Struct tendril::Tendril
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pub struct Tendril<F, A = NonAtomic> where F: Format, A: Atomicity {
// some fields omitted
}Compact string type for zero-copy parsing.
Tendrils have the semantics of owned strings, but are sometimes views
into shared buffers. When you mutate a Tendril, an owned copy is made
if necessary. Further mutations occur in-place until the string becomes
shared, e.g. with clone() or subtendril().
Buffer sharing is accomplished through thread-local (non-atomic) reference
counting, which has very low overhead. The Rust type system will prevent
you at compile time from sending a Tendril between threads. We plan to
relax this restriction in the future; see README.md.
Whereas String allocates in the heap for any non-empty string, Tendril
can store small strings (up to 8 bytes) in-line, without a heap allocation.
Tendril is also smaller than String on 64-bit platforms — 16 bytes
versus 24.
The type parameter F specifies the format of the tendril, for example
UTF-8 text or uninterpreted bytes. The parameter will be instantiated
with one of the marker types from tendril::fmt. See the StrTendril
and ByteTendril type aliases for two examples.
The type parameter A indicates the atomicity of the tendril; it is by
default NonAtomic, but can be specified as Atomic to get a tendril
which implements Send and Sync (viz. a thread-safe tendril).
The maximum length of a Tendril is 4 GB. The library will panic if
you attempt to go over the limit.
Methods
impl<F, A> Tendril<F, A> where F: Format, A: Atomicity
fn new() -> Tendril<F, A>
Create a new, empty Tendril in any format.
fn with_capacity(capacity: u32) -> Tendril<F, A>
Create a new, empty Tendril with a specified capacity.
fn reserve(&mut self, additional: u32)
Reserve space for additional bytes.
This is only a suggestion. There are cases where Tendril will
decline to allocate until the buffer is actually modified.
fn len32(&self) -> u32
Get the length of the Tendril.
This is named not to conflict with len() on the underlying
slice, if any.
fn is_shared(&self) -> bool
Is the backing buffer shared?
fn is_shared_with(&self, other: &Tendril<F, A>) -> bool
Is the backing buffer shared with this other Tendril?
fn clear(&mut self)
Truncate to length 0 without discarding any owned storage.
fn try_from_byte_slice(x: &[u8]) -> Result<Tendril<F, A>, ()>
Build a Tendril by copying a byte slice, if it conforms to the format.
fn as_bytes(&self) -> &Tendril<Bytes, A>
View as uninterpreted bytes.
fn into_bytes(self) -> Tendril<Bytes, A>
Convert into uninterpreted bytes.
fn into_send(self) -> SendTendril<F>
Convert self into a type which is Send.
If the tendril is owned or inline, this is free, but if it's shared this will entail a copy of the contents.
fn as_superset<Super>(&self) -> &Tendril<Super, A> where F: SubsetOf<Super>, Super: Format
View as a superset format, for free.
fn into_superset<Super>(self) -> Tendril<Super, A> where F: SubsetOf<Super>, Super: Format
Convert into a superset format, for free.
fn try_as_subset<Sub>(&self) -> Result<&Tendril<Sub, A>, ()> where Sub: SubsetOf<F>
View as a subset format, if the Tendril conforms to that subset.
fn try_into_subset<Sub>(self) -> Result<Tendril<Sub, A>, Self> where Sub: SubsetOf<F>
Convert into a subset format, if the Tendril conforms to that subset.
fn try_reinterpret_view<Other>(&self) -> Result<&Tendril<Other, A>, ()> where Other: Format
View as another format, if the bytes of the Tendril are valid for
that format.
fn try_reinterpret<Other>(self) -> Result<Tendril<Other, A>, Self> where Other: Format
Convert into another format, if the Tendril conforms to that format.
This only re-validates the existing bytes under the new format. It will not change the byte content of the tendril!
See the encode and decode methods for character encoding conversion.
fn try_push_bytes(&mut self, buf: &[u8]) -> Result<(), ()>
Push some bytes onto the end of the Tendril, if they conform to the
format.
fn push_tendril(&mut self, other: &Tendril<F, A>)
Push another Tendril onto the end of this one.
fn try_subtendril(&self, offset: u32, length: u32) -> Result<Tendril<F, A>, SubtendrilError>
Attempt to slice this Tendril as a new Tendril.
This will share the buffer when possible. Mutating a shared buffer will copy the contents.
The offset and length are in bytes. The function will return
Err if these are out of bounds, or if the resulting slice
does not conform to the format.
fn subtendril(&self, offset: u32, length: u32) -> Tendril<F, A>
Slice this Tendril as a new Tendril.
Panics on bounds or validity check failure.
fn try_pop_front(&mut self, n: u32) -> Result<(), SubtendrilError>
Try to drop n bytes from the front.
Returns Err if the bytes are not available, or the suffix fails
validation.
fn pop_front(&mut self, n: u32)
Drop n bytes from the front.
Panics if the bytes are not available, or the suffix fails validation.
fn try_pop_back(&mut self, n: u32) -> Result<(), SubtendrilError>
Drop n bytes from the back.
Returns Err if the bytes are not available, or the prefix fails
validation.
fn pop_back(&mut self, n: u32)
Drop n bytes from the back.
Panics if the bytes are not available, or the prefix fails validation.
unsafe fn reinterpret_view_without_validating<Other>(&self) -> &Tendril<Other, A> where Other: Format
View as another format, without validating.
unsafe fn reinterpret_without_validating<Other>(self) -> Tendril<Other, A> where Other: Format
Convert into another format, without validating.
unsafe fn from_byte_slice_without_validating(x: &[u8]) -> Tendril<F, A>
Build a Tendril by copying a byte slice, without validating.
unsafe fn push_bytes_without_validating(&mut self, buf: &[u8])
Push some bytes onto the end of the Tendril, without validating.
unsafe fn unsafe_subtendril(&self, offset: u32, length: u32) -> Tendril<F, A>
Slice this Tendril as a new Tendril.
Does not check validity or bounds!
unsafe fn unsafe_pop_front(&mut self, n: u32)
Drop n bytes from the front.
Does not check validity or bounds!
unsafe fn unsafe_pop_back(&mut self, n: u32)
Drop n bytes from the back.
Does not check validity or bounds!
impl<F, A> Tendril<F, A> where F: SliceFormat, A: Atomicity
fn from_slice(x: &F::Slice) -> Tendril<F, A>
Build a Tendril by copying a slice.
fn push_slice(&mut self, x: &F::Slice)
Push a slice onto the end of the Tendril.
impl<F, A> Tendril<F, A> where F: for<'a> CharFormat<'a>, A: Atomicity
fn pop_front_char<'a>(&'a mut self) -> Option<char>
Remove and return the first character, if any.
fn pop_front_char_run<'a, C, R>(&'a mut self, classify: C) -> Option<(Tendril<F, A>, R)> where C: FnMut(char) -> R, R: PartialEq
Remove and return a run of characters at the front of the Tendril
which are classified the same according to the function classify.
Returns None on an empty string.
fn try_push_char(&mut self, c: char) -> Result<(), ()>
Push a character, if it can be represented in this format.
impl<A> Tendril<Bytes, A> where A: Atomicity
fn decode(&self, encoding: EncodingRef, trap: DecoderTrap) -> Result<Tendril<UTF8, A>, Cow<'static, str>>
Decode from some character encoding into UTF-8.
See the rust-encoding docs for more information.
unsafe fn push_uninitialized(&mut self, n: u32)
Push "uninitialized bytes" onto the end.
Really, this grows the tendril without writing anything to the new area. It's only defined for byte tendrils because it's only useful if you plan to then mutate the buffer.
impl<A> Tendril<UTF8, A> where A: Atomicity
fn encode(&self, encoding: EncodingRef, trap: EncoderTrap) -> Result<Tendril<Bytes, A>, Cow<'static, str>>
Encode from UTF-8 into some other character encoding.
See the rust-encoding docs for more information.
fn push_char(&mut self, c: char)
Push a character onto the end.
fn from_char(c: char) -> Tendril<UTF8, A>
Create a Tendril from a single character.
fn format(args: Arguments) -> Tendril<UTF8, A>
Helper for the format_tendril! macro.