Fix to only localize the primary localization and not the fall-throug… (

#856)

* Fix to only localize the primary localization and not the fall-through localizations

Sources/MapboxMaps/Style/Style+Localization.swift

@@ -85,7 +85,7 @@ extension Style {
 
         if var stringExpression = String(data: try JSONEncoder().encode(symbolLayer.textField), encoding: .utf8),
            stringExpression != "null" {
-            stringExpression.updateExpression(replacement: replacement, regex: expressionCoalesce)
+            stringExpression.updateOnceExpression(replacement: replacement, regex: expressionCoalesce)
             stringExpression.updateExpression(replacement: replacement, regex: expressionAbbr)
 
             // Turn the new json string back into an Expression
@@ -113,4 +113,20 @@ extension String {
                                               range: range,
                                               withTemplate: replacement)
     }
+
+    /// Updates string once using the first occurrence of a regex
+    /// - Parameters:
+    ///   - replacement: New string to replace the matched pattern
+    ///   - regex: The regex pattern that will be matched for replacement
+    internal mutating func updateOnceExpression(replacement: String, regex: NSRegularExpression) {
+        var range = NSRange(location: 0, length: NSString(string: self).length)
+        range = regex.rangeOfFirstMatch(in: self, options: [], range: range)
+        if range.lowerBound == NSNotFound {
+            return
+        }
+        self = regex.stringByReplacingMatches(in: self,
+                                              options: [],
+                                              range: range,
+                                              withTemplate: replacement)
+    }
 }

Tests/MapboxMapsTests/Style/Style+LocalizationTests.swift

@@ -33,4 +33,52 @@ final class StyleLocalizationTests: MapViewIntegrationTestCase {
 
         XCTAssertThrowsError(try style.localizeLabels(into: Locale(identifier: "tlh")))
     }
+
+    func testOnlyLocalizesFirstLocalization() throws {
+        var source = GeoJSONSource()
+        source.data = .feature(Feature(geometry: Point(CLLocationCoordinate2D(latitude: 0, longitude: 0))))
+        try style.addSource(source, id: "a")
+
+        var symbolLayer = SymbolLayer(id: "a")
+        symbolLayer.source = "a"
+        symbolLayer.textField = .expression(
+            Exp(.format) {
+                Exp(.coalesce) {
+                    Exp(.get) {
+                        "name_en"
+                    }
+                    Exp(.get) {
+                        "name_fr"
+                    }
+                    Exp(.get) {
+                        "name"
+                    }
+                }
+                FormatOptions()
+            }
+        )
+
+        try style.addLayer(symbolLayer)
+
+        try style.localizeLabels(into: Locale(identifier: "de"))
+
+        let updatedLayer = try style.layer(withId: "a", type: SymbolLayer.self)
+
+        XCTAssertEqual(updatedLayer.textField, .expression(
+            Exp(.format) {
+                Exp(.coalesce) {
+                    Exp(.get) {
+                        "name_de"
+                    }
+                    Exp(.get) {
+                        "name_fr"
+                    }
+                    Exp(.get) {
+                        "name"
+                    }
+                }
+                FormatOptions()
+            }
+        ))
+    }
 }