Support built-in diff drivers for hunk header function names

The regexes defined for each built-in driver will be used to determine
the function name for a hunk header. Each driver can specify a list of
regexes to negate and match. They can also define pattern compilation
flags if needed. These drivers only apply to text files with unified
patch type.

Following built-in drivers have been added:
- cpp
- dts
- java
- python
- rust

Support for more languages can be added as needed to match the cgit
implementation.

Change-Id: Ice5430bfed7e4aaf9f00e52e44402479984953c5

1 files changed, 173 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/DiffFormatterBuiltInDriverTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/DiffFormatterBuiltInDriverTest.java
new file mode 100644
index 0000000000..1352871983
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/diff/DiffFormatterBuiltInDriverTest.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc.
+ * 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 v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.diff;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.junit.JGitTestUtil;
+import org.eclipse.jgit.junit.RepositoryTestCase;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.treewalk.CanonicalTreeParser;
+import org.junit.Test;
+
+public class DiffFormatterBuiltInDriverTest extends RepositoryTestCase {
+	@Test
+	public void testCppDriver() throws Exception {
+		String fileName = "greeting.c";
+		String body = Files.readString(
+				Path.of(JGitTestUtil.getTestResourceFile(fileName)
+						.getAbsolutePath()));
+		RevCommit c1;
+		RevCommit c2;
+		try (Git git = new Git(db)) {
+			createCommit(git, ".gitattributes", "*.c   diff=cpp");
+			c1 = createCommit(git, fileName, body);
+			c2 = createCommit(git, fileName,
+					body.replace("Good day", "Greetings")
+							.replace("baz", "qux"));
+		}
+		try (ByteArrayOutputStream os = new ByteArrayOutputStream();
+				DiffFormatter diffFormatter = new DiffFormatter(os)) {
+			String actual = getHunkHeaders(c1, c2, os, diffFormatter);
+			String expected =
+					"@@ -27,7 +27,7 @@ void getPersonalizedGreeting(char *result, const char *name, const char *timeOfD\n"
+							+ "@@ -37,7 +37,7 @@ int main() {";
+			assertEquals(expected, actual);
+		}
+	}
+
+	@Test
+	public void testDtsDriver() throws Exception {
+		String fileName = "sample.dtsi";
+		String body = Files.readString(
+				Path.of(JGitTestUtil.getTestResourceFile(fileName)
+						.getAbsolutePath()));
+		RevCommit c1;
+		RevCommit c2;
+		try (Git git = new Git(db)) {
+			createCommit(git, ".gitattributes", "*.dtsi   diff=dts");
+			c1 = createCommit(git, fileName, body);
+			c2 = createCommit(git, fileName,
+					body.replace("clock-frequency = <24000000>",
+							"clock-frequency = <48000000>"));
+		}
+		try (ByteArrayOutputStream os = new ByteArrayOutputStream();
+				DiffFormatter diffFormatter = new DiffFormatter(os)) {
+			String actual = getHunkHeaders(c1, c2, os, diffFormatter);
+			String expected = "@@ -20,6 +20,6 @@ uart0: uart@101f1000 {";
+			assertEquals(expected, actual);
+		}
+	}
+
+	@Test
+	public void testJavaDriver() throws Exception {
+		String resourceName = "greeting.javasource";
+		String body = Files.readString(
+				Path.of(JGitTestUtil.getTestResourceFile(resourceName)
+						.getAbsolutePath()));
+		RevCommit c1;
+		RevCommit c2;
+		try (Git git = new Git(db)) {
+			createCommit(git, ".gitattributes", "*.java   diff=java");
+			String fileName = "Greeting.java";
+			c1 = createCommit(git, fileName, body);
+			c2 = createCommit(git, fileName,
+					body.replace("Good day", "Greetings")
+							.replace("baz", "qux"));
+		}
+		try (ByteArrayOutputStream os = new ByteArrayOutputStream();
+				DiffFormatter diffFormatter = new DiffFormatter(os)) {
+			String actual = getHunkHeaders(c1, c2, os, diffFormatter);
+			String expected =
+					"@@ -22,7 +22,7 @@ public String getPersonalizedGreeting(String name, String timeOfDay) {\n"
+							+ "@@ -32,6 +32,6 @@ public static void main(String[] args) {";
+			assertEquals(expected, actual);
+		}
+	}
+
+	@Test
+	public void testPythonDriver() throws Exception {
+		String fileName = "greeting.py";
+		String body = Files.readString(
+				Path.of(JGitTestUtil.getTestResourceFile(fileName)
+						.getAbsolutePath()));
+		RevCommit c1;
+		RevCommit c2;
+		try (Git git = new Git(db)) {
+			createCommit(git, ".gitattributes", "*.py   diff=python");
+			c1 = createCommit(git, fileName, body);
+			c2 = createCommit(git, fileName,
+					body.replace("Good day", "Greetings"));
+		}
+		try (ByteArrayOutputStream os = new ByteArrayOutputStream();
+				DiffFormatter diffFormatter = new DiffFormatter(os)) {
+			String actual = getHunkHeaders(c1, c2, os, diffFormatter);
+			String expected = "@@ -16,7 +16,7 @@ def get_personalized_greeting(self, name, time_of_day):";
+			assertEquals(expected, actual);
+		}
+	}
+
+	@Test
+	public void testRustDriver() throws Exception {
+		String fileName = "greeting.rs";
+		String body = Files.readString(
+				Path.of(JGitTestUtil.getTestResourceFile(fileName)
+						.getAbsolutePath()));
+		RevCommit c1;
+		RevCommit c2;
+		try (Git git = new Git(db)) {
+			createCommit(git, ".gitattributes", "*.rs   diff=rust");
+			c1 = createCommit(git, fileName, body);
+			c2 = createCommit(git, fileName,
+					body.replace("Good day", "Greetings")
+							.replace("baz", "qux"));
+		}
+		try (ByteArrayOutputStream os = new ByteArrayOutputStream();
+				DiffFormatter diffFormatter = new DiffFormatter(os)) {
+			String actual = getHunkHeaders(c1, c2, os, diffFormatter);
+			String expected =
+					"@@ -14,7 +14,7 @@ fn get_personalized_greeting(&self, name: &str, time_of_day: &str) -> String {\n"
+							+ "@@ -23,5 +23,5 @@ fn main() {";
+			assertEquals(expected, actual);
+		}
+	}
+
+	private String getHunkHeaders(RevCommit c1, RevCommit c2,
+			ByteArrayOutputStream os, DiffFormatter diffFormatter)
+			throws IOException {
+		diffFormatter.setRepository(db);
+		diffFormatter.format(new CanonicalTreeParser(null, db.newObjectReader(),
+						c1.getTree()),
+				new CanonicalTreeParser(null, db.newObjectReader(),
+						c2.getTree()));
+		diffFormatter.flush();
+		return Arrays.stream(os.toString(StandardCharsets.UTF_8).split("\n"))
+				.filter(line -> line.startsWith("@@"))
+				.collect(Collectors.joining("\n"));
+	}
+
+	private RevCommit createCommit(Git git, String fileName, String body)
+			throws IOException, GitAPIException {
+		writeTrashFile(fileName, body);
+		git.add().addFilepattern(".").call();
+		return git.commit().setMessage("message").call();
+	}
+}