1 files changed, 28 insertions, 5 deletions

diff --git a/src/mbgl/style/expression/equals.cpp b/src/mbgl/style/expression/equals.cpp
index f2f59e31ef..245899f975 100644
--- a/src/mbgl/style/expression/equals.cpp
+++ b/src/mbgl/style/expression/equals.cpp
@@ -1,3 +1,4 @@
+#include <mbgl/style/expression/collator.hpp>
 #include <mbgl/style/expression/equals.hpp>
 
 namespace mbgl {
@@ -11,10 +12,11 @@ static bool isComparableType(const type::Type& type) {
         type == type::Null;
 }
 
-Equals::Equals(std::unique_ptr<Expression> lhs_, std::unique_ptr<Expression> rhs_, bool negate_)
+Equals::Equals(std::unique_ptr<Expression> lhs_, std::unique_ptr<Expression> rhs_, optional<std::unique_ptr<Expression>> collator_, bool negate_)
     : Expression(type::Boolean),
       lhs(std::move(lhs_)),
       rhs(std::move(rhs_)),
+      collator(std::move(collator_)),
       negate(negate_) {
     assert(isComparableType(lhs->getType()) || isComparableType(rhs->getType()));
     assert(lhs->getType() == rhs->getType() || lhs->getType() == type::Value || rhs->getType() == type::Value);
@@ -27,7 +29,15 @@ EvaluationResult Equals::evaluate(const EvaluationContext& params) const {
     EvaluationResult rhsResult = rhs->evaluate(params);
     if (!rhsResult) return lhsResult;
 
-    bool result = *lhsResult == *rhsResult;
+    bool result;
+    
+    if (collator) {
+        auto collatorResult = (*collator)->evaluate(params);
+        const Collator& c = collatorResult->get<Collator>();
+        result = c.compare(lhsResult->get<std::string>(), rhsResult->get<std::string>()) == 0;
+    } else {
+       result = *lhsResult == *rhsResult;
+    }
     if (negate) {
         result = !result;
     }
@@ -37,6 +47,9 @@ EvaluationResult Equals::evaluate(const EvaluationContext& params) const {
 void Equals::eachChild(const std::function<void(const Expression&)>& visit) const {
     visit(*lhs);
     visit(*rhs);
+    if (collator) {
+        visit(**collator);
+    }
 }
 
 bool Equals::operator==(const Expression& e) const {
@@ -54,8 +67,8 @@ using namespace mbgl::style::conversion;
 ParseResult Equals::parse(const Convertible& value, ParsingContext& ctx) {
     std::size_t length = arrayLength(value);
 
-    if (length != 3) {
-        ctx.error("Expected two arguments.");
+    if (length != 3 && length != 4) {
+        ctx.error("Expected two or three arguments.");
         return ParseResult();
     }
 
@@ -80,8 +93,18 @@ ParseResult Equals::parse(const Convertible& value, ParsingContext& ctx) {
         ctx.error("Cannot compare " + toString(lhsType) + " and " + toString(rhsType) + ".");
         return ParseResult();
     }
+    
+    ParseResult collatorParseResult;
+    if (length == 4) {
+        if (lhsType != type::String && rhsType != type::String) {
+            ctx.error("Cannot use collator to compare non-string types.");
+            return ParseResult();
+        }
+        collatorParseResult = ctx.parse(arrayMember(value, 3), 3, {type::Collator});
+        if (!collatorParseResult) return ParseResult();
+    }
 
-    return ParseResult(std::make_unique<Equals>(std::move(*lhs), std::move(*rhs), negate));
+    return ParseResult(std::make_unique<Equals>(std::move(*lhs), std::move(*rhs), std::move(collatorParseResult), negate));
 }
 
 } // namespace expression