Pull the find() function up to the abstract Grid

Author: rhaendel

src/main/kotlin/de/ronny_h/aoc/extensions/Grid.kt

@@ -65,6 +65,15 @@ abstract class Grid<T>(
         }
     }
 
+    /**
+     * Returns the first element matching the given `value`.
+     *
+     * @throws NoSuchElementException If no matching element can be found.
+     */
+    fun find(value: T): Coordinates = forEachElement { row, col, element ->
+        if (element == value) Coordinates(row, col) else null
+    }.filterNotNull().first()
+
     fun printGrid(
         overrides: Set<Coordinates> = setOf(),
         overrideChar: Char = '#',

src/main/kotlin/de/ronny_h/aoc/year24/day06/GuardGallivant.kt

@@ -58,10 +58,6 @@ private class Lab(input: List<String>) : Grid<Char>(input, ' ') {
     private val offMap = nullElement
     override fun Char.toElementType() = this
 
-    private fun findTheGuard(): Coordinates = forEachElement { row, col, element ->
-        if (element == guard) Coordinates(row, col) else null
-    }.filterNotNull().first()
-
     @OptIn(ExperimentalCoroutinesApi::class)
     fun freePositions(scope: CoroutineScope, bufferSize: Int) = scope.produce(capacity = bufferSize) {
         forEachElement { row, col, char ->
@@ -78,7 +74,7 @@ private class Lab(input: List<String>) : Grid<Char>(input, ' ') {
         visit: (Coordinates, Direction) -> Boolean,
     ) {
         var direction = NORTH
-        var position = findTheGuard()
+        var position = find(guard)
         var doWalkFurther = true
 
         while (getAt(position) != offMap && doWalkFurther) {

src/main/kotlin/de/ronny_h/aoc/year24/day15/WarehouseWoes.kt

@@ -56,7 +56,7 @@ abstract class Warehouse(input: List<String>) : Grid<Char>(input, '#') {
     protected abstract fun tryToMove(from: Coordinates, direction: Direction, thing: Char): Boolean
 
     fun moveRobot(movements: List<Direction>) {
-        movements.fold(findTheRobot()) { position, direction ->
+        movements.fold(find(robot)) { position, direction ->
             if (tryToMove(position, direction, robot)) {
                 position + direction
             } else {
@@ -65,10 +65,6 @@ abstract class Warehouse(input: List<String>) : Grid<Char>(input, '#') {
         }
     }
 
-    private fun findTheRobot(): Coordinates = forEachElement { row, col, element ->
-        if (element == robot) Coordinates(row, col) else null
-    }.filterNotNull().first()
-
     // GPS = Goods Positioning System
     fun sumGPSCoordinates(): Int = forEachElement { row, col, element ->
         if (element == leftGoodsChar) {

src/main/kotlin/de/ronny_h/aoc/year24/day20/RaceCondition.kt

@@ -27,13 +27,6 @@ private class RaceTrack(input: List<String>) : Grid<Char>(input, '#') {
     private val start = find('S')
     private val goal = find('E')
 
-    private fun find(symbol: Char): Coordinates = forEachElement { row, col, elem ->
-        when (elem) {
-            symbol -> Coordinates(row, col)
-            else -> null
-        }
-    }.filterNotNull().first()
-
     fun shortestPath(): ShortestPath<Coordinates> {
         val neighbours: (Coordinates) -> List<Coordinates> = { node ->
             Direction

src/test/kotlin/de/ronny_h/aoc/extensions/GridTest.kt

@@ -1,7 +1,10 @@
 package de.ronny_h.aoc.extensions
 
 import com.github.stefanbirkner.systemlambda.SystemLambda.tapSystemOut
+import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.core.spec.style.StringSpec
+import io.kotest.data.forAll
+import io.kotest.data.row
 import io.kotest.matchers.shouldBe
 import io.kotest.matchers.shouldNotBe
 
@@ -14,12 +17,21 @@ class GridTest : StringSpec() {
     private val newLine: String = System.lineSeparator()
 
     init {
-
         "a grid can be constructed from List of String" {
             val grid = simpleCharGridOf(listOf("12", "34"))
             grid shouldNotBe null
         }
 
+        "a grid can be constructed with overrides" {
+            val grid = object : Grid<Char>(2, 2, ' ', 'x', listOf(Coordinates(1, 1))) {
+                override fun Char.toElementType() = this
+            }
+            grid[0, 0] shouldBe ' '
+            grid[0, 1] shouldBe ' '
+            grid[1, 0] shouldBe ' '
+            grid[1, 1] shouldBe 'x'
+        }
+
         "width and height have the right values" {
             val grid = simpleCharGridOf(listOf("00", "00", "00"))
             grid.height shouldBe 3
@@ -101,6 +113,24 @@ class GridTest : StringSpec() {
                     )
         }
 
+        "find() finds all Coordinates" {
+            val grid = simpleCharGridOf(listOf("12", "34"))
+            forAll(
+                row('1', Coordinates(0, 0)),
+                row('2', Coordinates(0, 1)),
+                row('3', Coordinates(1, 0)),
+                row('4', Coordinates(1, 1)),
+            ) { char, result ->
+                grid.find(char) shouldBe result
+            }
+        }
+
+        "find() throws a NoSuchElementException if the value cannot be found" {
+            shouldThrow<NoSuchElementException> {
+                simpleCharGridOf(listOf("12", "34")).find('5')
+            }
+        }
+
         "printGrid prints the grid" {
             val output = tapSystemOut {
                 val grid = simpleCharGridOf(listOf("12", "34"))