/*
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Git Development Community nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.spearce.jgit.treewalk;
import java.io.IOException;
import java.util.Arrays;
import org.spearce.jgit.errors.IncorrectObjectTypeException;
import org.spearce.jgit.errors.MissingObjectException;
import org.spearce.jgit.lib.AnyObjectId;
import org.spearce.jgit.lib.Constants;
import org.spearce.jgit.lib.FileMode;
import org.spearce.jgit.lib.MutableObjectId;
import org.spearce.jgit.lib.ObjectId;
import org.spearce.jgit.lib.ObjectLoader;
import org.spearce.jgit.lib.Repository;
import org.spearce.jgit.lib.WindowCursor;
/** Parses raw Git trees from the canonical semi-text/semi-binary format. */
public class CanonicalTreeParser extends AbstractTreeIterator {
private static final byte[] EMPTY = {};
private byte[] raw;
/** First offset within {@link #raw} of the prior entry. */
private int prevPtr;
/** First offset within {@link #raw} of the current entry's data. */
private int currPtr;
/** Offset one past the current entry (first byte of next entry). */
private int nextPtr;
/** Create a new parser. */
public CanonicalTreeParser() {
reset(EMPTY);
}
/**
* Create a new parser for a tree appearing in a subset of a repository.
*
* @param prefix
* position of this iterator in the repository tree. The value
* may be null or the empty array to indicate the prefix is the
* root of the repository. A trailing slash ('/') is
* automatically appended if the prefix does not end in '/'.
* @param repo
* repository to load the tree data from.
* @param treeId
* identity of the tree being parsed; used only in exception
* messages if data corruption is found.
* @param curs
* a window cursor to use during data access from the repository.
* @throws MissingObjectException
* the object supplied is not available from the repository.
* @throws IncorrectObjectTypeException
* the object supplied as an argument is not actually a tree and
* cannot be parsed as though it were a tree.
* @throws IOException
* a loose object or pack file could not be read.
*/
public CanonicalTreeParser(final byte[] prefix, final Repository repo,
final AnyObjectId treeId, final WindowCursor curs)
throws IncorrectObjectTypeException, IOException {
super(prefix);
reset(repo, treeId, curs);
}
private CanonicalTreeParser(final CanonicalTreeParser p) {
super(p);
}
/**
* Reset this parser to walk through the given tree data.
*
* @param treeData
* the raw tree content.
*/
public void reset(final byte[] treeData) {
raw = treeData;
prevPtr = -1;
currPtr = 0;
if (!eof())
parseEntry();
}
/**
* Reset this parser to walk through the given tree.
*
* @param repo
* repository to load the tree data from.
* @param id
* identity of the tree being parsed; used only in exception
* messages if data corruption is found.
* @param curs
* window cursor to use during repository access.
* @return the root level parser.
* @throws MissingObjectException
* the object supplied is not available from the repository.
* @throws IncorrectObjectTypeException
* the object supplied as an argument is not actually a tree and
* cannot be parsed as though it were a tree.
* @throws IOException
* a loose object or pack file could not be read.
*/
public CanonicalTreeParser resetRoot(final Repository repo,
final AnyObjectId id, final WindowCursor curs)
throws IncorrectObjectTypeException, IOException {
CanonicalTreeParser p = this;
while (p.parent != null)
p = (CanonicalTreeParser) p.parent;
p.reset(repo, id, curs);
return p;
}
/** @return this iterator, or its parent, if the tree is at eof. */
public CanonicalTreeParser next() {
CanonicalTreeParser p = this;
for (;;) {
p.next(1);
if (p.eof() && p.parent != null) {
// Parent was left pointing at the entry for us; advance
// the parent to the next entry, possibly unwinding many
// levels up the tree.
//
p = (CanonicalTreeParser) p.parent;
continue;
}
return p;
}
}
/**
* Reset this parser to walk through the given tree.
*
* @param repo
* repository to load the tree data from.
* @param id
* identity of the tree being parsed; used only in exception
* messages if data corruption is found.
* @param curs
* window cursor to use during repository access.
* @throws MissingObjectException
* the object supplied is not available from the repository.
* @throws IncorrectObjectTypeException
* the object supplied as an argument is not actually a tree and
* cannot be parsed as though it were a tree.
* @throws IOException
* a loose object or pack file could not be read.
*/
public void reset(final Repository repo, final AnyObjectId id,
final WindowCursor curs)
throws IncorrectObjectTypeException, IOException {
final ObjectLoader ldr = repo.openObject(curs, id);
if (ldr == null) {
final ObjectId me = id.toObjectId();
throw new MissingObjectException(me, Constants.TYPE_TREE);
}
final byte[] subtreeData = ldr.getCachedBytes();
if (ldr.getType() != Constants.OBJ_TREE) {
final ObjectId me = id.toObjectId();
throw new IncorrectObjectTypeException(me, Constants.TYPE_TREE);
}
reset(subtreeData);
}
@Override
public CanonicalTreeParser createSubtreeIterator(final Repository repo,
final MutableObjectId idBuffer, final WindowCursor curs)
throws IncorrectObjectTypeException, IOException {
idBuffer.fromRaw(idBuffer(), idOffset());
if (!FileMode.TREE.equals(mode)) {
final ObjectId me = idBuffer.toObjectId();
throw new IncorrectObjectTypeException(me, Constants.TYPE_TREE);
}
return createSubtreeIterator0(repo, idBuffer, curs);
}
/**
* Back door to quickly create a subtree iterator for any subtree.
* <p>
* Don't use this unless you are ObjectWalk. The method is meant to be
* called only once the current entry has been identified as a tree and its
* identity has been converted into an ObjectId.
*
* @param repo
* repository to load the tree data from.
* @param id
* ObjectId of the tree to open.
* @param curs
* window cursor to use during repository access.
* @return a new parser that walks over the current subtree.
* @throws IOException
* a loose object or pack file could not be read.
*/
public final CanonicalTreeParser createSubtreeIterator0(
final Repository repo, final AnyObjectId id, final WindowCursor curs)
throws IOException {
final CanonicalTreeParser p = new CanonicalTreeParser(this);
p.reset(repo, id, curs);
return p;
}
public CanonicalTreeParser createSubtreeIterator(final Repository repo)
throws IncorrectObjectTypeException, IOException {
final WindowCursor curs = new WindowCursor();
try {
return createSubtreeIterator(repo, new MutableObjectId(), curs);
} finally {
curs.release();
}
}
@Override
public byte[] idBuffer() {
return raw;
}
@Override
public int idOffset() {
return nextPtr - Constants.OBJECT_ID_LENGTH;
}
@Override
public boolean first() {
return currPtr == 0;
}
public boolean eof() {
return currPtr == raw.length;
}
@Override
public void next(int delta) {
if (delta == 1) {
// Moving forward one is the most common case.
//
prevPtr = currPtr;
currPtr = nextPtr;
if (!eof())
parseEntry();
return;
}
// Fast skip over records, then parse the last one.
//
final int end = raw.length;
int ptr = nextPtr;
while (--delta > 0 && ptr != end) {
prevPtr = ptr;
while (raw[ptr] != 0)
ptr++;
ptr += Constants.OBJECT_ID_LENGTH + 1;
}
if (delta != 0)
throw new ArrayIndexOutOfBoundsException(delta);
currPtr = ptr;
if (!eof())
parseEntry();
}
@Override
public void back(int delta) {
if (delta == 1 && 0 <= prevPtr) {
// Moving back one is common in NameTreeWalk, as the average tree
// won't have D/F type conflicts to study.
//
currPtr = prevPtr;
prevPtr = -1;
if (!eof())
parseEntry();
return;
} else if (delta <= 0)
throw new ArrayIndexOutOfBoundsException(delta);
// Fast skip through the records, from the beginning of the tree.
// There is no reliable way to read the tree backwards, so we must
// parse all over again from the beginning. We hold the last "delta"
// positions in a buffer, so we can find the correct position later.
//
final int[] trace = new int[delta + 1];
Arrays.fill(trace, -1);
int ptr = 0;
while (ptr != currPtr) {
System.arraycopy(trace, 1, trace, 0, delta);
trace[delta] = ptr;
while (raw[ptr] != 0)
ptr++;
ptr += Constants.OBJECT_ID_LENGTH + 1;
}
if (trace[1] == -1)
throw new ArrayIndexOutOfBoundsException(delta);
prevPtr = trace[0];
currPtr = trace[1];
parseEntry();
}
private void parseEntry() {
int ptr = currPtr;
byte c = raw[ptr++];
int tmp = c - '0';
for (;;) {
c = raw[ptr++];
if (' ' == c)
break;
tmp <<= 3;
tmp += c - '0';
}
mode = tmp;
tmp = pathOffset;
for (;; tmp++) {
c = raw[ptr++];
if (c == 0)
break;
try {
path[tmp] = c;
} catch (ArrayIndexOutOfBoundsException e) {
growPath(tmp);
path[tmp] = c;
}
}
pathLen = tmp;
nextPtr = ptr + Constants.OBJECT_ID_LENGTH;
}
}