Chapter 1 Hints

Validation

1. u8::is_ascii_uppercase
2. u8::is_ascii_lowercase

Implementing FromStr

1. str::as_bytes

Stubs

#![allow(unused_variables)]
fn main() {
use std::convert::TryFrom;
use std::fmt;
use std::str::FromStr;

use crate::{Error, Result};

/// A validated PNG chunk type. See the PNG spec for more details.
/// http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ChunkType {
    // Write me!
}

impl ChunkType {
    /// Returns the raw bytes contained in this chunk
    pub fn bytes(&self) -> [u8; 4] {
        todo!()
    }

    /// Returns the property state of the first byte as described in the PNG spec
    pub fn is_critical(&self) -> bool {
        todo!()
    }

    /// Returns the property state of the second byte as described in the PNG spec
    pub fn is_public(&self) -> bool {
        todo!()
    }

    /// Returns the property state of the third byte as described in the PNG spec
    pub fn is_reserved_bit_valid(&self) -> bool {
        todo!()
    }

    /// Returns the property state of the fourth byte as described in the PNG spec
    pub fn is_safe_to_copy(&self) -> bool {
        todo!()
    }

    /// Returns true if the reserved byte is valid and all four bytes are represented by the characters A-Z or a-z.
    /// Note that this chunk type should always be valid as it is validated during construction.
    pub fn is_valid(&self) -> bool {
        todo!()
    }

    /// Valid bytes are represented by the characters A-Z or a-z
    pub fn is_valid_byte(byte: u8) -> bool {
        todo!()
    }
}

impl TryFrom<[u8; 4]> for ChunkType {
    type Error = Error;

    fn try_from(bytes: [u8; 4]) -> Result<Self> {
        todo!()
    }
}

impl fmt::Display for ChunkType {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        todo!()
    }
}

impl FromStr for ChunkType {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self> {
        todo!()
    }
}
}