From bb09da956d778fed357d55821a549e9da146b6cb Mon Sep 17 00:00:00 2001
From: Robin Rosenberg <robin.rosenberg@dewire.com>
Date: Mon, 13 Aug 2007 01:57:25 +0200
Subject: [PATCH] Add a revision parser

This one parses expressions like head~1 etc.

Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
---
 .../src/org/spearce/jgit/lib/Repository.java       | 121 +++++++++++++++++++++
 .../org/spearce/jgit/lib/T0008_testparserev.java   |  85 +++++++++++++++
 2 files changed, 206 insertions(+)
 create mode 100644 org.spearce.jgit/tst/org/spearce/jgit/lib/T0008_testparserev.java

diff --git a/org.spearce.jgit/src/org/spearce/jgit/lib/Repository.java b/org.spearce.jgit/src/org/spearce/jgit/lib/Repository.java
index 86b7f8b1..42ebc087 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/lib/Repository.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/lib/Repository.java
@@ -281,7 +281,128 @@ public class Repository {
 		return l.lock() ? l : null;
 	}
 
+	/** Parse a git revision string and return an object id.
+	 *
+	 *  It is not fully implemented, so it only deals with
+	 *  commits and to some extent tags. Reflogs are not
+	 *  supported yet.
+	 *  The plan is to implement it fully.
+	 * @param revstr A git object references expression
+	 * @return an ObjectId
+	 * @throws IOException on serious errors
+	 */
+	public ObjectId parse(String revstr) throws IOException {
+		char[] rev = revstr.toCharArray();
+		ObjectId ret = null;
+		Commit ref = null;
+		for (int i = 0; i < rev.length; ++i) {
+			switch (rev[i]) {
+			case '^':
+				if (ref == null) {
+					String refstr = new String(rev,0,i);
+					ObjectId refId = resolveSimple(refstr);
+					ref = mapCommit(refId);
+				}
+				if (i + 1 < rev.length) {
+					switch (rev[i + 1]) {
+					case '0':
+					case '1':
+					case '2':
+					case '3':
+					case '4':
+					case '5':
+					case '6':
+					case '7':
+					case '8':
+					case '9':
+						int j;
+						for (j=i+1; j<rev.length; ++j) {
+							if (!Character.isDigit(rev[j]))
+								break;
+						}
+						String parentnum = new String(rev, i+1, j-i-1);
+						int pnum = Integer.parseInt(parentnum);
+						if (pnum != 0)
+							ref = mapCommit(ref.getParentIds()[pnum - 1]);
+						i = j - 1;
+						break;
+					case '{':
+						int k;
+						String item = null;
+						for (k=i+2; k<rev.length; ++k) {
+							if (rev[k] == '}') {
+								item = new String(rev, i+2, k-i-2);
+								break;
+							}
+						}
+						i = k;
+						if (item != null)
+							if (item.equals("tree"))
+								ret = ref.getTreeId();
+							else if (item.equals("commit"))
+								; // just reference self
+							else
+								return null; // invalid
+						else
+							return null; // invalid
+						break;
+					default:
+						ref = mapCommit(ref.getParentIds()[0]);
+					}
+				} else {
+					ref = mapCommit(ref.getParentIds()[0]);
+				}
+				break;
+			case '~':
+				if (ref == null) {
+					String refstr = new String(rev,0,i);
+					ObjectId refId = resolveSimple(refstr);
+					ref = mapCommit(refId);
+				}
+				int l;
+				for (l = i + 1; l < rev.length; ++l) {
+					if (!Character.isDigit(rev[l]))
+						break;
+				}
+				String distnum = new String(rev, i+1, l-i-1);
+				int dist = Integer.parseInt(distnum);
+				while (dist >= 0) {
+					ref = mapCommit(ref.getParentIds()[0]);
+					--dist;
+				}
+				i = l - 1;
+				break;
+			case '@':
+				int m;
+				String time = null;
+				for (m=i+2; m<rev.length; ++m) {
+					if (rev[m] == '}') {
+						time = new String(rev, i+2, m-i-2);
+						break;
+					}
+				}
+				if (time != null)
+					throw new IllegalArgumentException("reflogs not yet supprted");
+				i = m - 1;
+				break;
+			default:
+				if (ref != null)
+					return null; // cannot parse, return null
+			}
+		}
+		if (ret == null)
+			if (ref != null)
+				ret = ref.getCommitId();
+			else
+				ret = resolveSimple(revstr);
+		return ret;
+	}
+
 	public ObjectId resolve(final String revstr) throws IOException {
+		return parse(revstr);
+	}
+
+	public ObjectId resolveSimple(final String revstr) throws IOException {
 		ObjectId id = null;
 
 		if (ObjectId.isId(revstr)) {
diff --git a/org.spearce.jgit/tst/org/spearce/jgit/lib/T0008_testparserev.java b/org.spearce.jgit/tst/org/spearce/jgit/lib/T0008_testparserev.java
new file mode 100644
index 00000000..d15ae6f1
--- /dev/null
+++ b/org.spearce.jgit/tst/org/spearce/jgit/lib/T0008_testparserev.java
@@ -0,0 +1,85 @@
+/*
+ *  Copyright (C) 2007  Robin Rosenberg
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public
+ *  License, version 2, as published by the Free Software Foundation.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+ */
+package org.spearce.jgit.lib;
+
+import java.io.IOException;
+
+public class T0008_testparserev extends RepositoryTestCase {
+
+	ObjectId resolve(String in) {
+		try {
+			return db.resolve(in);
+		} catch (IOException e) {
+			throw new Error(e);
+		}
+	}
+
+	public void testObjectId_existing() {
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0").toString());
+	}
+
+	public void testObjectId_nonexisting() {
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c1",resolve("49322bb17d3acc9146f98c97d078513228bbf3c1").toString());
+	}
+
+	public void testObjectId_objectid_implicit_firstparent() {
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^").toString());
+		assertEquals("1203b03dc816ccbb67773f28b3c19318654b0bc8",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^^").toString());
+		assertEquals("bab66b48f836ed950c99134ef666436fb07a09a0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^^^").toString());
+	}
+
+	public void testObjectId_objectid_self() {
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^0").toString());
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^0^0").toString());
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^0^0^0").toString());
+	}
+
+	public void testObjectId_objectid_explicit_firstparent() {
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^1").toString());
+		assertEquals("1203b03dc816ccbb67773f28b3c19318654b0bc8",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^1^1").toString());
+		assertEquals("bab66b48f836ed950c99134ef666436fb07a09a0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^1^1^1").toString());
+	}
+
+	public void testObjectId_objectid_explicit_otherparents() {
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^1").toString());
+		assertEquals("f73b95671f326616d66b2afb3bdfcdbbce110b44",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^2").toString());
+		assertEquals("d0114ab8ac326bab30e3a657a0397578c5a1af88",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^3").toString());
+		assertEquals("d0114ab8ac326bab30e3a657a0397578c5a1af88",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^03").toString());
+	}
+
+	public void testRef_refname() {
+		assertEquals("49322bb17d3acc9146f98c97d078513228bbf3c0",resolve("master^0").toString());
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("master^").toString());
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("refs/heads/master^1").toString());
+	}
+
+	public void testDistance() {
+		assertEquals("6e1475206e57110fcef4b92320436c1e9872a322",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0~0").toString());
+		assertEquals("1203b03dc816ccbb67773f28b3c19318654b0bc8",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0~1").toString());
+		assertEquals("bab66b48f836ed950c99134ef666436fb07a09a0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0~2").toString());
+		assertEquals("bab66b48f836ed950c99134ef666436fb07a09a0",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0~02").toString());
+	}
+
+	public void testTree() {
+		assertEquals("6020a3b8d5d636e549ccbd0c53e2764684bb3125",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^{tree}").toString());
+		assertEquals("02ba32d3649e510002c21651936b7077aa75ffa9",resolve("49322bb17d3acc9146f98c97d078513228bbf3c0^^{tree}").toString());
+	}
+
+	public void testHEAD() {
+		assertEquals("6020a3b8d5d636e549ccbd0c53e2764684bb3125",resolve("HEAD^{tree}").toString());
+	}
+}
-- 
2.11.4.GIT