From d4da7e0c251c352bb20bb7ad97766d404ce98baf Mon Sep 17 00:00:00 2001
From: Greg Johnston <greg.johnston@gmail.com>
Date: Sun, 13 Nov 2022 15:58:49 -0500
Subject: [PATCH] Allow returning `<template>` from `view`

---
 Cargo.toml                      |  1 +
 examples/view-tests/Cargo.toml  | 14 +++++++++++++
 examples/view-tests/index.html  |  7 +++++++
 examples/view-tests/src/main.rs | 35 +++++++++++++++++++++++++++++++++
 leptos_macro/src/view.rs        | 17 ++++++++++++++--
 5 files changed, 72 insertions(+), 2 deletions(-)
 create mode 100644 examples/view-tests/Cargo.toml
 create mode 100644 examples/view-tests/index.html
 create mode 100644 examples/view-tests/src/main.rs
diff --git a/Cargo.toml b/Cargo.toml
index 14817d44e..856b16752 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,6 +26,7 @@ members = [
   "examples/parent-child",
   "examples/router",
   "examples/todomvc",
+  "examples/view-tests",
 
   # book
   "docs/book/project/ch02_getting_started",
diff --git a/examples/view-tests/Cargo.toml b/examples/view-tests/Cargo.toml
new file mode 100644
index 000000000..791990121
--- /dev/null
+++ b/examples/view-tests/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "view-tests"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+leptos = { path = "../../leptos" }
+console_log = "0.2"
+log = "0.4"
+console_error_panic_hook = "0.1.7"
+
+[dev-dependencies]
+wasm-bindgen-test = "0.3.0"
+
diff --git a/examples/view-tests/index.html b/examples/view-tests/index.html
new file mode 100644
index 000000000..b5ec4d243
--- /dev/null
+++ b/examples/view-tests/index.html
@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+<html>
+	<head>
+		<link data-trunk rel="rust" data-wasm-opt="z"/>
+	</head>
+	<body></body>
+</html>
\ No newline at end of file
diff --git a/examples/view-tests/src/main.rs b/examples/view-tests/src/main.rs
new file mode 100644
index 000000000..146bd2ef3
--- /dev/null
+++ b/examples/view-tests/src/main.rs
@@ -0,0 +1,35 @@
+use leptos::*;
+
+pub fn main() {
+    _ = console_log::init_with_level(log::Level::Debug);
+    console_error_panic_hook::set_once();
+    mount_to_body(|cx| view! { cx, <TemplateConsumer/> })
+}
+
+#[component]
+fn TemplateConsumer(cx: Scope) -> Element {
+    let tpl = view! { cx, <TemplateExample/> };
+    let cloned_tpl = tpl
+        .unchecked_ref::<web_sys::HtmlTemplateElement>()
+        .content()
+        .clone_node_with_deep(true)
+        .expect("couldn't clone template node");
+
+    view! {
+        cx,
+        <div id="template">
+            <h1>"Template Consumer"</h1>
+            {cloned_tpl}
+        </div>
+    }
+}
+
+#[component]
+fn TemplateExample(cx: Scope) -> Element {
+    view! {
+        cx,
+        <template>
+            <div>"Template contents"</div>
+        </template>
+    }
+}
diff --git a/leptos_macro/src/view.rs b/leptos_macro/src/view.rs
index f6bef1ff2..6d0269828 100644
--- a/leptos_macro/src/view.rs
+++ b/leptos_macro/src/view.rs
@@ -88,6 +88,7 @@ fn root_element_to_tokens(
             &mut expressions,
             true,
             mode,
+            false
         );
 
         match mode {
@@ -179,6 +180,7 @@ fn element_to_tokens(
     expressions: &mut Vec<TokenStream>,
     is_root_el: bool,
     mode: Mode,
+    parent_is_template: bool,
 ) -> Ident {
     // create this element
     *next_el_id += 1;
@@ -186,6 +188,7 @@ fn element_to_tokens(
 
     // Open tag
     let name_str = node.name.to_string();
+    let is_template = name_str.to_lowercase() == "template";
     let span = node.name.span();
 
     if mode == Mode::Ssr {
@@ -288,6 +291,13 @@ fn element_to_tokens(
                     let #this_el_ident = #prev_sib.next_sibling().unwrap_throw();
                     //log::debug!("=> got {}", #this_el_ident.node_name());
             }
+        } else if parent_is_template {
+            quote_spanned! {
+                span => let #this_el_ident = #debug_name;
+                    //log::debug!("first_child ({})", #debug_name);
+                    let #this_el_ident = #parent.unchecked_ref::<web_sys::HtmlTemplateElement>().content().first_child().unwrap_throw();
+                    //log::debug!("=> got {}", #this_el_ident.node_name());
+            }
         } else {
             quote_spanned! {
                 span => let #this_el_ident = #debug_name;
@@ -354,7 +364,8 @@ fn element_to_tokens(
             expressions,
             multi,
             mode,
-            idx == 0
+            idx == 0,
+            is_template
         );
 
         prev_sib = match curr_id {
@@ -606,7 +617,8 @@ fn child_to_tokens(
     expressions: &mut Vec<TokenStream>,
     multi: bool,
     mode: Mode,
-    is_first_child: bool
+    is_first_child: bool,
+    parent_is_template: bool,
 ) -> PrevSibChange {
     match node {
         Node::Element(node) => {
@@ -639,6 +651,7 @@ fn child_to_tokens(
                     expressions,
                     false,
                     mode,
+                    parent_is_template
                 ))
             }
         }
