[ios, macos] Enable to-rgba operator for MGLColor or key path expressions.

7 files changed, 35 insertions, 16 deletions

diff --git a/platform/darwin/docs/guides/For Style Authors.md.ejs b/platform/darwin/docs/guides/For Style Authors.md.ejs
index dca6c2905c..60177e57c2 100644
--- a/platform/darwin/docs/guides/For Style Authors.md.ejs
+++ b/platform/darwin/docs/guides/For Style Authors.md.ejs
@@ -335,11 +335,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `number`               | |
 `string`               | |
 `to-boolean`           | `boolValue` |
-<% if (macOS) { -%>
-`to-color`             | | `CAST(var, 'NScolor')`
-<% } else { -%>
-`to-color`             | | `CAST(var, 'UIColor')`
-<% } -%>
+`to-color`             | | `CAST(var, '<%- cocoaPrefix %>Color')`
 `to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
 `to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
@@ -376,7 +372,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `rgb`                  | `+[UIColor colorWithRed:green:blue:alpha:]` |
 `rgba`                 | `+[UIColor colorWithRed:green:blue:alpha:]` |
 <% } -%>
-`to-rgba`              | | `CAST(var, 'NSArray')`
+`to-rgba`              | | `CAST(noindex(var), 'NSArray')`
 `-`                    | `from:subtract:` | `2 - 1`
 `*`                    | `multiply:by:` | `1 * 2`
 `/`                    | `divide:by:` | `1 / 2`
diff --git a/platform/darwin/src/NSExpression+MGLAdditions.mm b/platform/darwin/src/NSExpression+MGLAdditions.mm
index 7a1d73f43a..362a4986f8 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -817,7 +817,7 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             
         } else if ([op isEqualToString:@"to-rgba"]) {
             NSExpression *operand = [NSExpression expressionWithMGLJSONObject:argumentObjects.firstObject];
-            return [NSExpression expressionWithFormat:@"CAST(%@, 'NSArray')", operand];
+            return [NSExpression expressionWithFormat:@"CAST(noindex(%@), 'NSArray')", operand];
         } else if ([op isEqualToString:@"get"]) {
             if (argumentObjects.count == 2) {
                 NSExpression *operand = [NSExpression expressionWithMGLJSONObject:argumentObjects.lastObject];
@@ -1191,7 +1191,15 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                 }
 #endif
                 else if ([type isEqualToString:@"NSArray"]) {
-                    return @[@"to-rgba", object];
+                    NSExpression *operand = self.arguments.firstObject;
+                    if ([operand expressionType] == NSFunctionExpressionType ) {
+                        operand = self.arguments.firstObject.arguments.firstObject;
+                    }
+                    if (([operand expressionType] != NSConstantValueExpressionType) ||
+                        ([operand expressionType] == NSConstantValueExpressionType &&
+                         [[operand constantValue] isKindOfClass:[MGLColor class]])) {
+                        return @[@"to-rgba", object];
+                    }
                 }
                 [NSException raise:NSInvalidArgumentException
                             format:@"Casting expression to %@ not yet implemented.", type];
diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index 4980599985..4ed1f61eb1 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -685,12 +685,21 @@ using namespace std::string_literals;
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
     }
     {
-        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(x, 'NSArray')"];
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(noindex(x), 'NSArray')"];
         NSArray *jsonExpression = @[@"to-rgba", @[@"get", @"x"]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
         XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
     }
-
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(noindex(%@), 'NSArray')", MGLConstantExpression(MGLColor.blueColor)];
+        NSArray *jsonExpression = @[@"to-rgba", @[@"rgb", @0, @0, @255]];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(noindex('x'), 'NSArray')"];
+        XCTAssertThrowsSpecificNamed(expression.mgl_jsonExpressionObject, NSException, NSInvalidArgumentException);
+    }
 }
 
 - (void)testInterpolationExpressionObject {
diff --git a/platform/ios/docs/guides/For Style Authors.md b/platform/ios/docs/guides/For Style Authors.md
index cc92ee0433..d4fb17eb6a 100644
--- a/platform/ios/docs/guides/For Style Authors.md
+++ b/platform/ios/docs/guides/For Style Authors.md
@@ -357,7 +357,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `upcase`               | `uppercase:` | `uppercase('Elysian Fields')`
 `rgb`                  | `+[UIColor colorWithRed:green:blue:alpha:]` |
 `rgba`                 | `+[UIColor colorWithRed:green:blue:alpha:]` |
-`to-rgba`              | | `CAST(var, 'NSArray')`
+`to-rgba`              | | `CAST(noindex(var), 'NSArray')`
 `-`                    | `from:subtract:` | `2 - 1`
 `*`                    | `multiply:by:` | `1 * 2`
 `/`                    | `divide:by:` | `1 / 2`
diff --git a/platform/ios/src/UIColor+MGLAdditions.mm b/platform/ios/src/UIColor+MGLAdditions.mm
index 9ca39acda4..7c1fbddc20 100644
--- a/platform/ios/src/UIColor+MGLAdditions.mm
+++ b/platform/ios/src/UIColor+MGLAdditions.mm
@@ -66,7 +66,7 @@
     return [UIColor colorWithRed:[components[0].constantValue doubleValue] / 255.0
                            green:[components[1].constantValue doubleValue] / 255.0
                             blue:[components[2].constantValue doubleValue] / 255.0
-                           alpha:components.count == 3 ? [components[3].constantValue doubleValue] : 1.0];
+                           alpha:components.count == 3 ? 1.0 : [components[3].constantValue doubleValue]];
 }
 
 @end
diff --git a/platform/macos/docs/guides/For Style Authors.md b/platform/macos/docs/guides/For Style Authors.md
index e257b1fdb8..08385a66d9 100644
--- a/platform/macos/docs/guides/For Style Authors.md
+++ b/platform/macos/docs/guides/For Style Authors.md
@@ -318,7 +318,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `number`               | |
 `string`               | |
 `to-boolean`           | `boolValue` |
-`to-color`             | | `CAST(var, 'NScolor')`
+`to-color`             | | `CAST(var, 'NSColor')`
 `to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
 `to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
@@ -350,7 +350,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `upcase`               | `uppercase:` | `uppercase('Elysian Fields')`
 `rgb`                  | `+[NSColor colorWithCalibratedRed:green:blue:alpha:]` |
 `rgba`                 | `+[NSColor colorWithCalibratedRed:green:blue:alpha:]` |
-`to-rgba`              | | `CAST(var, 'NSArray')`
+`to-rgba`              | | `CAST(noindex(var), 'NSArray')`
 `-`                    | `from:subtract:` | `2 - 1`
 `*`                    | `multiply:by:` | `1 * 2`
 `/`                    | `divide:by:` | `1 / 2`
diff --git a/platform/macos/src/NSColor+MGLAdditions.mm b/platform/macos/src/NSColor+MGLAdditions.mm
index 8c9086ccf7..c73c1a41b7 100644
--- a/platform/macos/src/NSColor+MGLAdditions.mm
+++ b/platform/macos/src/NSColor+MGLAdditions.mm
@@ -79,8 +79,14 @@
         
         components.push_back(component.doubleValue / 255.0);
     }
-    // Alpha
-    components.back() *= 255.0;
+    
+    if (components.size() < 4) {
+        components.push_back(1.0);
+    } else {
+        // Alpha
+        components.back() *= 255.0;
+    }
+    
     
     // macOS 10.12 Sierra and below uses calibrated RGB by default.
     if ([NSColor redColor].colorSpaceName == NSCalibratedRGBColorSpace) {