/** Performs tokenization and saves the results to the <code>context</code>. */
public void tokenize(PreprocessingContext context) {
// Documents to tokenize
final List<Document> documents = context.documents;
// Fields to tokenize
final String[] fieldNames = documentFields.toArray(new String[documentFields.size()]);
if (fieldNames.length > 8) {
throw new ProcessingException("Maximum number of tokenized fields is 8.");
}
// Prepare arrays
images = Lists.newArrayList();
tokenTypes = new ShortArrayList();
documentIndices = new IntArrayList();
fieldIndices = new ByteArrayList();
final Iterator<Document> docIterator = documents.iterator();
int documentIndex = 0;
final ITokenizer ts = context.language.getTokenizer();
final MutableCharArray wrapper = new MutableCharArray(CharArrayUtils.EMPTY_ARRAY);
while (docIterator.hasNext()) {
final Document doc = docIterator.next();
boolean hadTokens = false;
for (int i = 0; i < fieldNames.length; i++) {
final byte fieldIndex = (byte) i;
final String fieldName = fieldNames[i];
final String fieldValue = doc.getField(fieldName);
if (!StringUtils.isEmpty(fieldValue)) {
try {
short tokenType;
ts.reset(new StringReader(fieldValue));
if ((tokenType = ts.nextToken()) != ITokenizer.TT_EOF) {
if (hadTokens) addFieldSeparator(documentIndex);
do {
ts.setTermBuffer(wrapper);
add(documentIndex, fieldIndex, context.intern(wrapper), tokenType);
} while ((tokenType = ts.nextToken()) != ITokenizer.TT_EOF);
hadTokens = true;
}
} catch (IOException e) {
// Not possible (StringReader above)?
throw ExceptionUtils.wrapAsRuntimeException(e);
}
}
}
if (docIterator.hasNext()) {
addDocumentSeparator();
}
documentIndex++;
}
addTerminator();
// Save results in the PreprocessingContext
context.allTokens.documentIndex = documentIndices.toArray();
context.allTokens.fieldIndex = fieldIndices.toArray();
context.allTokens.image = images.toArray(new char[images.size()][]);
context.allTokens.type = tokenTypes.toArray();
context.allFields.name = fieldNames;
// Clean up
images = null;
fieldIndices = null;
tokenTypes = null;
documentIndices = null;
}
/** Adds custom token code to the sequence. May be used to add separator constants. */
void add(int documentIndex, byte fieldIndex, char[] image, short tokenTypeCode) {
documentIndices.add(documentIndex);
fieldIndices.add(fieldIndex);
images.add(image);
tokenTypes.add(tokenTypeCode);
}