[ios, macos] Fix MGLSymbolStyleLayer.text localization issue. (#14405)

Fixed an MGLSymbolStyleLayer.text localization bug caused by the introduction of MGLAttributedExpression object. The localization parsing was ignoring the latter.

* [ios, macos] Fix a localization issue.

* [ios, macos] Add formating expressions localization test.

* [ios, macos] Update MGLSymbolStyleLayer.text documentation.

platform/darwin/scripts/generate-style-code.js

@@ -356,6 +356,9 @@ global.propertyDoc = function (propertyName, property, layerType, kind) {
             doc += '* Constant array, whose each element is any of the following constant string values:\n';
             doc += Object.keys(property.values).map(value => '  * `' + value + '`: ' + property.values[value].doc).join('\n') + '\n';
         }
+        if (property.type === 'formatted') {
+            doc += '* Formatted expressions.\n';
+        }
         doc += '* Predefined functions, including mathematical and string operators\n' +
             '* Conditional expressions\n' +
             '* Variable assignments and references to assigned variables\n';

platform/darwin/src/MGLSymbolStyleLayer.h

@@ -1086,6 +1086,7 @@ MGL_EXPORT
  You can set this property to an expression containing any of the following:
  
  * Constant string values
+ * Formatted expressions.
  * Predefined functions, including mathematical and string operators
  * Conditional expressions
  * Variable assignments and references to assigned variables

platform/darwin/src/NSExpression+MGLAdditions.mm

@@ -1471,6 +1471,12 @@ - (NSExpression *)mgl_expressionLocalizedIntoLocale:(nullable NSLocale *)locale
                 if (localizedValues != self.constantValue) {
                     return [NSExpression expressionForConstantValue:localizedValues];
                 }
+            } else if ([self.constantValue isKindOfClass:[MGLAttributedExpression class]]) {
+                MGLAttributedExpression *attributedExpression = (MGLAttributedExpression *)self.constantValue;
+                NSExpression *localizedExpression = [attributedExpression.expression mgl_expressionLocalizedIntoLocale:locale];
+                MGLAttributedExpression *localizedAttributedExpression = [MGLAttributedExpression attributedExpression:localizedExpression attributes:attributedExpression.attributes];
+
+                return [NSExpression expressionForConstantValue:localizedAttributedExpression];
             }
             return self;
         }

platform/darwin/test/MGLExpressionTests.mm

@@ -1200,6 +1200,16 @@ - (void)testLocalization {
         NSExpression *expected = original;
         XCTAssertEqualObjects([original mgl_expressionLocalizedIntoLocale:nil], expected);
     }
+    {
+        NSExpression *keyExpression = [NSExpression expressionForKeyPath:@"name_en"];
+        MGLAttributedExpression *attributedExpression = [MGLAttributedExpression attributedExpression:keyExpression attributes:@{}];
+        NSExpression *original = [NSExpression expressionForConstantValue:attributedExpression];
+
+        NSExpression *coalesceExpression = [NSExpression expressionWithFormat:@"mgl_coalesce({%K, %K})", @"name_en", @"name"];
+        MGLAttributedExpression *expectedAttributedExpression = [MGLAttributedExpression attributedExpression:coalesceExpression attributes:@{}];
+        NSExpression *expected = [NSExpression expressionForConstantValue:expectedAttributedExpression];
+        XCTAssertEqualObjects([original mgl_expressionLocalizedIntoLocale:nil], expected);
+    }
     {
         NSExpression *original = [NSExpression expressionForKeyPath:@"name_en"];
         NSExpression *expected = [NSExpression expressionWithFormat:@"mgl_coalesce({%K, %K})", @"name_en", @"name"];