feat(validator): Support validators for config values.

BREAKING CHANGE: `ValueManifest` and `ConfigValue` added a new type "UNIT" to mark the minimal unit value of this instance.

link #132

core/src/main/java/cc/carm/lib/configuration/source/loader/ConfigurationInitializer.java

@@ -1,6 +1,7 @@
 package cc.carm.lib.configuration.source.loader;
 
 import cc.carm.lib.configuration.Configuration;
+import cc.carm.lib.configuration.function.ValueValidator;
 import cc.carm.lib.configuration.source.ConfigurationHolder;
 import cc.carm.lib.configuration.source.meta.ConfigurationMetadata;
 import cc.carm.lib.configuration.source.meta.StandardMeta;
@@ -95,6 +96,14 @@ public class ConfigurationInitializer {
         registerFieldAnnotation(annotation, metadata, extractor);
     }
 
+    public <A extends Annotation> void registerValidAnnotation(@NotNull Class<A> annotation,
+                                                               @NotNull Function<A, ValueValidator<Object>> builder) {
+        appendFieldInitializer((holder, path, field, instance) -> {
+            A data = field.getAnnotation(annotation);
+            if (data == null) return;
+            instance.validate((h, t) -> builder.apply(data).validate(h, t));
+        });
+    }
 
     public @Nullable String getFieldPath(@NotNull ConfigurationHolder<?> holder, @Nullable String parentPath, @NotNull Field field) {
         return pathGenerator.getFieldPath(holder, parentPath, field);

features/validators/src/main/java/cc/carm/lib/configuration/validators/StandardValidators.java

@@ -1,8 +0,0 @@
-package cc.carm.lib.configuration.validators;
-
-public class StandardValidators {
-
-    
-
-
-}

features/validators/src/main/java/cc/carm/lib/configuration/validators/Validators.java

@@ -0,0 +1,40 @@
+package cc.carm.lib.configuration.validators;
+
+import cc.carm.lib.configuration.annotation.ValuePattern;
+import cc.carm.lib.configuration.annotation.ValueRange;
+import cc.carm.lib.configuration.function.ValueValidator;
+import cc.carm.lib.configuration.source.ConfigurationHolder;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.regex.Pattern;
+
+public class Validators {
+
+    public static void initialize(ConfigurationHolder<?> holder) {
+        holder.initializer().registerValidAnnotation(ValueRange.class, r -> (ho, value) -> {
+            if (!(value instanceof Number)) {
+                throw new IllegalArgumentException("Value is not a number: " + value);
+            }
+
+            Number number = (Number) value;
+            if (number.doubleValue() < r.min() || number.doubleValue() > r.max()) {
+                throw new IllegalArgumentException(r.message());
+            }
+        });
+
+        holder.initializer().registerValidAnnotation(ValuePattern.class, r -> new ValueValidator<Object>() {
+            private final Pattern pattern = Pattern.compile(r.value());
+
+            @Override
+            public void validate(@NotNull ConfigurationHolder<?> holder, @Nullable Object value) throws Exception {
+                if (value == null) return;
+                if (!pattern.matcher(value.toString()).matches()) {
+                    throw new IllegalArgumentException(r.message());
+                }
+            }
+        });
+
+    }
+
+}