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v0.1.0 ... main

Author SHA1 Message Date
Gleb Koval a6d7802a83
Fix README and test for throws on branch not found.
Test Workflow / Lint and test library (push) Successful in 1m52s Details
2024-01-10 12:40:10 +00:00
Gleb Koval dbc1bdd105 Branch support (#7)
Test Workflow / Lint and test library (push) Successful in 1m51s Details
Publish Workflow / Publish library (push) Successful in 2m18s Details
Closes #6.

Implements branch support by _only extending_ the existing functionality. Note that the existing functionality DOES NOT implement a `parent` pointer for commits, and as a result branches are also implemented differently to how git implements them.

git branches are simply a named pointer to a commit object (which then has a pointer to its parent commit), here branches store the entire sequence of pointers to commit objects.

### Why different to git?
I made a mistake in the initial implementation by using a `TreeSet` instead of manually implementing a tree for commits. This allowed the ability to insert commits in-between other commits, which isn't normally possible in `git` _without rebasing which changes commits' hashes_.

The specification for this feature stated:
> All functionality that is implemented already should be preserved.

And so since I cannot remove this functionality any more, I have to build on top of it.

Reviewed-on: #7
2024-01-10 12:21:25 +00:00
Gleb Koval 7233a7e8d1
Cleanup and privatise commit comparator
Publish Workflow / Publish library (push) Successful in 8m28s Details
Test Workflow / Lint and test library (push) Successful in 16m51s Details
2023-12-05 02:00:35 +00:00
Gleb Koval 6cb4f82fce
Cleanup comments in README and Commit.kt
Test Workflow / Lint and test library (push) Successful in 16m49s Details
2023-12-02 20:51:34 +00:00
6 changed files with 106 additions and 29 deletions

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@ -20,13 +20,14 @@ repositories {
}
dependencies {
implementation("net.koval.teamcity-gitea-test-task:tinyvm:0.1.0")
// other dependencies
implementation("net.koval.teamcity-gitea-test-task:tinyvm:0.1.1")
}
```
### Documentation
Use autocompletion and hover menus in your IDE, or download the
[generated HTML documentation](https://git.koval.net/cyclane/teamcity-gitea-test-task/releases/download/v0.1.0/tinyvm-0.1.0-javadoc.zip)
generated HTML documentation
from the [latest release](https://git.koval.net/cyclane/teamcity-gitea-test-task/releases).
## Instructions

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@ -1,22 +1,6 @@
package tinyvm
import java.security.MessageDigest
import java.time.Instant
import java.util.HexFormat
/**
* Represents an arbitrary version manager object.
*/
abstract class Object(val type: String) {
abstract val data: String
fun hash(): String =
HexFormat.of().formatHex(
MessageDigest
.getInstance("SHA-1")
.digest("$type ${data.length}\u0000$data".toByteArray()),
)
}
/**
* Commits are a pointer to a 'head' tree with some metadata.
@ -28,7 +12,6 @@ class Commit(
val timestamp: Instant,
) : Object("commit") {
override val data: String
// Use \n\n for end of header in-case additional metadata is implemented in the future.
get() = "tree ${tree.hash()}\nauthor $author\ntimestamp ${timestamp.epochSecond}\n\n$message"
override fun toString(): String = "commit ${hash()}\n$data"

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@ -0,0 +1,17 @@
package tinyvm
import java.security.MessageDigest
import java.util.HexFormat
/**
* Represents an arbitrary version manager object.
*/
abstract class Object(val type: String) {
abstract val data: String
fun hash(): String =
HexFormat.of().formatHex(
MessageDigest.getInstance("SHA-1")
.digest("$type ${data.length}\u0000$data".toByteArray()),
)
}

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@ -1,22 +1,59 @@
package tinyvm
import java.util.TreeSet
class HashCollisionException(hash: String) : Exception("Different object types with identical hash '$hash'")
class CommitTimeComparator : Comparator<Commit> {
private class CommitTimeComparator : Comparator<Commit> {
override fun compare(
o1: Commit,
o2: Commit,
): Int = (o1.timestamp.epochSecond - o2.timestamp.epochSecond).toInt()
}
class Repository {
private val commits = sortedSetOf(CommitTimeComparator())
private val commitTimeComparator = CommitTimeComparator()
private class Branch(val name: String, val commits: TreeSet<Commit>)
class Repository(initialBranch: String = "master") {
private var head = Branch(initialBranch, sortedSetOf(commitTimeComparator))
private val commits = mutableMapOf(initialBranch to head)
val branch: String
get() = head.name
val branches: Set<String>
get() = commits.keys
// Store all objects in one map like git does. This would simplify the data persistence implementation (if there was
// one) and allows for other objects to be added in the future without modifying the data persistence implementation
// at all.
private val objects = mutableMapOf<String, Object>()
/**
* Create a new branch as a copy of the current branch.
* @param name New branch name.
* @param use Whether to switch to this branch.
*/
fun createBranch(
name: String,
use: Boolean = true,
) {
commits[name] =
Branch(
name,
head.commits.clone() as? TreeSet<Commit> ?: throw Exception("TreeSet.clone() unexpected result"),
)
if (use) useBranch(name)
}
/**
* Use (switch to) a branch.
*/
fun useBranch(name: String) {
head = commits[name] ?: throw BranchNotFoundException(name)
}
/**
* (Deep) get or put a commit object into the repository.
* This will also get or put all child trees and blobs.
@ -33,7 +70,7 @@ class Repository {
timestamp = commit.timestamp,
)
objects[hash] = newCommit
commits.add(newCommit)
head.commits.add(newCommit)
return newCommit
}
@ -45,12 +82,12 @@ class Repository {
/**
* List all commits.
*/
fun listCommits(): List<Commit> = commits.toList()
fun listCommits(): List<Commit> = head.commits.toList()
/**
* Find commit.
*/
fun findCommit(predicate: (Commit) -> Boolean): Commit? = commits.find(predicate)
fun findCommit(predicate: (Commit) -> Boolean): Commit? = head.commits.find(predicate)
/**
* Dump repository objects
@ -89,4 +126,6 @@ class Repository {
*/
private inline fun <reified T : Object> findObject(hash: String): T? =
objects[hash]?.let { it as? T ?: throw HashCollisionException(hash) }
}
}
class BranchNotFoundException(name: String) : Exception("Branch '$name' does not exist")

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@ -22,7 +22,7 @@ class Tree(val nodes: Map<String, Node>) : Node("tree") {
when (node) {
is Tree -> "+$name/\n"
is Blob -> "+$name\n"
} + node.toString().leftMargin()
} + node.toString().insertLeftMargin()
}.sorted().joinToString("\n")
}
@ -30,7 +30,7 @@ class Tree(val nodes: Map<String, Node>) : Node("tree") {
* A blob is a data container.
*/
class Blob(override val data: String) : Node("blob") {
override fun toString(): String = "blob ${hash()}\n${data.leftMargin()}"
override fun toString(): String = "blob ${hash()}\n${data.insertLeftMargin()}"
}
private fun String.leftMargin(): String = split('\n').joinToString("\n") { "| $it" }
private fun String.insertLeftMargin(): String = split('\n').joinToString("\n") { "| $it" }

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@ -1,5 +1,6 @@
package tinyvm
import org.junit.jupiter.api.assertThrows
import java.time.Instant
import kotlin.test.Test
import kotlin.test.assertEquals
@ -118,6 +119,42 @@ internal class RepositoryTest {
assertEquals(null, repository.getCommit("00000000000000000000"))
}
@Test
fun `can create and use branch`() {
repository.commit(commits[0])
repository.commit(commits[1])
repository.commit(commits[2])
repository.createBranch("test-branch", use = false)
assertEquals("master", repository.branch)
repository.createBranch("test-branch-2")
assertEquals("test-branch-2", repository.branch)
assertEquals(setOf("master", "test-branch", "test-branch-2"), repository.branches)
assertEquals(commits.map { it.hash() }, repository.listCommits().map { it.hash() })
assertEquals(10, repository.dumpObjects().size)
}
@Test
fun `cannot use non-existent branch`() {
assertThrows<BranchNotFoundException> {
repository.useBranch("test-branch")
}
}
@Test
fun `can commit to branch`() {
repository.commit(commits[0])
repository.createBranch("test-branch")
repository.commit(commits[1])
repository.createBranch("test-branch-2")
repository.commit(commits[2])
assertEquals(commits.map { it.hash() }, repository.listCommits().map { it.hash() })
repository.useBranch("test-branch")
assertEquals(commits.take(2).map { it.hash() }, repository.listCommits().map { it.hash() })
repository.useBranch("master")
assertEquals(commits.take(1).map { it.hash() }, repository.listCommits().map { it.hash() })
}
@Test
fun `can display commit`() {
assertEquals(