syntax: implement ES6-like spread operator

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

3 files changed, 126 insertions, 0 deletions

diff --git a/tests/00_syntax/13_object_literals b/tests/00_syntax/13_object_literals
index 4b4f934..60c9f32 100644
--- a/tests/00_syntax/13_object_literals
+++ b/tests/00_syntax/13_object_literals
@@ -49,3 +49,44 @@ either JSON or JavaScript notation.
 	print(third_obj, "\n");
 	print(nested_obj, "\n");
 -- End --
+
+
+Additionally, utpl implements ES6-like spread operators to allow shallow copying
+of object properties into other objects.
+
+-- Expect stdout --
+{ "foo": true, "bar": false }
+{ "foo": true, "bar": false, "baz": 123, "qrx": 456 }
+{ "foo": false, "bar": true, "baz": 123, "qrx": 456 }
+{ "foo": true, "bar": false }
+{ "foo": true, "bar": false, "level2": { "baz": 123, "qrx": 456 } }
+{ "foo": true, "bar": false, "0": 7, "1": 8, "2": 9 }
+-- End --
+
+-- Testcase --
+{%
+	o1 = { foo: true, bar: false };
+	o2 = { baz: 123, qrx: 456 };
+	arr = [7, 8, 9];
+
+	print(join("\n", [
+		// copying one object into another
+		{ ...o1 },
+
+		// combining two objects
+		{ ...o1, ...o2 },
+
+		// copying object and override properties
+		{ ...o1, ...o2, foo: false, bar: true },
+
+		// default properties overwritten by spread operator
+		{ foo: 123, bar: 456, ...o1 },
+
+		// nested spread operators
+		{ ...o1, level2: { ...o2 } },
+
+		// merging array into objects
+		{ ...o1, ...arr }
+	]), "\n");
+%}
+-- End --
diff --git a/tests/00_syntax/14_array_literals b/tests/00_syntax/14_array_literals
index ea5f9c0..941ee4a 100644
--- a/tests/00_syntax/14_array_literals
+++ b/tests/00_syntax/14_array_literals
@@ -23,3 +23,60 @@ The utpl script language supports declaring arrays using JSON notation.
 	print(empty_array, "\n");
 	print(json_array, "\n");
 -- End --
+
+
+Additionally, utpl implements ES6-like spread operators to allow shallow copying
+of array values into other arrays.
+
+-- Expect stdout --
+[ 1, 2, 3 ]
+[ 1, 2, 3, 4, 5, 6 ]
+[ 1, 2, 3, 4, 5, 6, false, true ]
+[ 1, 2, 3, false, true, 4, 5, 6 ]
+[ 1, 2, 3, [ 4, 5, 6 ] ]
+-- End --
+
+-- Testcase --
+{%
+	a1 = [ 1, 2, 3 ];
+	a2 = [ 4, 5, 6 ];
+
+	print(join("\n", [
+		// copying one array into another
+		[ ...a1 ],
+
+		// combining two arrays
+		[ ...a1, ...a2 ],
+
+		// copying array and append values
+		[ ...a1, ...a2, false, true ],
+
+		// copy array and interleave values
+		[ ...a1, false, true, ...a2 ],
+
+		// nested spread operators
+		[ ...a1, [ ...a2 ] ]
+	]), "\n");
+%}
+-- End --
+
+Contrary to merging arrays into objects, objects cannot be merged into arrays.
+
+-- Expect stderr --
+Type error: ({ "foo": true, "bar": false }) is not iterable
+In line 5, byte 21:
+
+ `    print([ ...arr, ...obj ], "\n");`
+  Near here -------------^
+
+
+-- End --
+
+-- Testcase --
+{%
+	arr = [ 1, 2, 3 ];
+	obj = { foo: true, bar: false };
+
+	print([ ...arr, ...obj ], "\n");
+%}
+-- End --
diff --git a/tests/00_syntax/15_function_declarations b/tests/00_syntax/15_function_declarations
index 1ed6f83..f02f90a 100644
--- a/tests/00_syntax/15_function_declarations
+++ b/tests/00_syntax/15_function_declarations
@@ -96,3 +96,31 @@ function variadic_2(...args) { ... }
 	]), "\n");
 %}
 -- End --
+
+
+Complementary to the "rest" argument syntax, the spread operator may be
+used in function call arguments to pass arrays of values as argument list.
+
+-- Expect stdout --
+[ 1, 2, 3, 4, 5, 6 ]
+[ 4, 5, 6, 1, 2, 3 ]
+[ 1, 2, 3, 1, 2, 3 ]
+[ 1, 2, 3 ]
+-- End --
+
+-- Testcase --
+{%
+	arr = [ 1, 2, 3 ];
+
+	function test(...args) {
+		return args;
+	}
+
+	print(join("\n", [
+		test(...arr, 4, 5, 6),
+		test(4, 5, 6, ...arr),
+		test(...arr, ...arr),
+		test(...arr)
+	]), "\n");
+%}
+-- End --