From 87529da15f6039bdf179fe9f95b2a0629c0834bb Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Mon, 11 Sep 2017 18:55:59 -0700
Subject: [PATCH] Precompute all the transitions ahead of time.

---
 .../nwapw/abacus/number/PromotionManager.kt   | 31 ++++++++-----------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/core/src/main/kotlin/org/nwapw/abacus/number/PromotionManager.kt b/core/src/main/kotlin/org/nwapw/abacus/number/PromotionManager.kt
index 421d642..a49a61c 100644
--- a/core/src/main/kotlin/org/nwapw/abacus/number/PromotionManager.kt
+++ b/core/src/main/kotlin/org/nwapw/abacus/number/PromotionManager.kt
@@ -37,21 +37,6 @@ class PromotionManager(val abacus: Abacus) : PluginListener {
         return null
     }
 
-    /**
-     * If a path between the given implementations has already been computed, uses
-     * the already calculated path. Otherwise, calls [computePathBetween] to compute a new
-     * path.
-     *
-     * @param from the implementation to start from.
-     * @param to the implementation to get to.
-     * @return the resulting promotion path, or null if it is not found
-     */
-    fun getPathBetween(from: NumberImplementation, to: NumberImplementation): PromotionPath? {
-        return computePaths.computeIfAbsent(from to to, {
-             computePathBetween(it.first, it.second)
-        })
-    }
-
     /**
      * Promote all the numbers in the list to the same number implementation, to ensure
      * they can be used with each other. Finds the highest priority implementation
@@ -66,16 +51,26 @@ class PromotionManager(val abacus: Abacus) : PluginListener {
         val highestPriority = implementations.sortedBy { it.priority }.last()
         return PromotionResult(items = numbers.map {
             if(it.javaClass == highestPriority.implementation) it
-            else getPathBetween(pluginManager.interfaceImplementationFor(it.javaClass), highestPriority)
+            else computePaths[pluginManager.interfaceImplementationFor(it.javaClass) to highestPriority]
                     ?.promote(it) ?: return null
         }.toTypedArray(), promotedTo = highestPriority)
     }
 
-    override fun onLoad(manager: PluginManager?) {
+    override fun onLoad(manager: PluginManager) {
+        val implementations = manager.allNumberImplementations.map { manager.numberImplementationFor(it) }
+        for((index, value) in implementations.withIndex()){
+            for(i in index until implementations.size){
+                val other = implementations[i]
 
+                val promoteFrom = if(other.priority > value.priority) value else other
+                val promoteTo = if(other.priority > value.priority) other else value
+                val path = computePathBetween(promoteFrom, promoteTo)
+                computePaths.put(promoteFrom to promoteTo, path)
+            }
+        }
     }
 
-    override fun onUnload(manager: PluginManager?) {
+    override fun onUnload(manager: PluginManager) {
         computePaths.clear()
     }