[ios, macos] Add lookup and feature operators. #11528
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By the way, I’ve been using this header as a guide to which built-in syntaxes (like subscripting) correspond to which built-in expression functions ( |
| @@ -639,6 +663,9 @@ - (id)mgl_jsonExpressionObject { | |||
| } else if ([function isEqualToString:@"stringByAppendingString:"]) { | |||
| NSArray *arguments = self.arguments.mgl_jsonExpressionObject; | |||
| return [@[@"concat", self.operand.mgl_jsonExpressionObject] arrayByAddingObjectsFromArray:arguments]; | |||
| } else if ([function isEqualToString:@"objectAtIndex:"]) { | |||
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[NSExpression expressionWithFormat:@"{1, 2, 3}[index]"] has a function of objectFrom:withIndex: and an arguments consisting of the expression index.
| @@ -456,6 +465,12 @@ + (instancetype)mgl_expressionWithJSONObject:(id)object { | |||
| return [NSExpression expressionForVariable:@"zoomLevel"]; | |||
| } else if ([op isEqualToString:@"heatmap-density"]) { | |||
| return [NSExpression expressionForVariable:@"heatmapDensity"]; | |||
| } else if ([op isEqualToString:@"geometry-type"]) { | |||
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Conventional custom functions should be prefixed with mgl_ to avoid conflicting with functions that Apple may add to NSExpression in the future.
| @@ -544,6 +559,15 @@ - (id)mgl_jsonExpressionObject { | |||
| if ([self.variable isEqualToString:@"zoomLevel"]) { | |||
| return @[@"zoom"]; | |||
| } | |||
| if ([self.variable isEqualToString:@"geometryType"]) { | |||
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This SDK is using the $variable syntax both for these special built-in values that vary based on the execution context and also for user-defined variables. The assumption with zoomLevel and the like is that developers will be less likely to need a variable by that exact name.
| if ([self.variable isEqualToString:@"geometryType"]) { | ||
| return @[@"geometry-type"]; | ||
| } | ||
| if ([self.variable isEqualToString:@"featureId"]) { |
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For consistency with Cocoa and this SDK, either spell this function featureID or, better yet, featureIdentifier.
| XCTAssertEqualObjects([NSExpression mgl_expressionWithJSONObject:jsonExpression], expression); | ||
| } | ||
| { | ||
| NSExpression *expression = [NSExpression expressionWithFormat:@"FUNCTION('x', 'has')"]; |
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The has operator has two forms. You can think of the ["has", "something"] form as shorthand for ["has", "something", ["properties"]]. This PR only implements one of the two forms.
["has", "something"] should translate to FUNCTION(self, 'mgl_has:', 'something'), and ["has", "something", object] should translate to FUNCTION(object, 'mgl_has:', 'something').
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| NSArray *subexpressions = MGLSubexpressionsWithJSONObjects(argumentObjects); | ||
| NSExpression *operand = argumentObjects.count > 1 ? subexpressions[1] : [NSExpression expressionWithFormat:@"self"]; | ||
| NSExpression *property = subexpressions.firstObject; | ||
| return [NSExpression expressionWithFormat:@"FUNCTION(%@, 'mgl_has:', %@)", operand, property]; |
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By the way, a preexisting way to write this in an expression would be FUNCTION(%@, 'valueForKey:', %@) != nil. That seems a bit more natural, although I guess mgl_has: will be slightly more ergonomic once we implement an aftermarket function for it.
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For this case mgl_has: seems like the most ergonomic option as its closer to our spec.
| if ([self.variable isEqualToString:@"mgl_geometryType"]) { | ||
| return @[@"geometry-type"]; | ||
| } | ||
| if ([self.variable isEqualToString:@"featureIdentifier"]) { |
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mgl_geometryType is prefixed with the class prefix, but featureIdentifier and featureProperties are not.
| @@ -651,6 +690,12 @@ - (id)mgl_jsonExpressionObject { | |||
| return @[@"to-string", self.operand.mgl_jsonExpressionObject]; | |||
| } else if ([function isEqualToString:@"noindex:"]) { | |||
| return self.arguments.firstObject.mgl_jsonExpressionObject; | |||
| } else if ([function isEqualToString:@"mgl_has:"]) { | |||
| NSMutableArray *expressionObject = [NSMutableArray arrayWithObjects:@"has", self.arguments[0].mgl_jsonExpressionObject, nil]; | |||
| if (self.operand.expressionType == NSConstantValueExpressionType) { | |||
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FUNCTION($featureProperties, 'mgl_has:', 'property') should be translated as ["has", ["properties"], "property"], so we need to check here that the operand isn’t an NSEvaluatedObjectExpressionType (i.e., SELF).
Fixes #11006
Add operators