Add Dictionary.find_key()

5 files changed, 38 insertions, 1 deletions

diff --git a/core/variant/dictionary.cpp b/core/variant/dictionary.cpp
index d9f4359ee5..c1cb782a57 100644
--- a/core/variant/dictionary.cpp
+++ b/core/variant/dictionary.cpp
@@ -195,6 +195,15 @@ bool Dictionary::has_all(const Array &p_keys) const {
 	return true;
 }
 
+Variant Dictionary::find_key(const Variant &p_value) const {
+	for (const KeyValue<Variant, Variant> &E : _p->variant_map) {
+		if (E.value == p_value) {
+			return E.key;
+		}
+	}
+	return Variant();
+}
+
 bool Dictionary::erase(const Variant &p_key) {
 	ERR_FAIL_COND_V_MSG(_p->read_only, false, "Dictionary is in read-only state.");
 	if (p_key.get_type() == Variant::STRING_NAME) {
diff --git a/core/variant/dictionary.h b/core/variant/dictionary.h
index 2632893e8d..d9c9db56cf 100644
--- a/core/variant/dictionary.h
+++ b/core/variant/dictionary.h
@@ -66,6 +66,7 @@ public:
 
 	bool has(const Variant &p_key) const;
 	bool has_all(const Array &p_keys) const;
+	Variant find_key(const Variant &p_value) const;
 
 	bool erase(const Variant &p_key);
 
diff --git a/core/variant/variant_call.cpp b/core/variant/variant_call.cpp
index eba12b68bb..ab262629da 100644
--- a/core/variant/variant_call.cpp
+++ b/core/variant/variant_call.cpp
@@ -2009,6 +2009,7 @@ static void _register_variant_builtin_methods() {
 	bind_method(Dictionary, merge, sarray("dictionary", "overwrite"), varray(false));
 	bind_method(Dictionary, has, sarray("key"), varray());
 	bind_method(Dictionary, has_all, sarray("keys"), varray());
+	bind_method(Dictionary, find_key, sarray("value"), varray());
 	bind_method(Dictionary, erase, sarray("key"), varray());
 	bind_method(Dictionary, hash, sarray(), varray());
 	bind_method(Dictionary, keys, sarray(), varray());
diff --git a/doc/classes/Dictionary.xml b/doc/classes/Dictionary.xml
index 40b5e88fff..9dbeeb360c 100644
--- a/doc/classes/Dictionary.xml
+++ b/doc/classes/Dictionary.xml
@@ -4,7 +4,7 @@
 		Dictionary type.
 	</brief_description>
 	<description>
-		Dictionary type. Associative container which contains values referenced by unique keys. Dictionaries are composed of pairs of keys (which must be unique) and values. Dictionaries will preserve the insertion order when adding elements, even though this may not be reflected when printing the dictionary. In other programming languages, this data structure is sometimes referred to as a hash map or associative array.
+		Dictionary type. Associative container which contains values referenced by unique keys. Dictionaries are composed of pairs of keys (which must be unique) and values. Dictionaries will preserve the insertion order when adding elements. In other programming languages, this data structure is sometimes referred to as a hash map or associative array.
 		You can define a dictionary by placing a comma-separated list of [code]key: value[/code] pairs in curly braces [code]{}[/code].
 		Erasing elements while iterating over them [b]is not supported[/b] and will result in undefined behavior.
 		[b]Note:[/b] Dictionaries are always passed by reference. To get a copy of a dictionary which can be modified independently of the original dictionary, use [method duplicate].
@@ -218,6 +218,14 @@
 				[b]Note:[/b] Don't erase elements while iterating over the dictionary. You can iterate over the [method keys] array instead.
 			</description>
 		</method>
+		<method name="find_key" qualifiers="const">
+			<return type="Variant" />
+			<param index="0" name="value" type="Variant" />
+			<description>
+				Returns the first key whose associated value is equal to [param value], or [code]null[/code] if no such value is found.
+				[b]Node:[/b] [code]null[/code] is also a valid key. I you have it in your [Dictionary], the [method find_key] method can give misleading results.
+			</description>
+		</method>
 		<method name="get" qualifiers="const">
 			<return type="Variant" />
 			<param index="0" name="key" type="Variant" />
diff --git a/tests/core/variant/test_dictionary.h b/tests/core/variant/test_dictionary.h
index 729035919d..c98434d42c 100644
--- a/tests/core/variant/test_dictionary.h
+++ b/tests/core/variant/test_dictionary.h
@@ -500,6 +500,24 @@ TEST_CASE("[Dictionary] Recursive self comparison") {
 	d2.clear();
 }
 
+TEST_CASE("[Dictionary] Order and find") {
+	Dictionary d;
+	d[4] = "four";
+	d[8] = "eight";
+	d[12] = "twelve";
+	d["4"] = "four";
+
+	Array keys;
+	keys.append(4);
+	keys.append(8);
+	keys.append(12);
+	keys.append("4");
+
+	CHECK_EQ(d.keys(), keys);
+	CHECK_EQ(d.find_key("four"), Variant(4));
+	CHECK_EQ(d.find_key("does not exist"), Variant());
+}
+
 } // namespace TestDictionary
 
 #endif // TEST_DICTIONARY_H