package jalview.ext.htsjdk;
+import java.io.Closeable;
+import java.io.File;
+import java.io.IOException;
+
import htsjdk.samtools.util.CloseableIterator;
import htsjdk.variant.variantcontext.VariantContext;
import htsjdk.variant.vcf.VCFFileReader;
import htsjdk.variant.vcf.VCFHeader;
-import java.io.Closeable;
-import java.io.File;
-import java.io.IOException;
-
/**
* A thin wrapper for htsjdk classes to read either plain, or compressed, or
* compressed and indexed VCF files
/**
* Queries for records overlapping the region specified. Note that this method
- * requires a VCF file with an associated index. If no index exists a
- * TribbleException will be thrown. Client code should call close() on the
- * iterator when finished with it.
+ * is performant if the VCF file is indexed, and may be very slow if it is
+ * not.
+ * <p>
+ * Client code should call close() on the iterator when finished with it.
*
* @param chrom
* the chromosome to query
public CloseableIterator<VariantContext> query(final String chrom,
final int start, final int end)
{
- return reader == null ? null : reader.query(chrom, start, end);
+ if (reader == null) {
+ return null;
+ }
+ if (indexed)
+ {
+ return reader.query(chrom, start, end);
+ }
+ else
+ {
+ return queryUnindexed(chrom, start, end);
+ }
+ }
+
+ /**
+ * Returns an iterator over variant records read from a flat file which
+ * overlap the specified chromosomal positions. Call close() on the iterator
+ * when finished with it!
+ *
+ * @param chrom
+ * @param start
+ * @param end
+ * @return
+ */
+ protected CloseableIterator<VariantContext> queryUnindexed(
+ final String chrom, final int start, final int end)
+ {
+ final CloseableIterator<VariantContext> it = reader.iterator();
+
+ return new CloseableIterator()
+ {
+ boolean atEnd = false;
+
+ // prime look-ahead buffer with next matching record
+ private VariantContext next = findNext();
+
+ private VariantContext findNext()
+ {
+ if (atEnd)
+ {
+ return null;
+ }
+ VariantContext variant = null;
+ while (it.hasNext())
+ {
+ variant = it.next();
+ int vstart = variant.getStart();
+
+ if (vstart > end)
+ {
+ atEnd = true;
+ close();
+ return null;
+ }
+
+ int vend = variant.getEnd();
+ // todo what is the undeprecated way to get
+ // the chromosome for the variant?
+ if (chrom.equals(variant.getContig()) && (vstart <= end)
+ && (vend >= start))
+ {
+ return variant;
+ }
+ }
+ return null;
+ }
+
+ @Override
+ public boolean hasNext()
+ {
+ boolean hasNext = !atEnd && (next != null);
+ if (!hasNext)
+ {
+ close();
+ }
+ return hasNext;
+ }
+
+ @Override
+ public VariantContext next()
+ {
+ /*
+ * return the next match, and then re-prime
+ * it with the following one (if any)
+ */
+ VariantContext temp = next;
+ next = findNext();
+ return temp;
+ }
+
+ @Override
+ public void remove()
+ {
+ // not implemented
+ }
+
+ @Override
+ public void close()
+ {
+ it.close();
+ }
+ };
}
/**
{
return reader == null ? null : reader.getFileHeader();
}
+
+ /**
+ * Answers true if we are processing a tab-indexed VCF file, false if it is a
+ * plain text (uncompressed) file.
+ *
+ * @return
+ */
+ public boolean isIndex()
+ {
+ return indexed;
+ }
}