From 001a7ba016a19794e752546e8815a5388919d394 Mon Sep 17 00:00:00 2001
From: Bodil Stokke <bodil@bodil.org>
Date: Fri, 16 Nov 2018 22:55:25 +0000
Subject: [PATCH] Parameterise nodes etc on output type, so we can type event
 handlers based on it.

With this, Node<String> only accepts event handlers implemented
for String, etc. No danger of trying to stringify functions and vice versa.
---
 macros/src/declare.rs      | 26 +++++++++++----------
 rocket/src/main.rs         | 27 ++++++++++++++++------
 typed-html/src/bin/main.rs |  4 ++--
 typed-html/src/dom.rs      | 46 ++++++++++++++++++++------------------
 typed-html/src/elements.rs | 31 ++++++++++++-------------
 typed-html/src/events.rs   | 45 +++++++++++++++++++++++++------------
 typed-html/src/lib.rs      | 10 +++++++++
 wasm/src/main.rs           |  5 +++--
 8 files changed, 120 insertions(+), 74 deletions(-)

diff --git a/macros/src/declare.rs b/macros/src/declare.rs
index e5a1a5e..d401ee4 100644
--- a/macros/src/declare.rs
+++ b/macros/src/declare.rs
@@ -91,19 +91,20 @@ impl Declare {
         let mut body = TokenStream::new();
 
         for (child_name, child_type, _) in self.req_children() {
-            body.extend(quote!( pub $child_name: Box<$child_type>, ));
+            body.extend(quote!( pub $child_name: Box<$child_type<T>>, ));
         }
 
         if let Some(child_constraint) = &self.opt_children {
             let child_constraint = child_constraint.clone();
-            body.extend(quote!(pub children: Vec<Box<$child_constraint>>,));
+            body.extend(quote!(pub children: Vec<Box<$child_constraint<T>>>,));
         }
 
         quote!(
-            pub struct $elem_name {
+            pub struct $elem_name<T> where T: ::OutputType {
+                phantom_output: std::marker::PhantomData<T>,
                 pub attrs: $attr_type_name,
                 pub data_attributes: Vec<(&'static str, String)>,
-                pub events: ::events::Events,
+                pub events: ::events::Events<T>,
                 $body
             }
         )
@@ -115,7 +116,7 @@ impl Declare {
 
         let mut args = TokenStream::new();
         for (child_name, child_type, _) in self.req_children() {
-            args.extend(quote!( $child_name: Box<$child_type>, ));
+            args.extend(quote!( $child_name: Box<$child_type<T>>, ));
         }
 
         let mut attrs = TokenStream::new();
@@ -137,9 +138,10 @@ impl Declare {
         }
 
         quote!(
-            impl $elem_name {
+            impl<T> $elem_name<T> where T: ::OutputType {
                 pub fn new($args) -> Self {
                     $elem_name {
+                        phantom_output: std::marker::PhantomData,
                         events: ::events::Events::default(),
                         $body
                     }
@@ -194,8 +196,8 @@ impl Declare {
         let elem_name = self.elem_name();
         let vnode = self.impl_vnode();
         quote!(
-            impl ::dom::Node for $elem_name {
-                fn vnode<'a>(&'a mut self) -> ::dom::VNode<'a> {
+            impl<T> ::dom::Node<T> for $elem_name<T> where T: ::OutputType {
+                fn vnode(&'_ mut self) -> ::dom::VNode<'_, T> {
                     $vnode
                 }
             }
@@ -222,7 +224,7 @@ impl Declare {
         }
 
         quote!(
-            impl ::dom::Element for $elem_name {
+            impl<T> ::dom::Element<T> for $elem_name<T> where T: ::OutputType {
                 fn name() -> &'static str {
                     $name
                 }
@@ -253,7 +255,7 @@ impl Declare {
         for t in &self.traits {
             let name = t.clone();
             body.extend(quote!(
-                impl $name for $elem_name {}
+                impl<T> $name<T> for $elem_name<T> where T: ::OutputType {}
             ));
         }
         body
@@ -316,13 +318,13 @@ impl Declare {
             print_events.extend(quote!(
                 if let Some(ref value) = self.events.$event_name {
                     write!(f, " on{}=\"{}\"", $event_str,
-                           ::htmlescape::encode_attribute(&value.render().unwrap()))?;
+                           ::htmlescape::encode_attribute(value.render().unwrap().as_str()))?;
                 }
             ));
         }
 
         quote!(
-            impl std::fmt::Display for $elem_name {
+            impl<T> std::fmt::Display for $elem_name<T> where T: ::OutputType {
                 fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
                     write!(f, "<{}", $name)?;
                     $print_attrs
diff --git a/rocket/src/main.rs b/rocket/src/main.rs
index 81ba954..0de5d49 100644
--- a/rocket/src/main.rs
+++ b/rocket/src/main.rs
@@ -4,16 +4,29 @@ extern crate rocket;
 extern crate typed_html;
 extern crate typed_html_macros;
 
-use rocket::http::ContentType;
-use rocket::response::Content;
-use rocket::{get, routes};
-use typed_html::text;
+use rocket::http::{ContentType, Status};
+use rocket::response::{Responder, Result};
+use rocket::{get, routes, Request, Response};
+use std::io::Cursor;
 use typed_html::types::LinkType;
+use typed_html::{dom::Node, text};
 use typed_html_macros::html;
 
+struct Html(Box<Node<String>>);
+
+impl<'r> Responder<'r> for Html {
+    fn respond_to(self, _request: &Request) -> Result<'r> {
+        Ok(Response::build()
+            .status(Status::Ok)
+            .header(ContentType::HTML)
+            .sized_body(Cursor::new(self.0.to_string()))
+            .finalize())
+    }
+}
+
 #[get("/")]
-fn index() -> Content<String> {
-    Content(ContentType::HTML, html!(
+fn index() -> Html {
+    Html(html!(
         <html>
             <head>
                 <title>"Hello Kitty!"</title>
@@ -34,7 +47,7 @@ fn index() -> Content<String> {
                 <button onclick="alert('She is not a cat.')">"Click me!"</button>
             </body>
         </html>
-    ).to_string())
+    ))
 }
 
 fn main() {
diff --git a/typed-html/src/bin/main.rs b/typed-html/src/bin/main.rs
index f44948a..2a9523c 100644
--- a/typed-html/src/bin/main.rs
+++ b/typed-html/src/bin/main.rs
@@ -5,7 +5,7 @@
 extern crate typed_html;
 extern crate typed_html_macros;
 
-use typed_html::dom::Node;
+use typed_html::dom::TextNode;
 use typed_html::types::*;
 use typed_html_macros::html;
 
@@ -14,7 +14,7 @@ struct Foo {
 }
 
 fn main() {
-    let the_big_question = text!("How does she eat?");
+    let the_big_question: Box<TextNode<String>> = text!("How does she eat?");
     let splain_class = "well-actually";
     let wibble = Foo { foo: "welp" };
     let doc = html!(
diff --git a/typed-html/src/dom.rs b/typed-html/src/dom.rs
index 523a54e..8214367 100644
--- a/typed-html/src/dom.rs
+++ b/typed-html/src/dom.rs
@@ -1,7 +1,9 @@
 //! DOM and virtual DOM types.
 
 use std::fmt::Display;
+use std::marker::PhantomData;
 
+use super::OutputType;
 use elements::{FlowContent, PhrasingContent};
 use events::Events;
 use htmlescape::encode_minimal;
@@ -21,17 +23,17 @@ use htmlescape::encode_minimal;
 /// ```
 ///
 /// [Node]: trait.Node.html
-pub enum VNode<'a> {
+pub enum VNode<'a, T: OutputType> {
     Text(&'a str),
-    Element(VElement<'a>),
+    Element(VElement<'a, T>),
 }
 
 /// An untyped representation of an HTML element.
-pub struct VElement<'a> {
+pub struct VElement<'a, T: OutputType> {
     pub name: &'static str,
     pub attributes: Vec<(&'static str, String)>,
-    pub events: &'a mut Events,
-    pub children: Vec<VNode<'a>>,
+    pub events: &'a mut Events<T>,
+    pub children: Vec<VNode<'a, T>>,
 }
 
 /// Trait for rendering a typed HTML node.
@@ -46,11 +48,11 @@ pub struct VElement<'a> {
 /// [TextNode]: struct.TextNode.html
 /// [elements]: ../elements/index.html
 /// [vnode]: #tymethod.vnode
-pub trait Node: Display {
+pub trait Node<T: OutputType>: Display {
     /// Render the node into a [`VNode`][VNode] tree.
     ///
     /// [VNode]: enum.VNode.html
-    fn vnode<'a>(&'a mut self) -> VNode<'a>;
+    fn vnode<'a>(&'a mut self) -> VNode<'a, T>;
 }
 
 /// Trait for querying a typed HTML element.
@@ -58,7 +60,7 @@ pub trait Node: Display {
 /// All [HTML elements][elements] implement this.
 ///
 /// [elements]: ../elements/index.html
-pub trait Element: Node {
+pub trait Element<T: OutputType>: Node<T> {
     /// Get the name of the element.
     fn name() -> &'static str;
     /// Get a list of the attribute names for this element.
@@ -80,7 +82,7 @@ pub trait Element: Node {
 }
 
 /// An HTML text node.
-pub struct TextNode(String);
+pub struct TextNode<T: OutputType>(String, PhantomData<T>);
 
 /// Macro for creating text nodes.
 ///
@@ -112,7 +114,7 @@ macro_rules! text {
     };
 }
 
-impl TextNode {
+impl<T: OutputType> TextNode<T> {
     /// Construct a text node.
     ///
     /// The preferred way to construct a text node is with the [`text!()`][text]
@@ -120,39 +122,39 @@ impl TextNode {
     ///
     /// [text]: ../macro.text.html
     pub fn new<S: Into<String>>(s: S) -> Self {
-        TextNode(s.into())
+        TextNode(s.into(), PhantomData)
     }
 }
 
-impl Display for TextNode {
+impl<T: OutputType> Display for TextNode<T> {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
         f.write_str(&encode_minimal(&self.0))
     }
 }
 
-impl Node for TextNode {
-    fn vnode<'a>(&'a mut self) -> VNode<'a> {
+impl<T: OutputType> Node<T> for TextNode<T> {
+    fn vnode(&'_ mut self) -> VNode<'_, T> {
         VNode::Text(&self.0)
     }
 }
 
-impl IntoIterator for TextNode {
-    type Item = TextNode;
-    type IntoIter = std::vec::IntoIter<TextNode>;
+impl<T: OutputType> IntoIterator for TextNode<T> {
+    type Item = TextNode<T>;
+    type IntoIter = std::vec::IntoIter<TextNode<T>>;
 
     fn into_iter(self) -> Self::IntoIter {
         vec![self].into_iter()
     }
 }
 
-impl IntoIterator for Box<TextNode> {
-    type Item = Box<TextNode>;
-    type IntoIter = std::vec::IntoIter<Box<TextNode>>;
+impl<T: OutputType> IntoIterator for Box<TextNode<T>> {
+    type Item = Box<TextNode<T>>;
+    type IntoIter = std::vec::IntoIter<Box<TextNode<T>>>;
 
     fn into_iter(self) -> Self::IntoIter {
         vec![self].into_iter()
     }
 }
 
-impl FlowContent for TextNode {}
-impl PhrasingContent for TextNode {}
+impl<T: OutputType> FlowContent<T> for TextNode<T> {}
+impl<T: OutputType> PhrasingContent<T> for TextNode<T> {}
diff --git a/typed-html/src/elements.rs b/typed-html/src/elements.rs
index cdf9a15..669b8f3 100644
--- a/typed-html/src/elements.rs
+++ b/typed-html/src/elements.rs
@@ -2,29 +2,30 @@
 
 use typed_html_macros::declare_elements;
 
+use super::OutputType;
 use dom::{Node, TextNode};
 use types::*;
 
 // Marker traits for element content groups
 
-pub trait MetadataContent: Node {}
-pub trait FlowContent: Node {}
-pub trait SectioningContent: Node {}
-pub trait HeadingContent: Node {}
+pub trait MetadataContent<T: OutputType>: Node<T> {}
+pub trait FlowContent<T: OutputType>: Node<T> {}
+pub trait SectioningContent<T: OutputType>: Node<T> {}
+pub trait HeadingContent<T: OutputType>: Node<T> {}
 // Phrasing content seems to be entirely a subclass of FlowContent
-pub trait PhrasingContent: FlowContent {}
-pub trait EmbeddedContent: Node {}
-pub trait InteractiveContent: Node {}
-pub trait FormContent: Node {}
+pub trait PhrasingContent<T: OutputType>: FlowContent<T> {}
+pub trait EmbeddedContent<T: OutputType>: Node<T> {}
+pub trait InteractiveContent<T: OutputType>: Node<T> {}
+pub trait FormContent<T: OutputType>: Node<T> {}
 
 // Traits for elements that are more picky about their children
-pub trait DescriptionListContent: Node {}
-pub trait HGroupContent: Node {}
-pub trait MapContent: Node {}
-pub trait MediaContent: Node {} // <audio> and <video>
-pub trait SelectContent: Node {}
-pub trait TableContent: Node {}
-pub trait TableColumnContent: Node {}
+pub trait DescriptionListContent<T: OutputType>: Node<T> {}
+pub trait HGroupContent<T: OutputType>: Node<T> {}
+pub trait MapContent<T: OutputType>: Node<T> {}
+pub trait MediaContent<T: OutputType>: Node<T> {} // <audio> and <video>
+pub trait SelectContent<T: OutputType>: Node<T> {}
+pub trait TableContent<T: OutputType>: Node<T> {}
+pub trait TableColumnContent<T: OutputType>: Node<T> {}
 
 declare_elements!{
     html {
diff --git a/typed-html/src/events.rs b/typed-html/src/events.rs
index 3932bb9..c8a8400 100644
--- a/typed-html/src/events.rs
+++ b/typed-html/src/events.rs
@@ -1,16 +1,30 @@
+//! Event handlers.
+
 use std::marker::PhantomData;
 use stdweb::web::event::*;
 use stdweb::web::{Element, EventListenerHandle, IEventTarget};
 
+use super::{OutputType, DOM};
+
 macro_rules! declare_events {
     ($($name:ident : $type:ty ,)*) => {
-        #[derive(Default)]
-        pub struct Events {
+        /// Container type for DOM events.
+        pub struct Events<T: OutputType> {
             $(
-                pub $name: Option<Box<dyn EventHandler<$type>>>,
+                pub $name: Option<Box<dyn EventHandler<T, $type>>>,
             )*
         }
 
+        impl<T: OutputType> Default for Events<T> {
+            fn default() -> Self {
+                Events {
+                    $(
+                        $name: None,
+                    )*
+                }
+            }
+        }
+
         #[macro_export]
         macro_rules! for_events {
             ($event:ident in $events:expr => $body:block) => {
@@ -94,7 +108,7 @@ declare_events! {
 }
 
 /// Trait for event handlers.
-pub trait EventHandler<EventType> {
+pub trait EventHandler<T: OutputType, E> {
     /// Build a callback function from this event handler.
     ///
     /// Returns `None` is this event handler can't be used to build a callback
@@ -112,10 +126,13 @@ pub trait EventHandler<EventType> {
     fn render(&self) -> Option<String>;
 }
 
-pub trait IntoEventHandler<E> {
-    fn into_event_handler(self) -> Box<dyn EventHandler<E>>;
+/// Trait for building event handlers from other types.
+pub trait IntoEventHandler<T: OutputType, E> {
+    /// Construct an event handler from an instance of the source type.
+    fn into_event_handler(self) -> Box<dyn EventHandler<T, E>>;
 }
 
+/// Wrapper type for closures as event handlers.
 pub struct EFn<F, E>(Option<F>, PhantomData<E>);
 
 impl<F, E> EFn<F, E>
@@ -128,27 +145,27 @@ where
     }
 }
 
-impl<F, E> IntoEventHandler<E> for EFn<F, E>
+impl<F, E> IntoEventHandler<DOM, E> for EFn<F, E>
 where
     F: FnMut(E) + 'static,
     E: ConcreteEvent + 'static,
 {
-    fn into_event_handler(self) -> Box<dyn EventHandler<E>> {
+    fn into_event_handler(self) -> Box<dyn EventHandler<DOM, E>> {
         Box::new(self)
     }
 }
 
-impl<F, E> IntoEventHandler<E> for F
+impl<F, E> IntoEventHandler<DOM, E> for F
 where
     F: FnMut(E) + 'static,
     E: ConcreteEvent + 'static,
 {
-    fn into_event_handler(self) -> Box<dyn EventHandler<E>> {
+    fn into_event_handler(self) -> Box<dyn EventHandler<DOM, E>> {
         Box::new(EFn::new(self))
     }
 }
 
-impl<F, E> EventHandler<E> for EFn<F, E>
+impl<F, E> EventHandler<DOM, E> for EFn<F, E>
 where
     F: FnMut(E) + 'static,
     E: ConcreteEvent,
@@ -163,7 +180,7 @@ where
     }
 }
 
-impl<E> EventHandler<E> for &'static str {
+impl<E> EventHandler<String, E> for &'static str {
     fn attach(&mut self, _target: &Element) -> EventListenerHandle {
         panic!("Silly wabbit, strings as event handlers are only for printing.");
     }
@@ -173,8 +190,8 @@ impl<E> EventHandler<E> for &'static str {
     }
 }
 
-impl<E> IntoEventHandler<E> for &'static str {
-    fn into_event_handler(self) -> Box<dyn EventHandler<E>> {
+impl<E> IntoEventHandler<String, E> for &'static str {
+    fn into_event_handler(self) -> Box<dyn EventHandler<String, E>> {
         Box::new(self)
     }
 }
diff --git a/typed-html/src/lib.rs b/typed-html/src/lib.rs
index 704bc84..1f4384b 100644
--- a/typed-html/src/lib.rs
+++ b/typed-html/src/lib.rs
@@ -17,3 +17,13 @@ pub mod dom;
 pub mod elements;
 pub mod events;
 pub mod types;
+
+/// Marker trait for outputs
+pub trait OutputType {}
+
+/// String output
+impl OutputType for String {}
+
+/// DOM output
+pub struct DOM;
+impl OutputType for DOM {}
diff --git a/wasm/src/main.rs b/wasm/src/main.rs
index c00ef5a..114add1 100644
--- a/wasm/src/main.rs
+++ b/wasm/src/main.rs
@@ -9,9 +9,10 @@ use stdweb::web::{self, Element, IElement, INode};
 use typed_html::dom::{Node, VNode};
 use typed_html::events::Events;
 use typed_html::for_events;
+use typed_html::DOM;
 use typed_html_macros::html;
 
-fn install_handlers(target: &Element, handlers: &mut Events) {
+fn install_handlers(target: &Element, handlers: &mut Events<DOM>) {
     for_events!(handler in handlers => {
         handler.attach(target);
     });
@@ -19,7 +20,7 @@ fn install_handlers(target: &Element, handlers: &mut Events) {
 
 fn build(
     document: &web::Document,
-    vnode: VNode,
+    vnode: VNode<'_, DOM>,
 ) -> Result<web::Node, web::error::InvalidCharacterError> {
     match vnode {
         VNode::Text(text) => Ok(document.create_text_node(&text).into()),