Rewrite number reducer in Kotlin.

core/src/main/java/org/nwapw/abacus/tree/NumberReducer.java

@@ -1,93 +0,0 @@
-package org.nwapw.abacus.tree;
-
-import org.nwapw.abacus.Abacus;
-import org.nwapw.abacus.function.NumberFunction;
-import org.nwapw.abacus.function.NumberOperator;
-import org.nwapw.abacus.function.TreeValueFunction;
-import org.nwapw.abacus.function.TreeValueOperator;
-import org.nwapw.abacus.number.NumberInterface;
-import org.nwapw.abacus.number.PromotionManager;
-import org.nwapw.abacus.number.PromotionResult;
-import org.nwapw.abacus.variables.VariableDatabase;
-
-/**
- * A reducer implementation that turns a tree into a single number.
- * This is not always guaranteed to work.
- */
-public class NumberReducer implements Reducer<NumberInterface> {
-
-    /**
-     * The plugin manager from which to draw the functions.
-     */
-    private Abacus abacus;
-
-    /**
-     * Creates a new number reducer.
-     *
-     * @param abacus the calculator instance.
-     */
-    public NumberReducer(Abacus abacus) {
-        this.abacus = abacus;
-    }
-
-    @Override
-    public NumberInterface reduceNode(TreeNode node, Object... children) {
-        PromotionManager manager = abacus.getPromotionManager();
-        if (node instanceof NumberNode) {
-            return abacus.getNumberImplementation().instanceForString(((NumberNode) node).getNumber());
-        } else if (node instanceof VariableNode) {
-            VariableDatabase database = abacus.getVariableDatabase();
-            String name = ((VariableNode) node).getVariable();
-            NumberInterface variable = database.getVariables().get(name);
-            if(variable != null) return variable;
-            TreeNode definition = database.getDefinitions().get(name);
-            if(definition != null) return definition.reduce(this);
-            return abacus.getNumberImplementation().instanceForString("0");
-        } else if (node instanceof NumberBinaryNode) {
-            NumberInterface left = (NumberInterface) children[0];
-            NumberInterface right = (NumberInterface) children[1];
-            NumberOperator operator = abacus.getPluginManager().operatorFor(((BinaryNode) node).getOperation());
-            PromotionResult result = manager.promote(left, right);
-            if (result == null) return null;
-            return operator.apply(result.getPromotedTo(), result.getItems());
-        } else if (node instanceof NumberUnaryNode) {
-            NumberInterface child = (NumberInterface) children[0];
-            NumberOperator operator = abacus.getPluginManager().operatorFor(((UnaryNode) node).getOperation());
-            return operator.apply(abacus.getPluginManager().interfaceImplementationFor(child.getClass()), child);
-        } else if (node instanceof FunctionNode) {
-            NumberInterface[] convertedChildren = new NumberInterface[children.length];
-            for (int i = 0; i < convertedChildren.length; i++) {
-                convertedChildren[i] = (NumberInterface) children[i];
-            }
-            NumberFunction function = abacus.getPluginManager().functionFor(((FunctionNode) node).getCallTo());
-            if (function == null) return null;
-            PromotionResult result = manager.promote(convertedChildren);
-            if (result == null) return null;
-            return function.apply(result.getPromotedTo(), result.getItems());
-        } else if (node instanceof TreeValueFunctionNode) {
-            CallNode callNode = (CallNode) node;
-            TreeNode[] realChildren = new TreeNode[callNode.getChildren().size()];
-            for (int i = 0; i < realChildren.length; i++) {
-                realChildren[i] = callNode.getChildren().get(i);
-            }
-            TreeValueFunction function =
-                    abacus.getPluginManager().treeValueFunctionFor(callNode.getCallTo());
-            if (function == null) return null;
-            return function.applyWithReducer(abacus.getNumberImplementation(), this, realChildren);
-        } else if (node instanceof TreeValueBinaryNode) {
-            BinaryNode binaryNode = (BinaryNode) node;
-            TreeValueOperator operator = abacus.getPluginManager()
-                    .treeValueOperatorFor(binaryNode.getOperation());
-            if (operator == null) return null;
-            return operator.applyWithReducer(abacus.getNumberImplementation(), this, binaryNode.getLeft(), binaryNode.getRight());
-        } else if (node instanceof TreeValueUnaryNode) {
-            UnaryNode unaryNode = (UnaryNode) node;
-            TreeValueOperator operator = abacus.getPluginManager()
-                    .treeValueOperatorFor(unaryNode.getOperation());
-            if (operator == null) return null;
-            return operator.applyWithReducer(abacus.getNumberImplementation(), this, unaryNode.getApplyTo());
-        }
-        return null;
-    }
-
-}

core/src/main/kotlin/org/nwapw/abacus/Abacus.kt

@@ -1,6 +1,8 @@
 package org.nwapw.abacus
 
 import org.nwapw.abacus.config.Configuration
+import org.nwapw.abacus.context.MutableReductionContext
+import org.nwapw.abacus.context.ReductionContext
 import org.nwapw.abacus.number.NumberInterface
 import org.nwapw.abacus.number.PromotionManager
 import org.nwapw.abacus.parsing.LexerTokenizer
@@ -36,10 +38,6 @@ class Abacus(val configuration: Configuration) {
      * The plugin manager used to handle loading and unloading plugins.
      */
     val pluginManager = PluginManager(this)
-    /**
-     * The reducer used to turn trees into a single number.
-     */
-    val numberReducer = NumberReducer(this)
     /**
      * The tree builder that handles the conversion of strings into trees.
      */
@@ -52,16 +50,16 @@ class Abacus(val configuration: Configuration) {
      * The database of variable definitions.
      */
     val variableDatabase = VariableDatabase(this)
+
     /**
-     * The number implementation used by default.
+     * The hidden, mutable implementation of the context.
      */
-    val numberImplementation: NumberImplementation
-        get() {
-            val selectedImplementation =
-                    pluginManager.numberImplementationFor(configuration.numberImplementation)
-            if (selectedImplementation != null) return selectedImplementation
-            return StandardPlugin.IMPLEMENTATION_NAIVE
-        }
+    private val mutableContext = MutableReductionContext(numberImplementation = StandardPlugin.IMPLEMENTATION_NAIVE)
+    /**
+     * The base context from which calculations are started.
+     */
+    val context: ReductionContext
+        get() = mutableContext
 
     init {
         pluginManager.addListener(tokenizer)
@@ -85,6 +83,7 @@ class Abacus(val configuration: Configuration) {
      * @param tree the tree to reduce, must not be null.
      * @return the resulting number, or null of the reduction failed.
      */
-    fun evaluateTree(tree: TreeNode): NumberInterface? = tree.reduce(numberReducer)
+    fun evaluateTree(tree: TreeNode): NumberInterface? =
+            tree.reduce(NumberReducer(this, context.mutableSubInstance()))
 
 }

core/src/main/kotlin/org/nwapw/abacus/tree/NumberReducer.kt

@@ -0,0 +1,57 @@
+package org.nwapw.abacus.tree
+
+import org.nwapw.abacus.Abacus
+import org.nwapw.abacus.context.MutableReductionContext
+import org.nwapw.abacus.function.NumberFunction
+import org.nwapw.abacus.number.NumberInterface
+
+class NumberReducer(val abacus: Abacus, val context: MutableReductionContext) : Reducer<NumberInterface> {
+
+    override fun reduceNode(treeNode: TreeNode, vararg children: Any): NumberInterface? {
+        val promotionManager = abacus.promotionManager
+        return when(treeNode){
+            is NumberNode -> {
+                context.inheritedNumberImplementation?.instanceForString(treeNode.number)
+            }
+            is VariableNode -> {
+                val variable = context.getVariable(treeNode.variable)
+                if(variable != null) return variable
+                val definition = context.getDefinition(treeNode.variable)
+                if(definition != null) return definition.reduce(this)
+                null
+            }
+            is NumberUnaryNode -> {
+                val child = children[0] as NumberInterface
+                abacus.pluginManager.operatorFor(treeNode.operation)
+                        .apply(abacus.pluginManager.interfaceImplementationFor(child.javaClass), child)
+            }
+            is NumberBinaryNode -> {
+                val left = children[0] as NumberInterface
+                val right = children[1] as NumberInterface
+                val promotionResult = promotionManager.promote(left, right) ?: return null
+                abacus.pluginManager.operatorFor(treeNode.operation).apply(promotionResult.promotedTo, *promotionResult.items)
+            }
+            is FunctionNode -> {
+                val promotionResult = promotionManager
+                        .promote(*children.map { it as NumberInterface }.toTypedArray()) ?: return null
+                abacus.pluginManager.functionFor(treeNode.callTo).apply(promotionResult.promotedTo, *promotionResult.items)
+            }
+            is TreeValueUnaryNode -> {
+                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
+                        .applyWithReducer(context.inheritedNumberImplementation!!, this, children[0] as TreeNode)
+            }
+            is TreeValueBinaryNode -> {
+                abacus.pluginManager.treeValueOperatorFor(treeNode.operation)
+                        .applyWithReducer(context.inheritedNumberImplementation!!, this,
+                                children[0] as TreeNode, children[1] as TreeNode)
+            }
+            is TreeValueFunctionNode -> {
+                abacus.pluginManager.treeValueFunctionFor(treeNode.callTo)
+                        .applyWithReducer(context.inheritedNumberImplementation!!, this,
+                                *children.map { it as TreeNode }.toTypedArray())
+            }
+            else -> null
+        }
+    }
+
+}