Add not predicate and docs to custom predicates

[no changelog]

src/main/kotlin/moe/nea/firmament/features/texturepack/AlwaysPredicate.kt

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Linnea Gräf <nea@nea.moe>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package moe.nea.firmament.features.texturepack
+
+import com.google.gson.JsonElement
+import net.minecraft.item.ItemStack
+
+object AlwaysPredicate : FirmamentModelPredicate {
+    override fun test(stack: ItemStack): Boolean {
+        return true
+    }
+
+    object Parser : FirmamentModelPredicateParser {
+        override fun parse(jsonElement: JsonElement): FirmamentModelPredicate {
+            return AlwaysPredicate
+        }
+    }
+}

src/main/kotlin/moe/nea/firmament/features/texturepack/CustomModelOverrideParser.kt

@@ -23,6 +23,7 @@ object CustomModelOverrideParser {
         registerPredicateParser("lore", LorePredicate.Parser)
         registerPredicateParser("all", AndPredicate.Parser)
         registerPredicateParser("any", OrPredicate.Parser)
+        registerPredicateParser("not", NotPredicate.Parser)
     }
 
     fun parsePredicates(predicates: JsonObject): List<FirmamentModelPredicate> {

src/main/kotlin/moe/nea/firmament/features/texturepack/NotPredicate.kt

@@ -0,0 +1,23 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Linnea Gräf <nea@nea.moe>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package moe.nea.firmament.features.texturepack
+
+import com.google.gson.JsonElement
+import com.google.gson.JsonObject
+import net.minecraft.item.ItemStack
+
+class NotPredicate(val children: Array<FirmamentModelPredicate>) : FirmamentModelPredicate {
+    override fun test(stack: ItemStack): Boolean {
+        return children.none { it.test(stack) }
+    }
+
+    object Parser : FirmamentModelPredicateParser {
+        override fun parse(jsonElement: JsonElement): FirmamentModelPredicate {
+            return NotPredicate(CustomModelOverrideParser.parsePredicates(jsonElement as JsonObject).toTypedArray())
+        }
+    }
+}

src/main/kotlin/moe/nea/firmament/features/texturepack/StringMatcher.kt

@@ -52,7 +52,7 @@ interface StringMatcher {
             }
             if (jsonElement is JsonObject) {
                 val regex = jsonElement["regex"] as JsonPrimitive?
-                val text = jsonElement["text"] as JsonPrimitive?
+                val text = jsonElement["equals"] as JsonPrimitive?
                 val shouldStripColor = when (val color = (jsonElement["color"] as JsonPrimitive?)?.asString) {
                     "preserve" -> false
                     "strip", null -> true