Added SimplePlaceholder and SimpleInjectablePlaceholder

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

@@ -64,7 +64,10 @@ public final class StaticPlaceholder implements InjectablePlaceholder {
     @Override
     public String tryTranslateQuickly(@NotNull final String text,
                                       @NotNull final PlaceholderContext context) {
-        return text.replace("%" + this.identifier + "%", this.getValue(this.identifier, context));
+        return text.replace(
+                "%" + this.identifier + "%",
+                Objects.requireNonNullElse(this.getValue(this.identifier, context), "")
+        );
     }
 
     @NotNull

eco-api/src/main/java/com/willfp/eco/core/placeholder/templates/SimpleInjectablePlaceholder.java

@@ -0,0 +1,72 @@
+package com.willfp.eco.core.placeholder.templates;
+
+import com.willfp.eco.core.placeholder.InjectablePlaceholder;
+import com.willfp.eco.core.placeholder.context.PlaceholderContext;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+/**
+ * A template class for simple placeholders.
+ */
+public abstract class SimpleInjectablePlaceholder implements InjectablePlaceholder {
+    /**
+     * The name of the placeholder.
+     */
+    private final String identifier;
+
+    /**
+     * The placeholder pattern.
+     */
+    private final Pattern pattern;
+
+    /**
+     * Create a new simple injectable placeholder.
+     *
+     * @param identifier The identifier.
+     */
+    protected SimpleInjectablePlaceholder(@NotNull final String identifier) {
+        this.identifier = identifier;
+        this.pattern = Pattern.compile(identifier);
+    }
+
+    @Override
+    public String tryTranslateQuickly(@NotNull final String text,
+                                      @NotNull final PlaceholderContext context) {
+        return text.replace(
+                "%" + this.identifier + "%",
+                Objects.requireNonNullElse(this.getValue(this.identifier, context), "")
+        );
+    }
+
+    @Override
+    public @NotNull Pattern getPattern() {
+        return pattern;
+    }
+
+    @Override
+    public String toString() {
+        return "SimpleInjectablePlaceholder{" +
+                "identifier='" + identifier + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(@NotNull final Object o) {
+        if (this == o) {
+            return true;
+        }
+
+        if (!(o instanceof SimpleInjectablePlaceholder that)) {
+            return false;
+        }
+
+        return Objects.equals(identifier, that.identifier);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(identifier);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/placeholder/templates/SimplePlaceholder.java

@@ -0,0 +1,89 @@
+package com.willfp.eco.core.placeholder.templates;
+
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.placeholder.RegistrablePlaceholder;
+import com.willfp.eco.core.placeholder.context.PlaceholderContext;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+/**
+ * A template class for simple placeholders.
+ */
+public abstract class SimplePlaceholder implements RegistrablePlaceholder {
+    /**
+     * The plugin.
+     */
+    private final EcoPlugin plugin;
+
+    /**
+     * The name of the placeholder.
+     */
+    private final String identifier;
+
+    /**
+     * The placeholder pattern.
+     */
+    private final Pattern pattern;
+
+    /**
+     * Create a new simple placeholder.
+     *
+     * @param plugin     The plugin.
+     * @param identifier The identifier.
+     */
+    protected SimplePlaceholder(@NotNull final EcoPlugin plugin,
+                                @NotNull final String identifier) {
+        this.plugin = plugin;
+        this.identifier = identifier;
+        this.pattern = Pattern.compile(identifier);
+    }
+
+    @Override
+    public String tryTranslateQuickly(@NotNull final String text,
+                                      @NotNull final PlaceholderContext context) {
+        return text.replace(
+                "%" + this.identifier + "%",
+                Objects.requireNonNullElse(this.getValue(this.identifier, context), "")
+        );
+    }
+
+    @Override
+    public @NotNull Pattern getPattern() {
+        return pattern;
+    }
+
+    @NotNull
+    @Override
+    public EcoPlugin getPlugin() {
+        return plugin;
+    }
+
+    @Override
+    public String toString() {
+        return "SimplePlaceholder{" +
+                "plugin='" + plugin + '\'' +
+                "identifier='" + identifier + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(@NotNull final Object o) {
+        if (this == o) {
+            return true;
+        }
+
+        if (!(o instanceof SimpleInjectablePlaceholder that)) {
+            return false;
+        }
+
+        return Objects.equals(pattern, that.getPattern())
+                && Objects.equals(plugin, that.getPlugin());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(identifier, plugin);
+    }
+}