cpp: added to_lowercase and to_uppercase to SharedString (#6869)

* cpp: added to_lowercase and to_uppercase to SharedString

* Update api/cpp/include/slint_string.h

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* Update api/cpp/include/slint_string.h

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* Update api/cpp/include/slint_string.h

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* Update api/cpp/include/slint_string.h

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* Update internal/core/string.rs

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* Update internal/core/string.rs

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* Update internal/core/string.rs

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* Update internal/core/string.rs

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* Update api/cpp/tests/datastructures.cpp

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* Update api/cpp/include/slint_string.h

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* Update api/cpp/include/slint_string.h

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---------

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api/cpp/include/slint_string.h

@@ -127,6 +127,34 @@ struct SharedString
     /// \endcode
     static SharedString from_number(double n) { return SharedString(n); }
 
+    /// Returns the lowercase equivalent of this string, as a new SharedString.
+    ///
+    /// For example:
+    /// \code
+    ///     auto str = slint::SharedString("Hello");
+    ///     auto str2 = str.to_lowercase(); // creates "hello"
+    /// \endcode
+    SharedString to_lowercase() const
+    {
+        auto out = SharedString();
+        cbindgen_private::slint_shared_string_to_lowercase(&out, this);
+        return out;
+    }
+
+    /// Returns the uppercase equivalent of this string, as a new SharedString.
+    ///
+    /// For example:
+    /// \code
+    ///     auto str = slint::SharedString("Hello");
+    ///     auto str2 = str.to_uppercase(); // creates "HELLO"
+    /// \endcode
+    SharedString to_uppercase() const
+    {
+        auto out = SharedString();
+        cbindgen_private::slint_shared_string_to_uppercase(&out, this);
+        return out;
+    }
+
     /// Returns true if \a a is equal to \a b; otherwise returns false.
     friend bool operator==(const SharedString &a, const SharedString &b)
     {

api/cpp/tests/datastructures.cpp

@@ -52,6 +52,17 @@ SCENARIO("SharedString API")
         str = "Hello";
         REQUIRE(str.size() == 5);
     }
+
+    SECTION("to_lowercase")
+    {
+        str = "Hello";
+        REQUIRE(std::string_view(str.to_lowercase().data()) == "hello");
+    }
+    SECTION("to_uppercase")
+    {
+        str = "Hello";
+        REQUIRE(std::string_view(str.to_uppercase().data()) == "HELLO");
+    }
 }
 
 TEST_CASE("Basic SharedVector API", "[vector]")

internal/core/string.rs

@@ -474,6 +474,42 @@ pub(crate) mod ffi {
         append("!");
         assert_eq!(s.as_str(), "Hello, world!");
     }
+
+    #[no_mangle]
+    pub unsafe extern "C" fn slint_shared_string_to_lowercase(
+        out: &mut SharedString,
+        ss: &SharedString,
+    ) {
+        *out = SharedString::from(ss.to_lowercase());
+    }
+    #[test]
+    fn test_slint_shared_string_to_lowercase() {
+        let s = SharedString::from("Hello");
+        let mut out = SharedString::default();
+
+        unsafe {
+            slint_shared_string_to_lowercase(&mut out, &s);
+        }
+        assert_eq!(out.as_str(), "hello");
+    }
+
+    #[no_mangle]
+    pub unsafe extern "C" fn slint_shared_string_to_uppercase(
+        out: &mut SharedString,
+        ss: &SharedString,
+    ) {
+        *out = SharedString::from(ss.to_uppercase());
+    }
+    #[test]
+    fn test_slint_shared_string_to_uppercase() {
+        let s = SharedString::from("Hello");
+        let mut out = SharedString::default();
+
+        unsafe {
+            slint_shared_string_to_uppercase(&mut out, &s);
+        }
+        assert_eq!(out.as_str(), "HELLO");
+    }
 }
 
 #[cfg(feature = "serde")]