HSQLDB example source code file (Function.java)
The HSQLDB Function.java source code
/*
* For work developed by the HSQL Development Group:
*
* Copyright (c) 2001-2010, The HSQL Development Group
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the HSQL Development Group nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
*
* For work originally developed by the Hypersonic SQL Group:
*
* Copyright (c) 1995-2000, The Hypersonic SQL Group.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the Hypersonic SQL Group nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This software consists of voluntary contributions made by many individuals
* on behalf of the Hypersonic SQL Group.
*/
package org.hsqldb;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.sql.Connection;
import org.hsqldb.lib.HashMap;
import org.hsqldb.lib.HsqlArrayList;
import org.hsqldb.lib.StringConverter;
import org.hsqldb.types.Binary;
import org.hsqldb.types.JavaObject;
// fredt@users 20020912 - patch 1.7.1 - shortcut treatment of identity() call
// fredt@users 20020912 - patch 1.7.1 - cache java.lang.reflect.Method objects
// fredt@users 20021013 - patch 1.7.1 - ignore non-static methods
// boucherb@users 20030201 - patch 1.7.2 - direct calls for org.hsqldb.Library
// fredt@users 20030621 - patch 1.7.2 - shortcut treatment of session calls
// boucherb@users 200404xx - doc 1.7.2 - updates toward 1.7.2 final
/**
* Provides services to evaluate SQL function and stored procedure calls,
* by invoking Java methods.
*
* Extended in successive versions of HSQLDB.
*
* @author Thomas Mueller (Hypersonic SQL Group)
* @version 1.8.0
* @since Hypersonic SQL
*/
class Function {
private String sFunction;
private Method mMethod;
private String returnClassName;
private Class[] aArgClasses;
private int iReturnType;
private int iArgCount;
private int iSqlArgCount;
private int iSqlArgStart;
private int[] iArgType;
private boolean[] bArgNullable;
Expression[] eArg;
private boolean bConnection;
private static HashMap methodCache = new HashMap();
private int fID;
String name; // name used to call function
boolean isSimple; //CURRENT_TIME, NOW etc.
boolean hasAggregate;
/**
* Constructs a new Function object with the given function call name
* and using the specified Session context. <p>
*
* The call name is the fully qualified name of a static Java method, in
* the form "package.class.method." This implies that Java
* methods with the same fully qualified name but different signatures
* cannot be used properly as HSQLDB SQL functions or stored procedures.
* For instance, it is impossible to call both System.getProperty(String)
* and System.getProperty(String,String) under this arrangement, because
* the HSQLDB Function object is unable to differentiate between the two;
* it simply chooses the first method matching the FQN in the array of
* methods obtained from calling getMethods() on an instance of the
* Class indicated in the FQN, hiding all other methods with the same
* FQN. <p>
*
* The function FQN must match at least one static Java method FQN in the
* specified class or construction cannot procede and an HsqlException is
* thrown. <p>
*
* The isSimple parameter is true when certain SQL standard functions
* that are used without brackets are invokded.
*
* @param name this Function object's call name
* @param fqn the fully qualified name of a Java method
* @param isSimple if true, used to evalate CURRENT_TIME, NOW etc.
* evaluate
* @throws HsqlException if the specified function FQN corresponds to no
* Java method
*/
Function(String name, String fqn, boolean isSimple) throws HsqlException {
this.name = name;
this.isSimple = isSimple;
// cSession = session;
sFunction = fqn;
fID = Library.functionID(fqn);
int i = fqn.lastIndexOf('.');
Trace.check(i != -1, Trace.UNEXPECTED_TOKEN, fqn);
String classname = fqn.substring(0, i);
mMethod = (Method) methodCache.get(fqn);
if (mMethod == null) {
String methodname = fqn.substring(i + 1);
Class classinstance = null;
try {
classinstance = Class.forName(classname);
} catch (Exception e) {
throw Trace.error(Trace.FUNCTION_NOT_FOUND,
Trace.Message_Pair, new Object[] {
classname, e
});
}
// public only, but includes those inherited from
// superclasses and superinterfaces. List is unordered.
Method[] methods = classinstance.getMethods();
for (i = 0; i < methods.length; i++) {
Method m = methods[i];
if (m.getName().equals(methodname)
&& Modifier.isStatic(m.getModifiers())) {
mMethod = m;
break;
}
}
Trace.check(mMethod != null, Trace.UNKNOWN_FUNCTION, methodname);
methodCache.put(fqn, mMethod);
}
Class returnClass = mMethod.getReturnType();
if (returnClass.equals(org.hsqldb.Result.class)) {
// For now, we can write stored procedures whose
// descriptor explicitly specifies the above return type.
// Later, this will be modified or replaced to provide proper
// support for jdbcCallableStatement OUT mode return parameter,
// multiple results (Result.MULTI etc.)
iReturnType = Types.OTHER;
} else {
// Now we support the following construction-time return type
// Classes, as specified by the method descriptor:
//
// 1.) any primitive or primitive wrapper type, except Byte(.TYPE),
// Short(.TYPE) and Float(.TYPE) (TBD; narrow if no truncation)
//
// 2.) any primitive array type
//
// 3.) any non-primitive array whose base component implements
// java.io.Serializable
//
// 4.) any class implementing java.io.Serializable, except those
// described in 1.) as currently unsupported
//
// 5.) java.lang.Object
//
// For java.lang.Object, checking is deferred from the construction
// stage to the evaluation stage. In general, for the evaluation
// to succeed, the runtime class of the retrieved Object must be
//
// 1.) any primitive or primitive wrapper type, except Byte(.TYPE),
// Short(.TYPE) and Float(.TYPE) (TBD; narrow if no trunction)
//
// 2.) any primitive array type
// 3.) any non-primitive array whose base component implements
// java.io.Serializable
//
// 4.) any class implementing java.io.Serializable, except those
// described in 1.) as currently unsupported
//
// Additionally, it is possible for the evaluation to succeed under
// an SQL CALL if the runtime Class of the returned Object is not
// from the list above but is from the list below:
//
// 1.) is org.hsqldb.Result
// 2.) is org.hsqldb.jdbc.jdbcResultSet
//
// In these special cases, the statement executor notices the
// types and presents the client with a view the underlying result
// rather than with a view of the object as an opaque scalar value
//
iReturnType = Types.getParameterTypeNr(returnClass);
}
returnClassName =
Types.getFunctionReturnClassName(returnClass.getName());
aArgClasses = mMethod.getParameterTypes();
iArgCount = aArgClasses.length;
iArgType = new int[iArgCount];
bArgNullable = new boolean[iArgCount];
for (i = 0; i < aArgClasses.length; i++) {
Class a = aArgClasses[i];
String type = a.getName();
if ((i == 0) && a.equals(Connection.class)) {
// TODO: provide jdbc:default:connection url functionality
//
// only the first parameter can be a Connection
bConnection = true;
} else {
// see discussion above for iReturnType
iArgType[i] = Types.getParameterTypeNr(a);
bArgNullable[i] = !a.isPrimitive();
}
}
iSqlArgCount = iArgCount;
if (bConnection) {
iSqlArgCount--;
iSqlArgStart = 1;
} else {
iSqlArgStart = 0;
}
eArg = new Expression[iArgCount];
}
/**
* Evaluates and returns this Function in the context of the session.<p>
*/
Object getValue(Session session) throws HsqlException {
switch (fID) {
case Library.curtime :
return session.getCurrentTime();
case Library.curdate :
return session.getCurrentDate();
case Library.database :
return session.getDatabase().getPath();
case Library.getAutoCommit :
return session.isAutoCommit() ? Boolean.TRUE
: Boolean.FALSE;
case Library.identity :
return session.getLastIdentity();
case Library.isReadOnlyDatabase :
return session.getDatabase().databaseReadOnly ? Boolean.TRUE
: Boolean.FALSE;
case Library.isReadOnlyConnection :
return session.isReadOnly() ? Boolean.TRUE
: Boolean.FALSE;
case Library.isReadOnlyDatabaseFiles :
return session.getDatabase().isFilesReadOnly() ? Boolean.TRUE
: Boolean
.FALSE;
case Library.now :
return session.getCurrentTimestamp();
case Library.user :
return session.getUsername();
}
Object[] oArg = getArguments(session);
if (oArg == null) {
return null;
}
return getValue(session, oArg);
}
/**
* Evaluates the Function with the given arguments in the session context.
*/
Object getValue(Session session,
Object[] arguments) throws HsqlException {
if (bConnection) {
arguments[0] = session.getInternalConnection();
}
try {
Object ret = (fID >= 0) ? Library.invoke(fID, arguments)
: mMethod.invoke(null, arguments);
return Column.convertObject(ret, iReturnType);
} catch (InvocationTargetException e) {
// thrown by user functions
Throwable t = e.getTargetException();
String s = sFunction + " : " + t.toString();
throw Trace.error(Trace.FUNCTION_CALL_ERROR, s);
} catch (IllegalAccessException e) {
// never thrown in this method
throw Trace.error(Trace.FUNCTION_CALL_ERROR);
}
// Library function throw HsqlException
}
private Object[] getArguments(Session session) throws HsqlException {
int i = bConnection ? 1
: 0;
Object[] oArg = new Object[iArgCount];
for (; i < iArgCount; i++) {
Expression e = eArg[i];
Object o = null;
if (e != null) {
// no argument: null
o = e.getValue(session, iArgType[i]);
}
if ((o == null) &&!bArgNullable[i]) {
// null argument for primitive datatype: don't call
return null;
}
if (o instanceof JavaObject) {
o = ((JavaObject) o).getObject();
} else if (o instanceof Binary) {
o = ((Binary) o).getBytes();
}
oArg[i] = o;
}
return oArg;
}
/**
* returns null if any non-nullable element of values is null
*/
private Object[] getNotNull(Object[] values) throws HsqlException {
int i = bConnection ? 1
: 0;
for (; i < iArgCount; i++) {
Object o = values[i];
if (o == null &&!bArgNullable[i]) {
// null argument for primitive datatype: don't call
return null;
}
}
return values;
}
void collectInGroupByExpressions(HsqlArrayList colExps) {
for (int i = 0; i < iArgCount; i++) {
Expression e = eArg[i];
if (e != null) {
e.collectInGroupByExpressions(colExps);
}
}
}
Object getAggregatedValue(Session session,
Object currValue) throws HsqlException {
Object[] valueArray = (Object[]) currValue;
if (valueArray == null) {
valueArray = new Object[iArgCount];
}
for (int i = 0; i < iArgCount; i++) {
Expression e = eArg[i];
if (eArg[i] != null) {
if (eArg[i].isAggregate()) {
valueArray[i] = Column.convertObject(
e.getAggregatedValue(session, valueArray[i]),
iArgType[i]);
} else {
valueArray[i] = e.getValue(session, iArgType[i]);
}
}
}
valueArray = getNotNull(valueArray);
if (valueArray == null) {
return null;
}
return getValue(session, valueArray);
}
Object updateAggregatingValue(Session session,
Object currValue) throws HsqlException {
Object[] valueArray = (Object[]) currValue;
if (valueArray == null) {
valueArray = new Object[iArgCount];
}
for (int i = 0; i < iArgCount; i++) {
Expression e = eArg[i];
if (eArg[i] != null) {
valueArray[i] = e.updateAggregatingValue(session,
valueArray[i]);
}
}
return valueArray;
}
/**
* Returns the number of parameters that must be supplied to evaluate
* this Function object from SQL. <p>
*
* This value may be different than the number of parameters of the
* underlying Java method. This is because HSQLDB automatically detects
* if the first parameter is of type java.sql.Connection, and supplies a
* live Connection object constructed from the evaluating session context
* if so.
*/
int getArgCount() {
return iSqlArgCount;
}
/**
* Remnoves the Table filters from Expression parameters to this Function.
*
* @throws HsqlException if there is a problem resolving a parameter
* against the specified TableFilter
*/
/*
void removeFilters() throws HsqlException {
Expression e;
for (int i = iSqlArgStart; i < iArgCount; i++) {
e = eArg[i];
if (e != null) {
e.removeFilters();
}
}
}
*/
void replaceAliases(Expression[] columns,
int length) throws HsqlException {
Expression e;
for (int i = iSqlArgStart; i < iArgCount; i++) {
e = eArg[i];
if (e != null) {
if (e.exprType == Expression.COLUMN) {
eArg[i] = e.getExpressionForAlias(columns, length);
} else {
e.replaceAliases(columns, length);
}
}
}
}
/**
* Checks the Expresion parameters to this Function object against the
* set of TableFilter.
*/
void checkTables(HsqlArrayList fa) throws HsqlException {
Expression e;
for (int i = iSqlArgStart; i < iArgCount; i++) {
e = eArg[i];
if (e != null) {
e.checkTables(fa);
}
}
}
/**
* Resolves the Expression parameters to this Function object against the
* specified TableFilter.
*/
void resolveTables(TableFilter f) throws HsqlException {
Expression e;
for (int i = iSqlArgStart; i < iArgCount; i++) {
e = eArg[i];
if (e != null) {
e.resolveTables(f);
}
}
}
/**
* Resolves the type of this expression and performs certain
* transformations and optimisations of the expression tree.
*/
void resolveType(Session session) throws HsqlException {
Expression e;
for (int i = iSqlArgStart; i < iArgCount; i++) {
e = eArg[i];
if (e != null) {
if (e.isParam()) {
e.setDataType(iArgType[i]);
e.nullability = getArgNullability(i);
e.valueClassName = getArgClass(i).getName();
} else {
e.resolveTypes(session);
}
}
}
}
/**
* Checks each of this object's arguments for resolution, throwing an
* HsqlException if any arguments have not yet been resolved. <p>
* The check boolean argument is passed on to further check calls.<p>
*/
boolean checkResolved(boolean check) throws HsqlException {
boolean result = true;
for (int i = iSqlArgStart; i < iArgCount; i++) {
if (eArg[i] != null) {
result = result && eArg[i].checkResolved(check);
}
}
return result;
}
/**
* Returns the type of the argument at the specified
* offset in this Function object's paramter list. <p>
*/
int getArgType(int i) {
return iArgType[i];
}
/**
* Returns the type of this Function
* object's return type. <p>
*/
int getReturnType() {
return iReturnType;
}
/**
* Binds the specified expression to the specified position in this
* Function object's parameter list. <p>
*/
void setArgument(int i, Expression e) {
if (bConnection) {
i++;
}
eArg[i] = e;
hasAggregate = hasAggregate || (e != null && e.isAggregate());
}
/**
* Returns a DDL representation of this object. <p>
*/
String getDLL() throws HsqlException {
StringBuffer sb = new StringBuffer();
// get the name as used by the CHECK statement
String ddlName = name;
if (isSimple) {
return name;
} else if (Token.T_TRIM.equals(name)) {
// special case for TRIM
sb.append(name).append('(');
boolean leading = eArg[2].testCondition(null);
boolean trailing = eArg[3].testCondition(null);
if (leading && trailing) {
sb.append(Token.T_BOTH);
} else {
sb.append(leading ? Token.T_LEADING
: Token.T_TRAILING);
}
// to do change to string
sb.append(' ');
String charval = (String) eArg[1].getValue(null);
sb.append(Column.createSQLString(charval)).append(' ');
sb.append(Token.T_FROM).append(' ');
sb.append(eArg[0].getDDL()).append(')');
return sb.toString();
}
if (sFunction.equals(name)) {
ddlName = StringConverter.toQuotedString(name, '"', true);
}
sb.append(ddlName).append('(');
for (int i = iSqlArgStart; i < eArg.length; i++) {
sb.append(eArg[i].getDDL());
if (i < eArg.length - 1) {
sb.append(',');
}
}
sb.append(')');
return sb.toString();
}
/**
* Returns a String representation of this object. <p>
*/
public String describe(Session session) {
StringBuffer sb = new StringBuffer();
sb.append(super.toString()).append("=[\n");
sb.append(sFunction).append("(");
for (int i = iSqlArgStart; i < eArg.length; i++) {
sb.append("[").append(eArg[i].describe(session)).append("]");
}
sb.append(") returns ").append(Types.getTypeString(getReturnType()));
sb.append("]\n");
return sb.toString();
}
/**
* Returns the Java Class of the object returned by getValue(). <p>
*/
String getReturnClassName() {
return returnClassName;
}
/**
* Returns the Java Class of the i'th argument. <p>
*/
Class getArgClass(int i) {
return aArgClasses[i];
}
/**
* Returns the SQL nullability code of the i'th argument. <p>
*/
int getArgNullability(int i) {
return bArgNullable[i] ? Expression.NULLABLE
: Expression.NO_NULLS;
}
Method getMethod() {
return mMethod;
}
}
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