[−][src]Trait char_circle::StringTransform
A factory trait for in-place string transformations.
This trait allows character-iterator adaptors to modify strings in-place.
It is implemented by adaptor factories with a single required method,
transform_chars
, for constructing the adaptors. In return, this trait
provides a method, transform
, which can apply the transformation to
both owned strings and string slices, without allocating when possible.
The in-place operation works by treating the underlying string as a
circular buffer. The transform reads characters from the front of the
buffer and writes characters to the back of the buffer. Once the transform
returns None
, the unread characters are deleted and the circular buffer
is cast back into a string. Note that the transformation cannot always be
applied in place; if the transform ever returns more bytes than it has
read, an allocation is required to grow the buffer.
This trait supports copy-on-write optimizations. Implementors can override
the StringTransform::will_modify
method to short-circuit the transform.
See SimpleTransform
for a variant of this trait that is implemented
directly by iterator adaptors.
The lifetime 'a
refers to the lifetime of the transform
method.
Associated Types
Loading content...Required methods
fn transform_chars(&self, chars: Chars<'a>) -> Self::Iter
Transform the characters of a string.
Provided methods
fn will_modify(&self, val: &str) -> bool
A hint to short-circuit string transformations.
If true, the string might be modified by the transform. If false, the string will definitely not be modified by the transform.
Implementors may override this function to facilitate copy-on-write optimizations. The default implementation always returns true, which disables copy-on-write.
fn transform<'b, T: Into<Cow<'b, str>>>(&self, s: T) -> Cow<'b, str>
Transform a string in-place
This method can operate on both String
and &str
.
A new string may be allocated if the input is not owned or if the transformation needs to buffer more characters than the string has capacity.