Struct parsa::ParserString

pub struct ParserString { /* private fields */ }

A shrinking-window read-only string.

String slices can be taken from the front, and reset, with zero allocations or copies.

Implementations

impl ParserString

pub fn take(&mut self, n: usize) -> &str

Splits the string at n, shrinking it. Panics if n is larger than the remaining slice.

let mut input = ParserString::from("abc123");

assert_eq!(input.take(3), "abc");
assert_eq!(input.take(3), "123");

let mut input = ParserString::from("🗻∈🌏");
assert_eq!(input.take(2), "🗻∈");
assert_eq!(input.take(1), "🌏");

pub fn try_take(&mut self, n: usize) -> Option<&str>

Splits the string at n, shrinking it. Returns None if n is larger than the remaining slice.

let mut input = ParserString::from("abc123");
assert_eq!(input.try_take(5), Some("abc12"));
assert_eq!(input.try_take(5), None);

pub unsafe fn give(&mut self, n: usize)

Rewinds the string slice n spaces. Panics if n is larger than the taken space.

let mut input = ParserString::from("abc123");

assert_eq!(input.take(3), "abc");

unsafe { input.give(3); }

assert_eq!(input.take(3), "abc");
assert_eq!(input.take(3), "123");

Safety

Caller must assure that the resulting pointer lands on a UTF-8 code point. This library assumes that a function will never add back more than its taken, and thus is considered undefined behavior. This will never cause memory-unsafety, but can cause unpredictable things to happen.

pub unsafe fn set_ptr(&mut self, ptr: usize)

Set the current start position manually.

Safety

Caller must assure that the resulting pointer lands on a UTF-8 code point.

let mut input = ParserString::from("abc123");
unsafe { input.set_ptr(3); }
assert_eq!(input.get(), "123");

pub fn get(&self) -> &str

Get a reference to the string slice.

let mut input = ParserString::from("abc123");
let _ = input.take(2);

assert_eq!(input.get(), "c123");

pub fn len(&self) -> usize

Get the length of the string.

let mut input = ParserString::from("abc123");
let _ = input.take(2);
assert_eq!(input.len(), 4);

pub fn start(&self) -> usize

Get the current start of the string, relative to the “true” start.

let mut input = ParserString::from("abc123");
let _ = input.take(2);
assert_eq!(input.start(), 2);

Trait Implementations

impl Debug for ParserString

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ParserString

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<&str> for ParserString

fn from(value: &str) -> Self

Converts to this type from the input type.

impl From<String> for ParserString

fn from(value: String) -> Self

Converts to this type from the input type.