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Former-commit-id: bdede6ed1b6f578f2ef046c338caf02d0b29d453 [formerly 7187de361b53e9c8ec121df379b762f2db736ea2]
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_embed/public/ace/demo/kitchen-sink/docs/kotlin.kt

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+/*Taken from http://try.kotlinlang.org/#/Examples/Longer%20examples/Life/Life.kt*/
+/**
+ * This is a straightforward implementation of The Game of Life
+ * See http://en.wikipedia.org/wiki/Conway's_Game_of_Life
+ */
+package life
+
+/*
+ * A field where cells live. Effectively immutable
+ */
+class Field(
+        val width: Int,
+        val height: Int,
+        // This function tells the constructor which cells are alive
+        // if init(i, j) is true, the cell (i, j) is alive
+        init: (Int, Int) -> Boolean
+) {
+    private val live: Array<Array<Boolean>> = Array(height) { i -> Array(width) { j -> init(i, j) } }
+
+    private fun liveCount(i: Int, j: Int)
+            = if (i in 0..height - 1 &&
+            j in 0..width - 1 &&
+            live[i][j]) 1 else 0
+
+    // How many neighbors of (i, j) are alive?
+    fun liveNeighbors(i: Int, j: Int) =
+            liveCount(i - 1, j - 1) +
+                    liveCount(i - 1, j) +
+                    liveCount(i - 1, j + 1) +
+                    liveCount(i, j - 1) +
+                    liveCount(i, j + 1) +
+                    liveCount(i + 1, j - 1) +
+                    liveCount(i + 1, j) +
+                    liveCount(i + 1, j + 1)
+
+    // You can say field[i, j], and this function gets called
+    operator fun get(i: Int, j: Int) = live[i][j]
+}
+
+/**
+ * This function takes the present state of the field
+ * and returns a new field representing the next moment of time
+ */
+fun next(field: Field): Field {
+    return Field(field.width, field.height) { i, j ->
+        val n = field.liveNeighbors(i, j)
+        if (field[i, j])
+        // (i, j) is alive
+            n in 2..3 // It remains alive iff it has 2 or 3 neighbors
+        else
+        // (i, j) is dead
+            n == 3 // A new cell is born if there are 3 neighbors alive
+    }
+}
+
+/** A few colony examples here */
+fun main(args: Array<String>) {
+    // Simplistic demo
+    runGameOfLife("***", 3)
+    // "Star burst"
+    runGameOfLife("""
+        _______
+        ___*___
+        __***__
+        ___*___
+        _______
+    """, 10)
+    // Stable colony
+    runGameOfLife("""
+        _____
+        __*__
+        _*_*_
+        __*__
+        _____
+    """, 3)
+    // Stable from the step 2
+    runGameOfLife("""
+        __**__
+        __**__
+        __**__
+    """, 3)
+    // Oscillating colony
+    runGameOfLife("""
+        __**____
+        __**____
+        ____**__
+        ____**__
+    """, 6)
+    // A fancier oscillating colony
+    runGameOfLife("""
+        -------------------
+        -------***---***---
+        -------------------
+        -----*----*-*----*-
+        -----*----*-*----*-
+        -----*----*-*----*-
+        -------***---***---
+        -------------------
+        -------***---***---
+        -----*----*-*----*-
+        -----*----*-*----*-
+        -----*----*-*----*-
+        -------------------
+        -------***---***---
+        -------------------
+    """, 10)
+}
+
+// UTILITIES
+
+fun runGameOfLife(fieldText: String, steps: Int) {
+    var field = makeField(fieldText)
+    for (step in 1..steps) {
+        println("Step: $step")
+        for (i in 0..field.height - 1) {
+            for (j in 0..field.width - 1) {
+                print(if (field[i, j]) "*" else " ")
+            }
+            println("")
+        }
+        field = next(field)
+    }
+}
+
+fun makeField(s: String): Field {
+    val lines = s.replace(" ", "").split('\n').filter({ it.isNotEmpty() })
+    val longestLine = lines.toList().maxBy { it.length } ?: ""
+
+    return Field(longestLine.length, lines.size) { i, j -> lines[i][j] == '*' }
+}