/*
* JBoss, Home of Professional Open Source.
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership. Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA.
*/
package org.teiid.query.sql.symbol;
import org.teiid.core.types.DataTypeManager;
import org.teiid.core.util.EquivalenceUtil;
import org.teiid.core.util.HashCodeUtil;
import org.teiid.query.function.FunctionDescriptor;
import org.teiid.query.sql.LanguageObject;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.visitor.SQLStringVisitor;
/**
* Represents a function in a sql statement. A function is a type of expression.
* Functions have a name and some arguments (0..n). Each argument is also
* an expression. After resolution, a function should have a type and a function
* descriptor.
*/
public class Function implements Expression {
private String name;
private Expression[] args;
protected Class<?> type;
private FunctionDescriptor descriptor;
private boolean implicit = false;
private boolean eval = true;
/**
* Construct a function with function name and array of arguments. For
* functions that have no args, pass empty array, not null.
* @param name Name of function
* @param args Function arguments
*/
public Function(String name, Expression[] args) {
this.name = name;
this.args = args;
}
/**
* Get name of function
* @return Name of function
*/
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
/**
* Get function arguments
* @return Get function arguments
*/
public Expression[] getArgs() {
return this.args;
}
/**
* Get argument at specified index
* @param index Index of argument
*/
public Expression getArg(int index) {
return this.args[index];
}
/**
* Set the function arguments - it is assumed that the args
* are not null. For no arg functions, use an empty Expression array.
* @param args Function arguments
*/
public void setArgs(Expression[] args) {
this.args = args;
}
/**
* Make this function implicit / hidden.
*/
public void makeImplicit() {
this.implicit = true;
}
/**
* Return true if this function is implicit and should not be shown in SQL representations
* @return True if implicit
*/
public boolean isImplicit() {
return this.implicit;
}
public void setImplicit(boolean implicit) {
this.implicit = implicit;
}
/**
* Insert a conversion function at specified index. This is a convenience
* method to insert a conversion into the function tree.
* @param index Argument index to insert conversion function at
* @param functionDescriptor Conversion function descriptor
*/
public void insertConversion(int index, FunctionDescriptor functionDescriptor) {
// Get target type for conversion
Class<?> t = functionDescriptor.getReturnType();
String typeName = DataTypeManager.getDataTypeName(t);
// Pull old expression at index
Expression newArg[] = new Expression[] { args[index], new Constant(typeName) };
// Replace old expression with new expression, using old as arg
Function func = new Function(functionDescriptor.getName(), newArg);
args[index] = func;
// Set function descriptor and type of new function
func.setFunctionDescriptor(functionDescriptor);
func.setType(t);
func.makeImplicit();
}
/**
* Get type of function, if known
* @return Java class name of type, or null if not yet resolved
*/
public Class<?> getType() {
return this.type;
}
/**
* Set type of function
* @param type New type
*/
public void setType(Class<?> type) {
this.type = type;
}
/**
* Get the function descriptor that this function resolves to.
* @return Descriptor or null if resolution has not yet occurred
*/
public FunctionDescriptor getFunctionDescriptor() {
return this.descriptor;
}
/**
* Set the descriptor for this function.
* @param fd Function descriptor
*/
public void setFunctionDescriptor(FunctionDescriptor fd) {
this.descriptor = fd;
}
public void acceptVisitor(LanguageVisitor visitor) {
visitor.visit(this);
}
/**
* Compare for equality
* @param obj Other object to compare
* @return Return true if objects are equivalent
*/
public boolean equals(Object obj) {
if(this == obj) {
return true;
}
if(! (obj instanceof Function)) {
return false;
}
Function other = (Function) obj;
if (this.descriptor != null && other.descriptor != null) {
if (!this.descriptor.getMethod().equals(other.descriptor.getMethod())) {
return false;
}
} else if(! other.getName().equalsIgnoreCase(getName())) {
return false;
}
if (this.isImplicit() != other.isImplicit()) {
return false;
}
Expression[] otherArgs = other.getArgs();
Expression[] thisArgs = getArgs();
return EquivalenceUtil.areEquivalent(thisArgs, otherArgs);
}
/**
* Compute hash code for the object - based on name and hashcode of first arg (if there is one)
* @return Hash code
*/
public int hashCode() {
int hashCode = HashCodeUtil.hashCode(0, this.getName().toUpperCase());
Expression[] thisArgs = getArgs();
if(thisArgs != null && thisArgs.length > 0 && thisArgs[0] != null) {
hashCode = HashCodeUtil.hashCode(hashCode, thisArgs[0].hashCode());
}
return hashCode;
}
/**
* Return a deep copy of this object.
* @return Deep copy of the object
*/
public Object clone() {
Expression[] copyArgs = LanguageObject.Util.deepClone(this.args);
Function copy = new Function(getName(), copyArgs);
copy.setType(getType());
copy.setFunctionDescriptor(getFunctionDescriptor());
if(this.isImplicit()) {
copy.makeImplicit();
}
copy.eval = this.eval;
return copy;
}
public boolean isAggregate() {
return getFunctionDescriptor().getMethod().getAggregateAttributes() != null;
}
/**
* Return string representation of the function.
* @return String representation
*/
public String toString() {
return SQLStringVisitor.getSQLString(this);
}
public boolean isEval() {
return eval;
}
public void setEval(boolean eval) {
this.eval = eval;
}
}