svn-gvsig-desktop / trunk / libraries / libGDBMS / src / com / hardcode / gdbms / engine / instruction / ProductExprAdapter.java @ 1956
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package com.hardcode.gdbms.engine.instruction; |
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import com.hardcode.gdbms.engine.data.driver.DriverException; |
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import com.hardcode.gdbms.engine.values.Value; |
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import com.hardcode.gdbms.parser.SimpleNode; |
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/**
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* Adaptador sobre las expresiones producto del arbol sint?ctico
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*
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* @author Fernando Gonz?lez Cort?s
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*/
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public class ProductExprAdapter extends AbstractExpression implements Expression { |
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private static final int UNDEFINED = -1; |
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private static final int PRODUCTO = 0; |
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private static final int DIVISION = 1; |
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private int operator = UNDEFINED; |
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/**
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* Evalua expresi?n invocando el m?todo adecuado en funci?n del tipo de
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* expresion (suma, producto, ...) de los objetos Value de la expresion,
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* de las subexpresiones y de los objetos Field
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*
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* @param row Fila en la que se eval?a la expresi?n, en este caso no es
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* necesario, pero las subexpresiones sobre las que se opera pueden
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* ser campos de una tabla, en cuyo caso si es necesario
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*
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* @return Objeto Value resultado de la operaci?n propia de la expresi?n
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* representada por el nodo sobre el cual ?ste objeto es adaptador
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*
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* @throws SemanticException Si se produce un error sem?ntico
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* @throws DriverException Si se produce un error de I/O
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*/
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public Value evaluate(long row) throws SemanticException, DriverException { |
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Value ret = null;
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Adapter[] expr = (Adapter[]) getChilds(); |
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if (expr.length > 0) { |
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ret = ((Expression) expr[0]).evaluateExpression(row); |
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if (expr.length == 2) { |
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if (getOperator(this.getEntity()) == PRODUCTO) { |
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ret = ret.producto(((Expression) expr[1]).evaluateExpression( |
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row)); |
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} else if (getOperator(this.getEntity()) == DIVISION) { |
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ret = ret.producto(((Expression) expr[1]).evaluateExpression( |
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row).inversa()); |
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} |
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} |
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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.engine.instruction.Expression#getFieldName()
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*/
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public String getFieldName() { |
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Adapter[] expr = (Adapter[]) getChilds(); |
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if (expr.length != 1) { |
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return null; |
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} else {
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return ((Expression) expr[0]).getFieldName(); |
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} |
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} |
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/**
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* @see com.hardcode.gdbms.engine.instruction.Expression#isLiteral()
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*/
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public boolean isLiteral() { |
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return literal;
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} |
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/**
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* @see com.hardcode.gdbms.engine.instruction.Expression#simplify()
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*/
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public void simplify() { |
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Adapter[] childs = getChilds();
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if (childs.length == 1) { |
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getParent().replaceChild(this, childs[0]); |
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} |
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} |
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/**
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* @see com.hardcode.gdbms.engine.instruction.Expression#calculateLiteralCondition()
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*/
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public void calculateLiteralCondition() { |
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literal = Utilities.checkExpressions(getChilds());
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} |
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/**
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* DOCUMENT ME!
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*
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* @param expr DOCUMENT ME!
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*
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* @return DOCUMENT ME!
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*/
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private int getOperator(SimpleNode expr) { |
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if (operator == UNDEFINED) {
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SimpleNode sn1 = (SimpleNode) expr.jjtGetChild(0);
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SimpleNode sn2 = (SimpleNode) expr.jjtGetChild(1);
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int pos1 = sn1.last_token.endColumn;
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int pos2 = sn2.first_token.beginColumn;
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String text = getInstructionContext().getSql();
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text = text.substring(pos1, pos2 - 1);
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if (text.indexOf('*') != -1) { |
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operator = PRODUCTO; |
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} |
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if (text.indexOf('/') != -1) { |
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operator = DIVISION; |
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} |
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} |
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return operator;
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} |
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} |