1 files changed, 223 insertions, 0 deletions
diff --git a/src/fixed_string/mod.rs b/src/fixed_string/mod.rs
new file mode 100644
index 0000000..ca369ce
--- /dev/null
+++ b/src/fixed_string/mod.rs
@@ -0,0 +1,223 @@
+// Copyright 2024 Gabriel Bjørnager Jensen.
+//
+// This file is part of bzipper.
+//
+// bzipper is free software: you can redistribute
+// it and/or modify it under the terms of the GNU
+// Lesser General Public License as published by
+// the Free Software Foundation, either version 3
+// of the License, or (at your option) any later
+// version.
+//
+// bzipper is distributed in the hope that it will
+// be useful, but WITHOUT ANY WARRANTY; without
+// even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Less-
+// er General Public License along with bzipper. If
+// not, see <https://www.gnu.org/licenses/>.
+
+use crate::{
+	Deserialise,
+	DStream,
+	Error,
+	FixedStringIter,
+	Serialise,
+	SStream,
+};
+
+use std::fmt::{Display, Debug, Formatter};
+use std::str::FromStr;
+
+/// Owned string with maximum size.
+///
+/// This is in contrast to [String], which has no size limit is practice, and [str], which is unsized.
+#[derive(Clone)]
+pub struct FixedString<const N: usize> {
+	buf: [char; N],
+	len: usize,
+}
+
+impl<const N: usize> FixedString<N> {
+	/// Constructs a new fixed string.
+	///
+	/// The contents of the provided string are copied into the internal buffer.
+	/// All residual characters are instanced as U+0000 `NULL`.
+	///
+	/// # Errors
+	///
+	/// If the given string `s` cannot fit into `N` characters, a [`FixedStringTooShort`](Error::FixedStringTooShort) error is returned.
+	pub fn new(s: &str) -> Result<Self, Error> {
+		let mut buf = ['\0'; N];
+		let     len = s.chars().count();
+
+		for (i, c) in s.chars().enumerate() {
+			if i >= N { return Err(Error::FixedStringTooShort { len: N, s: s.to_owned() }) }
+
+			buf[i] = c;
+		}
+
+		Ok(Self { buf, len })
+	}
+
+	/// Returns the length of the string.
+	///
+	/// This does not necessarily equal the value of `N`, as the internal buffer is not required to be used fully.
+	#[inline(always)]
+	#[must_use]
+	pub const fn len(&self) -> usize { self.len }
+
+	/// Checks if the string is empty, i.e. `self.len() == 0x0`.
+	#[inline(always)]
+	#[must_use]
+	pub const fn is_empty(&self) -> bool { self.len == 0x0 }
+
+	/// Returns an iterator to the contained characters.
+	#[inline(always)]
+	pub fn iter(&self) -> std::slice::Iter<'_, char> { self.buf[0x0..self.len].iter() }
+
+	/// Returns a mutable iterator to the contained characters.
+	#[inline(always)]
+	pub fn iter_mut(&mut self) -> std::slice::IterMut<'_, char> { self.buf[0x0..self.len].iter_mut() }
+}
+
+impl<const N: usize> Debug for FixedString<N> {
+	fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+		write!(f, "\"")?;
+
+		for c in self {
+			if c.is_ascii_graphic() {
+				write!(f, "{c}")?;
+			} else if *c == '\0' {
+				write!(f, "\\0")?;
+			} else {
+				write!(f, "{c}")?;
+			}
+ 		}
+
+		 write!(f, "\"")?;
+
+		Ok(())
+	}
+}
+
+impl<const N: usize> Deserialise for FixedString<N> {
+	type Error = Error;
+
+	fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
+		let len = usize::try_from(u64::deserialise(stream)?).unwrap();
+
+		let data = stream.take(len)?;
+		let s = std::str::from_utf8(data)
+			.map_err(|e| Error::InvalidUtf8 { source: e })?;
+
+		let len = s.chars().count();
+		if len > N {
+			return Err(Error::FixedStringTooShort { len, s: s.to_owned() });
+		}
+
+		let mut buf = ['\0'; N];
+		for (i, c) in s.chars().enumerate() {
+			buf[i] = c;
+		}
+
+		Ok(Self { buf, len })
+	}
+}
+
+impl<const N: usize> Default for FixedString<N> {
+	#[inline(always)]
+	fn default() -> Self { Self {
+		buf: ['\0'; N],
+		len: 0x0,
+	} }
+}
+
+impl<const N: usize> Display for FixedString<N> {
+	fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+		for c in self { write!(f, "{c}")? }
+
+		Ok(())
+	}
+}
+
+impl<const N: usize> Eq for FixedString<N> { }
+
+impl<const N: usize> FromStr for FixedString<N> {
+	type Err = Error;
+
+	fn from_str(s: &str) -> Result<Self, Error> { Self::new(s) }
+}
+
+impl<const N: usize> IntoIterator for FixedString<N> {
+	type Item = char;
+
+	type IntoIter = FixedStringIter<N>;
+
+	fn into_iter(self) -> Self::IntoIter {
+		FixedStringIter {
+			buf: self.buf,
+			len: self.len,
+
+			pos: Some(0x0),
+		}
+	}
+}
+
+impl<'a, const N: usize> IntoIterator for &'a FixedString<N> {
+	type Item = &'a char;
+
+	type IntoIter = std::slice::Iter<'a, char>;
+
+	fn into_iter(self) -> Self::IntoIter { self.iter() }
+}
+
+impl<'a, const N: usize> IntoIterator for &'a mut FixedString<N> {
+	type Item = &'a mut char;
+
+	type IntoIter = std::slice::IterMut<'a, char>;
+
+	fn into_iter(self) -> Self::IntoIter { self.iter_mut() }
+}
+
+impl<const N: usize> PartialEq for FixedString<N> {
+	fn eq(&self, other: &Self) -> bool {
+		if self.len() != other.len() { return false };
+
+		for i in 0x0..self.len() {
+			if self.buf[i] != other.buf[i] { return false };
+		}
+
+		true
+	}
+}
+
+impl<const N: usize> PartialEq<&str> for FixedString<N> {
+	fn eq(&self, other: &&str) -> bool {
+		for (i, c) in other.chars().enumerate() {
+			if self.buf.get(i) != Some(&c) { return false };
+		}
+
+		true
+	}
+}
+
+impl<const N: usize> Serialise for FixedString<N> {
+	fn serialise(&self, stream: &mut SStream) {
+		let s: String = self.iter().collect();
+
+		let len = u64::try_from(s.len()).unwrap();
+
+		stream.append(&len.to_be_bytes());
+		stream.append(&s.into_bytes());
+	}
+}
+
+impl<const N: usize> TryFrom<&str> for FixedString<N> {
+	type Error = Error;
+
+	#[inline(always)]
+	fn try_from(value: &str) -> Result<Self, Self::Error> { Self::new(value) }
+}