1 files changed, 79 insertions, 0 deletions
diff --git a/platform/default/src/mbgl/text/collator.cpp b/platform/default/src/mbgl/text/collator.cpp
new file mode 100644
index 0000000000..400fa4d94d
--- /dev/null
+++ b/platform/default/src/mbgl/text/collator.cpp
@@ -0,0 +1,79 @@
+#include <mbgl/style/expression/collator.hpp>
+#include <mbgl/util/platform.hpp>
+#include <libnu/strcoll.h>
+#include <mbgl/text/unaccent.hpp>
+
+/*
+    The default implementation of Collator ignores locale.
+    Case sensitivity and collation order are based on
+    Default Unicode Collation Element Table (DUCET).
+
+    Diacritic-insensitivity is implemented with nunicode's
+    non-standard "unaccent" functionality, which is tailored
+    to European languages.
+
+    It would be possible to implement locale awareness using ICU,
+    but would require bundling locale data.
+*/
+
+namespace mbgl {
+namespace style {
+namespace expression {
+
+class Collator::Impl {
+public:
+    Impl(bool caseSensitive_, bool diacriticSensitive_, optional<std::string>)
+        : caseSensitive(caseSensitive_)
+        , diacriticSensitive(diacriticSensitive_)
+    {}
+
+    bool operator==(const Impl& other) const {
+        return caseSensitive == other.caseSensitive &&
+            diacriticSensitive == other.diacriticSensitive;
+    }
+
+    int compare(const std::string& lhs, const std::string& rhs) const {
+        if (caseSensitive && diacriticSensitive) {
+            return nu_strcoll(lhs.c_str(), rhs.c_str(),
+                              nu_utf8_read, nu_utf8_read);
+        } else if (!caseSensitive && diacriticSensitive) {
+            return nu_strcasecoll(lhs.c_str(), rhs.c_str(),
+                                  nu_utf8_read, nu_utf8_read);
+        } else if (caseSensitive && !diacriticSensitive) {
+            return nu_strcoll(platform::unaccent(lhs).c_str(), platform::unaccent(rhs).c_str(),
+                              nu_utf8_read, nu_utf8_read);
+        } else {
+            return nu_strcasecoll(platform::unaccent(lhs).c_str(), platform::unaccent(rhs).c_str(),
+                                  nu_utf8_read, nu_utf8_read);
+        }
+    }
+
+    std::string resolvedLocale() const {
+        return "";
+    }
+private:
+    bool caseSensitive;
+    bool diacriticSensitive;
+};
+
+
+Collator::Collator(bool caseSensitive, bool diacriticSensitive, optional<std::string> locale_)
+    : impl(std::make_shared<Impl>(caseSensitive, diacriticSensitive, std::move(locale_)))
+{}
+
+bool Collator::operator==(const Collator& other) const {
+    return *impl == *(other.impl);
+}
+
+int Collator::compare(const std::string& lhs, const std::string& rhs) const {
+    return impl->compare(lhs, rhs);
+}
+
+std::string Collator::resolvedLocale() const {
+    return impl->resolvedLocale();
+}
+
+
+} // namespace expression
+} // namespace style
+} // namespace mbgl