root / trunk / libraries / libGDBMS / src / main / java / com / hardcode / gdbms / engine / strategies / PDataSource.java @ 10627
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package com.hardcode.gdbms.engine.strategies; |
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import com.hardcode.gdbms.driver.exceptions.ReadDriverException; |
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import com.hardcode.gdbms.engine.data.DataSource; |
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import com.hardcode.gdbms.engine.data.FieldNameAccessSupport; |
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import com.hardcode.gdbms.engine.data.persistence.Memento; |
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import com.hardcode.gdbms.engine.data.persistence.MementoException; |
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import com.hardcode.gdbms.engine.data.persistence.OperationLayerMemento; |
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import com.hardcode.gdbms.engine.values.Value; |
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/**
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* Clase que representa el producto cartesiano de dos o m?s tablas. El
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* almacenamiento de dicha tabla se realiza en las propias tablas sobre las
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* que se opera, haciendo los c?lculos en cada acceso para saber en qu? tabla
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* y en qu? posici?n de la tabla se encuentra el dato buscado
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*
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* @author Fernando Gonz?lez Cort?s
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*/
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public class PDataSource extends OperationDataSource { |
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private DataSource[] tables; |
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private long tablesArity; |
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private FieldNameAccessSupport fnaSupport = new FieldNameAccessSupport(this); |
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/**
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* Creates a new PDataSource object.
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*
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* @param tables Array de tablas que forman el producto
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*/
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public PDataSource(DataSource[] tables) { |
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this.tables = tables;
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} |
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/**
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* Dado un ?ndice de campo en la tabla producto, devuelve el ?ndice en la
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* tabla operando a la cual pertenence el campo
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*
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* @param fieldId ?ndice en la tabla producto
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*
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* @return ?ndice en la tabla operando
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* @throws ReadDriverException TODO
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*/
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private int getFieldIndex(int fieldId) throws ReadDriverException { |
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int table = 0; |
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while (fieldId >= tables[table].getFieldCount()) {
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fieldId -= tables[table].getFieldCount(); |
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table++; |
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} |
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return fieldId;
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} |
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/**
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* Dado un ?ndice de campo en la tabla producto, devuelve el ?ndice en el
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* array de tablas de la tabla operando que contiene dicho campo
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*
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* @param fieldId ?ndice del campo en la tabla producto
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*
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* @return ?ndice de la tabla en el array de tablas
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* @throws ReadDriverException TODO
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*/
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private int getTableIndexByFieldId(int fieldId) throws ReadDriverException { |
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int table = 0; |
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while (fieldId >= tables[table].getFieldCount()) {
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fieldId -= tables[table].getFieldCount(); |
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table++; |
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} |
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return table;
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} |
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/**
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* Devuelve la fila de la tabla operando con ?ndice tableIndex que contiene
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* la informaci?n de la fila rowIndex en la tabla producto
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*
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* @param rowIndex fila en la tabla producto a la que se quiere acceder
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* @param tableIndex ?ndice de la tabla
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*
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* @return fila en la tabla operando de ?ndice tableIndex que se quiere
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* acceder
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* @throws ReadDriverException TODO
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* @throws ArrayIndexOutOfBoundsException Si la fila que se pide (rowIndex)
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* supera el n?mero de filas de la tabla producto
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*/
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private long getTableRowIndexByTablePosition(long rowIndex, int tableIndex) |
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throws ReadDriverException {
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if (rowIndex >= tablesArity) {
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throw new ArrayIndexOutOfBoundsException(); |
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} |
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int arity = 1; |
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for (int i = tableIndex + 1; i < tables.length; i++) { |
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arity *= tables[i].getRowCount(); |
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} |
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long selfArity = tables[tableIndex].getRowCount();
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return (rowIndex / arity) % selfArity;
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#getFieldName(int)
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*/
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public String getFieldName(int fieldId) throws ReadDriverException { |
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return tables[getTableIndexByFieldId(fieldId)].getFieldName(getFieldIndex(
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fieldId)); |
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#getIntFieldValue(int, int)
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*/
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public Value getFieldValue(long rowIndex, int fieldId) |
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throws ReadDriverException {
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int tableIndex = getTableIndexByFieldId(fieldId);
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return tables[tableIndex].getFieldValue(getTableRowIndexByTablePosition(
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rowIndex, tableIndex), getFieldIndex(fieldId)); |
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#getFieldCount()
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*/
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public int getFieldCount() throws ReadDriverException { |
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int ret = 0; |
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for (int i = 0; i < tables.length; i++) { |
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ret += tables[i].getFieldCount(); |
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} |
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return ret;
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#getRowCount()
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*/
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public long getRowCount() throws ReadDriverException { |
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return tablesArity;
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#open(java.io.File)
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*/
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public void start() throws ReadDriverException { |
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for (int i = 0; i < tables.length; i++) { |
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try {
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tables[i].start(); |
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} catch (ReadDriverException e) {
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for (int j = 0; j < i; j++) { |
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tables[i].stop(); |
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} |
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throw e;
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} |
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} |
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tablesArity = 1;
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for (int i = 0; i < tables.length; i++) { |
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tablesArity *= tables[i].getRowCount(); |
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} |
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#close()
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*/
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public void stop() throws ReadDriverException { |
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for (int i = 0; i < tables.length; i++) { |
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tables[i].stop(); |
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} |
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} |
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/**
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* @see com.hardcode.gdbms.data.DataSource#getFieldIndexByName(String)
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*/
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public int getFieldIndexByName(String fieldName) throws ReadDriverException { |
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return fnaSupport.getFieldIndexByName(fieldName);
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} |
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/**
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* @see com.hardcode.gdbms.engine.data.driver.ObjectDriver#getFieldType(int)
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*/
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public int getFieldType(int i) throws ReadDriverException { |
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int table = getTableIndexByFieldId(i);
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return tables[table].getFieldType(getFieldIndex(i));
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} |
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/**
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* @see com.hardcode.gdbms.engine.data.DataSource#getMemento()
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*/
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public Memento getMemento() throws MementoException { |
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Memento[] mementos = new Memento[tables.length]; |
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for (int i = 0; i < mementos.length; i++) { |
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mementos[i] = tables[i].getMemento(); |
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} |
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return new OperationLayerMemento(getName(), mementos, getSQL()); |
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} |
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public int getFieldWidth(int i) throws ReadDriverException { |
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int table = getTableIndexByFieldId(i);
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return tables[table].getFieldWidth(getFieldIndex(i));
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} |
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} |