sq3-rs 0.2.14

SQLite reader with no dependencies
Documentation 
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use std::ops::Deref;

use sq3_derive::Name;

use crate::{
    result::SqliteResult,
    traits::{ParseBytes, TypeName},
    VERSION_NUMBER,
};

/// # Version-valid-for number (4 Bytes)
///
///  The 4-byte big-endian integer at offset 92 is the value of the change
/// counter when the version number was stored. The integer at offset 92
/// indicates which transaction the version number is valid for and is sometimes
/// called the "version-valid-for number".
///
/// >  The entries at offsets 92 and 96 were added in later version of the
/// > SQLite library.
/// >
/// >  When an older version modifies the file, it will change the change
/// > counter (offset 24), but not adjust the version-valid-for number or the
/// > write library version number. So the library version number is no longer
/// > correct, because a different version last wrote to the file.
/// >
/// >  The version-valid-for number allows a new library to detect this case: if
/// > the change counter and the version-valid-for number do not match, then the
/// > write library version number is outdated, and must be ignored.
/// >
/// >  **Reference:** https://stackoverflow.com/a/45420823
#[derive(Debug, Name)]
pub struct VersionValidFor(u32);
impl Default for VersionValidFor {
    fn default() -> Self {
        Self(*VERSION_NUMBER.get().unwrap_or(&0))
    }
}
impl Deref for VersionValidFor {
    type Target = u32;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl ParseBytes for VersionValidFor {
    const LENGTH_BYTES: usize = 4;

    fn parsing_handler(bytes: &[u8]) -> SqliteResult<Self> {
        let buf: [u8; Self::LENGTH_BYTES] = bytes.try_into()?;

        let database_size = u32::from_be_bytes(buf);

        Ok(Self(database_size))
    }
}