package org.apache.lucene.index;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.InputStream;
import java.io.IOException;
/** TODO: relax synchro!
*/
class TermVectorsReader {
private FieldInfos fieldInfos;
private InputStream tvx;
private InputStream tvd;
private InputStream tvf;
private int size;
TermVectorsReader(Directory d, String segment, FieldInfos fieldInfos)
throws IOException {
if (d.fileExists(segment + TermVectorsWriter.TVX_EXTENSION)) {
tvx = d.openFile(segment + TermVectorsWriter.TVX_EXTENSION);
checkValidFormat(tvx);
tvd = d.openFile(segment + TermVectorsWriter.TVD_EXTENSION);
checkValidFormat(tvd);
tvf = d.openFile(segment + TermVectorsWriter.TVF_EXTENSION);
checkValidFormat(tvf);
size = (int) tvx.length() / 8;
}
this.fieldInfos = fieldInfos;
}
private void checkValidFormat(InputStream in) throws IOException
{
int format = in.readInt();
if (format > TermVectorsWriter.FORMAT_VERSION)
{
throw new IOException("Incompatible format version: " + format + " expected "
+ TermVectorsWriter.FORMAT_VERSION + " or less");
}
}
synchronized void close() throws IOException {
// why don't we trap the exception and at least make sure that
// all streams that we can close are closed?
if (tvx != null) tvx.close();
if (tvd != null) tvd.close();
if (tvf != null) tvf.close();
}
/**
*
* @return The number of documents in the reader
*/
int size() {
return size;
}
/**
* Retrieve the term vector for the given document and field
* @param docNum The document number to retrieve the vector for
* @param field The field within the document to retrieve
* @return The TermFreqVector for the document and field or null
*/
synchronized TermFreqVector get(int docNum, String field) {
// Check if no term vectors are available for this segment at all
int fieldNumber = fieldInfos.fieldNumber(field);
TermFreqVector result = null;
if (tvx != null) {
try {
//We need to account for the FORMAT_SIZE at when seeking in the tvx
//We don't need to do this in other seeks because we already have the file pointer
//that was written in another file
tvx.seek((docNum * 8L) + TermVectorsWriter.FORMAT_SIZE);
//System.out.println("TVX Pointer: " + tvx.getFilePointer());
long position = tvx.readLong();
tvd.seek(position);
int fieldCount = tvd.readVInt();
//System.out.println("Num Fields: " + fieldCount);
// There are only a few fields per document. We opt for a full scan
// rather then requiring that they be ordered. We need to read through
// all of the fields anyway to get to the tvf pointers.
int number = 0;
int found = -1;
for (int i = 0; i < fieldCount; i++) {
number += tvd.readVInt();
if (number == fieldNumber) found = i;
}
// This field, although valid in the segment, was not found in this document
if (found != -1) {
// Compute position in the tvf file
position = 0;
for (int i = 0; i <= found; i++)
{
position += tvd.readVLong();
}
result = readTermVector(field, position);
}
else {
//System.out.println("Field not found");
}
} catch (Exception e) {
//e.printStackTrace();
}
}
else
{
System.out.println("No tvx file");
}
return result;
}
/** Return all term vectors stored for this document or null if the could not be read in. */
synchronized TermFreqVector[] get(int docNum) {
TermFreqVector[] result = null;
// Check if no term vectors are available for this segment at all
if (tvx != null) {
try {
//We need to offset by
tvx.seek((docNum * 8L) + TermVectorsWriter.FORMAT_SIZE);
long position = tvx.readLong();
tvd.seek(position);
int fieldCount = tvd.readVInt();
// No fields are vectorized for this document
if (fieldCount != 0) {
int number = 0;
String[] fields = new String[fieldCount];
for (int i = 0; i < fieldCount; i++) {
number += tvd.readVInt();
fields[i] = fieldInfos.fieldName(number);
}
// Compute position in the tvf file
position = 0;
long[] tvfPointers = new long[fieldCount];
for (int i = 0; i < fieldCount; i++) {
position += tvd.readVLong();
tvfPointers[i] = position;
}
result = readTermVectors(fields, tvfPointers);
}
} catch (IOException e) {
e.printStackTrace();
}
}
else
{
System.out.println("No tvx file");
}
return result;
}
private SegmentTermVector[] readTermVectors(String fields[], long tvfPointers[])
throws IOException {
SegmentTermVector res[] = new SegmentTermVector[fields.length];
for (int i = 0; i < fields.length; i++) {
res[i] = readTermVector(fields[i], tvfPointers[i]);
}
return res;
}
/**
*
* @param fieldNum The field to read in
* @param tvfPointer The pointer within the tvf file where we should start reading
* @return The TermVector located at that position
* @throws IOException
*/
private SegmentTermVector readTermVector(String field, long tvfPointer)
throws IOException {
// Now read the data from specified position
//We don't need to offset by the FORMAT here since the pointer already includes the offset
tvf.seek(tvfPointer);
int numTerms = tvf.readVInt();
//System.out.println("Num Terms: " + numTerms);
// If no terms - return a constant empty termvector
if (numTerms == 0) return new SegmentTermVector(field, null, null);
int length = numTerms + tvf.readVInt();
String terms[] = new String[numTerms];
int termFreqs[] = new int[numTerms];
int start = 0;
int deltaLength = 0;
int totalLength = 0;
char [] buffer = {};
String previousString = "";
for (int i = 0; i < numTerms; i++) {
start = tvf.readVInt();
deltaLength = tvf.readVInt();
totalLength = start + deltaLength;
if (buffer.length < totalLength)
{
buffer = new char[totalLength];
for (int j = 0; j < previousString.length(); j++) // copy contents
buffer[j] = previousString.charAt(j);
}
tvf.readChars(buffer, start, deltaLength);
terms[i] = new String(buffer, 0, totalLength);
previousString = terms[i];
termFreqs[i] = tvf.readVInt();
}
SegmentTermVector tv = new SegmentTermVector(field, terms, termFreqs);
return tv;
}
}
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