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use std::ops::RangeInclusive;
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct FieldNumber(pub(crate) u32);
impl FieldNumber {
/// Maximum allowed field number.
///
/// This is determined by the fact that the field number is
/// part of the tag and the tag is a u32 composed of a 3 bit
/// value for the "wire type" and 29 bit for the "field number".
pub const MAX_ALLOWED_U32: u32 = u32::MAX >> 3;
/// Range of field values reserved for protobuf internal usage.
pub const RESERVED_FOR_PROTO_INTERNAL: RangeInclusive<u32> = 19000..=19999;
/// Number one field number.
pub const ONE: FieldNumber = FieldNumber(1);
/// Converts a given [`u32`] to a [`FieldNumber`] as long as it is smaller or
/// equal `0x1FFFFFFF` ([`FieldNumber::MAX_ALLOWED_U32`]) and at least `1` or
/// bigger. Otherwise an error is returned.
#[inline]
pub const fn try_from_u32(value: u32) -> Result<FieldNumber, FieldNumberIntoError> {
if value < 1 || value > (u32::MAX >> 3) {
Err(FieldNumberIntoError {
invalid_value: value,
})
} else {
Ok(FieldNumber(value))
}
}
/// Convert an [`u32`] to a field number without checking it is smaller
/// or equal [`FieldNumber::MAX_ALLOWED_U32`] and at least `1`.
///
/// # Safety
///
/// The caller must ensure the provided value is smaller or equal
/// [`FieldNumber::MAX_ALLOWED_U32`] and at least `1`. If not undefined
/// behavior will occur when the field number is serialized.
/// In debug an assertion will panic the program if a value greater then
/// [`FieldNumber::MAX_ALLOWED_U32`] is passed as argument.
#[inline]
pub const unsafe fn from_u32_unchecked(value: u32) -> FieldNumber {
debug_assert!(value <= (u32::MAX >> 3));
debug_assert!(1 <= value);
FieldNumber(value)
}
#[inline]
pub const fn value(&self) -> u32 {
self.0
}
/// Return the next unreserved FieldNumber.
///
/// Panics if the field number exceeds `0x1FFFFFFF`
/// ([`FieldNumber::MAX_ALLOWED_U32`]).
#[inline]
pub const fn get_next_unreserved(&self) -> FieldNumber {
assert!(self.0 <= FieldNumber::MAX_ALLOWED_U32);
if 19000 <= self.0 + 1 && self.0 < 19999 {
// According to https://protobuf.dev/programming-guides/proto3/#assigning
// 19000 till 19999 are reserved, jump after these
FieldNumber(20000)
} else {
FieldNumber(self.0 + 1)
}
}
}
impl TryFrom<u32> for FieldNumber {
type Error = FieldNumberIntoError;
#[inline]
fn try_from(value: u32) -> Result<Self, Self::Error> {
FieldNumber::try_from_u32(value)
}
}
impl From<FieldNumber> for u32 {
#[inline]
fn from(value: FieldNumber) -> Self {
value.0
}
}
#[derive(Debug, Clone, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct FieldNumberIntoError {
invalid_value: u32,
}