Merge branch 'develop' into releases/Release_2_11_Branch

[jalview.git] / src / jalview / ext / htsjdk / VCFReader.java

diff --git a/src/jalview/ext/htsjdk/VCFReader.java b/src/jalview/ext/htsjdk/VCFReader.java
new file mode 100644 (file)
index 0000000..14c057f
--- /dev/null
+++ b/src/jalview/ext/htsjdk/VCFReader.java
@@ -0,0 +1,214 @@
+package jalview.ext.htsjdk;
+
+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
+ */
+public class VCFReader implements Closeable, Iterable<VariantContext>
+{
+  private static final String GZ = "gz";
+
+  private static final String TBI_EXTENSION = ".tbi";
+
+  private boolean indexed;
+
+  private VCFFileReader reader;
+
+  /**
+   * Constructor given a raw or compressed VCF file or a (tabix) index file
+   * <p>
+   * For now, file type is inferred from its suffix: .gz or .bgz for compressed
+   * data, .tbi for an index file, anything else is assumed to be plain text
+   * VCF.
+   * 
+   * @param f
+   * @throws IOException
+   */
+  public VCFReader(String filePath) throws IOException
+  {
+    if (filePath.endsWith(GZ))
+    {
+      if (new File(filePath + TBI_EXTENSION).exists())
+      {
+        indexed = true;
+      }
+    }
+    else if (filePath.endsWith(TBI_EXTENSION))
+    {
+      indexed = true;
+      filePath = filePath.substring(0, filePath.length() - 4);
+    }
+
+    reader = new VCFFileReader(new File(filePath), indexed);
+  }
+
+  @Override
+  public void close() throws IOException
+  {
+    if (reader != null)
+    {
+      reader.close();
+    }
+  }
+
+  /**
+   * Returns an iterator over VCF variants in the file. The client should call
+   * close() on the iterator when finished with it.
+   */
+  @Override
+  public CloseableIterator<VariantContext> iterator()
+  {
+    return reader == null ? null : reader.iterator();
+  }
+
+  /**
+   * Queries for records overlapping the region specified. Note that this method
+   * 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
+   * @param start
+   *          query interval start
+   * @param end
+   *          query interval end
+   * @return
+   */
+  public CloseableIterator<VariantContext> query(final String chrom,
+          final int start, final int 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<VariantContext>()
+    {
+      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.getChr()) && (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();
+      }
+    };
+  }
+
+  /**
+   * Returns an object that models the VCF file headers
+   * 
+   * @return
+   */
+  public VCFHeader getFileHeader()
+  {
+    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;
+  }
+}