Fix number to string conversion in C++

api/sixtyfps-cpp/include/sixtyfps_string.h

@@ -31,7 +31,11 @@ struct SharedString
     operator std::string_view() const { return internal::sixtyfps_shared_string_bytes(this); }
     auto data() const -> const char * { return internal::sixtyfps_shared_string_bytes(this); }
 
+    static SharedString from_number(double n) { return SharedString(n); }
+
 private:
+    /// Use SharedString::from_number
+    explicit SharedString(double n) { internal::sixtyfps_shared_string_from_number(this, n); }
     void *inner; // opaque
 };
 }

examples/cpptest/hello.60

@@ -79,7 +79,7 @@ Hello := Rectangle {
         button_text: "+";
     }
     property<int32> counter;
-    counter_label := Text { x: 100; y: 300; text: "0"; color: black; }
+    counter_label := Text { x: 100; y: 300; text: counter; color: black; }
     ButtonRectangle {
         color: 4289374890;
         x: 50;

examples/cpptest/main.cpp

@@ -11,17 +11,11 @@ int main() {
     component.plus_clicked.set_handler([](auto...){
         auto &counter = component.counter;
         counter.set(counter.get() + 1);
-        // FIXME: this _13 is an internal detail and should be private anyway.  We muse use some
-        // alias or way to expose the property  (same for the _ before signals)
-        component.counter_label_11.text.set(std::string_view(std::to_string(counter.get())));
-        std::cout << "PLUS: " << std::string_view(component.counter_label_11.text.get()) << std::endl;
     });
 
     component.minus_clicked.set_handler([](auto...){
         auto &counter = component.counter;
         counter.set(counter.get() - 1);
-        component.counter_label_11.text.set(std::string_view(std::to_string(counter.get())));
-        std::cout << "MINUS: " << std::string_view(component.counter_label_11.text.get()) << std::endl;
     });
 
     sixtyfps::run(&component);

sixtyfps_compiler/generator/cpp.rs

@@ -162,7 +162,7 @@ fn handle_item(
 
     let id = &item.id;
     init.extend(item.bindings.iter().map(|(s, i)| {
-        use crate::expression_tree::{Expression, Expression::*};
+        use crate::expression_tree::Expression;
         match i {
             Expression::SignalReference { component:_, element:_, name } => {
                 let signal_accessor_prefix = if item.signals_declaration.contains(s) {
@@ -183,14 +183,7 @@ fn handle_item(
                     format!("{id}.", id = id.clone())
                 };
 
-                let init = match &i {
+                let init = compile_expression(i);
-                    StringLiteral(s) => {
-                        format!(r#"sixtyfps::SharedString("{}")"#, s.escape_default())
-                    }
-                    NumberLiteral(n) => n.to_string(),
-                    PropertyReference { name, .. } => format!(r#"{}.get()"#, name),
-                    _ => format!("\n#error: unsupported expression {:?}\n", i),
-                };
                 format!(
                     "{accessor_prefix}{cpp_prop}.set({init});",
                     accessor_prefix = accessor_prefix,
@@ -298,18 +291,28 @@ pub fn generate(component: &Component, diag: &mut Diagnostics) -> Option<impl st
         init: Some("{ nullptr, sixtyfps::dummy_destory, tree_fn }".to_owned()),
     }));
 
-    /*x.declarations.push(Declaration::Function(Function {
-        name: "main".into(),
-        signature: "() -> int".to_owned(),
-        statements: Some(vec![
-            format!("static {} component;", component.id),
-            format!("sixtyfps::run(&component);"),
-        ]),
-        ..Default::default()
-    }));*/
     if diag.has_error() {
         None
     } else {
         Some(x)
     }
 }
+
+fn compile_expression(e: &crate::expression_tree::Expression) -> String {
+    use crate::expression_tree::Expression::*;
+    match e {
+        StringLiteral(s) => format!(r#"sixtyfps::SharedString("{}")"#, s.escape_default()),
+        NumberLiteral(n) => n.to_string(),
+        PropertyReference { name, .. } => format!(r#"{}.get()"#, name),
+        Cast { from, to } => {
+            let f = compile_expression(&*from);
+            match (from.ty(), to) {
+                (Type::Float32, Type::String) | (Type::Int32, Type::String) => {
+                    format!("sixtyfps::SharedString::from_number({})", f)
+                }
+                _ => f,
+            }
+        }
+        _ => format!("\n#error: unsupported expression {:?}\n", e),
+    }
+}

sixtyfps_runtime/corelib/abi/string.rs

@@ -228,40 +228,6 @@ where
 
 impl Eq for SharedString {}
 
-/// for cbingen.
-#[allow(non_camel_case_types)]
-type c_char = u8;
-
-#[no_mangle]
-pub extern "C" fn sixtyfps_shared_string_bytes(ss: &SharedString) -> *const c_char {
-    ss.as_ptr()
-}
-
-#[no_mangle]
-/// Destroy the shared string
-pub unsafe extern "C" fn sixtyfps_shared_string_drop(ss: *const SharedString) {
-    core::ptr::read(ss);
-}
-
-#[no_mangle]
-/// Increment the reference count of the string.
-/// the resulting structure must be passed to sixtyfps_shared_string_drop
-pub unsafe extern "C" fn sixtyfps_shared_string_clone(out: *mut SharedString, ss: &SharedString) {
-    core::ptr::write(out, ss.clone())
-}
-
-#[no_mangle]
-/// Safety: bytes must be a valid utf-8 string of size len wihout null inside.
-/// the resulting structure must be passed to sixtyfps_shared_string_drop
-pub unsafe extern "C" fn sixtyfps_shared_string_from_bytes(
-    out: *mut SharedString,
-    bytes: *const c_char,
-    len: usize,
-) {
-    let str = core::str::from_utf8_unchecked(core::slice::from_raw_parts(bytes, len));
-    core::ptr::write(out, SharedString::from(str));
-}
-
 #[test]
 fn simple_test() {
     let x = SharedString::from("hello world!");
@@ -279,3 +245,67 @@ fn simple_test() {
         &*std::ffi::CString::new("hello world!").unwrap()
     );
 }
+
+/// for cbingen.
+#[allow(non_camel_case_types)]
+type c_char = u8;
+
+#[no_mangle]
+pub extern "C" fn sixtyfps_shared_string_bytes(ss: &SharedString) -> *const c_char {
+    ss.as_ptr()
+}
+
+#[no_mangle]
+/// Destroy the shared string
+pub unsafe extern "C" fn sixtyfps_shared_string_drop(ss: *const SharedString) {
+    core::ptr::read(ss);
+}
+
+#[no_mangle]
+/// Increment the reference count of the string.
+/// The resulting structure must be passed to sixtyfps_shared_string_drop
+pub unsafe extern "C" fn sixtyfps_shared_string_clone(out: *mut SharedString, ss: &SharedString) {
+    core::ptr::write(out, ss.clone())
+}
+
+#[no_mangle]
+/// Safety: bytes must be a valid utf-8 string of size len wihout null inside.
+/// The resulting structure must be passed to sixtyfps_shared_string_drop
+pub unsafe extern "C" fn sixtyfps_shared_string_from_bytes(
+    out: *mut SharedString,
+    bytes: *const c_char,
+    len: usize,
+) {
+    let str = core::str::from_utf8_unchecked(core::slice::from_raw_parts(bytes, len));
+    core::ptr::write(out, SharedString::from(str));
+}
+
+/// Create a string from a number.
+/// The resulting structure must be passed to sixtyfps_shared_string_drop
+#[no_mangle]
+pub unsafe extern "C" fn sixtyfps_shared_string_from_number(out: *mut SharedString, n: f64) {
+    // TODO: implement Write for SharedString so this can be done without alocation
+    let str = format!("{}", n);
+    core::ptr::write(out, SharedString::from(str.as_str()));
+}
+
+#[test]
+fn test_sixtyfps_shared_string_from_number() {
+    unsafe {
+        let mut s = core::mem::MaybeUninit::uninit();
+        sixtyfps_shared_string_from_number(s.as_mut_ptr(), 45.);
+        assert_eq!(s.assume_init(), "45");
+
+        let mut s = core::mem::MaybeUninit::uninit();
+        sixtyfps_shared_string_from_number(s.as_mut_ptr(), 45.12);
+        assert_eq!(s.assume_init(), "45.12");
+
+        let mut s = core::mem::MaybeUninit::uninit();
+        sixtyfps_shared_string_from_number(s.as_mut_ptr(), -1325466.);
+        assert_eq!(s.assume_init(), "-1325466");
+
+        let mut s = core::mem::MaybeUninit::uninit();
+        sixtyfps_shared_string_from_number(s.as_mut_ptr(), -0.);
+        assert_eq!(s.assume_init(), "0");
+    }
+}