pub struct StateID(/* private fields */);Expand description
The identifier of a finite automaton state.
It is represented by a u32 even on 64-bit systems in order to conserve
space. Namely, on all targets, this type guarantees that its value will
fit in a u32, i32, usize and an isize. This means that on 16-bit
targets, for example, this type’s maximum value will never overflow an
isize, which means it will never overflow a i16 even though its
internal representation is still a u32.
§Safety
While a StateID is meant to guarantee that its value fits into usize
without using as much space as a usize on all targets, callers must
not rely on this property for safety. Callers may choose to rely on this
property for correctness however. For example, creating a StateID with an
invalid value can be done in entirely safe code. This may in turn result in
panics or silent logical errors.
Implementations§
Source§impl StateID
impl StateID
Sourcepub const LIMIT: usize = 2_147_483_647usize
pub const LIMIT: usize = 2_147_483_647usize
The total number of values that can be represented.
Sourcepub fn new(value: usize) -> Result<StateID, StateIDError>
pub fn new(value: usize) -> Result<StateID, StateIDError>
Create a new value that is represented by a “small index.”
If the given index exceeds the maximum allowed value, then this returns an error.
Sourcepub const fn new_unchecked(value: usize) -> StateID
pub const fn new_unchecked(value: usize) -> StateID
Create a new value without checking whether the given argument exceeds the maximum.
Using this routine with an invalid value will result in unspecified behavior, but not undefined behavior. In particular, an invalid ID value is likely to cause panics or possibly even silent logical errors.
Callers must never rely on this type to be within a certain range for memory safety.
Sourcepub const fn from_u32_unchecked(index: u32) -> StateID
pub const fn from_u32_unchecked(index: u32) -> StateID
Create a new value from a u32 without checking whether the
given value exceeds the maximum.
Using this routine with an invalid value will result in unspecified behavior, but not undefined behavior. In particular, an invalid ID value is likely to cause panics or possibly even silent logical errors.
Callers must never rely on this type to be within a certain range for memory safety.
Sourcepub const fn as_usize(&self) -> usize
pub const fn as_usize(&self) -> usize
Return the internal value as a usize. This is guaranteed to
never overflow usize.
Sourcepub const fn as_u64(&self) -> u64
pub const fn as_u64(&self) -> u64
Return the internal value as a u64. This is guaranteed to
never overflow.
Sourcepub const fn as_u32(&self) -> u32
pub const fn as_u32(&self) -> u32
Return the internal value as a u32. This is guaranteed to
never overflow u32.
Sourcepub const fn as_i32(&self) -> i32
pub const fn as_i32(&self) -> i32
Return the internal value as a i32. This is guaranteed to
never overflow an i32.
Sourcepub fn one_more(&self) -> usize
pub fn one_more(&self) -> usize
Returns one more than this value as a usize.
Since values represented by a “small index” have constraints
on their maximum value, adding 1 to it will always fit in a
usize, u32 and a i32.
Sourcepub fn from_ne_bytes(bytes: [u8; 4]) -> Result<StateID, StateIDError>
pub fn from_ne_bytes(bytes: [u8; 4]) -> Result<StateID, StateIDError>
Decode this value from the bytes given using the native endian byte order for the current target.
If the decoded integer is not representable as a small index for the current target, then this returns an error.
Sourcepub fn from_ne_bytes_unchecked(bytes: [u8; 4]) -> StateID
pub fn from_ne_bytes_unchecked(bytes: [u8; 4]) -> StateID
Decode this value from the bytes given using the native endian byte order for the current target.
This is analogous to new_unchecked in that is does not check
whether the decoded integer is representable as a small index.
Sourcepub fn to_ne_bytes(&self) -> [u8; 4]
pub fn to_ne_bytes(&self) -> [u8; 4]
Return the underlying integer as raw bytes in native endian format.