DirCacheIterator.java

  1. /*
  2.  * Copyright (C) 2008-2009, Google Inc.
  3.  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> and others
  4.  *
  5.  * This program and the accompanying materials are made available under the
  6.  * terms of the Eclipse Distribution License v. 1.0 which is available at
  7.  * https://www.eclipse.org/org/documents/edl-v10.php.
  8.  *
  9.  * SPDX-License-Identifier: BSD-3-Clause
  10.  */

  12. package org.eclipse.jgit.dircache;

  14. import static java.nio.charset.StandardCharsets.UTF_8;

  16. import java.io.IOException;
  17. import java.io.InputStream;
  18. import java.util.Collections;

  20. import org.eclipse.jgit.attributes.AttributesNode;
  21. import org.eclipse.jgit.attributes.AttributesRule;
  22. import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  23. import org.eclipse.jgit.lib.Constants;
  24. import org.eclipse.jgit.lib.FileMode;
  25. import org.eclipse.jgit.lib.ObjectId;
  26. import org.eclipse.jgit.lib.ObjectLoader;
  27. import org.eclipse.jgit.lib.ObjectReader;
  28. import org.eclipse.jgit.treewalk.AbstractTreeIterator;
  29. import org.eclipse.jgit.treewalk.EmptyTreeIterator;
  30. import org.eclipse.jgit.util.RawParseUtils;

  32. /**
  33.  * Iterate a {@link org.eclipse.jgit.dircache.DirCache} as part of a
  34.  * <code>TreeWalk</code>.
  35.  * <p>
  36.  * This is an iterator to adapt a loaded <code>DirCache</code> instance (such as
  37.  * read from an existing <code>.git/index</code> file) to the tree structure
  38.  * used by a <code>TreeWalk</code>, making it possible for applications to walk
  39.  * over any combination of tree objects already in the object database, index
  40.  * files, or working directories.
  41.  *
  42.  * @see org.eclipse.jgit.treewalk.TreeWalk
  43.  */
  44. public class DirCacheIterator extends AbstractTreeIterator {
  45.     /** Byte array holding ".gitattributes" string */
  46.     private static final byte[] DOT_GIT_ATTRIBUTES_BYTES = Constants.DOT_GIT_ATTRIBUTES
  47.             .getBytes(UTF_8);

  49.     /** The cache this iterator was created to walk. */
  50.     protected final DirCache cache;

  52.     /** The tree this iterator is walking. */
  53.     private final DirCacheTree tree;

  55.     /** First position in this tree. */
  56.     private final int treeStart;

  58.     /** Last position in this tree. */
  59.     private final int treeEnd;

  61.     /** Special buffer to hold the ObjectId of {@link #currentSubtree}. */
  62.     private final byte[] subtreeId;

  64.     /** Index of entry within {@link #cache}. */
  65.     protected int ptr;

  67.     /** Next subtree to consider within {@link #tree}. */
  68.     private int nextSubtreePos;

  70.     /** The current file entry from {@link #cache}. */
  71.     protected DirCacheEntry currentEntry;

  73.     /** The subtree containing {@link #currentEntry} if this is first entry. */
  74.     protected DirCacheTree currentSubtree;

  76.     /**
  77.      * Create a new iterator for an already loaded DirCache instance.
  78.      * <p>
  79.      * The iterator implementation may copy part of the cache's data during
  80.      * construction, so the cache must be read in prior to creating the
  81.      * iterator.
  82.      *
  83.      * @param dc
  84.      *            the cache to walk. It must be already loaded into memory.
  85.      */
  86.     public DirCacheIterator(DirCache dc) {
  87.         cache = dc;
  88.         tree = dc.getCacheTree(true);
  89.         treeStart = 0;
  90.         treeEnd = tree.getEntrySpan();
  91.         subtreeId = new byte[Constants.OBJECT_ID_LENGTH];
  92.         if (!eof())
  93.             parseEntry();
  94.     }

  96.     DirCacheIterator(DirCacheIterator p, DirCacheTree dct) {
  97.         super(p, p.path, p.pathLen + 1);
  98.         cache = p.cache;
  99.         tree = dct;
  100.         treeStart = p.ptr;
  101.         treeEnd = treeStart + tree.getEntrySpan();
  102.         subtreeId = p.subtreeId;
  103.         ptr = p.ptr;
  104.         parseEntry();
  105.     }

  107.     /** {@inheritDoc} */
  108.     @Override
  109.     public AbstractTreeIterator createSubtreeIterator(ObjectReader reader)
  110.             throws IncorrectObjectTypeException, IOException {
  111.         if (currentSubtree == null)
  112.             throw new IncorrectObjectTypeException(getEntryObjectId(),
  113.                     Constants.TYPE_TREE);
  114.         return new DirCacheIterator(this, currentSubtree);
  115.     }

  117.     /** {@inheritDoc} */
  118.     @Override
  119.     public EmptyTreeIterator createEmptyTreeIterator() {
  120.         final byte[] n = new byte[Math.max(pathLen + 1, DEFAULT_PATH_SIZE)];
  121.         System.arraycopy(path, 0, n, 0, pathLen);
  122.         n[pathLen] = '/';
  123.         return new EmptyTreeIterator(this, n, pathLen + 1);
  124.     }

  126.     /** {@inheritDoc} */
  127.     @Override
  128.     public boolean hasId() {
  129.         if (currentSubtree != null)
  130.             return currentSubtree.isValid();
  131.         return currentEntry != null;
  132.     }

  134.     /** {@inheritDoc} */
  135.     @Override
  136.     public byte[] idBuffer() {
  137.         if (currentSubtree != null)
  138.             return currentSubtree.isValid() ? subtreeId : zeroid;
  139.         if (currentEntry != null)
  140.             return currentEntry.idBuffer();
  141.         return zeroid;
  142.     }

  144.     /** {@inheritDoc} */
  145.     @Override
  146.     public int idOffset() {
  147.         if (currentSubtree != null)
  148.             return 0;
  149.         if (currentEntry != null)
  150.             return currentEntry.idOffset();
  151.         return 0;
  152.     }

  154.     /** {@inheritDoc} */
  155.     @Override
  156.     public void reset() {
  157.         if (!first()) {
  158.             ptr = treeStart;
  159.             nextSubtreePos = 0;
  160.             currentEntry = null;
  161.             currentSubtree = null;
  162.             if (!eof())
  163.                 parseEntry();
  164.         }
  165.     }

  167.     /** {@inheritDoc} */
  168.     @Override
  169.     public boolean first() {
  170.         return ptr == treeStart;
  171.     }

  173.     /** {@inheritDoc} */
  174.     @Override
  175.     public boolean eof() {
  176.         return ptr == treeEnd;
  177.     }

  179.     /** {@inheritDoc} */
  180.     @Override
  181.     public void next(int delta) {
  182.         while (--delta >= 0) {
  183.             if (currentSubtree != null)
  184.                 ptr += currentSubtree.getEntrySpan();
  185.             else
  186.                 ptr++;
  187.             if (eof())
  188.                 break;
  189.             parseEntry();
  190.         }
  191.     }

  193.     /** {@inheritDoc} */
  194.     @Override
  195.     public void back(int delta) {
  196.         while (--delta >= 0) {
  197.             if (currentSubtree != null)
  198.                 nextSubtreePos--;
  199.             ptr--;
  200.             parseEntry(false);
  201.             if (currentSubtree != null)
  202.                 ptr -= currentSubtree.getEntrySpan() - 1;
  203.         }
  204.     }

  206.     private void parseEntry() {
  207.         parseEntry(true);
  208.     }

  210.     private void parseEntry(boolean forward) {
  211.         currentEntry = cache.getEntry(ptr);
  212.         final byte[] cep = currentEntry.path;

  214.         if (!forward) {
  215.             if (nextSubtreePos > 0) {
  216.                 final DirCacheTree p = tree.getChild(nextSubtreePos - 1);
  217.                 if (p.contains(cep, pathOffset, cep.length)) {
  218.                     nextSubtreePos--;
  219.                     currentSubtree = p;
  220.                 }
  221.             }
  222.         }
  223.         if (nextSubtreePos != tree.getChildCount()) {
  224.             final DirCacheTree s = tree.getChild(nextSubtreePos);
  225.             if (s.contains(cep, pathOffset, cep.length)) {
  226.                 // The current position is the first file of this subtree.
  227.                 // Use the subtree instead as the current position.
  228.                 //
  229.                 currentSubtree = s;
  230.                 nextSubtreePos++;

  232.                 if (s.isValid())
  233.                     s.getObjectId().copyRawTo(subtreeId, 0);
  234.                 mode = FileMode.TREE.getBits();
  235.                 path = cep;
  236.                 pathLen = pathOffset + s.nameLength();
  237.                 return;
  238.             }
  239.         }

  241.         // The current position is a file/symlink/gitlink so we
  242.         // do not have a subtree located here.
  243.         //
  244.         mode = currentEntry.getRawMode();
  245.         path = cep;
  246.         pathLen = cep.length;
  247.         currentSubtree = null;
  248.         // Checks if this entry is a .gitattributes file
  249.         if (RawParseUtils.match(path, pathOffset, DOT_GIT_ATTRIBUTES_BYTES) == path.length)
  250.             attributesNode = new LazyLoadingAttributesNode(
  251.                     currentEntry.getObjectId());
  252.     }

  254.     /**
  255.      * Get the DirCacheEntry for the current file.
  256.      *
  257.      * @return the current cache entry, if this iterator is positioned on a
  258.      *         non-tree.
  259.      */
  260.     public DirCacheEntry getDirCacheEntry() {
  261.         return currentSubtree == null ? currentEntry : null;
  262.     }

  264.     /**
  265.      * Retrieves the {@link org.eclipse.jgit.attributes.AttributesNode} for the
  266.      * current entry.
  267.      *
  268.      * @param reader
  269.      *            {@link org.eclipse.jgit.lib.ObjectReader} used to parse the
  270.      *            .gitattributes entry.
  271.      * @return {@link org.eclipse.jgit.attributes.AttributesNode} for the
  272.      *         current entry.
  273.      * @throws java.io.IOException
  274.      * @since 3.7
  275.      */
  276.     public AttributesNode getEntryAttributesNode(ObjectReader reader)
  277.             throws IOException {
  278.         if (attributesNode instanceof LazyLoadingAttributesNode)
  279.             attributesNode = ((LazyLoadingAttributesNode) attributesNode)
  280.                     .load(reader);
  281.         return attributesNode;
  282.     }

  284.     /**
  285.      * {@link AttributesNode} implementation that provides lazy loading
  286.      * facilities.
  287.      */
  288.     private static class LazyLoadingAttributesNode extends AttributesNode {
  289.         final ObjectId objectId;

  291.         LazyLoadingAttributesNode(ObjectId objectId) {
  292.             super(Collections.<AttributesRule> emptyList());
  293.             this.objectId = objectId;

  295.         }

  297.         AttributesNode load(ObjectReader reader) throws IOException {
  298.             AttributesNode r = new AttributesNode();
  299.             ObjectLoader loader = reader.open(objectId);
  300.             if (loader != null) {
  301.                 try (InputStream in = loader.openStream()) {
  302.                     r.parse(in);
  303.                 }
  304.             }
  305.             return r.getRules().isEmpty() ? null : r;
  306.         }
  307.     }

  309. }
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