com.opengamma.elsql.PagingSqlFragment.java Source code

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Here is the source code for com.opengamma.elsql.PagingSqlFragment.java

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/**
 * Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies
 *
 * Please see distribution for license.
 */
package com.opengamma.elsql;

import org.apache.commons.lang.StringUtils;
import org.springframework.jdbc.core.namedparam.SqlParameterSource;

/**
 * Representation of paging over an SQL clause.
 */
final class PagingSqlFragment extends ContainerSqlFragment {

    /**
     * The offset variable.
     */
    private final String _offsetVariable;
    /**
     * The fetch variable or numeric amount.
     */
    private final String _fetchVariable;

    /**
     * Creates an instance.
     * 
     * @param offsetVariable  the offset variable, not null
     * @param fetchVariable  the fetch variable, not null
     */
    PagingSqlFragment(String offsetVariable, String fetchVariable) {
        _offsetVariable = offsetVariable;
        _fetchVariable = fetchVariable;
    }

    //-------------------------------------------------------------------------
    @Override
    protected void toSQL(StringBuilder buf, ElSqlBundle bundle, SqlParameterSource paramSource) {
        int oldLen = buf.length();
        super.toSQL(buf, bundle, paramSource);
        int newLen = buf.length();
        String select = buf.substring(oldLen, newLen);
        if (select.startsWith("SELECT ")) {
            buf.setLength(oldLen);
            buf.append(applyPaging(select, bundle, paramSource));
        }
    }

    /**
     * Applies the paging.
     * 
     * @param selectToPage  the contents of the enclosed block, not null
     * @param bundle  the elsql bundle for context, not null
     * @param paramSource  the SQL parameters, not null
     */
    protected String applyPaging(String selectToPage, ElSqlBundle bundle, SqlParameterSource paramSource) {
        int offset = 0;
        int fetchLimit = 0;
        if (_offsetVariable != null && paramSource.hasValue(_offsetVariable)) {
            offset = ((Number) paramSource.getValue(_offsetVariable)).intValue();
        }
        if (paramSource.hasValue(_fetchVariable)) {
            fetchLimit = ((Number) paramSource.getValue(_fetchVariable)).intValue();
        } else if (StringUtils.containsOnly(_fetchVariable, "0123456789")) {
            fetchLimit = Integer.parseInt(_fetchVariable);
        }
        return bundle.getConfig().addPaging(selectToPage, offset, fetchLimit == Integer.MAX_VALUE ? 0 : fetchLimit);
    }

    //-------------------------------------------------------------------------
    @Override
    public String toString() {
        return getClass().getSimpleName() + " " + getFragments();
    }

}