Move first line parsing for v0 push out of BaseReceivePack

This simplifies the BaseReceivePack class and decreases its API
surface, which should make merging with ReceivePack easier.

Inspired by 6aca8899a5c02b3f6be7b9196cf5e935914476f0 (Move first line
parsing for v0/v1 pack negotiation out of UploadPack, 2018-09-17).

Change-Id: I1fc175d15aa7cb5968c26fc83a95480403af617c

3 files changed, 121 insertions, 15 deletions

diff --git a/org.eclipse.jgit/META-INF/MANIFEST.MF b/org.eclipse.jgit/META-INF/MANIFEST.MF
index ad2a9d381c..7d09fd6385 100644
--- a/org.eclipse.jgit/META-INF/MANIFEST.MF
+++ b/org.eclipse.jgit/META-INF/MANIFEST.MF
@@ -132,6 +132,7 @@ Export-Package: org.eclipse.jgit.annotations;version="5.3.0",
    org.eclipse.jgit.util,
    org.eclipse.jgit.util.io,
    org.eclipse.jgit.internal.storage.file,
+   org.eclipse.jgit.internal.transport.parser,
    org.eclipse.jgit.lib,
    org.eclipse.jgit.transport.http,
    org.eclipse.jgit.errors,
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/parser/FirstCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/parser/FirstCommand.java
new file mode 100644
index 0000000000..0426b17f04
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/transport/parser/FirstCommand.java
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2018, Google LLC.
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * 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 Eclipse Foundation, Inc. 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.eclipse.jgit.internal.transport.parser;
+
+import static java.util.Arrays.asList;
+import static java.util.Collections.emptySet;
+import static java.util.Collections.unmodifiableSet;
+import static java.util.stream.Collectors.toSet;
+
+import java.util.Set;
+
+import org.eclipse.jgit.annotations.NonNull;
+
+/**
+ * In a push, the client sends a list of commands. The first command
+ * is special, as it can include a list of capabilities at its end.
+ * <p>
+ * For example:
+ * "oid oid name\0cap1 cap cap3"
+ * <p>
+ * Not to be confused with {@link FirstWant}, nor with the first line
+ * of the reference advertisement parsed by
+ * {@code BasePackConnection.readAdvertisedRefs}.
+ * <p>
+ * This class parses the inputted command line and holds the results:
+ * the actual command line and the capabilities.
+ */
+public final class FirstCommand {
+	private final String line;
+	private final Set<String> capabilities;
+
+	/**
+	 * Parse the first line of a receive-pack request.
+	 *
+	 * @param line
+	 *            line from the client.
+	 * @return an instance of FirstCommand with capabilities parsed out
+	 */
+	@NonNull
+	public static FirstCommand fromLine(String line) {
+		int nul = line.indexOf('\0');
+		if (nul < 0) {
+			return new FirstCommand(line, emptySet());
+		}
+		Set<String> opts =
+				asList(line.substring(nul + 1).split(" ")) //$NON-NLS-1$
+					.stream()
+					.collect(toSet());
+		return new FirstCommand(line.substring(0, nul), unmodifiableSet(opts));
+	}
+
+	private FirstCommand(String line, Set<String> capabilities) {
+		this.line = line;
+		this.capabilities = capabilities;
+	}
+
+	/** @return non-capabilities part of the line. */
+	@NonNull
+	public String getLine() {
+		return line;
+	}
+
+	/** @return capabilities parsed from the line, as an immutable set. */
+	@NonNull
+	public Set<String> getCapabilities() {
+		return capabilities;
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BaseReceivePack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BaseReceivePack.java
index 03763368a8..2439d4fab9 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BaseReceivePack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BaseReceivePack.java
@@ -80,6 +80,7 @@ import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.file.PackLock;
 import org.eclipse.jgit.internal.submodule.SubmoduleValidator;
 import org.eclipse.jgit.internal.submodule.SubmoduleValidator.SubmoduleValidationException;
+import org.eclipse.jgit.internal.transport.parser.FirstCommand;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.BatchRefUpdate;
 import org.eclipse.jgit.lib.Config;
@@ -119,10 +120,14 @@ import org.eclipse.jgit.util.io.TimeoutOutputStream;
  * Subclasses compose these operations into full service implementations.
  */
 public abstract class BaseReceivePack {
-	/** Data in the first line of a request, the line itself plus capabilities. */
+	/**
+	 * Data in the first line of a request, the line itself plus capabilities.
+	 *
+	 * @deprecated Use {@link FirstCommand} instead.
+	 */
+	@Deprecated
 	public static class FirstLine {
-		private final String line;
-		private final Set<String> capabilities;
+		private final FirstCommand command;
 
 		/**
 		 * Parse the first line of a receive-pack request.
@@ -131,25 +136,17 @@ public abstract class BaseReceivePack {
 		 *            line from the client.
 		 */
 		public FirstLine(String line) {
-			final HashSet<String> caps = new HashSet<>();
-			final int nul = line.indexOf('\0');
-			if (nul >= 0) {
-				for (String c : line.substring(nul + 1).split(" ")) //$NON-NLS-1$
-					caps.add(c);
-				this.line = line.substring(0, nul);
-			} else
-				this.line = line;
-			this.capabilities = Collections.unmodifiableSet(caps);
+			command = FirstCommand.fromLine(line);
 		}
 
 		/** @return non-capabilities part of the line. */
 		public String getLine() {
-			return line;
+			return command.getLine();
 		}
 
 		/** @return capabilities parsed from the line. */
 		public Set<String> getCapabilities() {
-			return capabilities;
+			return command.getCapabilities();
 		}
 	}
 
@@ -1310,7 +1307,7 @@ public abstract class BaseReceivePack {
 
 				if (firstPkt) {
 					firstPkt = false;
-					FirstLine firstLine = new FirstLine(line);
+					FirstCommand firstLine = FirstCommand.fromLine(line);
 					enabledCapabilities = firstLine.getCapabilities();
 					line = firstLine.getLine();
 					enableCapabilities();