Static attribute lists

packages/yew-macro/src/html_tree/html_element.rs

@@ -1,14 +1,14 @@
 use super::{HtmlChildrenTree, HtmlDashedName, TagTokens};
 use crate::props::{ClassesForm, ElementProps, Prop};
-use crate::stringify::Stringify;
+use crate::stringify::{Stringify, Value};
 use crate::{non_capitalized_ascii, Peek, PeekValue};
 use boolinator::Boolinator;
 use proc_macro2::{Delimiter, TokenStream};
 use quote::{quote, quote_spanned, ToTokens};
 use syn::buffer::Cursor;
 use syn::parse::{Parse, ParseStream};
 use syn::spanned::Spanned;
-use syn::{Block, Ident, Token};
+use syn::{Block, Expr, Ident, Lit, LitStr, Token};
 
 pub struct HtmlElement {
     name: TagName,
@@ -147,17 +147,35 @@ impl ToTokens for HtmlElement {
 
         let attributes = {
             let normal_attrs = attributes.iter().map(|Prop { label, value, .. }| {
-                let key = label.to_lit_str();
-                let value = value.optimize_literals();
-                quote! {
-                    ::yew::virtual_dom::PositionalAttr::new(#key, #value)
-                }
+                (label.to_lit_str(), value.optimize_literals_tagged())
             });
-            let boolean_attrs = booleans.iter().map(|Prop { label, value, .. }| {
+            let boolean_attrs = booleans.iter().filter_map(|Prop { label, value, .. }| {
                 let key = label.to_lit_str();
-                quote! {
-                    ::yew::virtual_dom::PositionalAttr::new_boolean(#key, #value)
-                }
+                Some((
+                    key.clone(),
+                    match value {
+                        Expr::Lit(e) => match &e.lit {
+                            Lit::Bool(b) => Value::Static(if b.value {
+                                quote! { #key }
+                            } else {
+                                return None;
+                            }),
+                            _ => Value::Dynamic(quote_spanned! {value.span()=> {
+                                ::yew::utils::__ensure_type::<bool>(#value);
+                                #key
+                            }}),
+                        },
+                        expr => Value::Dynamic(quote_spanned! {expr.span()=>
+                            if #expr {
+                                ::std::option::Option::Some(
+                                    ::std::borrow::Cow::<'static, str>::Borrowed(#key)
+                                )
+                            } else {
+                                None
+                            }
+                        }),
+                    },
+                ))
             });
             let class_attr = classes.as_ref().and_then(|classes| match classes {
                 ClassesForm::Tuple(classes) => {
@@ -176,36 +194,78 @@ impl ToTokens for HtmlElement {
                         };
                     };
 
-                    Some(quote! {
-                        {
-                            let mut __yew_classes = ::yew::html::Classes::with_capacity(#n);
-                            #(__yew_classes.push(#classes);)*
+                    Some((
+                        LitStr::new("class", span),
+                        Value::Dynamic(quote! {
+                            {
+                                #deprecation_warning
 
-                            #deprecation_warning
-
-                            ::yew::virtual_dom::PositionalAttr::new("class", __yew_classes)
-                        }
-                    })
+                                let mut __yew_classes = ::yew::html::Classes::with_capacity(#n);
+                                #(__yew_classes.push(#classes);)*
+                                __yew_classes
+                            }
+                        }),
+                    ))
                 }
-                ClassesForm::Single(classes) => match classes.try_into_lit() {
-                    Some(lit) => {
-                        if lit.value().is_empty() {
-                            None
-                        } else {
-                            let sr = lit.stringify();
-                            Some(quote! { ::yew::virtual_dom::PositionalAttr::new("class", #sr) })
+                ClassesForm::Single(classes) => {
+                    match classes.try_into_lit() {
+                        Some(lit) => {
+                            if lit.value().is_empty() {
+                                None
+                            } else {
+                                Some((
+                                    LitStr::new("class", lit.span()),
+                                    Value::Static(quote! { #lit }),
+                                ))
+                            }
+                        }
+                        None => {
+                            Some((
+                                LitStr::new("class", classes.span()),
+                                Value::Dynamic(quote! {
+                                    ::std::convert::Into::<::yew::html::Classes>::into(#classes)
+                                }),
+                            ))
                         }
-                    }
-                    None => {
-                        Some(quote! { ::yew::virtual_dom::PositionalAttr::new("class", ::std::convert::Into::<::yew::html::Classes>::into(#classes)) })
                     }
                 }
             });
 
-            let attrs = normal_attrs.chain(boolean_attrs).chain(class_attr);
-            quote! {
-                ::yew::virtual_dom::Attributes::Vec(::std::vec![#(#attrs),*])
+            /// Try to turn attribute list into a `::yew::virtual_dom::Attributes::Static`
+            fn try_into_static(src: &[(LitStr, Value)]) -> Option<TokenStream> {
+                let mut kv = Vec::with_capacity(src.len());
+                for (k, v) in src.iter() {
+                    let v = match v {
+                        Value::Static(v) => quote! { #v },
+                        Value::Dynamic(_) => return None,
+                    };
+                    kv.push(quote! { [ #k, #v ] });
+                }
+
+                Some(quote! { ::yew::virtual_dom::Attributes::Static(&[#(#kv),*]) })
             }
+
+            let attrs = normal_attrs
+                .chain(boolean_attrs)
+                .chain(class_attr)
+                .collect::<Vec<(LitStr, Value)>>();
+            try_into_static(&attrs).unwrap_or_else(|| {
+                let keys = attrs.iter().map(|(k, _)| quote! { #k });
+                let values = attrs.iter().map(|(_, v)| {
+                    quote_spanned! {v.span()=>
+                        ::yew::html::IntoPropValue::<
+                            ::std::option::Option::<::yew::virtual_dom::AttrValue>
+                        >
+                        ::into_prop_value(#v)
+                    }
+                });
+                quote! {
+                    ::yew::virtual_dom::Attributes::Dynamic{
+                        keys: &[#(#keys),*],
+                        values: ::std::boxed::Box::new([#(#values),*]),
+                    }
+                }
+            })
         };
 
         let listeners = if listeners.is_empty() {
@@ -291,9 +351,7 @@ impl ToTokens for HtmlElement {
                 let handle_value_attr = props.value.as_ref().map(|prop| {
                     let v = prop.value.optimize_literals();
                     quote_spanned! {v.span()=> {
-                        __yew_vtag.__macro_push_attr(
-                            ::yew::virtual_dom::PositionalAttr::new("value", #v),
-                        );
+                        __yew_vtag.__macro_push_attr("value", #v);
                     }}
                 });
 

packages/yew-macro/src/stringify.rs

@@ -21,13 +21,21 @@ pub trait Stringify {
 
     /// Optimize literals to `&'static str`, otherwise keep the value as is.
     fn optimize_literals(&self) -> TokenStream
+    where
+        Self: ToTokens,
+    {
+        self.optimize_literals_tagged().to_token_stream()
+    }
+
+    /// Like `optimize_literals` but tags static or dynamic strings with [Value]
+    fn optimize_literals_tagged(&self) -> Value
     where
         Self: ToTokens,
     {
         if let Some(lit) = self.try_into_lit() {
-            lit.to_token_stream()
+            Value::Static(lit.to_token_stream())
         } else {
-            self.to_token_stream()
+            Value::Dynamic(self.to_token_stream())
         }
     }
 }
@@ -41,6 +49,21 @@ impl<T: Stringify + ?Sized> Stringify for &T {
     }
 }
 
+/// A stringified value that can be either static (known at compile time) or dynamic (known only at
+/// runtime)
+pub enum Value {
+    Static(TokenStream),
+    Dynamic(TokenStream),
+}
+
+impl ToTokens for Value {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.extend(match self {
+            Value::Static(tt) | Value::Dynamic(tt) => tt.clone(),
+        });
+    }
+}
+
 impl Stringify for LitStr {
     fn try_into_lit(&self) -> Option<LitStr> {
         Some(self.clone())

packages/yew-macro/tests/classes_macro/classes-fail.stderr

@@ -51,9 +51,9 @@ error[E0277]: the trait bound `Classes: From<{integer}>` is not satisfied
             <Classes as From<&[T]>>
           and 4 others
   = note: required because of the requirements on the impl of `Into<Classes>` for `{integer}`
-  = note: required because of the requirements on the impl of `From<std::vec::Vec<{integer}>>` for `Classes`
+  = note: required because of the requirements on the impl of `From<Vec<{integer}>>` for `Classes`
   = note: 1 redundant requirements hidden
-  = note: required because of the requirements on the impl of `Into<Classes>` for `std::vec::Vec<{integer}>`
+  = note: required because of the requirements on the impl of `Into<Classes>` for `Vec<{integer}>`
 
 error[E0277]: the trait bound `Classes: From<{integer}>` is not satisfied
   --> $DIR/classes-fail.rs:13:14

packages/yew-macro/tests/html_macro/element-fail.stderr

@@ -177,10 +177,7 @@ error[E0277]: the trait bound `(): IntoPropValue<Option<Cow<'static, str>>>` is
 43 |     html! { <input type={()} /> };
    |                          ^^ the trait `IntoPropValue<Option<Cow<'static, str>>>` is not implemented for `()`
    |
-  ::: $WORKSPACE/packages/yew/src/virtual_dom/mod.rs
-   |
-   |     pub fn new(key: &'static str, value: impl IntoPropValue<Option<AttrValue>>) -> Self {
-   |                                               -------------------------------- required by this bound in `PositionalAttr::new`
+   = note: required by `into_prop_value`
 
 error[E0277]: the trait bound `(): IntoPropValue<Option<Cow<'static, str>>>` is not satisfied
   --> $DIR/element-fail.rs:44:27
@@ -196,53 +193,39 @@ error[E0277]: the trait bound `(): IntoPropValue<Option<Cow<'static, str>>>` is
 45 |     html! { <a href={()} /> };
    |                      ^^ the trait `IntoPropValue<Option<Cow<'static, str>>>` is not implemented for `()`
    |
-  ::: $WORKSPACE/packages/yew/src/virtual_dom/mod.rs
-   |
-   |     pub fn new(key: &'static str, value: impl IntoPropValue<Option<AttrValue>>) -> Self {
-   |                                               -------------------------------- required by this bound in `PositionalAttr::new`
+   = note: required by `into_prop_value`
 
 error[E0277]: the trait bound `NotToString: IntoPropValue<Option<Cow<'static, str>>>` is not satisfied
   --> $DIR/element-fail.rs:46:28
    |
 46 |     html! { <input string={NotToString} /> };
    |                            ^^^^^^^^^^^ the trait `IntoPropValue<Option<Cow<'static, str>>>` is not implemented for `NotToString`
    |
-  ::: $WORKSPACE/packages/yew/src/virtual_dom/mod.rs
-   |
-   |     pub fn new(key: &'static str, value: impl IntoPropValue<Option<AttrValue>>) -> Self {
-   |                                               -------------------------------- required by this bound in `PositionalAttr::new`
+   = note: required by `into_prop_value`
 
 error[E0277]: the trait bound `Option<NotToString>: IntoPropValue<Option<Cow<'static, str>>>` is not satisfied
   --> $DIR/element-fail.rs:47:23
    |
 47 |     html! { <a media={Some(NotToString)} /> };
    |                       ^^^^^^^^^^^^^^^^^ the trait `IntoPropValue<Option<Cow<'static, str>>>` is not implemented for `Option<NotToString>`
    |
-  ::: $WORKSPACE/packages/yew/src/virtual_dom/mod.rs
-   |
-   |     pub fn new(key: &'static str, value: impl IntoPropValue<Option<AttrValue>>) -> Self {
-   |                                               -------------------------------- required by this bound in `PositionalAttr::new`
-   |
    = help: the following implementations were found:
              <Option<&'static str> as IntoPropValue<Option<Cow<'static, str>>>>
              <Option<&'static str> as IntoPropValue<Option<String>>>
              <Option<String> as IntoPropValue<Option<Cow<'static, str>>>>
+   = note: required by `into_prop_value`
 
 error[E0277]: the trait bound `Option<{integer}>: IntoPropValue<Option<Cow<'static, str>>>` is not satisfied
   --> $DIR/element-fail.rs:48:22
    |
 48 |     html! { <a href={Some(5)} /> };
    |                      ^^^^^^^ the trait `IntoPropValue<Option<Cow<'static, str>>>` is not implemented for `Option<{integer}>`
    |
-  ::: $WORKSPACE/packages/yew/src/virtual_dom/mod.rs
-   |
-   |     pub fn new(key: &'static str, value: impl IntoPropValue<Option<AttrValue>>) -> Self {
-   |                                               -------------------------------- required by this bound in `PositionalAttr::new`
-   |
    = help: the following implementations were found:
              <Option<&'static str> as IntoPropValue<Option<Cow<'static, str>>>>
              <Option<&'static str> as IntoPropValue<Option<String>>>
              <Option<String> as IntoPropValue<Option<Cow<'static, str>>>>
+   = note: required by `into_prop_value`
 
 error[E0277]: the trait bound `{integer}: IntoPropValue<Option<yew::Callback<MouseEvent>>>` is not satisfied
    --> $DIR/element-fail.rs:51:28

packages/yew-macro/tests/props_macro/resolve-prop-fail.stderr

@@ -1,8 +1,8 @@
-error[E0277]: the trait bound `std::vec::Vec<_>: yew::Properties` is not satisfied
+error[E0277]: the trait bound `Vec<_>: yew::Properties` is not satisfied
   --> $DIR/resolve-prop-fail.rs:38:17
    |
 38 |     yew::props!(Vec<_> {});
-   |                 ^^^ the trait `yew::Properties` is not implemented for `std::vec::Vec<_>`
+   |                 ^^^ the trait `yew::Properties` is not implemented for `Vec<_>`
    |
    = note: required by `builder`
 

packages/yew/src/html/classes.rs

@@ -3,6 +3,7 @@ use crate::virtual_dom::AttrValue;
 use indexmap::IndexSet;
 use std::{
     borrow::{Borrow, Cow},
+    hint::unreachable_unchecked,
     iter::FromIterator,
 };
 
@@ -65,16 +66,22 @@ impl Classes {
 }
 
 impl IntoPropValue<AttrValue> for Classes {
+    #[inline]
     fn into_prop_value(mut self) -> AttrValue {
         if self.set.len() == 1 {
-            self.set.pop().unwrap()
+            match self.set.pop() {
+                Some(attr) => attr,
+                // SAFETY: the collection is checked to be non-empty above
+                None => unsafe { unreachable_unchecked() },
+            }
         } else {
             Cow::Owned(self.to_string())
         }
     }
 }
 
 impl IntoPropValue<Option<AttrValue>> for Classes {
+    #[inline]
     fn into_prop_value(self) -> Option<AttrValue> {
         if self.is_empty() {
             None

packages/yew/src/utils/mod.rs

@@ -95,6 +95,12 @@ impl<IN, OUT> IntoIterator for NodeSeq<IN, OUT> {
     }
 }
 
+/// Hack to force type mismatch compile errors in yew-macro.
+//
+// TODO: replace with `compile_error!`, when `type_name_of_val` is stabilised.
+#[doc(hidden)]
+pub fn __ensure_type<T>(_: T) {}
+
 /// Print the [web_sys::Node]'s contents as a string for debugging purposes
 pub fn print_node(n: &web_sys::Node) -> String {
     use wasm_bindgen::JsCast;