Merge pull request #80085 from vnen/gdscript-pattern-guards

GDScript: Implement pattern guards for match statement

modules/gdscript/tests/scripts/analyzer/errors/match_guard_invalid_expression.gd

@@ -0,0 +1,4 @@
+func test():
+	match 0:
+		_ when a == 0:
+			print("a does not exist")

modules/gdscript/tests/scripts/analyzer/errors/match_guard_invalid_expression.out

@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Identifier "a" not declared in the current scope.

modules/gdscript/tests/scripts/parser/errors/match_guard_with_assignment.gd

@@ -0,0 +1,5 @@
+func test():
+	var a = 0
+	match a:
+		0 when a = 1:
+			print("assignment not allowed on pattern guard")

modules/gdscript/tests/scripts/parser/errors/match_guard_with_assignment.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Assignment is not allowed inside an expression.

modules/gdscript/tests/scripts/parser/features/allowed_keywords_as_identifiers.gd

@@ -14,3 +14,7 @@ func test():
 
 	var TAU = "TAU"
 	print(TAU)
+
+	# New keyword for pattern guards.
+	var when = "when"
+	print(when)

modules/gdscript/tests/scripts/parser/features/allowed_keywords_as_identifiers.out

@@ -4,3 +4,4 @@ PI
 INF
 NAN
 TAU
+when

modules/gdscript/tests/scripts/runtime/features/match_with_pattern_guards.gd

@@ -0,0 +1,71 @@
+var global := 0
+
+func test():
+	var a = 0
+	var b = 1
+
+	match a:
+		0 when b == 0:
+			print("does not run" if true else "")
+		0 when b == 1:
+			print("guards work")
+		_:
+			print("does not run")
+
+	match a:
+		var a_bind when b == 0:
+			prints("a is", a_bind, "and b is 0")
+		var a_bind when b == 1:
+			prints("a is", a_bind, "and b is 1")
+		_:
+			print("does not run")
+
+	match a:
+		var a_bind when a_bind < 0:
+			print("a is less than zero")
+		var a_bind when a_bind == 0:
+			print("a is equal to zero")
+		_:
+			print("a is more than zero")
+
+	match [1, 2, 3]:
+		[1, 2, var element] when element == 0:
+			print("does not run")
+		[1, 2, var element] when element == 3:
+			print("3rd element is 3")
+
+	match a:
+		_ when b == 0:
+			print("does not run")
+		_ when b == 1:
+			print("works with wildcard too.")
+		_:
+			print("does not run")
+
+	match a:
+		0, 1 when b == 0:
+			print("does not run")
+		0, 1 when b == 1:
+			print("guard with multiple patterns")
+		_:
+			print("does not run")
+
+	match a:
+		0 when b == 0:
+			print("does not run")
+		0:
+			print("regular pattern after guard mismatch")
+
+	match a:
+		1 when side_effect():
+			print("should not run the side effect call")
+		0 when side_effect():
+			print("will run the side effect call, but not this")
+		_:
+			assert(global == 1)
+			print("side effect only ran once")
+
+func side_effect():
+	print("side effect")
+	global += 1
+	return false

modules/gdscript/tests/scripts/runtime/features/match_with_pattern_guards.out

@@ -0,0 +1,10 @@
+GDTEST_OK
+guards work
+a is 0 and b is 1
+a is equal to zero
+3rd element is 3
+works with wildcard too.
+guard with multiple patterns
+regular pattern after guard mismatch
+side effect
+side effect only ran once