BranchAndMerge now work with generics

- add gson dependencies

build.gradle.kts

@@ -1,7 +1,7 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-    kotlin("jvm") version "1.3.21"
+    kotlin("jvm") version Config.Versions.kotlin
 }
 
 group = "norangebit"
@@ -16,6 +16,7 @@ dependencies {
     implementation(kotlin("stdlib-jdk8"))
     implementation(Config.Libs.arrowCore)
     implementation(Config.Libs.koin)
+    implementation(Config.Libs.gson)
 
     testImplementation(Config.Libs.junit)
     testImplementation(Config.Libs.kluent)

buildSrc/src/main/java/Config.kt

@@ -30,8 +30,9 @@ object Config {
         val koin = "1.0.2"
         val junit = "5.1.0"
         val spek = "2.0.1"
-        val kotlin = "1.3.21."
+        val kotlin = "1.3.21"
         val mockk = "1.9.2"
+        val gson = "2.8.5"
     }
 
     object Libs {
@@ -43,5 +44,6 @@ object Config {
         val kotlinReflect = "org.jetbrains.kotlin:kotlin-reflect:${Versions.kotlin}"
         val spekRunner = "org.spekframework.spek2:spek-runner-junit5:${Versions.spek}"
         val mockk = "io.mockk:mockk:${Versions.mockk}"
+        val gson = "com.google.code.gson:gson:${Versions.gson}"
     }
 }

src/main/kotlin/it/norangeb/algorithms/exercises/BranchAndMerge.kt

@@ -6,7 +6,7 @@
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, tryMerge, publish, distribute, sublicense, and/or sell
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
@@ -25,13 +25,20 @@
 
 package it.norangeb.algorithms.exercises
 
+import com.google.gson.Gson
 import java.io.File
 import java.io.PrintStream
 import java.util.Scanner
 
-object BranchAndMerge {
+class BranchAndMerge<T>(
-    private const val TMP_FILE_PATH_1 = "/tmp/file1"
+    private val typeClass: Class<T>,
-    private const val TMP_FILE_PATH_2 = "/tmp/file2"
+    var compare: (obj1: T, obj2: T) -> Int
+) {
+    companion object {
+        private const val TMP_FILE_PATH_1 = "/tmp/file1"
+        private const val TMP_FILE_PATH_2 = "/tmp/file2"
+    }
+    private val GSON = Gson()
 
     fun run(source: File) {
         tryBranch(source)
@@ -45,7 +52,7 @@ object BranchAndMerge {
     private fun isSorted(): Boolean {
         val sc1 = Scanner(File(TMP_FILE_PATH_1))
         val sc2 = Scanner(File(TMP_FILE_PATH_2))
-        return !sc1.hasNextInt() || !sc2.hasNextInt()
+        return !sc1.hasNextLine() || !sc2.hasNextLine()
     }
 
     private fun tryBranch(fileToSort: File) {
@@ -70,16 +77,16 @@ object BranchAndMerge {
         destination2: PrintStream
     ) {
         var destination = destination1
-        var current: Int
+        var current: T
-        var last: Int? = null
+        var last: T? = null
 
-        while (source.hasNextInt()) {
+        while (source.hasNextLine()) {
-            current = source.nextInt()
+            current = fromJson(source.nextLine())
             if (isLess(current, last))
                 destination = switchDestination(
                     destination, destination1, destination2
                 )
-            destination.println(current)
+            destination.println(toJson(current))
             last = current
         }
     }
@@ -103,23 +110,25 @@ object BranchAndMerge {
     private fun merge(source1: Scanner, source2: Scanner, destination: PrintStream) {
         var source = source1
 
-        var current: Int
+        var current: T
-        var cache: Int? = null
+        var cache: T? = null
 
-        while (source1.hasNextInt() && source2.hasNextInt()) {
+        while (source1.hasNextLine() && source2.hasNextLine()) {
             if (cache == null)
-                cache = switchSource(source, source1, source2).nextInt()
+                cache = fromJson(
+                    switchSource(source, source1, source2).nextLine()
+                )
 
-            current = source.nextInt()
+            current = fromJson(source.nextLine())
 
             if (!isLess(current, cache)) {
                 source = switchSource(source, source1, source2)
-                current = cache.also { cache = current }
+                current = cache!!.also { cache = current }
             }
 
-            destination.println(current)
+            destination.println(toJson(current))
         }
-        destination.println(cache)
+        destination.println(toJson(cache!!))
 
         mergeTail(source1, source2, destination)
     }
@@ -129,18 +138,18 @@ object BranchAndMerge {
         source2: Scanner,
         destination: PrintStream
     ) {
-        while (source1.hasNextInt())
+        while (source1.hasNextLine())
-            destination.println(source1.nextInt())
+            destination.println(source1.nextLine())
 
-        while (source2.hasNextInt())
+        while (source2.hasNextLine())
-            destination.println(source2.nextInt())
+            destination.println(source2.nextLine())
     }
 
-    private fun isLess(current: Int, last: Int?): Boolean {
+    private fun isLess(first: T, second: T?): Boolean {
-        if (last == null)
+        if (second == null)
             return false
 
-        return current < last
+        return compare(first, second) < 0
     }
 
     private fun switchDestination(
@@ -160,4 +169,8 @@ object BranchAndMerge {
         source1 -> source2
         else -> source1
     }
+
+    private fun fromJson(json: String) = GSON.fromJson(json, typeClass)
+
+    private fun toJson(obj: T) = GSON.toJson(obj)
 }

src/test/kotlin/it/norangeb/algorithms/exercises/BranchAndMergeTest.kt

@@ -25,6 +25,7 @@
 
 package it.norangeb.algorithms.exercises
 
+import com.google.gson.Gson
 import io.mockk.every
 import io.mockk.mockk
 import org.amshove.kluent.`should equal`
@@ -43,22 +44,30 @@ class BranchAndMergeTest {
             .find { it.name == "branch" }
             .also { it?.isAccessible = true }
 
-        val list1 = arrayListOf<Int>()
+        val list1 = arrayListOf<String>()
-        val list2 = arrayListOf<Int>()
+        val list2 = arrayListOf<String>()
         val source = mockk<Scanner>()
         val destination1 = mockk<PrintStream>()
         val destination2 = mockk<PrintStream>()
 
-        every { source.hasNextInt() } returnsMany
+        every { source.hasNextLine() } returnsMany
                 listOf(true, true, true, true, true, false)
-        every { source.nextInt() } returnsMany listOf(3, 1, 4, 2, 0)
+        every { source.nextLine() } returnsMany
-        every { destination1.println(any() as Int) } answers { list1.add(arg(0)) }
+                listOf(3, 1, 4, 2, 0).map { it.toString() }
-        every { destination2.println(any() as Int) } answers { list2.add(arg(0)) }
+        every { destination1.println(any() as String) } answers { list1.add(arg(0)) }
+        every { destination2.println(any() as String) } answers { list2.add(arg(0)) }
 
-        branch?.call(BranchAndMerge, source, destination1, destination2)
+        branch?.call(
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source,
+            destination1,
+            destination2
+        )
 
-        list1.toIntArray() `should equal` intArrayOf(3, 2)
+        list1.map { it.toInt() }
-        list2.toIntArray() `should equal` intArrayOf(1, 4, 0)
+            .toIntArray() `should equal` intArrayOf(3, 2)
+        list2.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf(1, 4, 0)
     }
 
     @Test
@@ -67,21 +76,29 @@ class BranchAndMergeTest {
             .find { it.name == "branch" }
             .also { it?.isAccessible = true }
 
-        val list1 = arrayListOf<Int>()
+        val list1 = arrayListOf<String>()
-        val list2 = arrayListOf<Int>()
+        val list2 = arrayListOf<String>()
         val source = mockk<Scanner>()
         val destination1 = mockk<PrintStream>()
         val destination2 = mockk<PrintStream>()
 
-        every { source.hasNextInt() } returnsMany
+        every { source.hasNextLine() } returnsMany
                 listOf(true, true, true, true, true, false)
-        every { source.nextInt() } returnsMany listOf(1, 2, 3, 10, 12)
+        every { source.nextLine() } returnsMany
-        every { destination1.println(any() as Int) } answers { list1.add(arg(0)) }
+                listOf(1, 2, 3, 10, 12).map { it.toString() }
+        every { destination1.println(any() as String) } answers { list1.add(arg(0)) }
 
-        branch?.call(BranchAndMerge, source, destination1, destination2)
+        branch?.call(
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source,
+            destination1,
+            destination2
+        )
 
-        list1.toIntArray() `should equal` intArrayOf(1, 2, 3, 10, 12)
+        list1.map { it.toInt() }
-        list2.toIntArray() `should equal` intArrayOf()
+            .toIntArray() `should equal` intArrayOf(1, 2, 3, 10, 12)
+        list2.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf()
     }
 
     @Test
@@ -90,23 +107,33 @@ class BranchAndMergeTest {
             .find { it.name == "merge" }
             .also { it?.isAccessible = true }
 
-        val list = arrayListOf<Int>()
+        val list = arrayListOf<String>()
         val source1 = mockk<Scanner>()
         val source2 = mockk<Scanner>()
         val destination = mockk<PrintStream>()
 
-        every { source1.hasNextInt() } returnsMany
+        every { source1.hasNextLine() } returnsMany
                 listOf(true, true, true, false)
-        every { source1.nextInt() } returnsMany listOf(3, 2)
+        every { source1.nextLine() } returnsMany
-        every { source2.hasNextInt() } returnsMany
+                listOf(3, 2).map { it.toString() }
+        every { source2.hasNextLine() } returnsMany
                 listOf(true, true, true, true, false)
-        every { source2.nextInt() } returnsMany listOf(1, 4, 0)
+        every { source2.nextLine() } returnsMany
-        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+                listOf(1, 4, 0).map { it.toString() }
-        every { destination.println(any() as Int?) } answers { list.add(arg(0)) }
+        every { destination.println(any() as String) }
+            .answers { list.add(arg(0)) }
+        every { destination.println(any() as String?) }
+            .answers { list.add(arg(0)) }
 
-        merge?.call(BranchAndMerge, source1, source2, destination)
+        merge?.call(
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source1,
+            source2,
+            destination
+        )
 
-        list.toIntArray() `should equal` intArrayOf(1, 3, 2, 4, 0)
+        list.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf(1, 3, 2, 4, 0)
     }
 
     @Test
@@ -119,10 +146,16 @@ class BranchAndMergeTest {
         val source2 = mockk<Scanner>()
 
         val result1 = switchSource?.call(
-            BranchAndMerge, source1, source1, source2
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source1,
+            source1,
+            source2
         )
         val result2 = switchSource?.call(
-            BranchAndMerge, source2, source1, source2
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source2,
+            source1,
+            source2
         )
 
         result1 `should equal` source2
@@ -139,10 +172,16 @@ class BranchAndMergeTest {
         val destination2 = mockk<PrintStream>()
 
         val result1 = switchDestination?.call(
-            BranchAndMerge, destination1, destination1, destination2
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            destination1,
+            destination1,
+            destination2
         )
         val result2 = switchDestination?.call(
-            BranchAndMerge, destination2, destination1, destination2
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            destination2,
+            destination1,
+            destination2
         )
 
         result1 `should equal` destination2
@@ -155,20 +194,24 @@ class BranchAndMergeTest {
             .find { it.name == "mergeTail" }
             .also { it?.isAccessible = true }
 
-        val list = arrayListOf<Int>()
+        val list = arrayListOf<String>()
         val source1 = mockk<Scanner>()
         val source2 = mockk<Scanner>()
         val destination = mockk<PrintStream>()
 
-        every { source1.hasNextInt() } returns false
+        every { source1.hasNextLine() } returns false
-        every { source2.hasNextInt() } returns false
+        every { source2.hasNextLine() } returns false
-        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+        every { destination.println(any() as String) } answers { list.add(arg(0)) }
 
         mergeTail?.call(
-            BranchAndMerge, source1, source2, destination
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source1,
+            source2,
+            destination
         )
 
-        list.toIntArray() `should equal` intArrayOf()
+        list.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf()
     }
 
     @Test
@@ -177,21 +220,27 @@ class BranchAndMergeTest {
             .find { it.name == "mergeTail" }
             .also { it?.isAccessible = true }
 
-        val list = arrayListOf<Int>()
+        val list = arrayListOf<String>()
         val source1 = mockk<Scanner>()
         val source2 = mockk<Scanner>()
         val destination = mockk<PrintStream>()
 
-        every { source1.hasNextInt() } returns false
+        every { source1.hasNextLine() } returns false
-        every { source2.hasNextInt() } returnsMany listOf(true, true, false)
+        every { source2.hasNextLine() } returnsMany listOf(true, true, false)
-        every { source2.nextInt() } returnsMany listOf(3, 7)
+        every { source2.nextLine() } returnsMany
-        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+                listOf(3, 7).map { it.toString() }
+        every { destination.println(any() as String) }
+            .answers { list.add(arg(0)) }
 
         mergeTail?.call(
-            BranchAndMerge, source1, source2, destination
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source1,
+            source2,
+            destination
         )
 
-        list.toIntArray() `should equal` intArrayOf(3, 7)
+        list.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf(3, 7)
     }
 
     @Test
@@ -200,48 +249,108 @@ class BranchAndMergeTest {
             .find { it.name == "mergeTail" }
             .also { it?.isAccessible = true }
 
-        val list = arrayListOf<Int>()
+        val list = arrayListOf<String>()
         val source1 = mockk<Scanner>()
         val source2 = mockk<Scanner>()
         val destination = mockk<PrintStream>()
 
-        every { source1.hasNextInt() } returnsMany listOf(true, false)
+        every { source1.hasNextLine() } returnsMany listOf(true, false)
-        every { source1.nextInt() } returns 1
+        every { source1.nextLine() } returns "1"
-        every { source2.hasNextInt() } returns false
+        every { source2.hasNextLine() } returns false
-        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+        every { destination.println(any() as String) }
+            .answers { list.add(arg(0)) }
 
         mergeTail?.call(
-            BranchAndMerge, source1, source2, destination
+            BranchAndMerge(Int::class.java, this::defaultComparator),
+            source1,
+            source2,
+            destination
         )
 
-        list.toIntArray() `should equal` intArrayOf(1)
+        list.map { it.toInt() }
+            .toIntArray() `should equal` intArrayOf(1)
     }
 
     @Test
     fun sortAlreadySortedTest() {
-        val path = "/tmp/test"
+        val filePath = "/tmp/test"
-        val ps = PrintStream(path)
+        val ps = PrintStream(filePath)
         val testSet = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 16, 21, 34, 45)
 
         testSet.forEach { ps.println(it) }
         ps.close()
 
-        BranchAndMerge.run(File(path))
+        BranchAndMerge(Int::class.java, this::defaultComparator)
+            .run(File(filePath))
 
-        File(path).readLines().map { it.toInt() } `should equal` testSet
+        File(filePath).readLines()
+            .map { it.toInt() } `should equal` testSet
     }
 
     @Test
     fun sortTest() {
-        val path = "/tmp/test"
+        val filePath = "/tmp/test"
-        val ps = PrintStream(path)
+        val ps = PrintStream(filePath)
         val testSet = listOf(6, 2, 39, 4, 5, 11, 7, 99, 9, 10, 3, 16, 1, 45, 44)
 
         testSet.forEach { ps.println(it) }
         ps.close()
 
-        BranchAndMerge.run(File(path))
+        BranchAndMerge(Int::class.java, this::defaultComparator)
+            .run(File(filePath))
 
-        File(path).readLines().map { it.toInt() } `should equal` testSet.sorted()
+        File(filePath).readLines()
+            .map { it.toInt() } `should equal` testSet.sorted()
+    }
+
+    @Test
+    fun reverseSortTest() {
+        val filePath = "/tmp/test"
+        val ps = PrintStream(filePath)
+        val testSet = listOf(6, 2, 39, 4, 5, 11, 7, 99, 9, 10, 3, 16, 1, 45, 44)
+
+        testSet.forEach { ps.println(it) }
+        ps.close()
+
+        BranchAndMerge(Int::class.java) { it1, it2 -> it2.compareTo(it1) }
+            .run(File(filePath))
+
+        File(filePath).readLines()
+            .map { it.toInt() } `should equal` testSet.sorted().reversed()
+    }
+
+    data class Person(val firstName: String, val lastName: String, val age: Int)
+
+    @Test
+    fun sortPersonsByAge() {
+        val filePath = "/tmp/test"
+        val ps = PrintStream(filePath)
+        val gson = Gson()
+        val testSet = listOf(
+            Person("Name1", "Surname1", 25),
+            Person("Name2", "Surname2", 15),
+            Person("Name3", "Surname3", 39),
+            Person("Name4", "Surname4", 10),
+            Person("Name5", "Surname5", 4)
+        )
+
+        testSet.map { gson.toJson(it) }
+            .forEach { ps.println(it) }
+        ps.close()
+
+        val sortByAge = { p1: Person, p2: Person ->
+            p1.age.compareTo(p2.age)
+        }
+
+        BranchAndMerge(Person::class.java, sortByAge)
+            .run(File(filePath))
+
+        File(filePath).readLines()
+            .map { gson.fromJson(it, Person::class.java) } `should equal`
+                testSet.sortedBy { it.age }
+    }
+
+    private fun <T> defaultComparator(obj1: T, obj2: T): Int {
+        return (obj1 as Comparable<T>).compareTo(obj2)
     }
 }