Struct StringPool 

pub struct StringPool { /* private fields */ }

Every string too long to sit inside a Data, with the character count of each one remembered.

A position on a string counts characters, so an index or a slice has to find where character i starts. Counting a long string’s characters for every one of those would turn a loop over it into quadratic work, so a slot’s count is taken once and kept until the slot holds a different string. A string whose character count equals its byte length holds nothing but single-byte characters, and on it a character position is a byte position; that is the route indexing and slicing take. The cursor remembers where the last walk stopped, so stepping through a multi-byte string forwards resumes there instead of restarting at its first byte.

The pool also carries the collector’s marks for its strings. Interning a string hands out a slot it found by its text, and the slot it finds has to count as reached by a cycle in progress, which is what Self::shade does without the interning caller needing the collector.

Implementations

impl StringPool

pub fn with_capacity(capacity: usize) -> Self

pub fn from_strings(strings: Vec<String>) -> Self

pub const fn len(&self) -> usize

pub const fn is_empty(&self) -> bool

pub fn push(&mut self, value: String)

pub fn iter(&self) -> impl Iterator<Item = &String>

pub fn get_mut(&mut self, index: usize) -> &mut String

A slot to write a different string into. What was worked out about the slot describes the string being replaced, so it goes.

pub fn release(&mut self, index: usize)

Empties a slot the collector freed. A long string’s buffer goes back to the allocator rather than waiting in a dead slot for the next string written there.

pub fn char_len(&self, id: usize) -> usize

The character count of the string in id, walked once and then remembered on the slot.

pub fn is_ascii(&self, id: usize) -> bool

Whether every character in id takes a single byte, answered from the remembered count rather than a second walk.

pub fn byte_offset(&self, id: usize, char_idx: usize) -> usize

The byte offset character char_idx starts at. The string has at least char_idx characters; at exactly that many the answer is its byte length, which is what a slice bound on the end of the string asks for.

Trait Implementations

impl Default for StringPool

fn default() -> Self

Returns the “default value” for a type.

impl Index<usize> for StringPool

type Output = String

The returned type after indexing.

fn index(&self, index: usize) -> &Self::Output

Performs the indexing (container[index]) operation.