[ios, macos] Add support for to-rgba expression operator.

5 files changed, 22 insertions, 6 deletions

diff --git a/platform/darwin/docs/guides/For Style Authors.md.ejs b/platform/darwin/docs/guides/For Style Authors.md.ejs
index 37ddd68410..dca6c2905c 100644
--- a/platform/darwin/docs/guides/For Style Authors.md.ejs
+++ b/platform/darwin/docs/guides/For Style Authors.md.ejs
@@ -335,7 +335,11 @@ In style specification | Method, function, or predicate type | Format string syn
 `number`               | |
 `string`               | |
 `to-boolean`           | `boolValue` |
-`to-color`             | |
+<% if (macOS) { -%>
+`to-color`             | | `CAST(var, 'NScolor')`
+<% } else { -%>
+`to-color`             | | `CAST(var, 'UIColor')`
+<% } -%>
 `to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
 `to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
@@ -372,7 +376,7 @@ 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, 'UIColor')` or `CAST(var, 'NSColor')`
+`to-rgba`              | | `CAST(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 5fc9eb6cb9..4ef744e918 100644
--- a/platform/darwin/src/NSExpression+MGLAdditions.mm
+++ b/platform/darwin/src/NSExpression+MGLAdditions.mm
@@ -810,6 +810,9 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
             return [NSExpression expressionWithFormat:@"CAST(%@, 'NSColor')", operand];
 #endif
             
+        } else if ([op isEqualToString:@"to-rgba"]) {
+            NSExpression *operand = [NSExpression expressionWithMGLJSONObject:argumentObjects.firstObject];
+            return [NSExpression expressionWithFormat:@"CAST(%@, 'NSArray')", operand];
         } else if ([op isEqualToString:@"get"]) {
             if (argumentObjects.count == 2) {
                 NSExpression *operand = [NSExpression expressionWithMGLJSONObject:argumentObjects.lastObject];
@@ -1182,6 +1185,9 @@ NSArray *MGLSubexpressionsWithJSONObjects(NSArray *objects) {
                     return @[@"to-color", object];
                 }
 #endif
+                else if ([type isEqualToString:@"NSArray"]) {
+                    return @[@"to-rgba", object];
+                }
                 [NSException raise:NSInvalidArgumentException
                             format:@"Casting expression to %@ not yet implemented.", type];
             } else if ([function isEqualToString:@"MGL_FUNCTION"]) {
diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index 942658e326..531c326f31 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -684,6 +684,12 @@ using namespace std::string_literals;
         NSArray *jsonExpression = @[@"to-color", @[@"get", @"x"]];
         XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
     }
+    {
+        NSExpression *expression = [NSExpression expressionWithFormat:@"CAST(x, 'NSArray')"];
+        NSArray *jsonExpression = @[@"to-rgba", @[@"get", @"x"]];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
 }
 
 - (void)testInterpolationExpressionObject {
diff --git a/platform/ios/docs/guides/For Style Authors.md b/platform/ios/docs/guides/For Style Authors.md
index 30697b357c..cc92ee0433 100644
--- a/platform/ios/docs/guides/For Style Authors.md
+++ b/platform/ios/docs/guides/For Style Authors.md
@@ -325,7 +325,7 @@ In style specification | Method, function, or predicate type | Format string syn
 `number`               | |
 `string`               | |
 `to-boolean`           | `boolValue` |
-`to-color`             | |
+`to-color`             | | `CAST(var, 'UIColor')`
 `to-number`            | `mgl_numberWithFallbackValues:` | `CAST(zipCode, 'NSNumber')`
 `to-string`            | `stringValue` | `CAST(ele, 'NSString')`
 `typeof`               | |
@@ -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, 'UIColor')` or `CAST(var, 'NSColor')`
+`to-rgba`              | | `CAST(var, 'NSArray')`
 `-`                    | `from:subtract:` | `2 - 1`
 `*`                    | `multiply:by:` | `1 * 2`
 `/`                    | `divide:by:` | `1 / 2`
diff --git a/platform/macos/docs/guides/For Style Authors.md b/platform/macos/docs/guides/For Style Authors.md
index 842866a3c0..e257b1fdb8 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`             | |
+`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, 'UIColor')` or `CAST(var, 'NSColor')`
+`to-rgba`              | | `CAST(var, 'NSArray')`
 `-`                    | `from:subtract:` | `2 - 1`
 `*`                    | `multiply:by:` | `1 * 2`
 `/`                    | `divide:by:` | `1 / 2`