From 3faca18dc64a702f98356f6a062173bbbcc86c5c Mon Sep 17 00:00:00 2001
From: Juliette Cordor <professional@maybejules.com>
Date: Sun, 28 Jul 2024 15:24:12 +1000
Subject: [PATCH] add sized string struct and macro

---
 Cargo.toml                     |  3 +-
 quork-proc/src/lib.rs          | 13 ++++++
 quork-proc/src/sized_string.rs | 27 ++++++++++++
 src/lib.rs                     |  3 ++
 src/sized_string.rs            | 79 ++++++++++++++++++++++++++++++++++
 5 files changed, 124 insertions(+), 1 deletion(-)
 create mode 100644 quork-proc/src/sized_string.rs
 create mode 100644 src/sized_string.rs

diff --git a/Cargo.toml b/Cargo.toml
index 2bad8b7..efb2e39 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,11 +38,12 @@ windows = { version = "0.56", features = [
 nix = { version = "0.28", features = ["user"] }
 
 [features]
-all = ["macros", "network", "root", "std", "traits"]
+all = ["macros", "network", "root", "std", "traits", "sized_string"]
 default = ["all"]
 macros = ["quork-proc"]
 network = []
 root = ["std"]
+sized_string = []
 std = []
 traits = []
 
diff --git a/quork-proc/src/lib.rs b/quork-proc/src/lib.rs
index d80cb5b..cba8404 100644
--- a/quork-proc/src/lib.rs
+++ b/quork-proc/src/lib.rs
@@ -10,6 +10,7 @@ mod const_str;
 mod enum_list;
 mod from_tuple;
 mod new;
+mod sized_string;
 mod time_fn;
 mod trim_lines;
 
@@ -122,3 +123,15 @@ pub fn lstrip_lines(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 
     trim_lines::trim_lines(&literal, &trim_lines::Alignment::Left).into()
 }
+
+/// Creates a [`SizedString`] from a string literal
+///
+/// # Examples
+///
+/// ```rust
+/// let s = sized_string!("Hello, World!");
+/// ```
+#[proc_macro]
+pub fn sized_string(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    sized_string::sized_string(&syn::parse_macro_input!(input as LitStr)).into()
+}
diff --git a/quork-proc/src/sized_string.rs b/quork-proc/src/sized_string.rs
new file mode 100644
index 0000000..fd5e641
--- /dev/null
+++ b/quork-proc/src/sized_string.rs
@@ -0,0 +1,27 @@
+use proc_macro2::Span;
+use proc_macro_crate::FoundCrate;
+use syn::Ident;
+
+pub fn sized_string(input: &syn::LitStr) -> proc_macro2::TokenStream {
+    let length = input.value().chars().count();
+    let chars = input
+        .value()
+        .chars()
+        .map(|c| quote::quote! { #c as u8 })
+        .collect::<Vec<_>>();
+
+    let quork_crate =
+        match proc_macro_crate::crate_name("quork").expect("quork is present in `Cargo.toml`") {
+            FoundCrate::Itself => quote::quote! { crate },
+            FoundCrate::Name(name) => {
+                let ident = Ident::new(&name, Span::call_site());
+                quote::quote! { #ident }
+            }
+        };
+
+    let output = quote::quote! {
+        #quork_crate::sized_string::SizedString::<#length>::new([#(#chars),*])
+    };
+
+    output
+}
diff --git a/src/lib.rs b/src/lib.rs
index b1a3e65..4798454 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -44,6 +44,9 @@ pub mod traits;
 #[cfg(feature = "network")]
 pub mod network;
 
+#[cfg(feature = "sized_string")]
+pub mod sized_string;
+
 cfg_if::cfg_if! {
     if #[cfg(all(feature = "root", feature = "std"))] {
         pub mod root;
diff --git a/src/sized_string.rs b/src/sized_string.rs
new file mode 100644
index 0000000..1b073f9
--- /dev/null
+++ b/src/sized_string.rs
@@ -0,0 +1,79 @@
+//! A sized, stack allocated string type.
+//!
+//! This is useful for when you need a string to be stack allocated, but you also need it to be sized (i.e not a reference to a [`str`]).
+//!
+//! Especially when using shared memory this can be useful as the actual string will be stored in shared memory, rather than just the pointer to the string.
+
+use std::ops::Deref;
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+/// A sized, stack allocated string type.
+///
+/// This is useful for when you need a string to be stack allocated, but you also need it to be sized (i.e not a reference to a [`str`]).
+///
+/// Especially when using shared memory this can be useful as the actual string will be stored in shared memory, rather than just the pointer to the string.
+pub struct SizedString<const N: usize>([u8; N]);
+
+impl<const N: usize> SizedString<N> {
+    #[must_use]
+    /// Construct a new [`SizedString`] from a byte array
+    pub const fn new(bytes: [u8; N]) -> Self {
+        Self(bytes)
+    }
+
+    #[must_use]
+    /// Get the string as a [`str`]
+    pub const fn as_str(&self) -> &str {
+        unsafe { std::str::from_utf8_unchecked(&self.0) }
+    }
+}
+
+impl<const N: usize> Deref for SizedString<N> {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        unsafe { std::str::from_utf8_unchecked(&self.0) }
+    }
+}
+
+impl<const N: usize> AsRef<str> for SizedString<N> {
+    fn as_ref(&self) -> &str {
+        self
+    }
+}
+
+impl<const N: usize, T> AsRef<T> for SizedString<N>
+where
+    str: std::convert::AsRef<T>,
+{
+    fn as_ref(&self) -> &T {
+        let s: &str = self.as_ref();
+        s.as_ref()
+    }
+}
+
+mod string_trait_impls {
+    use std::fmt::Debug;
+
+    use super::SizedString;
+
+    impl<const N: usize> Debug for SizedString<N> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            f.debug_tuple("SizedString").field(&self.as_str()).finish()
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    #[test]
+    fn test_sized_string() {
+        let s = quork_proc::sized_string!("hello world");
+
+        let s_str: &str = s.as_ref();
+
+        assert_eq!(s.len(), 11);
+        assert_eq!(s_str, "hello world");
+    }
+}