html string

src/node.rs

@@ -1,3 +1,5 @@
+use crate::Render;
+use crate::RenderContext;
 use crate::{cached_set::CacheId, RootRender, VdomWeak};
 use bumpalo::Bump;
 use std::fmt;
@@ -269,3 +271,32 @@ impl Listener<'_> {
         }
     }
 }
+
+pub fn html_string<R>(component: &R) -> String
+where
+    R: Render,
+{
+    fn html_string_recursive(cx: &mut RenderContext, s: &mut String, node: &Node) {
+        match node.kind {
+            NodeKind::Text(ref t) => s.push_str(t.text),
+            NodeKind::Element(ref e) => {
+                s.push_str(e.tag_name);
+                for c in e.children {
+                    html_string_recursive(cx, s, c);
+                }
+
+                s.push_str(&format!("</{}>", e.tag_name));
+            }
+            NodeKind::Cached(ref c) => {
+                html_string_recursive(cx, s, cx.cached_set.borrow().get(c.id).0);
+            }
+        }
+    }
+
+    RenderContext::empty(|cx| {
+        let node = component.render(cx);
+        let mut s = String::new();
+        html_string_recursive(cx, &mut s, &node);
+        s
+    })
+}

src/render_context.rs

@@ -5,6 +5,7 @@ use crate::{
 };
 use bumpalo::Bump;
 use fxhash::FxHashMap;
+use std::cell::RefCell;
 use std::fmt;
 
 /// Common context available to all `Render` implementations.
@@ -58,6 +59,23 @@ impl<'a> RenderContext<'a> {
             }
         }
     }
+    /// return an empty rendering context
+    pub_unstable_internal! {
+        pub(crate) fn empty<F, T>(f: F) -> T
+            where F: FnOnce(&mut RenderContext) -> T,
+            {
+            let cached_set = &RefCell::new(CachedSet::default());
+            let bump = &Bump::new();
+            let templates = &mut FxHashMap::default();
+
+            f(&mut RenderContext {
+                bump,
+                cached_set,
+                templates,
+                _non_exhaustive: (),
+            })
+        }
+    }
 
     pub(crate) fn cache<F>(&mut self, pinned: bool, template: Option<CacheId>, f: F) -> CacheId
     where

tests/web/render.rs

@@ -1,4 +1,4 @@
-use super::{assert_rendered, before_after, create_element, RenderFn};
+use super::{assert_rendered, before_after, create_element, RenderFn, html_string};
 use dodrio::{builder::*, Vdom};
 use futures::prelude::*;
 use std::rc::Rc;
@@ -10,7 +10,18 @@ fn render_initial_text() {
 
     let container = create_element("div");
     let _vdom = Vdom::new(&container, hello.clone());
-    assert_rendered(&container, &hello);
+    assert_rendered(container, &hello);
+}
+
+fn render_to_string() {
+   let hello = Rc::new(RenderFn(|cx| {
+       div(&cx)
+            .attr("id", "hello-world")
+            .children([text("Hello "), span(&cx).child(text("World!")).finish()])
+            .finish()
+    }));
+    let string_html = html_string(&hello);
+    assert!(&string_html, "<div id=hello_world> Hello <span>World!</span></div>");
 }
 
 #[wasm_bindgen_test]