Examples with SqlXmlUtil org.apache.derby.iapi.types.SqlXmlUtil used on opensource projects

Example 1 with SqlXmlUtil

use of org.apache.derby.iapi.types.SqlXmlUtil in project derby by apache.

the class OperatorNode method pushSqlXmlUtil.

/**
 * <p>
 * Generate code that pushes an SqlXmlUtil instance onto the stack. The
 * instance will be created and cached in the activation's constructor, so
 * that we don't need to create a new instance for every row.
 * </p>
 *
 * <p>
 * If the {@code xmlQuery} parameter is non-null, there will also be code
 * that compiles the query when the SqlXmlUtil instance is created.
 * </p>
 *
 * @param acb builder for the class in which the generated code lives
 * @param mb builder for the method that implements this operator
 * @param xmlQuery the XML query to be executed by the operator, or
 * {@code null} if this isn't an XMLEXISTS or XMLQUERY operator
 * @param xmlOpName the name of the operator (ignored if {@code xmlQuery}
 * is {@code null})
 */
static void pushSqlXmlUtil(ExpressionClassBuilder acb, MethodBuilder mb, String xmlQuery, String xmlOpName) {
    // Create a field in which the instance can be cached.
    LocalField sqlXmlUtil = acb.newFieldDeclaration(Modifier.PRIVATE | Modifier.FINAL, SqlXmlUtil.class.getName());
    // Add code that creates the SqlXmlUtil instance in the constructor.
    MethodBuilder constructor = acb.getConstructor();
    constructor.pushNewStart(SqlXmlUtil.class.getName());
    constructor.pushNewComplete(0);
    constructor.putField(sqlXmlUtil);
    // Compile the query, if one is specified.
    if (xmlQuery == null) {
        // No query. The SqlXmlUtil instance is still on the stack. Pop it
        // to restore the initial state of the stack.
        constructor.pop();
    } else {
        // Compile the query. This will consume the SqlXmlUtil instance
        // and leave the stack in its initial state.
        constructor.push(xmlQuery);
        constructor.push(xmlOpName);
        constructor.callMethod(VMOpcode.INVOKEVIRTUAL, SqlXmlUtil.class.getName(), "compileXQExpr", "void", 2);
    }
    // Read the cached value and push it onto the stack in the method
    // generated for the operator.
    mb.getField(sqlXmlUtil);
}