescriptor(
TypeId.BOOLEAN_ID,
true));
}
else
{
if ( ! testCondition.getTypeServices().getTypeId().equals(
TypeId.BOOLEAN_ID))
{
throw StandardException.newException(SQLState.LANG_CONDITIONAL_NON_BOOLEAN);
}
}
/* We can't determine the type for the result expression if
* all result expressions are ?s.
*/
if (thenElseList.containsAllParameterNodes())
{
throw StandardException.newException(SQLState.LANG_ALL_RESULT_EXPRESSIONS_PARAMS, "conditional");
}
else if (thenElseList.containsParameterNode())
{
/* Set the parameter's type to be the same as the other element in
* the list
*/
DataTypeDescriptor dts;
ValueNode typeExpression;
if (thenExpression.requiresTypeFromContext())
{
dts = elseExpression.getTypeServices();
}
else
{
dts = thenExpression.getTypeServices();
}
thenElseList.setParameterDescriptor(dts);
}
/* The then and else expressions must be type compatible */
ClassInspector cu = getClassFactory().getClassInspector();
/*
** If it is comparable, then we are ok. Note that we
** could in fact allow any expressions that are convertible()
** since we are going to generate a cast node, but that might
** be confusing to users...
*/
// RESOLVE DJDOI - this looks wrong, why should the then expression
// be comparable to the then expression ??
if (! thenExpression.getTypeServices().
comparable(elseExpression.getTypeServices(), false, getClassFactory()) &&
! cu.assignableTo(thenExpression.getTypeId().getCorrespondingJavaTypeName(),
elseExpression.getTypeId().getCorrespondingJavaTypeName()) &&
! cu.assignableTo(elseExpression.getTypeId().getCorrespondingJavaTypeName(),
thenExpression.getTypeId().getCorrespondingJavaTypeName()))
{
throw StandardException.newException(SQLState.LANG_NOT_TYPE_COMPATIBLE,
thenExpression.getTypeId().getSQLTypeName(),
elseExpression.getTypeId().getSQLTypeName()
);
}
/*
** Set the result type of this conditional to be the dominant type
** of the result expressions.
*/
setType(thenElseList.getDominantTypeServices());
/*
** Generate a CastNode if necessary and
** stick it over the original expression
*/
TypeId condTypeId = getTypeId();
TypeId thenTypeId = ((ValueNode) thenElseList.elementAt(0)).getTypeId();
TypeId elseTypeId = ((ValueNode) thenElseList.elementAt(1)).getTypeId();
/* Need to generate conversion if thenExpr or elseExpr is not of
* dominant type. (At least 1 of them must be of the dominant type.)
*/
if (thenTypeId.typePrecedence() != condTypeId.typePrecedence())
{
ValueNode cast = (ValueNode) getNodeFactory().getNode(
C_NodeTypes.CAST_NODE,
thenElseList.elementAt(0),
getTypeServices(), // cast to dominant type
getContextManager());
cast = cast.bindExpression(fromList,
subqueryList,
aggregateVector);
thenElseList.setElementAt(cast, 0);
}
else if (elseTypeId.typePrecedence() != condTypeId.typePrecedence())
{
ValueNode cast = (ValueNode) getNodeFactory().getNode(
C_NodeTypes.CAST_NODE,
thenElseList.elementAt(1),
getTypeServices(), // cast to dominant type
getContextManager());
cast = cast.bindExpression(fromList,
subqueryList,
aggregateVector);
thenElseList.setElementAt(cast, 1);
}
return this;
}
/**
* Preprocess an expression tree. We do a number of transformations
* here (including subqueries, IN lists, LIKE and BETWEEN) plus
* subquery flattening.
* NOTE: This is done before the outer ResultSetNode is preprocessed.
*
* @param numTables Number of tables in the DML Statement
* @param outerFromList FromList from outer query block
* @param outerSubqueryList SubqueryList from outer query block
* @param outerPredicateList PredicateList from outer query block
*
* @return The modified expression
*
* @exception StandardException Thrown on error
*/
public ValueNode preprocess(int numTables,
FromList outerFromList,
SubqueryList outerSubqueryList,
PredicateList outerPredicateList)
throws StandardException
{
testCondition = testCondition.preprocess(numTables,
outerFromList, outerSubqueryList,
outerPredicateList);
thenElseList.preprocess(numTables,
outerFromList, outerSubqueryList,
outerPredicateList);
return this;
}
/**
* Categorize this predicate. Initially, this means
* building a bit map of the referenced tables for each predicate.
* If the source of this ColumnReference (at the next underlying level)
* is not a ColumnReference or a VirtualColumnNode then this predicate
* will not be pushed down.
*
* For example, in:
* select * from (select 1 from s) a (x) where x = 1
* we will not push down x = 1.
* NOTE: It would be easy to handle the case of a constant, but if the
* inner SELECT returns an arbitrary expression, then we would have to copy
* that tree into the pushed predicate, and that tree could contain
* subqueries and method calls.
* RESOLVE - revisit this issue once we have views.
*
* @param referencedTabs JBitSet with bit map of referenced FromTables
* @param simplePredsOnly Whether or not to consider method
* calls, field references and conditional nodes
* when building bit map
*
* @return boolean Whether or not source.expression is a ColumnReference
* or a VirtualColumnNode.
* @exception StandardException Thrown on error
*/
public boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly)
throws StandardException
{
/* We stop here when only considering simple predicates
* as we don't consider conditional operators when looking
* for null invariant predicates.
*/
if (simplePredsOnly)
{
return false;
}
boolean pushable;
pushable = testCondition.categorize(referencedTabs, simplePredsOnly);
pushable = (thenElseList.categorize(referencedTabs, simplePredsOnly) && pushable);
return pushable;
}
/**
* Remap all ColumnReferences in this tree to be clones of the
* underlying expression.
*
* @return ValueNode The remapped expression tree.
*
* @exception StandardException Thrown on error
*/
public ValueNode remapColumnReferencesToExpressions()
throws StandardException
{
testCondition = testCondition.remapColumnReferencesToExpressions();
thenElseList = thenElseList.remapColumnReferencesToExpressions();
return this;
}
/**
* Return whether or not this expression tree represents a constant expression.
*
* @return Whether or not this expression tree represents a constant expression.
*/
public boolean isConstantExpression()
{
return (testCondition.isConstantExpression() &&
thenElseList.isConstantExpression());
}
/** @see ValueNode#constantExpression */
public boolean constantExpression(PredicateList whereClause)
{
return (testCondition.constantExpression(whereClause) &&
thenElseList.constantExpression(whereClause));
}
/**
* Eliminate NotNodes in the current query block. We traverse the tree,
* inverting ANDs and ORs and eliminating NOTs as we go. We stop at
* ComparisonOperators and boolean expressions. We invert
* ComparisonOperators and replace boolean expressions with
* boolean expression = false.
* NOTE: Since we do not recurse under ComparisonOperators, there
* still could be NotNodes left in the tree.
*
* @param underNotNode Whether or not we are under a NotNode.
*
*
* @return The modified expression
*
* @exception StandardException Thrown on error
*/
ValueNode eliminateNots(boolean underNotNode)
throws StandardException
{
ValueNode thenExpression;
ValueNode elseExpression;
if (! underNotNode)
{
return this;
}
/* Simply swap the then and else expressions */
thenExpression = (ValueNode) thenElseList.elementAt(0);
elseExpression = (ValueNode) thenElseList.elementAt(1);
thenElseList.setElementAt(elseExpression, 0);
thenElseList.setElementAt(thenExpression, 1);
return this;
}
/**
* Do code generation for this conditional expression.
*
* @param acb The ExpressionClassBuilder for the class we're generating
* @param mb The method the expression will go into
*
* @exception StandardException Thrown on error
*/
public void generateExpression(ExpressionClassBuilder acb,
MethodBuilder mb)
throws StandardException
{
testCondition.generateExpression(acb, mb);
mb.cast(ClassName.BooleanDataValue);
mb.push(true);
mb.callMethod(VMOpcode.INVOKEINTERFACE, (String) null, "equals", "boolean", 1);
mb.conditionalIf();
((ValueNode) thenElseList.elementAt(0)).generateExpression(acb, mb);
mb.startElseCode();
((ValueNode) thenElseList.elementAt(1)).generateExpression(acb, mb);
mb.completeConditional();
}
/**
* Accept a visitor, and call v.visit()
* on child nodes as necessary.
*
* @param v the visitor
*
* @exception StandardException on error
*/
public Visitable accept(Visitor v)
throws StandardException
{
Visitable returnNode = v.visit(this);
if (v.skipChildren(this))
{
return returnNode;
}
if (testCondition != null && !v.stopTraversal())
{
testCondition = (ValueNode)testCondition.accept(v);
}
if (thenElseList != null && !v.stopTraversal())
{
thenElseList = (ValueNodeList)thenElseList.accept(v);
}
return returnNode;
}
/**
* {@inheritDoc}
*/
protected boolean isEquivalent(ValueNode o) throws StandardException
{
if (isSameNodeType(o))
{
ConditionalNode other = (ConditionalNode)o;
if (thenElseList.size() == other.thenElseList.size()
&& (testCondition.isEquivalent(other.testCondition)))
{
int sz = thenElseList.size();
for (int i = 0; i < sz; i++)
{
ValueNode v1 = (ValueNode)thenElseList.elementAt(i);
ValueNode v2 = (ValueNode)other.thenElseList.elementAt(i);
if (!v1.isEquivalent(v2))
{
return false;
}
}
return true;
}
}
return false;
}
}