//! This module is intended for internal use only. Only a few
//! type aliases are exported. A tiny string or tstr<N>, with N<=256,
//! is a version of fixed str that represents the best compromise between
//! memory and runtime efficiency. Each tstr<N> can hold a string of up to
//! N-1 bytes, with max N=256. A tstr<N> is represented underneath
//! by a `[u8;N]` with the first byte always representing the length of the
//! string. A tstr is not necessarily zero-terminated.
//! Because currently Rust does not allow conditions on const generics
//! such as `where N<=256`, this type is not fully exported and one can
//! only use the type aliases.
#![allow(unused_variables)]
#![allow(non_snake_case)]
#![allow(non_camel_case_types)]
#![allow(unused_parens)]
#![allow(unused_assignments)]
#![allow(unused_mut)]
#![allow(dead_code)]
use crate::fstr;
use crate::zstr;
use std::cmp::Ordering;
/// **THIS STRUCTURE IS NOT EXPORTED.** It can only be used through the
/// public type aliases [crate::str8] through [crate::str256].
#[derive(Copy,Clone,Eq,PartialEq,Hash)]
pub struct tstr<const N:usize=256>
{
chrs : [u8;N],
}//tstr
impl<const N:usize> tstr<N>
{
/// creates a new tstr<N> with given &str. If the length of s exceeds
/// N, the extra characters are ignored. This function is also called by
/// several others including [tstr::from]. This function can now handle
/// utf8 strings properly.
pub fn make(s:&str) -> tstr<N>
{
if (N>256 || N<1) {panic!("only tstr<1> to tstr<256> are valid");}
let mut chars = [0u8; N];
let bytes = s.as_bytes(); // &[u8]
let blen = bytes.len();
if (blen>=N) {eprintln!("!Fixedstr Warning in str::make: length of string literal \"{}\" exceeds the capacity of type str{}; string truncated",s,N);}
for i in 0..blen
{
if i<N-1 {chars[i+1] = bytes[i];}
else { chars[0] = i as u8; break; }
}
if chars[0]==0 {chars[0]=blen as u8;}
tstr {
chrs: chars,
}
}//make
/// version of make that does not truncate
pub fn try_make(s:&str) -> Result<tstr<N>,&str>
{
if s.len()>N-1 {Err(s)}
else {Ok(tstr::make(s))}
}
/// creates an empty string, equivalent to tstr::default()
pub fn new() -> tstr<N>
{
tstr::make("")
}
/// length of the string in bytes (consistent with [str::len]). This
/// is a constant-time operation.
pub fn len(&self)->usize {
self.chrs[0] as usize
}
/// returns the number of characters in the string regardless of
/// character class
pub fn charlen(&self) -> usize
{
let v:Vec<_> = self.to_str().chars().collect(); v.len()
}
/// returns maximum capacity in bytes
pub fn capacity(&self) -> usize { N-1 }
/// converts tstr to an owned string
pub fn to_string(&self) -> String
{
let vs:Vec<_> = self.chrs[1..self.len()+1].iter().map(|x|{*x}).collect();
std::string::String::from_utf8(vs).expect("Invalid utf8 string")
}
/// returns copy of u8 array underneath the tstr
pub fn as_bytes(&self) -> &[u8]
{
&self.chrs[1..self.len()+1]
}
/// converts tstr to &str using [std::str::from_utf8_unchecked]
pub fn to_str(&self) -> &str
{
unsafe {std::str::from_utf8_unchecked(&self.chrs[1..self.len()+1])}
}
/// alias for [tstr::to_str]
pub fn as_str(&self) -> &str
{
std::str::from_utf8(&self.chrs[1..self.len()+1]).unwrap()
}
/// changes a character at character position i to c. This function
/// requires that c is in the same character class (ascii or unicode)
/// as the char being replaced. It never shuffles the bytes underneath.
/// The function returns true if the change was successful.
pub fn set(&mut self,i:usize, c:char) -> bool
{
let ref mut cbuf = [0u8;4];
c.encode_utf8(cbuf);
let clen = c.len_utf8();
if let Some((bi,rc)) = self.to_str().char_indices().nth(i) {
if clen==rc.len_utf8() {
for k in 0..clen {self.chrs[bi+k+1] = cbuf[k];}
return true;
}
}
return false;
}//set
/// adds chars to end of current string up to maximum size N of tstr<N>,
/// returns the portion of the push string that was NOT pushed due to
/// capacity, so
/// if "" is returned then all characters were pushed successfully.
pub fn push<'t>(&mut self,s:&'t str) -> &'t str
{
if s.len()<1 {return s;}
let mut buf = [0u8;4];
let mut i = self.len();
let mut sci = 0; // indexes characters in s
for c in s.chars()
{
let clen = c.len_utf8();
c.encode_utf8(&mut buf);
if i<=N-clen-1 {
for k in 0..clen
{
self.chrs[i+k+1] = buf[k];
}
i += clen;
} else { self.chrs[0]=i as u8; return &s[sci..];}
sci += 1;
}
if i<N {self.chrs[0]=i as u8;} // set length
&s[sci..]
}//push
/// returns the nth char of the tstr
pub fn nth(&self,n:usize) -> Option<char>
{
self.to_str().chars().nth(n)
}
/// returns the nth byte of the string as a char. This
/// function should only be called on ascii strings. It
/// is designed to be quicker than [tstr::nth], and does not check array bounds or
/// check n against the length of the string. Nor does it check
/// if the value returned is within the ascii range.
pub fn nth_ascii(&self,n:usize) -> char
{
self.chrs[n+1] as char
}
/// determines if string is an ascii string
pub fn is_ascii(&self) -> bool
{ self.to_str().is_ascii() }
/// shortens the tstr in-place (mutates). If n is greater than the
/// current length of the string, this operation will have no effect.
pub fn truncate(&mut self, n:usize) // n is char position, not binary position
{
if let Some((bi,c)) = self.to_str().char_indices().nth(n) {
self.chrs[0] = bi as u8;
}
}
/// mimics same function on str
pub fn chars(&self) -> std::str::Chars<'_>
{ self.to_str().chars() }
/// mimics same function on str
pub fn char_indices(&self) ->std::str::CharIndices<'_>
{ self.to_str().char_indices() }
}//impl tstr<N>
impl<const N:usize> std::convert::AsRef<str> for tstr<N>
{
fn as_ref(&self) -> &str { self.to_str() }
}
impl<const N:usize> std::convert::AsMut<str> for tstr<N>
{
fn as_mut(&mut self) -> &mut str
{
let blen = self.len()+1;
unsafe {
std::str::from_utf8_unchecked_mut(&mut self.chrs[1..blen])
}
}
}
impl<T:AsRef<str>+?Sized, const N:usize> std::convert::From<&T> for tstr<N>
{
fn from(s:&T) -> tstr<N> { tstr::make(s.as_ref()) }
}
impl<T:AsMut<str>+?Sized, const N:usize> std::convert::From<&mut T> for tstr<N>
{
fn from(s:&mut T) -> tstr<N> { tstr::make(s.as_mut()) }
}
impl<const N:usize> std::convert::From<String> for tstr<N>
{
fn from(s:String) -> tstr<N>
{
tstr::<N>::make(&s[..])
}
}
impl<const N:usize,const M:usize> std::convert::From<fstr<M>> for tstr<N>
{
fn from(s:fstr<M>) -> tstr<N>
{
tstr::<N>::make(s.to_str())
}
}
impl<const N:usize,const M:usize> std::convert::From<zstr<M>> for tstr<N>
{
fn from(s:zstr<M>) -> tstr<N>
{
tstr::<N>::make(s.to_str())
}
}
impl<const N:usize> std::cmp::PartialOrd for tstr<N>
{
fn partial_cmp(&self, other:&Self) -> Option<Ordering>
{
//Some(self.chrs[0..self.len()].cmp(other.chrs[0..other.len()]))
Some(self.cmp(other))
}
}
impl<const N:usize> std::cmp::Ord for tstr<N>
{
fn cmp(&self, other:&Self) -> Ordering
{
self.chrs[1..self.len()+1].cmp(&other.chrs[1..other.len()+1])
}
}
impl<const M:usize> tstr<M>
{
/// converts an tstr\<M\> to an tstr\<N\>. If the length of the string being
/// converted is greater than N, the extra characters will be ignored.
/// This operation produces a copy (non-destructive).
/// Example:
///```ignore
/// let s1:tstr<8> = tstr::from("abcdefg");
/// let s2:tstr<16> = s1.resize();
///```
pub fn resize<const N:usize>(&self) -> tstr<N>
{
let slen = self.len();
if (slen>=N) {eprintln!("!Fixedstr Warning in str::resize: string \"{}\" truncated while resizing to str{}",self,N);}
let length = if (slen<N-1) {slen} else {N-1};
let mut chars = [0u8;N];
for i in 0..length {chars[i+1] = self.chrs[i+1];}
chars[0] = (length) as u8;
tstr {
chrs: chars,
}
}//resize
}//impl tstr<M>
impl<const N:usize> std::fmt::Display for tstr<N>
{
fn fmt(&self,f:&mut std::fmt::Formatter<'_>) -> std::fmt::Result
{
write!(f,"{}",self.to_str())
}
}
impl<const N:usize> PartialEq<&str> for tstr<N>
{
fn eq(&self, other:&&str) -> bool
{
self.to_str()==*other // see below
}//eq
}
impl<const N:usize> PartialEq<&str> for &tstr<N>
{
fn eq(&self, other:&&str) -> bool
{
&self.to_str() == other
}//eq
}
impl<'t, const N:usize> PartialEq<tstr<N>> for &'t str
{
fn eq(&self, other:&tstr<N>) -> bool
{ &other.to_str()==self }
}
impl<'t, const N:usize> PartialEq<&tstr<N>> for &'t str
{
fn eq(&self, other:&&tstr<N>) -> bool
{ &other.to_str()==self }
}
/// defaults to empty string
impl<const N:usize> Default for tstr<N>
{
fn default() -> Self { tstr::<N>::make("") }
}
impl<const N:usize,const M:usize> PartialEq<tstr<N>> for fstr<M>
{
fn eq(&self, other:&tstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
/*
impl<const N:usize, const M:usize> PartialEq<&tstr<N>> for fstr<M>
{
fn eq(&self, other:&&tstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
*/
impl<const N:usize,const M:usize> PartialEq<fstr<N>> for tstr<M>
{
fn eq(&self, other:&fstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
impl<const N:usize, const M:usize> PartialEq<&fstr<N>> for tstr<M>
{
fn eq(&self, other:&&fstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
impl<const N:usize,const M:usize> PartialEq<zstr<N>> for tstr<M>
{
fn eq(&self, other:&zstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
impl<const N:usize, const M:usize> PartialEq<&zstr<N>> for tstr<M>
{
fn eq(&self, other:&&zstr<N>) -> bool
{ other.to_str()==self.to_str() }
}
impl<const N:usize> std::fmt::Debug for tstr<N>
{
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// let ds = format!("tstr<{}>:\"{}\"",N,&self.to_str());
f.pad(&self.to_str())
// f.debug_struct("tstr")
// .field("chrs:",&self.to_str())
// .finish()
}
} // Debug impl
/*
///Convert tstr to &[u8] slice
impl<IndexType,const N:usize> std::ops::Index<IndexType> for tstr<N>
where IndexType:std::slice::SliceIndex<[u8]>,
{
type Output = IndexType::Output;
fn index(&self, index:IndexType)-> &Self::Output
{
&self.chrs[index+1]
}
}//impl Index
// couldn't get it to work properly, [char] is not same as &str
// because there's no allocated string!
*/
impl<const N:usize> tstr<N>
{
/// returns a copy of the portion of the string, string could be truncated
/// if indices are out of range. Similar to slice [start..end]
pub fn substr(&self,start:usize, end:usize) -> tstr<N>
{
let mut chars = [0u8;N];
let mut inds = self.char_indices();
let len = self.len();
if start>=len || end<=start {return tstr{chrs:chars};}
chars[0] = (end-start) as u8;
let (si,_) = inds.nth(start).unwrap();
let last = if (end>=len) {len} else {
match inds.nth(end-start-1) {
Some((ei,_)) => ei,
None => len,
}//match
};//let last =...
for i in si..last
{
chars[i-si+1] = self.chrs[i+1];
}
tstr { chrs: chars,}
}//substr
}