package fedora.services.oaiprovider;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
/**
* Combines three RDF query results into a single iterator that can be used to
* construct FedoraRecord objects.
* Input
* The input is provided to the constructor using Files or BufferedReaders in
* CSV format.
*
*
* File 1:
* "item","itemID","date","state"
* info:fedora/nsdl:10013,oai:nsdl.org:nsdl:10011:nsdl:10013,2005-09-20T12:49:14.77,info:fedora/fedora-system:def/model#Active
* info:fedora/nsdl:10015,oai:nsdl.org:nsdl:10011:nsdl:10015,2005-09-20T12:49:15.391,info:fedora/fedora-system:def/model#Active
* info:fedora/nsdl:2051858,oai:nsdl.org:nsdl:10059:nsdl:2051858,2005-09-20T12:50:01,info:fedora/fedora-system:def/model#Active
* info:fedora/nsdl:2052376,oai:nsdl.org:nsdl:10059:nsdl:2052376,2005-09-20T12:50:02.23.123,info:fedora/fedora-system:def/model#Active
*
* File 2:
* "itemID","setSpec"
* oai:nsdl.org:nsdl:10059:nsdl:2051858,5101
* oai:nsdl.org:nsdl:10059:nsdl:2051858,set2
* oai:nsdl.org:nsdl:10059:nsdl:2052376,5101
* oai:nsdl.org:nsdl:10059:nsdl:2052420,5101
*
* File 3:
* "itemID"
* oai:nsdl.org:nsdl:10011:nsdl:10013
* oai:nsdl.org:nsdl:10011:nsdl:10015
* oai:nsdl.org:nsdl:10059:nsdl:2051858
* oai:nsdl.org:nsdl:10059:nsdl:2052376
*
*
* Output
* The output is given one line at a time in the format below. The header is not
* actually provided, but is shown here for clarity. Each item has exactly one
* line with at least five comma-separated values. An additional value is
* provided for each set the item is a member of.
*
*
* "item","itemID","date","state","hasAbout"[,"setSpec1"[,"setSpec2"[,...]]]
* info:fedora/nsdl:10013,oai:nsdl.org:nsdl:10011:nsdl:10013,2005-09-20T12:49:14.77,info:fedora/fedora-system:def/model#Active,true
* info:fedora/nsdl:10015,oai:nsdl.org:nsdl:10011:nsdl:10015,2005-09-20T12:49:15.391,info:fedora/fedora-system:def/model#Active,true
* info:fedora/nsdl:2051858,oai:nsdl.org:nsdl:10059:nsdl:2051858,2005-09-20T12:50:01,info:fedora/fedora-system:def/model#Active,true,5101,set2
* info:fedora/nsdl:2052376,oai:nsdl.org:nsdl:10059:nsdl:2052376,2005-09-20T12:50:02.23.123,info:fedora/fedora-system:def/model#Active,true,5101
*
*
* @author cwilper@cs.cornell.edu
*/
public class ResultCombiner {
private File m_f1;
private File m_f2;
private File m_f3;
private boolean m_deleteOnClose;
private BufferedReader m_r1;
private BufferedReader m_r2;
private BufferedReader m_r3;
private String m_l2;
private String m_l3;
private static final String _START = "START";
/**
* Initialize with BufferedReaders containing the input data.
*
* @param r1
* The results of the first query. Must be provided.
* @param r2
* The results of the second query. If given as null, output will not
* contain set membership information.
* @param r3
* The results of the thrid query. If given as null, output will
* always indicate that no "about" information exist for the item.
*/
public ResultCombiner(BufferedReader r1,
BufferedReader r2,
BufferedReader r3) {
m_r1 = r1;
m_r2 = r2;
m_r3 = r3;
m_l2 = _START;
m_l3 = _START;
}
/**
* Initialize with Files containing the input data, optionally deleting them
* when the ResultCombiner is closed.
*
* @param f1
* The results of the first query. Must be provided.
* @param f2
* The results of the second query. If given as null, output will not
* contain set membership information.
* @param f3
* The results of the thrid query. If given as null, output will
* always indicate that no "about" information exist for the item.
* @param deleteOnClose
* Whether to delete all provided files when this ResultCombiner is
* closed.
*/
public ResultCombiner(File f1, File f2, File f3, boolean deleteOnClose)
throws FileNotFoundException {
m_f1 = f1;
m_f2 = f2;
m_f3 = f3;
m_deleteOnClose = deleteOnClose;
m_r1 =
new BufferedReader(new InputStreamReader(new FileInputStream(m_f1)));
if (m_f2 != null)
m_r2 =
new BufferedReader(new InputStreamReader(new FileInputStream(m_f2)));
if (m_f3 != null)
m_r3 =
new BufferedReader(new InputStreamReader(new FileInputStream(m_f3)));
m_l2 = _START;
m_l3 = _START;
}
/**
* Get the next line of output, or null if we've reached the end.
*/
public String readLine() {
String l1 = nextLine(m_r1);
if (l1 == null) {
close();
return null;
} else {
StringBuffer line = new StringBuffer();
line.append(l1 + ",");
String itemID = l1.split(",")[1];
line.append(hasAbout(itemID));
line.append(setSpecs(itemID));
return line.toString();
}
}
// tell whether this item has an about dissemination
private boolean hasAbout(String itemID) {
if (m_r3 == null) return false;
if (m_l3 == _START) {
m_l3 = nextLine(m_r3);
}
if (m_l3 == null) {
return false;
} else {
if (m_l3.equals(itemID)) {
m_l3 = nextLine(m_r3);
return true;
} else {
return false;
}
}
}
// get comma-separated setSpecs for this item, or the empty string if none
private String setSpecs(String itemID) {
if (m_r2 == null) return "";
if (m_l2 == _START) {
m_l2 = nextLine(m_r2);
}
if (m_l2 == null) {
return "";
} else {
StringBuffer out = new StringBuffer();
while (m_l2 != null && m_l2.split(",")[0].equals(itemID)) {
out.append("," + m_l2.split(",")[1]);
m_l2 = nextLine(m_r2);
}
return out.toString();
}
}
/**
* Get the next line, skipping any that start with " or are blank.
*/
private static String nextLine(BufferedReader r) {
try {
String line = r.readLine();
while (line != null
&& (line.startsWith("\"") || (line.trim().equals("")))) {
line = r.readLine();
}
if (line == null) {
return null;
} else {
return line.trim();
}
} catch (IOException e) {
System.err.println("WARNING: " + e.getMessage());
return null;
}
}
/**
* Close the input readers and delete the associated files if the combiner
* was constructed with the option to do so.
*/
public void close() {
try {
m_r1.close();
} catch (Throwable th) {
}
try {
m_r2.close();
} catch (Throwable th) {
}
try {
m_r3.close();
} catch (Throwable th) {
}
if (m_deleteOnClose) {
m_f1.delete();
if (m_f2 != null) m_f2.delete();
if (m_f3 != null) m_f3.delete();
}
}
/**
* Ensure resources are freed up at garbage collection time.
*/
protected void finalize() {
close();
}
/**
* A simple command-line test of this class. Give it three filenames.
*/
public static void main(String[] args) throws Exception {
if (args.length == 3) {
ResultCombiner c =
new ResultCombiner(new BufferedReader(new InputStreamReader(new FileInputStream(new File(args[0])))),
new BufferedReader(new InputStreamReader(new FileInputStream(new File(args[1])))),
new BufferedReader(new InputStreamReader(new FileInputStream(new File(args[2])))));
String line = c.readLine();
while (line != null) {
System.out.println(line);
line = c.readLine();
}
} else {
System.err
.println("ERROR: Three args expected (csv files to be combined)");
}
}
}