add Cowy util trait

src/types/document.rs

@@ -3,6 +3,7 @@ use std::fmt;
 
 use itertools::Itertools;
 use crate::types::URIReference;
+use crate::util::Cowy;
 
 #[derive(Default)]
 pub struct Document {
@@ -42,7 +43,7 @@ impl Document {
         self
     }
 
-    pub fn add_link<'a, U>(&mut self, uri: U, label: impl AsRef<str> + Into<String>) -> &mut Self
+    pub fn add_link<'a, U>(&mut self, uri: U, label: impl Cowy<str>) -> &mut Self
     where
         U: TryInto<URIReference<'a>>,
     {
@@ -92,7 +93,7 @@ impl Document {
         self
     }
 
-    pub fn add_heading(&mut self, level: HeadingLevel, text: impl AsRef<str> + Into<String>) -> &mut Self {
+    pub fn add_heading(&mut self, level: HeadingLevel, text: impl Cowy<str>) -> &mut Self {
         let text = HeadingText::new_lossy(text);
         let heading = Heading {
             level,
@@ -182,7 +183,7 @@ impl Text {
         Self::default()
     }
 
-    pub fn new_lossy(line: impl AsRef<str> + Into<String>) -> Self {
+    pub fn new_lossy(line: impl Cowy<str>) -> Self {
         Self(lossy_escaped_line(line, SPECIAL_STARTS))
     }
 }
@@ -195,7 +196,7 @@ pub struct Link {
 pub struct LinkLabel(String);
 
 impl LinkLabel {
-    pub fn from_lossy(line: impl AsRef<str> + Into<String>) -> Self {
+    pub fn from_lossy(line: impl Cowy<str>) -> Self {
         let line = strip_newlines(line);
         
         LinkLabel(line)
@@ -210,7 +211,7 @@ pub struct Preformatted {
 pub struct PreformattedText(String);
 
 impl PreformattedText {
-    pub fn new_lossy(line: impl AsRef<str> + Into<String>) -> Self {
+    pub fn new_lossy(line: impl Cowy<str>) -> Self {
         Self(lossy_escaped_line(line, &[PREFORMATTED_TOGGLE_START]))
     }
 }
@@ -248,7 +249,7 @@ impl Heading {
 pub struct HeadingText(String);
 
 impl HeadingText {
-    pub fn new_lossy(line: impl AsRef<str> + Into<String>) -> Self {
+    pub fn new_lossy(line: impl Cowy<str>) -> Self {
         let line = strip_newlines(line);
 
         Self(lossy_escaped_line(line, &[HEADING_START]))
@@ -298,7 +299,7 @@ fn starts_with_any(s: &str, starts: &[&str]) -> bool {
     false
 }
 
-fn lossy_escaped_line(line: impl AsRef<str> + Into<String>, escape_starts: &[&str]) -> String {
+fn lossy_escaped_line(line: impl Cowy<str>, escape_starts: &[&str]) -> String {
     let line_ref = line.as_ref();
     let contains_newline = line_ref.contains('\n');
     let has_special_start = starts_with_any(line_ref, escape_starts);
@@ -320,7 +321,7 @@ fn lossy_escaped_line(line: impl AsRef<str> + Into<String>, escape_starts: &[&st
     line
 }
 
-fn strip_newlines(text: impl AsRef<str> + Into<String>) -> String {
+fn strip_newlines(text: impl Cowy<str>) -> String {
     if !text.as_ref().contains(&['\r', '\n'][..]) {
         return text.into();
     }

src/types/meta.rs

@@ -1,5 +1,7 @@
 use anyhow::*;
-use mime::Mime;
+use crate::Mime;
+use crate::util::Cowy;
+
 
 #[derive(Debug,Clone,PartialEq,Eq,Default)]
 pub struct Meta(String);
@@ -9,7 +11,7 @@ impl Meta {
 
     /// Creates a new "Meta" string.
     /// Fails if `meta` contains `\n`.
-    pub fn new(meta: impl AsRef<str> + Into<String>) -> Result<Self> {
+    pub fn new(meta: impl Cowy<str>) -> Result<Self> {
         ensure!(!meta.as_ref().contains("\n"), "Meta must not contain newlines");
         ensure!(meta.as_ref().len() <= Self::MAX_LEN, "Meta must not exceed {} bytes", Self::MAX_LEN);
 
@@ -20,7 +22,7 @@ impl Meta {
     /// Truncates `meta` to before:
     /// - the first occurrence of `\n`
     /// - the character that makes `meta` exceed `Meta::MAX_LEN`
-    pub fn new_lossy(meta: impl AsRef<str> + Into<String>) -> Self {
+    pub fn new_lossy(meta: impl Cowy<str>) -> Self {
         let meta = meta.as_ref();
         let truncate_pos = meta.char_indices().position(|(i, ch)| {
             let is_newline = ch == '\n';

src/types/response.rs

@@ -1,5 +1,6 @@
 use anyhow::*;
 use crate::types::{ResponseHeader, Body, Mime, Document};
+use crate::util::Cowy;
 use crate::GEMINI_MIME;
 
 pub struct Response {
@@ -19,12 +20,12 @@ impl Response {
         Self::success(&GEMINI_MIME).with_body(document)
     }
 
-    pub fn input(prompt: impl AsRef<str> + Into<String>) -> Result<Self> {
+    pub fn input(prompt: impl Cowy<str>) -> Result<Self> {
         let header = ResponseHeader::input(prompt)?;
         Ok(Self::new(header))
     }
 
-    pub fn input_lossy(prompt: impl AsRef<str> + Into<String>) -> Self {
+    pub fn input_lossy(prompt: impl Cowy<str>) -> Self {
         let header = ResponseHeader::input_lossy(prompt);
         Self::new(header)
     }
@@ -34,7 +35,7 @@ impl Response {
         Self::new(header)
     }
 
-    pub fn server_error(reason: impl AsRef<str> + Into<String>) -> Result<Self>  {
+    pub fn server_error(reason: impl Cowy<str>) -> Result<Self>  {
         let header = ResponseHeader::server_error(reason)?;
         Ok(Self::new(header))
     }

src/types/response_header.rs

@@ -1,5 +1,6 @@
 use anyhow::*;
-use mime::Mime;
+use crate::Mime;
+use crate::util::Cowy;
 use crate::types::{Status, Meta};
 
 #[derive(Debug,Clone)]
@@ -9,14 +10,14 @@ pub struct ResponseHeader {
 }
 
 impl ResponseHeader {
-    pub fn input(prompt: impl AsRef<str> + Into<String>) -> Result<Self> {
+    pub fn input(prompt: impl Cowy<str>) -> Result<Self> {
         Ok(Self {
             status: Status::INPUT,
             meta: Meta::new(prompt).context("Invalid input prompt")?,
         })
     }
 
-    pub fn input_lossy(prompt: impl AsRef<str> + Into<String>) -> Self {
+    pub fn input_lossy(prompt: impl Cowy<str>) -> Self {
         Self {
             status: Status::INPUT,
             meta: Meta::new_lossy(prompt),
@@ -30,14 +31,14 @@ impl ResponseHeader {
         }
     }
 
-    pub fn server_error(reason: impl AsRef<str> + Into<String>) -> Result<Self> {
+    pub fn server_error(reason: impl Cowy<str>) -> Result<Self> {
         Ok(Self {
             status: Status::PERMANENT_FAILURE,
             meta: Meta::new(reason).context("Invalid server error reason")?,
         })
     }
 
-    pub fn server_error_lossy(reason: impl AsRef<str> + Into<String>) -> Self {
+    pub fn server_error_lossy(reason: impl Cowy<str>) -> Self {
         Self {
             status: Status::PERMANENT_FAILURE,
             meta: Meta::new_lossy(reason),

src/util.rs

@@ -102,3 +102,19 @@ pub fn guess_mime_from_path<P: AsRef<Path>>(path: P) -> Mime {
     
     mime.parse::<Mime>().unwrap_or(mime::APPLICATION_OCTET_STREAM)
 }
+
+/// A convenience trait alias for `AsRef<T> + Into<T::Owned>`,
+/// most commonly used to accept `&str` or `String`:
+///
+/// `Cowy<str>` ⇔ `AsRef<str> + Into<String>`
+pub trait Cowy<T>
+where
+    Self: AsRef<T> + Into<T::Owned>,
+    T: ToOwned + ?Sized,
+{}
+
+impl<C, T> Cowy<T> for C
+where
+    C: AsRef<T> + Into<T::Owned>,
+    T: ToOwned + ?Sized,
+{}