.github/workflows/main.yaml

@@ -7,23 +7,3 @@ on:
     branches:
       - main
 jobs:
-  lint-and-test:
-    name: Lint and test library
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Set up Java
-        uses: actions/setup-java@v3
-        with:
-          distribution: 'adopt'
-          java-version: 17
-
-      - name: Verify Gradle wrapper
-        uses: gradle/wrapper-validation-action@v1
-
-      - name: Setup Gradle
-        uses: gradle/gradle-build-action@v2
-
-      - name: Run checks
-        run: ./gradlew check

.idea/gradle.xml

@@ -5,7 +5,6 @@
     <option name="linkedExternalProjectsSettings">
       <GradleProjectSettings>
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleJvm" value="corretto-19" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />

src/main/kotlin/tinyvm/Commit.kt

@@ -7,19 +7,17 @@ abstract class Object(
     val type: String,
 ) {
     abstract val data: String
-
+    fun hash(): String = MessageDigest
-    fun hash(): String =
+        .getInstance("SHA-1")
-        MessageDigest
+        .digest("$type ${data.length}\u0000$data".toByteArray())
-            .getInstance("SHA-1")
+        .toHex()
-            .digest("$type ${data.length}\u0000$data".toByteArray())
-            .toHex()
 }
 
 class Commit(
     val tree: Tree,
     val author: Author,
     val message: String,
-    val timestamp: Instant,
+    val timestamp: Instant
 ) : Object("commit") {
     // Use \n\n for end of header in-case additional metadata is implemented in the future.
     override val data: String
@@ -28,7 +26,8 @@ class Commit(
 
 data class Author(
     val name: String,
-    val email: String,
+    val email: String
 ) {
-    override fun toString(): String = "$name <$email>"
+    override fun toString(): String =
+        "$name <$email>"
 }

src/main/kotlin/tinyvm/Extensions.kt

@@ -2,4 +2,5 @@ package tinyvm
 
 import java.util.HexFormat
 
-fun ByteArray.toHex(): String = HexFormat.of().formatHex(this)
+fun ByteArray.toHex(): String =
+     HexFormat.of().formatHex(this)

src/main/kotlin/tinyvm/Repository.kt

@@ -2,11 +2,9 @@ package tinyvm
 
 class HashCollisionException(hash: String) : Exception("Different object types with identical hash '$hash'")
 
-class CommitTimeComparator : Comparator<Commit> {
+class CommitTimeComparator: Comparator<Commit> {
-    override fun compare(
+    override fun compare(o1: Commit, o2: Commit): Int =
-        o1: Commit,
+        (o1.timestamp.epochSecond - o2.timestamp.epochSecond).toInt()
-        o2: Commit,
-    ): Int = (o1.timestamp.epochSecond - o2.timestamp.epochSecond).toInt()
 }
 
 class Repository {
@@ -25,13 +23,12 @@ class Repository {
         val hash = commit.hash()
         val obj = findObject<Commit>(hash)
         if (obj != null) return obj
-        val newCommit =
+        val newCommit = Commit(
-            Commit(
+            tree = addTree(commit.tree),
-                tree = addTree(commit.tree),
+            author = commit.author,
-                author = commit.author,
+            message = commit.message,
-                message = commit.message,
+            timestamp = commit.timestamp
-                timestamp = commit.timestamp,
+        )
-            )
         objects[hash] = newCommit
         commits.add(newCommit)
         return newCommit
@@ -50,7 +47,8 @@ class Repository {
     /**
      * Find commit.
      */
-    fun findCommit(predicate: (Commit) -> Boolean): Commit? = commits.find(predicate)
+    fun findCommit(predicate: (Commit) -> Boolean): Commit? =
+        commits.find(predicate)
 
     /**
      * Dump repository objects
@@ -65,15 +63,14 @@ class Repository {
         val hash = tree.hash()
         val obj = findObject<Tree>(hash)
         if (obj != null) return obj
-        val newTree =
+        val newTree = Tree(
-            Tree(
+            tree.nodes.map { (name, node) ->
-                tree.nodes.map { (name, node) ->
+                when (node) {
-                    when (node) {
+                    is Tree -> name to addTree(node)
-                        is Tree -> name to addTree(node)
+                    is Blob -> name to addObject(node)
-                        is Blob -> name to addObject(node)
+                }
-                    }
+            }.toMap()
-                }.toMap(),
+        )
-            )
         objects[hash] = newTree
         return tree
     }
@@ -89,4 +86,5 @@ class Repository {
      */
     private inline fun <reified T : Object> findObject(hash: String): T? =
         objects[hash]?.let { it as? T ?: throw HashCollisionException(hash) }
+
 }

src/main/kotlin/tinyvm/Tree.kt

@@ -1,14 +1,13 @@
 package tinyvm
 
-sealed class Node(type: String) : Object(type)
+sealed class Node(type: String): Object(type)
 
 class Tree(val nodes: Map<String, Node>) : Node("tree") {
     // For simplicity just use the hex-formatted hash, not the actual value like git does.
     override val data: String
-        get() =
+        get() = nodes.map { (name, node) ->
-            nodes.map { (name, node) ->
+            "${node.type} $name\u0000${node.hash()}"
-                "${node.type} $name\u0000${node.hash()}"
+        }.sorted().joinToString()
-            }.sorted().joinToString()
 }
 
 class Blob(override val data: String) : Node("blob")

src/test/kotlin/tinyvm/RepositoryTest.kt

@@ -6,60 +6,51 @@ import kotlin.test.assertEquals
 
 internal class RepositoryTest {
     private val repository = Repository()
-    private val commits =
+    private val commits = listOf(
-        listOf(
+        Commit(
-            Commit(
+            tree = Tree(mapOf("test1.txt" to Blob("Hello World!"))),
-                tree = Tree(mapOf("test1.txt" to Blob("Hello World!"))),
+            author = Author("Gleb Koval", "gleb@koval.net"),
-                author = Author("Gleb Koval", "gleb@koval.net"),
+            message = "Add test1.txt",
-                message = "Add test1.txt",
+            timestamp = Instant.ofEpochSecond(0)
-                timestamp = Instant.ofEpochSecond(0),
+        ), Commit(
-            ),
+            tree = Tree(
-            Commit(
+                mapOf(
-                tree =
+                    "dir1" to Tree(
-                    Tree(
                         mapOf(
-                            "dir1" to
+                            "test1.txt" to Blob("Hello World!")
-                                Tree(
+                        )
-                                    mapOf(
-                                        "test1.txt" to Blob("Hello World!"),
-                                    ),
-                                ),
-                            "dir2" to
-                                Tree(
-                                    mapOf(
-                                        "test2.txt" to Blob("This is a second file"),
-                                    ),
-                                ),
-                        ),
                     ),
-                author = Author("Gleb Koval", "gleb@koval.net"),
+                    "dir2" to Tree(
-                message = "Move test1.txt and add dir2/test2.txt",
-                timestamp = Instant.ofEpochSecond(50),
-            ),
-            Commit(
-                tree =
-                    Tree(
                         mapOf(
-                            "dir1" to
+                            "test2.txt" to Blob("This is a second file")
-                                Tree(
+                        )
-                                    mapOf(
+                    )
-                                        "test1.txt" to Blob("Hello World!"),
+                )
-                                    ),
-                                ),
-                            "dir2" to
-                                Tree(
-                                    mapOf(
-                                        "test2.txt" to Blob("This is a second file"),
-                                    ),
-                                ),
-                            "README.md" to Blob("# This is a test repo!"),
-                        ),
-                    ),
-                author = Author("Gleb Koval", "gleb@koval.net"),
-                message = "Add README.md",
-                timestamp = Instant.ofEpochSecond(100),
             ),
+            author = Author("Gleb Koval", "gleb@koval.net"),
+            message = "Move test1.txt and add dir2/test2.txt",
+            timestamp = Instant.ofEpochSecond(50)
+        ), Commit(
+            tree = Tree(
+                mapOf(
+                    "dir1" to Tree(
+                        mapOf(
+                            "test1.txt" to Blob("Hello World!")
+                        )
+                    ),
+                    "dir2" to Tree(
+                        mapOf(
+                            "test2.txt" to Blob("This is a second file")
+                        )
+                    ),
+                    "README.md" to Blob("# This is a test repo!")
+                )
+            ),
+            author = Author("Gleb Koval", "gleb@koval.net"),
+            message = "Add README.md",
+            timestamp = Instant.ofEpochSecond(100)
         )
+    )
 
     @Test
     fun `can commit`() {