uefi(data-types): allow is_ascii function on &[Char16] and CStr16

Offers a way to know if a certain UTF-16 string contains only ASCII characters.

Author: RaitoBezarius

uefi/src/data_types/chars.rs

@@ -5,6 +5,8 @@
 
 use core::fmt::{self, Display, Formatter};
 
+use alloc::vec::Vec;
+
 /// Character conversion error
 #[derive(Clone, Copy, Debug)]
 pub struct CharConversionError;
@@ -83,6 +85,30 @@ impl Char16 {
     pub const unsafe fn from_u16_unchecked(val: u16) -> Self {
         Self(val)
     }
+
+    /// Checks if the value is within the ASCII range.
+    #[must_use]
+    pub const fn is_ascii(&self) -> bool {
+        self.0 <= 127
+    }
+}
+
+/// Provides various functions on slice-like container (e.g. Vec) of Char16.
+pub trait SliceLikeChar16 {
+    /// Checks if all char16 in this slice are within the ASCII range.
+    fn is_ascii(&self) -> bool;
+}
+
+impl SliceLikeChar16 for [Char16] {
+    fn is_ascii(&self) -> bool {
+        self.iter().all(|c| c.is_ascii())
+    }
+}
+
+impl SliceLikeChar16 for Vec<Char16> {
+    fn is_ascii(&self) -> bool {
+        self.iter().all(|c| c.is_ascii())
+    }
 }
 
 impl TryFrom<char> for Char16 {

uefi/src/data_types/owned_strs.rs

@@ -1,4 +1,4 @@
-use super::chars::{Char16, NUL_16};
+use super::chars::{Char16, NUL_16, SliceLikeChar16};
 use super::strs::{CStr16, FromSliceWithNulError};
 use crate::data_types::strs::EqStrUntilNul;
 use crate::data_types::UnalignedSlice;
@@ -109,6 +109,12 @@ impl CString16 {
     pub fn is_empty(&self) -> bool {
         self.num_chars() == 0
     }
+
+    /// Checks if all characters in this string are within the ASCII range.
+    #[must_use]
+    pub fn is_ascii(&self) -> bool {
+        self.0.is_ascii()
+    }
 }
 
 impl Default for CString16 {

uefi/src/data_types/strs.rs

@@ -1,4 +1,4 @@
-use super::chars::{Char16, Char8, NUL_16, NUL_8};
+use super::chars::{Char16, Char8, NUL_16, NUL_8, SliceLikeChar16};
 use super::UnalignedSlice;
 use crate::polyfill::maybe_uninit_slice_assume_init_ref;
 use core::borrow::Borrow;
@@ -415,6 +415,12 @@ impl CStr16 {
         self.0.len() * 2
     }
 
+    /// Checks if all characters in this string are within the ASCII range.
+    #[must_use]
+    pub fn is_ascii(&self) -> bool {
+        self.0.is_ascii()
+    }
+
     /// Writes each [`Char16`] as a [`char`] (4 bytes long in Rust language) into the buffer.
     /// It is up to the implementer of [`core::fmt::Write`] to convert the char to a string
     /// with proper encoding/charset. For example, in the case of [`alloc::string::String`]