[ios] predicateWithMGLJSONObject: Unknown expression "!has"

[mfazekas]

The following code on ios:

statesLayer.predicate = [NSPredicate predicateWithMGLJSONObject: @[ @"!has", @"foo"]];

results in an exception:
"[1][0]: Unknown expression "!has". If you wanted a literal array, use ["literal", [...]]."

Steps to reproduce

statesLayer.predicate = [NSPredicate predicateWithMGLJSONObject: @[ @"!has", @"foo"]];

Expected behavior

Work as expected.

Actual behavior

Raises an exception.

2019-06-06 10:40:48.527990+0200 Mapbox GL[75351:710524] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid filter value: [1][0]: Unknown expression "!has". If you wanted a literal array, use ["literal", [...]].'
*** First throw call stack:
(
	0   CoreFoundation                      0x000000010a8e46fb __exceptionPreprocess + 331
	1   libobjc.A.dylib                     0x0000000109e88ac5 objc_exception_throw + 48
	2   CoreFoundation                      0x000000010a8e4555 +[NSException raise:format:] + 197
	3   Mapbox                              0x00000001058e7703 -[NSPredicate(MGLPrivateAdditions) mgl_filter] + 387
	4   Mapbox                              0x0000000105901a80 -[MGLFillStyleLayer setPredicate:] + 928

Notes:

• [NSPredicate predicateWithMGLJSONObject: @[ @"!has", @"foo"]] is MGL_FUNCTION("!has", "foo") == 1
• mgl_jsonExpressionObject retruns [==,[!has,foo],1]

This is where we set this error:

mapbox-gl-native/src/mbgl/style/expression/compound_expression.cpp

Lines 1037 to 1047 in 64559a2

	ParseResult parseCompoundExpression(const std::string name, const Convertible& value, ParsingContext& ctx) {
	assert(isArray(value) && arrayLength(value) > 0);
	const auto definitions = compoundExpressionRegistry.equal_range(name.c_str());
	if (definitions.first == definitions.second) {
	ctx.error(
	R"(Unknown expression ")" + name + R"(". If you wanted a literal array, use ["literal", [...]].)",
	0
	);
	return ParseResult();
	}

Stack:

#0	0x000000010c89280f in mbgl::style::expression::parseCompoundExpression(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, mbgl::style::conversion::Convertible const&, mbgl::style::expression::ParsingContext&) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/compound_expression.cpp:1042
#1	0x000000010c91e8ec in mbgl::style::expression::ParsingContext::parse(mbgl::style::conversion::Convertible const&, std::experimental::optional<mbgl::style::expression::TypeAnnotationOption>) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/parsing_context.cpp:161
#2	0x000000010c91e235 in mbgl::style::expression::ParsingContext::parse(mbgl::style::conversion::Convertible const&, unsigned long, std::experimental::optional<mapbox::util::variant<mbgl::style::expression::type::NullType, mbgl::style::expression::type::NumberType, mbgl::style::expression::type::BooleanType, mbgl::style::expression::type::StringType, mbgl::style::expression::type::ColorType, mbgl::style::expression::type::ObjectType, mbgl::style::expression::type::ValueType, mapbox::util::recursive_wrapper<mbgl::style::expression::type::Array>, mbgl::style::expression::type::CollatorType, mbgl::style::expression::type::FormattedType, mbgl::style::expression::type::ErrorType> >, std::experimental::optional<mbgl::style::expression::TypeAnnotationOption>) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/parsing_context.cpp:88
#3	0x000000010c886646 in mbgl::style::expression::parseComparison(mbgl::style::conversion::Convertible const&, mbgl::style::expression::ParsingContext&) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/comparison.cpp:221
#4	0x000000010c91e86b in mbgl::style::expression::ParsingContext::parse(mbgl::style::conversion::Convertible const&, std::experimental::optional<mbgl::style::expression::TypeAnnotationOption>) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/parsing_context.cpp:159
#5	0x000000010c92102f in mbgl::style::expression::ParsingContext::parseExpression(mbgl::style::conversion::Convertible const&, std::experimental::optional<mbgl::style::expression::TypeAnnotationOption>) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/expression/parsing_context.cpp:229
#6	0x000000010c7cea32 in mbgl::style::conversion::Converter<mbgl::style::Filter, void>::operator()(mbgl::style::conversion::Convertible const&, mbgl::style::conversion::Error&) const at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/src/mbgl/style/conversion/filter.cpp:23
#7	0x000000010c2e18f8 in std::experimental::optional<mbgl::style::Filter> mbgl::style::conversion::convert<mbgl::style::Filter>(mbgl::style::conversion::Convertible const&, mbgl::style::conversion::Error&) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/include/mbgl/style/conversion_impl.hpp:286
#8	0x000000010c2e1627 in ::-[NSPredicate(MGLPrivateAdditions) mgl_filter]() at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/platform/darwin/src/NSPredicate+MGLAdditions.mm:15
#9	0x000000010c2fba80 in ::-[MGLFillStyleLayer setPredicate:](NSPredicate *) at /Work/Freelance/Ruby/MlkFestival/RNMPGL/mapbox-gl-native/platform/darwin/src/MGLFillStyleLayer.mm:74

As a workaround
[NSPredicate predicateWithMGLJSONObject: @[ @"!",@[@"has", @"foo"]]]

Configuration

Mapbox SDK versions: 198ed88 - 5.1.0.alpha1
iOS/macOS versions: 12.2/10.14.4
Device/simulator models: iPhone X
Xcode version: 10.2.1

[1ec5]

!has is part of the filter syntax in the style specification. Filters are deprecated and are no longer supported in the native SDKs. Instead, wrap a has expression inside a ! expression.

[mfazekas]

@1ec5 thanks, i was just searching for '!has' in docs and was confused by avaiability, as it statediOS > 3.3.0. I have not noticed it's in the filter part of docs.