sqlwherevisitor.java

大名鼎鼎的java动态脚本语言。已经通过了sun的认证

package groovy.sql;

import java.util.ArrayList;
import java.util.List;

import org.codehaus.groovy.ast.CodeVisitorSupport;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.BooleanExpression;
import org.codehaus.groovy.ast.expr.ConstantExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.PropertyExpression;
import org.codehaus.groovy.ast.stmt.ReturnStatement;
import org.codehaus.groovy.syntax.Token;
import org.codehaus.groovy.syntax.Types;

/**
 * @author James Strachan
 * @version $Revision: 1.2 $
 */
public class SqlWhereVisitor extends CodeVisitorSupport {

    private StringBuffer buffer = new StringBuffer();
    private List parameters = new ArrayList();

    public String getWhere() {
        return buffer.toString();
    }

    public void visitReturnStatement(ReturnStatement statement) {
        statement.getExpression().visit(this);
    }

    public void visitBinaryExpression(BinaryExpression expression) {
        Expression left = expression.getLeftExpression();
        Expression right = expression.getRightExpression();

        left.visit(this);
        buffer.append(" ");

        Token token = expression.getOperation();
        buffer.append(tokenAsSql(token));

        buffer.append(" ");
        right.visit(this);
    }

    public void visitBooleanExpression(BooleanExpression expression) {
        expression.getExpression().visit(this);
    }

    public void visitConstantExpression(ConstantExpression expression) {
        getParameters().add(expression.getValue());
        buffer.append("?");
    }

    public void visitPropertyExpression(PropertyExpression expression) {
        buffer.append(expression.getProperty());
    }
    
    public List getParameters() {
        return parameters;
    }
    
    protected String tokenAsSql(Token token) {
        switch (token.getType()) {
            case Types.COMPARE_EQUAL :
                return "=";
            case Types.LOGICAL_AND :
                return "and";
            case Types.LOGICAL_OR :
                return "or";
            default :
                return token.getText();
        }
    }
}