implement own charset system

README.md

@@ -88,7 +88,7 @@ Todo:
  - [ ] test over other datasets (jpbush, ml, my inbox)
  - [ ] backport to aerogramme
 
-## Targeted RFC
+## Targeted RFC and IANA references
 
 | 🚩 | # | Name |
 |----|---|------|
@@ -104,6 +104,10 @@ Todo:
 | 🟩 |6532	| Internationalized Email Headers |
 | 🔴 |9228   | Delivered-To Email Header Field |
 
+IANA references :
+ - (tbd) MIME subtypes
+ - [IANA character sets](https://www.iana.org/assignments/character-sets/character-sets.xhtml)
+
 ## Alternatives
 
 `stalwartlab/mail_parser`

src/fragments/mime.rs

@@ -16,8 +16,18 @@ pub struct Version {
 
 #[derive(Debug, PartialEq)]
 pub enum Type<'a> {
+    // Composite types
     Multipart(MultipartSubtype<'a>),
     Message(MessageSubtype<'a>),
+
+    // Discrete types
+    Text(&'a str),
+    Image(&'a str),
+    Audio(&'a str),
+    Video(&'a str),
+    Application(&'a str),
+
+    // Unknown
     Other(&'a str, &'a str, Vec<Parameter<'a>>),
 }
 
@@ -40,11 +50,48 @@ pub enum MessageSubtype<'a> {
 
 #[derive(Debug, PartialEq)]
 pub enum Parameter<'a> {
-    Charset(&'static Encoding),
+    Charset(EmailCharset<'a>),
     Boundary(&'a str),
     Other(&'a str, &'a str),
 }
 
+/// Specific implementation of charset
+///
+/// imf_codec has its own charset list to follow IANA's one.
+/// encoding_rs implements a different standard that does not know US_ASCII.
+/// using encoding_rs datastructures directly would lead to a loss of information.
+/// https://www.iana.org/assignments/character-sets/character-sets.xhtml
+#[allow(non_camel_case_types)]
+#[derive(Debug, PartialEq)]
+pub enum EmailCharset<'a> {
+    US_ASCII,
+    ISO_8859_1,
+    ISO_8859_2,
+    ISO_8859_3,
+    ISO_8859_4,
+    ISO_8859_5,
+    ISO_8859_6,
+    ISO_8859_7,
+    ISO_8859_8,
+    ISO_8859_9,
+    ISO_8859_10,
+    Shift_JIS,
+    EUC_JP,
+    ISO_2022_KR,
+    EUC_KR,
+    ISO_2022_JP,
+    ISO_2022_JP_2,
+    ISO_8859_6_E,
+    ISO_8859_6_I,
+    ISO_8859_8_E,
+    ISO_8859_8_I,
+    GB2312,
+    Big5,
+    KOI8_R,
+    UTF_8,
+    Other(&'a str),
+}
+
 #[derive(Debug, PartialEq)]
 pub enum Mechanism<'a> {
     _7Bit,
@@ -55,6 +102,78 @@ pub enum Mechanism<'a> {
     Other(&'a str),
 }
 
+impl<'a> From<&'a str> for EmailCharset<'a> {
+    fn from(s: &'a str) -> Self {
+        match s.to_lowercase().as_ref() {
+            "us-ascii" => EmailCharset::US_ASCII,
+            "iso-8859-1" => EmailCharset::ISO_8859_1,
+            "iso-8859-2" => EmailCharset::ISO_8859_2,
+            "iso-8859-3" => EmailCharset::ISO_8859_3,
+            "iso-8859-4" => EmailCharset::ISO_8859_4,
+            "iso-8859-5" => EmailCharset::ISO_8859_5,
+            "iso-8859-6" => EmailCharset::ISO_8859_6,
+            "iso-8859-7" => EmailCharset::ISO_8859_7,
+            "iso-8859-8" => EmailCharset::ISO_8859_8,
+            "iso-8859-9" => EmailCharset::ISO_8859_9,
+            "iso-8859-10" => EmailCharset::ISO_8859_10,
+            "shift_jis" => EmailCharset::Shift_JIS,
+            "euc-jp" => EmailCharset::EUC_JP,
+            "iso-2022-kr" => EmailCharset::ISO_2022_KR,
+            "euc-kr" => EmailCharset::EUC_KR,
+            "iso-2022-jp" => EmailCharset::ISO_2022_JP,
+            "iso-2022-jp-2" => EmailCharset::ISO_2022_JP_2,
+            "iso-8859-6-e" => EmailCharset::ISO_8859_6_E,
+            "iso-8859-6-i" => EmailCharset::ISO_8859_6_I,
+            "iso-8859-8-e" => EmailCharset::ISO_8859_8_E,
+            "iso-8859-8-i" => EmailCharset::ISO_8859_8_I,
+            "gb2312" => EmailCharset::GB2312,
+            "big5" => EmailCharset::Big5,
+            "koi8-r" => EmailCharset::KOI8_R,
+            "utf-8" => EmailCharset::UTF_8,
+            _ => EmailCharset::Other(s)
+        }
+    }   
+}
+
+impl<'a> EmailCharset<'a> {
+    pub fn as_str(&self) -> &'a str {
+        use EmailCharset::*;
+        match self {
+            US_ASCII => "US-ASCII",
+            ISO_8859_1 => "ISO-8859-1",
+            ISO_8859_2 => "ISO-8859-2",
+            ISO_8859_3 => "ISO-8859-3",
+            ISO_8859_4 => "ISO-8859-4",
+            ISO_8859_5 => "ISO-8859-5",
+            ISO_8859_6 => "ISO-8859-6",
+            ISO_8859_7 => "ISO-8859-7",
+            ISO_8859_8 => "ISO-8859-8",
+            ISO_8859_9 => "ISO-8859-9",
+            ISO_8859_10 => "ISO-8859-10",
+            Shift_JIS => "Shift_JIS",
+            EUC_JP => "EUC-JP",
+            ISO_2022_KR => "ISO-2022-KR",
+            EUC_KR => "EUC-KR",
+            ISO_2022_JP => "ISO-2022-JP",
+            ISO_2022_JP_2 => "ISO-2022-JP-2",
+            ISO_8859_6_E => "ISO-8859-6-E",
+            ISO_8859_6_I => "ISO-8859-6-I",
+            ISO_8859_8_E => "ISO-8859-8-E",
+            ISO_8859_8_I => "ISO-8859-8-I",
+            GB2312 => "GB2312",
+            Big5 => "Big5",
+            KOI8_R => "KOI8-R",
+            UTF_8 => "UTF-8",
+            Other(raw) => raw,
+        }
+    }
+
+    pub fn as_encoding(&self) -> &'static Encoding {
+        Encoding::for_label(self.as_str().as_bytes())
+            .unwrap_or(encoding_rs::WINDOWS_1252)
+    }
+}
+
 impl<'a> TryFrom<&'a lazy::Version<'a>> for Version {
     type Error = IMFError<'a>;
 
@@ -117,4 +236,42 @@ mod tests {
             Ok(("", Version { major: 1, minor: 0 })),
         );
     }
+
+    #[test]
+    fn test_charset() {
+        assert_eq!(
+            EmailCharset::from("Us-Ascii").as_str(),
+            "US-ASCII",
+        );
+
+        assert_eq!(
+            EmailCharset::from("Us-Ascii").as_encoding(),
+            encoding_rs::WINDOWS_1252,
+        );
+
+        assert_eq!(
+            EmailCharset::from("ISO-8859-1").as_encoding(),
+            encoding_rs::WINDOWS_1252,
+        );
+
+        assert_eq!(
+            EmailCharset::from("utf-8").as_encoding(),
+            encoding_rs::UTF_8,
+        );
+
+        assert_eq!(
+            EmailCharset::from("utf8").as_encoding(),
+            encoding_rs::UTF_8,
+        );
+    }
+
+/*    #[test]
+    fn test_parameter() {
+        assert_eq!(
+            parameter("charset=us-ascii (Plain text)"),
+            Ok(("", Parameter::charset(EmailCharset::US_ASCII)))
+        );
+
+    }
+*/
 }