pub(crate) fn decode<'a>(&'a mut self, input: &'a str) -> Result<Decode<'a>, ()> {
        self.insertions.clear();
        // Handle "basic" (ASCII) code points.
        // They are encoded as-is before the last delimiter, if any.
        let (base, input) = match input.rfind(DELIMITER) {
            None => ("", input),
            Some(position) => (
                &input[..position],
                if position > 0 {
                    &input[position + 1..]
                } else {
                    input
                },
            ),
        };

        if !base.is_ascii() {
            return Err(());
        }

        let base_len = base.len();
        let mut length = base_len as u32;
        let mut code_point = INITIAL_N;
        let mut bias = INITIAL_BIAS;
        let mut i = 0;
        let mut iter = input.bytes();
        loop {
            let previous_i = i;
            let mut weight = 1;
            let mut k = BASE;
            let mut byte = match iter.next() {
                None => break,
                Some(byte) => byte,
            };

            // Decode a generalized variable-length integer into delta,
            // which gets added to i.
            loop {
                let digit = match byte {
                    byte @ b'0'..=b'9' => byte - b'0' + 26,
                    byte @ b'A'..=b'Z' => byte - b'A',
                    byte @ b'a'..=b'z' => byte - b'a',
                    _ => return Err(()),
                } as u32;
                if digit > (u32::MAX - i) / weight {
                    return Err(()); // Overflow
                }
                i += digit * weight;
                let t = if k <= bias {
                    T_MIN
                } else if k >= bias + T_MAX {
                    T_MAX
                } else {
                    k - bias
                };
                if digit < t {
                    break;
                }
                if weight > u32::MAX / (BASE - t) {
                    return Err(()); // Overflow
                }
                weight *= BASE - t;
                k += BASE;
                byte = match iter.next() {
                    None => return Err(()), // End of input before the end of this delta
                    Some(byte) => byte,
                };
            }

            bias = adapt(i - previous_i, length + 1, previous_i == 0);
            if i / (length + 1) > u32::MAX - code_point {
                return Err(()); // Overflow
            }

            // i was supposed to wrap around from length+1 to 0,
            // incrementing code_point each time.
            code_point += i / (length + 1);
            i %= length + 1;
            let c = match char::from_u32(code_point) {
                Some(c) => c,
                None => return Err(()),
            };

            // Move earlier insertions farther out in the string
            for (idx, _) in &mut self.insertions {
                if *idx >= i as usize {
                    *idx += 1;
                }
            }
            self.insertions.push((i as usize, c));
            length += 1;
            i += 1;
        }

        self.insertions.sort_by_key(|(i, _)| *i);
        Ok(Decode {
            base: base.chars(),
            insertions: &self.insertions,
            inserted: 0,
            position: 0,
            len: base_len + self.insertions.len(),
        })
    }
/// Split the input iterator and return a Vec with insertions of encoded characters
Split the input iterator and return a Vec with insertions of encoded characters
Split the input iterator and return a Vec with insertions of encoded characters
pub(crate) fn decode<'a>(&'a mut self, input: &'a str) -> Result<Decode<'a>, ()> {
        self.insertions.clear();
        // Handle "basic" (ASCII) code points.
        // They are encoded as-is before the last delimiter, if any.
        let (base, input) = match input.rfind(DELIMITER) {
            None => ("", input),
            Some(position) => (
                &input[..position],
                if position > 0 {
                    &input[position + 1..]
                } else {
                    input
                },
            ),
        };
        if !base.is_ascii() {
            return Err(());
        }
        let base_len = base.len();
        let mut length = base_len as u32;
        let mut code_point = INITIAL_N;
        let mut bias = INITIAL_BIAS;
        let mut i = 0;
        let mut iter = input.bytes();
        loop {
            let previous_i = i;
            let mut weight = 1;
            let mut k = BASE;
            let mut byte = match iter.next() {
                None => break,
                Some(byte) => byte,
            };
            // Decode a generalized variable-length integer into delta,
            // which gets added to i.
            loop {
                let digit = match byte {
                    byte @ b'0'..=b'9' => byte - b'0' + 26,
                    byte @ b'A'..=b'Z' => byte - b'A',
                    byte @ b'a'..=b'z' => byte - b'a',
                    _ => return Err(()),
                } as u32;
                if digit > (u32::MAX - i) / weight {
                    return Err(()); // Overflow
                }
                i += digit * weight;
                let t = if k <= bias {
                    T_MIN
                } else if k >= bias + T_MAX {
                    T_MAX
                } else {
                    k - bias
                };
                if digit < t {
                    break;
                }
                if weight > u32::MAX / (BASE - t) {
                    return Err(()); // Overflow
                }
                weight *= BASE - t;
                k += BASE;
                byte = match iter.next() {
                    None => return Err(()), // End of input before the end of this delta
                    Some(byte) => byte,
                };
            }
            bias = adapt(i - previous_i, length + 1, previous_i == 0);
            if i / (length + 1) > u32::MAX - code_point {
                return Err(()); // Overflow
            }
            // i was supposed to wrap around from length+1 to 0,
            // incrementing code_point each time.
            code_point += i / (length + 1);
            i %= length + 1;
            let c = match char::from_u32(code_point) {
                Some(c) => c,
                None => return Err(()),
            };
            // Move earlier insertions farther out in the string
            for (idx, _) in &mut self.insertions {
                if *idx >= i as usize {
                    *idx += 1;
                }
            }
            self.insertions.push((i as usize, c));
            length += 1;
            i += 1;
        }
        self.insertions.sort_by_key(|(i, _)| *i);
        Ok(Decode {
            base: base.chars(),
            insertions: &self.insertions,
            inserted: 0,
            position: 0,
            len: base_len + self.insertions.len(),
        })
    }
pub ( crate ) fn decode < ' a > ( & ' a mut self , input : & ' a str ) -> Result < Decode < ' a > , ( ) > { self . insertions . clear ( ) ; // Handle "basic" (ASCII) code points. // They are encoded as-is before the last delimiter, if any. let ( base , input ) = match input . rfind ( DELIMITER ) { None => ( " " , input ) , Some ( position ) => ( & input [ .. position ] , if position > 0 { & input [ position + 1 .. ] } else { input } , ) , } ; if ! base . is_ascii ( ) { return Err ( ( ) ) ; } let base_len = base . len ( ) ; let mut length = base_len as u32 ; let mut code_point = INITIAL_N ; let mut bias = INITIAL_BIAS ; let mut i = 0 ; let mut iter = input . bytes ( ) ; loop { let previous_i = i ; let mut weight = 1 ; let mut k = BASE ; let mut byte = match iter . next ( ) { None => break , Some ( byte ) => byte , } ; // Decode a generalized variable-length integer into delta, // which gets added to i. loop { let digit = match byte { byte @ b'0' ..= b'9' => byte - b'0' + 26 , byte @ b'A' ..= b'Z' => byte - b'A' , byte @ b'a' ..= b'z' => byte - b'a' , _ => return Err ( ( ) ) , } as u32 ; if digit > ( u32 :: MAX - i ) / weight { return Err ( ( ) ) ; // Overflow } i += digit * weight ; let t = if k <= bias { T_MIN } else if k >= bias + T_MAX { T_MAX } else { k - bias } ; if digit < t { break ; } if weight > u32 :: MAX / ( BASE - t ) { return Err ( ( ) ) ; // Overflow } weight *= BASE - t ; k += BASE ; byte = match iter . next ( ) { None => return Err ( ( ) ) , // End of input before the end of this delta Some ( byte ) => byte , } ; } bias = adapt ( i - previous_i , length + 1 , previous_i == 0 ) ; if i / ( length + 1 ) > u32 :: MAX - code_point { return Err ( ( ) ) ; // Overflow } // i was supposed to wrap around from length+1 to 0, // incrementing code_point each time. code_point += i / ( length + 1 ) ; i %= length + 1 ; let c = match char :: from_u32 ( code_point ) { Some ( c ) => c , None => return Err ( ( ) ) , } ; // Move earlier insertions farther out in the string for ( idx , _ ) in & mut self . insertions { if * idx >= i as usize { * idx += 1 ; } } self . insertions . push ( ( i as usize , c ) ) ; length += 1 ; i += 1 ; } self . insertions . sort_by_key ( | ( i , _ ) | * i ) ; Ok ( Decode { base : base . chars ( ) , insertions : & self . insertions , inserted : 0 , position : 0 , len : base_len + self . insertions . len ( ) , } ) }
Split the input iterator and return a Vec with insertions of encoded characters
Split the input iterator and return a Vec with insertions of encoded characters
&'a mut self
input
&'a str
&'a mut self
input
&'a str