Added support for evaluating mathematical expressions via Crunch

eco-api/src/main/java/com/willfp/eco/core/integrations/placeholder/PlaceholderIntegration.java

@@ -5,6 +5,9 @@ import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Wrapper class for placeholder integrations.
  */
@@ -24,4 +27,14 @@ public interface PlaceholderIntegration extends Integration {
      */
     String translate(@NotNull String text,
                      @Nullable Player player);
+
+    /**
+     * Find all placeholders in a given text.
+     *
+     * @param text The text.
+     * @return The placeholders.
+     */
+    default List<String> findPlaceholdersIn(@NotNull String text) {
+        return new ArrayList<>();
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/integrations/placeholder/PlaceholderManager.java

@@ -4,8 +4,10 @@ import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -80,6 +82,21 @@ public final class PlaceholderManager {
         return processed;
     }
 
+    /**
+     * Find all placeholders in a given text.
+     *
+     * @param text The text.
+     * @return The placeholders.
+     */
+    public static List<String> findPlaceholdersIn(@NotNull final String text) {
+        List<String> found = new ArrayList<>();
+        for (PlaceholderIntegration integration : REGISTERED_INTEGRATIONS) {
+            found.addAll(integration.findPlaceholdersIn(text));
+        }
+
+        return found;
+    }
+
     private PlaceholderManager() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }

eco-api/src/main/java/com/willfp/eco/util/NumberUtils.java

@@ -1,11 +1,15 @@
 package com.willfp.eco.util;
 
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.text.DecimalFormat;
 import java.util.Map;
 import java.util.TreeMap;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.BiFunction;
 
 /**
  * Utilities / API methods for numbers.
@@ -16,6 +20,11 @@ public final class NumberUtils {
      */
     private static final double[] SIN_LOOKUP = new double[65536];
 
+    /**
+     * Crunch handler.
+     */
+    private static BiFunction<@NotNull String, @Nullable Player, @NotNull Double> crunch;
+
     /**
      * Set of roman numerals to look up.
      */
@@ -218,6 +227,38 @@ public final class NumberUtils {
         return formatted.endsWith("00") ? String.valueOf((int) toFormat) : formatted;
     }
 
+    /**
+     * Evaluate an expression.
+     *
+     * @param expression The expression.
+     * @return The value of the expression.
+     */
+    public static double evaluateExpression(@NotNull final String expression) {
+        return evaluateExpression(expression, null);
+    }
+
+    /**
+     * Evaluate an expression with respect to a player (for placeholders).
+     *
+     * @param expression The expression.
+     * @param player     The player.
+     * @return The value of the expression.
+     */
+    public static double evaluateExpression(@NotNull final String expression,
+                                            @Nullable final Player player) {
+        return crunch.apply(expression, player);
+    }
+
+    /**
+     * Init crunch handler.
+     *
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public static void initCrunch(@NotNull final BiFunction<@NotNull String, @Nullable Player, @NotNull Double> handler) {
+        crunch = handler;
+    }
+
     private NumberUtils() {
         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
     }