wip

src/message/body.rs

@@ -1,11 +1,11 @@
-use std::{mem, ops::Deref};
+use std::{mem, ops::Deref, sync::Arc};
 
 use crate::message::header::ContentTransferEncoding;
 
 /// A [`Message`][super::Message] or [`SinglePart`][super::SinglePart] body that has already been encoded.
 #[derive(Debug, Clone)]
 pub struct Body {
-    buf: Vec<u8>,
+    buf: Arc<[u8]>,
     encoding: ContentTransferEncoding,
 }
 
@@ -39,7 +39,7 @@ impl Body {
 
         let encoding = buf.encoding(false);
         buf.encode_crlf();
-        Self::new_impl(buf.into(), encoding)
+        Self::new_impl(Vec::from(buf).into(), encoding)
     }
 
     /// Encode the supplied `buf`, using the provided `encoding`.
@@ -77,7 +77,7 @@ impl Body {
         }
 
         buf.encode_crlf();
-        Ok(Self::new_impl(buf.into(), encoding))
+        Ok(Self::new_impl(Vec::from(buf).into(), encoding))
     }
 
     /// Builds a new `Body` using a pre-encoded buffer.
@@ -87,11 +87,14 @@ impl Body {
     /// `buf` shouldn't contain non-ascii characters, lines longer than 1000 characters or nul bytes.
     #[inline]
     pub fn dangerous_pre_encoded(buf: Vec<u8>, encoding: ContentTransferEncoding) -> Self {
-        Self { buf, encoding }
+        Self {
+            buf: buf.into(),
+            encoding,
+        }
     }
 
     /// Encodes the supplied `buf` using the provided `encoding`
-    fn new_impl(buf: Vec<u8>, encoding: ContentTransferEncoding) -> Self {
+    fn new_impl(buf: Arc<[u8]>, encoding: ContentTransferEncoding) -> Self {
         match encoding {
             ContentTransferEncoding::SevenBit
             | ContentTransferEncoding::EightBit
@@ -133,7 +136,16 @@ impl Body {
 
     /// Consumes `Body` and returns the inner `Vec<u8>`
     #[inline]
+    #[deprecated(
+        note = "The inner memory is not stored into `Vec<u8>` anymore. Consider using `into_inner`"
+    )]
     pub fn into_vec(self) -> Vec<u8> {
+        self.buf.to_vec()
+    }
+
+    /// Consumes `Body` and returns the inner `Arc<[u8]>`
+    #[inline]
+    pub fn into_inner(self) -> Arc<[u8]> {
         self.buf
     }
 }

src/message/header/mod.rs

@@ -18,6 +18,7 @@ pub use self::{
     special::*,
     textual::*,
 };
+use super::EmailFormat;
 use crate::BoxError;
 
 mod content;
@@ -154,6 +155,19 @@ impl Display for Headers {
     }
 }
 
+impl EmailFormat for Headers {
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
+        for value in &self.headers {
+            out.extend([
+                Cow::Borrowed(value.name.as_bytes()),
+                Cow::Borrowed(b": "),
+                Cow::Borrowed(value.encoded_value.as_bytes()),
+                Cow::Borrowed(b"\r\n"),
+            ]);
+        }
+    }
+}
+
 /// A possible error when converting a `HeaderName` from another type.
 // comes from `http` crate
 #[allow(missing_copy_implementations)]

src/message/mimebody.rs

@@ -1,4 +1,4 @@
-use std::{io::Write, iter::repeat_with};
+use std::{borrow::Cow, iter::repeat_with, sync::Arc};
 
 use mime::Mime;
 
@@ -28,7 +28,7 @@ impl Part {
 }
 
 impl EmailFormat for Part {
-    fn format(&self, out: &mut Vec<u8>) {
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
         match self {
             Part::Single(part) => part.format(out),
             Part::Multi(part) => part.format(out),
@@ -71,7 +71,7 @@ impl SinglePartBuilder {
 
         SinglePart {
             headers: self.headers,
-            body: body.into_vec(),
+            body: body.into_inner(),
         }
     }
 }
@@ -100,7 +100,7 @@ impl Default for SinglePartBuilder {
 #[derive(Debug, Clone)]
 pub struct SinglePart {
     headers: Headers,
-    body: Vec<u8>,
+    body: Arc<[u8]>,
 }
 
 impl SinglePart {
@@ -138,24 +138,18 @@ impl SinglePart {
 
     /// Get message content formatted for sending
     pub fn formatted(&self) -> Vec<u8> {
-        let mut out = Vec::new();
+        self.format_to_vec()
-        self.format(&mut out);
-        out
-    }
-
-    /// Format only the signlepart body
-    fn format_body(&self, out: &mut Vec<u8>) {
-        out.extend_from_slice(&self.body);
-        out.extend_from_slice(b"\r\n");
     }
 }
 
 impl EmailFormat for SinglePart {
-    fn format(&self, out: &mut Vec<u8>) {
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        write!(out, "{}", self.headers)
+        self.headers.format(out);
-            .expect("A Write implementation panicked while formatting headers");
+        out.extend([
-        out.extend_from_slice(b"\r\n");
+            Cow::Borrowed("\r\n".as_bytes()),
-        self.format_body(out);
+            Cow::Borrowed(&self.body),
+            Cow::Borrowed(b"\r\n"),
+        ]);
     }
 }
 
@@ -384,33 +378,36 @@ impl MultiPart {
 
     /// Get message content formatted for SMTP
     pub fn formatted(&self) -> Vec<u8> {
-        let mut out = Vec::new();
+        self.format_to_vec()
-        self.format(&mut out);
-        out
     }
 
     /// Format only the multipart body
-    fn format_body(&self, out: &mut Vec<u8>) {
+    fn format_body<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
         let boundary = self.boundary();
 
         for part in &self.parts {
-            out.extend_from_slice(b"--");
+            out.extend([
-            out.extend_from_slice(boundary.as_bytes());
+                Cow::Borrowed("--".as_bytes()),
-            out.extend_from_slice(b"\r\n");
+                // FIXME: this clone shouldn't exist
+                Cow::Owned(boundary.clone().into()),
+                Cow::Borrowed("\r\n".as_bytes()),
+            ]);
             part.format(out);
         }
 
-        out.extend_from_slice(b"--");
+        out.extend([
-        out.extend_from_slice(boundary.as_bytes());
+            Cow::Borrowed("--".as_bytes()),
-        out.extend_from_slice(b"--\r\n");
+            Cow::Owned(boundary.into()),
+            Cow::Borrowed("--\r\n".as_bytes()),
+        ]);
     }
 }
 
 impl EmailFormat for MultiPart {
-    fn format(&self, out: &mut Vec<u8>) {
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        write!(out, "{}", self.headers)
+        self.headers.format(out);
-            .expect("A Write implementation panicked while formatting headers");
+        out.extend([Cow::Borrowed("\r\n".as_bytes())]);
-        out.extend_from_slice(b"\r\n");
+
         self.format_body(out);
     }
 }

src/message/mod.rs

@@ -198,7 +198,7 @@
 //! ```
 //! </details>
 
-use std::{io::Write, iter, time::SystemTime};
+use std::{borrow::Cow, iter, sync::Arc, time::SystemTime};
 
 pub use attachment::Attachment;
 pub use body::{Body, IntoBody, MaybeString};
@@ -226,7 +226,23 @@ const DEFAULT_MESSAGE_ID_DOMAIN: &str = "localhost";
 /// Something that can be formatted as an email message
 trait EmailFormat {
     // Use a writer?
-    fn format(&self, out: &mut Vec<u8>);
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>);
+
+    fn format_to_vec(&self) -> Vec<u8> {
+        struct Formatter(Vec<u8>);
+
+        impl<'a> Extend<Cow<'a, [u8]>> for Formatter {
+            fn extend<T: IntoIterator<Item = Cow<'a, [u8]>>>(&mut self, iter: T) {
+                for chunk in iter {
+                    self.0.extend_from_slice(&chunk);
+                }
+            }
+        }
+
+        let mut formatted = Formatter(Vec::new());
+        self.format(&mut formatted);
+        formatted.0
+    }
 }
 
 /// A builder for messages
@@ -454,7 +470,7 @@ impl MessageBuilder {
         let body = body.into_body(maybe_encoding);
 
         self.headers.set(body.encoding());
-        self.build(MessageBody::Raw(body.into_vec()))
+        self.build(MessageBody::Raw(body.into_inner()))
     }
 
     /// Create message using mime body ([`MultiPart`][self::MultiPart])
@@ -489,7 +505,7 @@ pub struct Message {
 #[derive(Clone, Debug)]
 enum MessageBody {
     Mime(Part),
-    Raw(Vec<u8>),
+    Raw(Arc<[u8]>),
 }
 
 impl Message {
@@ -515,9 +531,7 @@ impl Message {
 
     /// Get message content formatted for SMTP
     pub fn formatted(&self) -> Vec<u8> {
-        let mut out = Vec::new();
+        self.format_to_vec()
-        self.format(&mut out);
-        out
     }
 
     #[cfg(feature = "dkim")]
@@ -593,15 +607,13 @@ impl Message {
 }
 
 impl EmailFormat for Message {
-    fn format(&self, out: &mut Vec<u8>) {
+    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        write!(out, "{}", self.headers)
+        self.headers.format(out);
-            .expect("A Write implementation panicked while formatting headers");
 
         match &self.body {
             MessageBody::Mime(p) => p.format(out),
             MessageBody::Raw(r) => {
-                out.extend_from_slice(b"\r\n");
+                out.extend([Cow::Borrowed("\r\n".as_bytes()), Cow::Borrowed(r)]);
-                out.extend_from_slice(r)
             }
         }
     }