add write function and remove todo Sink impl

src/element.rs

@@ -3,7 +3,7 @@
 #![feature(drain_filter)]
 
 use std::{
-    collections::{HashMap, HashSet, VecDeque},
+    collections::{vec_deque, HashMap, HashSet, VecDeque},
     convert::Infallible,
     str::FromStr,
 };
@@ -580,6 +580,10 @@ impl ElementBuilder {
 }
 
 pub trait IntoContent {
+    fn into_content(&self) -> Content {
+        self.builder().build().unwrap()
+    }
+
     fn builder(&self) -> ContentBuilder;
 }
 
@@ -592,9 +596,14 @@ where
     }
 }
 
+pub trait FromContent: Sized {
+    fn from_content(content: Content) -> DeserializeResult<Self>;
+}
+
 pub enum ContentBuilder {
     Element(ElementBuilder),
     Text(String),
+    Comment(String),
 }
 
 impl ContentBuilder {
@@ -604,6 +613,7 @@ impl ContentBuilder {
                 Ok(Content::Element(element_builder.build()?))
             }
             ContentBuilder::Text(text) => Ok(Content::Text(text.to_string())),
+            ContentBuilder::Comment(s) => Ok(Content::Comment(s.to_string())),
         }
     }
 }

src/writer.rs

@@ -1,4 +1,4 @@
-use std::{collections::HashSet, str::FromStr};
+use std::{collections::HashSet, pin::pin, str::FromStr};
 
 use async_recursion::async_recursion;
 use futures::Sink;
@@ -6,7 +6,7 @@ use tokio::io::{AsyncWrite, AsyncWriteExt};
 
 use crate::{
     declaration::{Declaration, VersionInfo},
-    element::{escape_str, Content, Element, IntoElement, Name, NamespaceDeclaration},
+    element::{escape_str, Content, Element, IntoContent, IntoElement, Name, NamespaceDeclaration},
     error::Error,
     xml::{self, composers::Composer, parsers_complete::Parser, ETag, XMLDecl},
     Result, XMLNS_NS, XML_NS,
@@ -79,6 +79,11 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
         Ok(())
     }
 
+    pub async fn write(&mut self, into_content: &impl IntoContent) -> Result<()> {
+        let content = into_content.into_content();
+        Ok(self.write_content(&content).await?)
+    }
+
     #[async_recursion]
     pub async fn write_element(&mut self, element: &Element) -> Result<()> {
         if element.content.is_empty() {
@@ -357,35 +362,6 @@ impl<W: AsyncWrite + Unpin + Send> Writer<W> {
     }
 }
 
-impl<W: AsyncWrite, E: Into<Element>> Sink<E> for Writer<W> {
-    type Error = Error;
-
-    fn poll_ready(
-        self: std::pin::Pin<&mut Self>,
-        cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<()>> {
-        todo!()
-    }
-
-    fn start_send(self: std::pin::Pin<&mut Self>, item: E) -> Result<()> {
-        todo!()
-    }
-
-    fn poll_flush(
-        self: std::pin::Pin<&mut Self>,
-        cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<()>> {
-        todo!()
-    }
-
-    fn poll_close(
-        self: std::pin::Pin<&mut Self>,
-        cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Result<()>> {
-        todo!()
-    }
-}
-
 #[cfg(test)]
 mod test {
     use crate::{