Migrate the project to KMP

build.gradle.kts

@@ -1,19 +1,33 @@
 plugins {
-  kotlin("jvm") version "1.8.20"
+  kotlin("multiplatform") version "1.8.20"
   id("org.jetbrains.kotlinx.binary-compatibility-validator") version "0.13.0"
   id("org.jetbrains.dokka") version "1.8.10"
 }
 
 repositories { mavenCentral() }
 
-dependencies {
-  implementation(kotlin("stdlib"))
-  testImplementation(kotlin("test"))
-  // For future benchmarking.
-  // testImplementation("com.google.guava:guava:31.1-jre")
-}
-
 kotlin {
   explicitApi()
-  sourceSets.all { languageSettings.optIn("kotlin.contracts.ExperimentalContracts") }
+  jvm()
+  js(IR) {
+    browser()
+    nodejs()
+  }
+  sourceSets {
+    val commonMain by getting { dependencies { implementation(kotlin("stdlib-common")) } }
+    val commonTest by getting {
+      dependencies {
+        implementation(kotlin("test-common"))
+        implementation(kotlin("test-annotations-common"))
+      }
+    }
+    val jvmMain by getting
+    val jvmTest by getting { dependencies { implementation(kotlin("test-junit")) } }
+    val jsMain by getting
+    val jsTest by getting { dependencies { implementation(kotlin("test-js")) } }
+    all { languageSettings.optIn("kotlin.contracts.ExperimentalContracts") }
+  }
 }
+
+// For future benchmarking.
+// testImplementation("com.google.guava:guava:31.1-jre")

src/main/kotlin/io/github/alexandrepiveteau/graphs/Arc.kt → src/commonMain/kotlin/io/github/alexandrepiveteau/graphs/Arc.kt

@@ -3,6 +3,7 @@ package io.github.alexandrepiveteau.graphs
 import io.github.alexandrepiveteau.graphs.util.packInts
 import io.github.alexandrepiveteau.graphs.util.unpackInt1
 import io.github.alexandrepiveteau.graphs.util.unpackInt2
+import kotlin.jvm.JvmInline
 
 /** A directed arc in a [UndirectedGraph] between two [Vertex]. */
 @JvmInline

src/main/kotlin/io/github/alexandrepiveteau/graphs/Edge.kt → src/commonMain/kotlin/io/github/alexandrepiveteau/graphs/Edge.kt

@@ -3,6 +3,7 @@ package io.github.alexandrepiveteau.graphs
 import io.github.alexandrepiveteau.graphs.util.packInts
 import io.github.alexandrepiveteau.graphs.util.unpackInt1
 import io.github.alexandrepiveteau.graphs.util.unpackInt2
+import kotlin.jvm.JvmInline
 import kotlin.math.max
 import kotlin.math.min
 

src/main/kotlin/io/github/alexandrepiveteau/graphs/Vertex.kt → src/commonMain/kotlin/io/github/alexandrepiveteau/graphs/Vertex.kt

@@ -1,5 +1,7 @@
 package io.github.alexandrepiveteau.graphs
 
+import kotlin.jvm.JvmInline
+
 /**
  * A vertex in a [Graph], which is uniquely identified. Vertices can be compared to each other, and
  * are totally ordered within a [Graph] instance.

src/main/kotlin/io/github/alexandrepiveteau/graphs/VertexArray.kt → src/commonMain/kotlin/io/github/alexandrepiveteau/graphs/VertexArray.kt

@@ -1,5 +1,7 @@
 package io.github.alexandrepiveteau.graphs
 
+import kotlin.jvm.JvmInline
+
 /** Creates a new array of the specified [size], with all elements initialized to zero. */
 public fun VertexArray(size: Int): VertexArray = VertexArray(IntArray(size))
 
@@ -152,4 +154,26 @@ public fun VertexArray.binarySearch(
     element: Vertex,
     fromIndex: Int = 0,
     toIndex: Int = size,
-): Int = array.binarySearch(element.index, fromIndex, toIndex)
+): Int {
+  if (fromIndex < 0) throw IndexOutOfBoundsException()
+  if (toIndex > size) throw IndexOutOfBoundsException()
+  if (fromIndex > toIndex) throw IllegalArgumentException()
+
+  var low = fromIndex
+  var high = toIndex - 1
+
+  while (low <= high) {
+    val mid = (low + high).ushr(1) // safe from overflows
+    val midVal = get(mid)
+    val cmp = midVal.index.compareTo(element.index)
+
+    if (cmp < 0) {
+      low = mid + 1
+    } else if (cmp > 0) {
+      high = mid - 1
+    } else {
+      return mid
+    } // key found
+  }
+  return -(low + 1) // key not found
+}

src/main/kotlin/io/github/alexandrepiveteau/graphs/VertexMap.kt → src/commonMain/kotlin/io/github/alexandrepiveteau/graphs/VertexMap.kt

@@ -1,5 +1,7 @@
 package io.github.alexandrepiveteau.graphs
 
+import kotlin.jvm.JvmInline
+
 /**
  * Creates a new [VertexMap] with the given [size], with all elements initialized to the result of
  * calling the specified [init] function on the index of each element.

src/test/kotlin/io/github/alexandrepiveteau/graphs/Arc.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/Arc.kt

@@ -8,7 +8,7 @@ import kotlin.test.assertTrue
 class ArcTests {
 
   @Test
-  fun `opposite arcs are not equal`() {
+  fun oppositeArcsAreNotEqual() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a arcTo b
@@ -17,7 +17,7 @@ class ArcTests {
   }
 
   @Test
-  fun `arcs are properly reversed`() {
+  fun arcsAreProperlyReversed() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a arcTo b
@@ -27,7 +27,7 @@ class ArcTests {
   }
 
   @Test
-  fun `arc contains both extremities`() {
+  fun arcContainsBothExtremities() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a arcTo b
@@ -36,7 +36,7 @@ class ArcTests {
   }
 
   @Test
-  fun `arc destructuring returns extremities in order`() {
+  fun arcDestructuringReturnsExtremitiesInOrder() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a arcTo b

src/test/kotlin/io/github/alexandrepiveteau/graphs/DirectedNetwork.flows.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/DirectedNetwork.flows.kt

@@ -8,7 +8,7 @@ import kotlin.test.Test
 class DirectedNetworkFlowsTests {
 
   @Test
-  fun `no edges has empty flow`() {
+  fun noEdgesHasEmptyFlow() {
     val capacities = buildDirectedNetwork {
       addVertex()
       addVertex()
@@ -22,7 +22,7 @@ class DirectedNetworkFlowsTests {
   }
 
   @Test
-  fun `single arc has non-empty flow`() {
+  fun singleArcHasNonEmptyFlow() {
     val capacities = buildDirectedNetwork {
       val (a, b) = addVertices()
       addArc(a arcTo b, 1)
@@ -41,7 +41,7 @@ class DirectedNetworkFlowsTests {
   }
 
   @Test
-  fun `two arcs has minimum of capacities`() {
+  fun twoArcsHasMinimumOfCapacities() {
     val capacities = buildDirectedNetwork {
       val (a, b, c) = addVertices()
       addArc(a arcTo b, 1)
@@ -62,7 +62,7 @@ class DirectedNetworkFlowsTests {
   }
 
   @Test
-  fun `three arcs has sum of capacities`() {
+  fun threeArcsHasSumOfCapacities() {
     val capacities = buildDirectedNetwork {
       val (a, b, c, d) = addVertices()
       addArc(a arcTo b, 1)
@@ -87,7 +87,7 @@ class DirectedNetworkFlowsTests {
   }
 
   @Test
-  fun `wikipedia example has right total flow`() {
+  fun wikipediaExampleHasCorrectTotalFlow() {
     // Source: https://en.wikipedia.org/wiki/Edmonds–Karp_algorithm
     val capacities = buildDirectedNetwork {
       val (a, b, c, d, e, f, g) = addVertices()
@@ -112,7 +112,7 @@ class DirectedNetworkFlowsTests {
   }
 
   @Test
-  fun `complete graphs`() {
+  fun completeGraphsHaveCorrectTotalFlow() {
     for (count in 2 until Repeats) {
       val capacities = buildDirectedNetwork {
         val vertices = VertexArray(count) { addVertex() }

src/test/kotlin/io/github/alexandrepiveteau/graphs/Edge.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/Edge.kt

@@ -8,7 +8,7 @@ import kotlin.test.assertTrue
 class EdgeTests {
 
   @Test
-  fun `opposite edges are equal`() {
+  fun oppositeEdgesAreEqual() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a edgeTo b
@@ -17,7 +17,7 @@ class EdgeTests {
   }
 
   @Test
-  fun `edge contains both extremities`() {
+  fun edgeContainsBothExtremities() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a edgeTo b
@@ -26,7 +26,7 @@ class EdgeTests {
   }
 
   @Test
-  fun `other returns other edge extremity`() {
+  fun otherReturnsOtherEdgeExtremity() {
     val a = Vertex(0)
     val b = Vertex(1)
     val e = a edgeTo b
@@ -36,7 +36,7 @@ class EdgeTests {
   }
 
   @Test
-  fun `any returns an extremity`() {
+  fun anyReturnsAnExtremity() {
     val a = Vertex(1000)
     val b = Vertex(1001)
 
@@ -45,7 +45,7 @@ class EdgeTests {
   }
 
   @Test
-  fun `other with an unknown vertex throws an IllegalArgumentException`() {
+  fun otherWithAnUnknownVertexThrowsAnIllegalArgumentException() {
     val a = Vertex(0)
     val b = Vertex(1)
     val c = Vertex(2)

src/test/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.complete.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.complete.kt

@@ -9,7 +9,7 @@ import kotlin.test.assertFalse
 class UndirectedEmptyGraphTests {
 
   @Test
-  fun `empty graph has no vertices nor edges`() {
+  fun emptyGraphHasNoVerticesNorEdges() {
     val graph = UndirectedGraph.empty()
 
     assertEquals(0, graph.size)
@@ -25,12 +25,12 @@ class UndirectedEmptyGraphTests {
 class UndirectedCompleteGraphTests {
 
   @Test
-  fun `complete graph has non-zero vertex count`() {
+  fun completeGraphHasNonZeroVertexCount() {
     assertFailsWith<IllegalArgumentException> { UndirectedGraph.complete(-1) }
   }
 
   @Test
-  fun `complete graph has all edges`() {
+  fun completeGraphHasAllEdges() {
     for (count in 0..Repeats) {
       val graph = UndirectedGraph.complete(count)
       for (i in 0 until count) {
@@ -46,7 +46,7 @@ class UndirectedCompleteGraphTests {
   }
 
   @Test
-  fun `complete graph has no self-edges`() {
+  fun completeGraphHasNoSelfEdges() {
     for (count in 0..Repeats) {
       val graph = UndirectedGraph.complete(count)
       for (i in 0 until count) {

src/test/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.transformations.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.transformations.kt

@@ -7,15 +7,15 @@ import kotlin.test.assertEquals
 class SCCTests {
 
   @Test
-  fun `empty graph has no scc`() {
+  fun emptyGraphHasNoScc() {
     val graph = UndirectedGraph.empty()
     val (scc, map) = graph.scc()
     assertEquals(0, scc.size)
     assertEquals(0, map.size)
   }
 
   @Test
-  fun `complete graph has one scc`() {
+  fun completeGraphHasOneScc() {
     for (count in 1..Repeats) {
       val graph = UndirectedGraph.complete(count)
       val (scc, map) = graph.scc()
@@ -25,7 +25,7 @@ class SCCTests {
   }
 
   @Test
-  fun `disjoint graph with n vertices has n scc`() {
+  fun disjointGraphWithNVerticesHasNScc() {
     for (count in 1..Repeats) {
       val graph = buildUndirectedGraph { repeat(count) { addVertex() } }
       val (scc, map) = graph.scc()

src/test/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.traversals.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/UndirectedGraph.traversals.kt

@@ -8,7 +8,7 @@ import kotlin.test.assertFalse
 class UndirectedGraphDFSTests {
 
   @Test
-  fun `forEachVertex iterates exactly once over each vertex`() {
+  fun forEachVertexIteratesExactlyOnceOverEachVertex() {
     for (count in 0..Repeats) {
       val graph = UndirectedGraph.complete(count)
       val visited = BooleanArray(count)
@@ -21,15 +21,15 @@ class UndirectedGraphDFSTests {
   }
 
   @Test
-  fun `bfs on singleton graph visits one vertex`() {
+  fun bfsOnSingletonGraphVisitsOneVertex() {
     val graph = UndirectedGraph.complete(1)
     var visited = 0
     graph.forEachVertexBreadthFirst(graph[0]) { visited++ }
     assertEquals(1, visited)
   }
 
   @Test
-  fun `bfs on line graph visits all vertices`() {
+  fun bfsOnLineGraphVisitsAllVertices() {
     for (count in 1..Repeats) {
       val graph = buildUndirectedGraph {
         var last = addVertex()
@@ -46,15 +46,15 @@ class UndirectedGraphDFSTests {
   }
 
   @Test
-  fun `dfs on singleton graph visits one vertex`() {
+  fun dfsOnSingletonGraphVisitsOneVertex() {
     val graph = UndirectedGraph.complete(1)
     var visited = 0
     graph.forEachVertexDepthFirst(graph[0]) { visited++ }
     assertEquals(1, visited)
   }
 
   @Test
-  fun `dfs on line graph visits all vertices`() {
+  fun dfsOnLineGraphVisitsAllVertices() {
     for (count in 1..Repeats) {
       val graph = buildUndirectedGraph {
         var last = addVertex()

src/test/kotlin/io/github/alexandrepiveteau/graphs/UndirectedNetwork.traversals.kt → src/commonTest/kotlin/io/github/alexandrepiveteau/graphs/UndirectedNetwork.traversals.kt

@@ -8,21 +8,21 @@ import kotlin.test.assertFailsWith
 class UndirectedNetworkTraversalTests {
 
   @Test
-  fun `spfa on empty network throws exception`() {
+  fun spfaOnEmptyNetworkThrowsException() {
     assertFailsWith<NoSuchVertexException> {
       UndirectedNetwork.empty().shortestPathFasterAlgorithm(Vertex(0))
     }
   }
 
   @Test
-  fun `spfa on singleton associates distance zero`() {
+  fun spfaOnSingletonAssociatesDistanceZero() {
     val graph = buildUndirectedNetwork { addVertex() }
     val spfa = graph.shortestPathFasterAlgorithm(graph[0])
     assertEquals(0, spfa[0])
   }
 
   @Test
-  fun `spfa on complete graph associates distance one except for source`() {
+  fun spfaOnCompleteGraphAssociatesDistanceOneExceptForSource() {
     for (count in 1 until Repeats) {
       val graph = UndirectedNetwork.complete(count, 1)
       val spfa = graph.shortestPathFasterAlgorithm(graph[0])
@@ -34,7 +34,7 @@ class UndirectedNetworkTraversalTests {
   }
 
   @Test
-  fun `spfa computes minimum distance on simple graph`() {
+  fun spfaComputesMinimumDistanceOnSimpleGraph() {
     val graph = buildUndirectedNetwork {
       val (a, b, c, d, e) = addVertices()
       addEdge(a edgeTo b, 1)