Enum deno_core::FastString

pub enum FastString {
    Static(&'static str),
    StaticAscii(&'static str),
    Owned(Box<str>),
    Arc(Arc<str>),
}

Module names and code can be sourced from strings or bytes that are either owned or borrowed. This enumeration allows us to perform a minimal amount of cloning and format-shifting of the underlying data.

Note that any FastString created from a 'static byte array or string must contain ASCII characters.

Examples of ways to construct a FastString:

let code: FastString = ascii_str!("a string");
let code: FastString = format!("a string").into();

Variants

Static(&'static str)

Created from static data.

StaticAscii(&'static str)

Created from static data, known to contain only ASCII chars.

Owned(Box<str>)

An owned chunk of data. Note that we use Box rather than Vec to avoid the storage overhead.

Arc(Arc<str>)

Implementations

impl FastString

pub const fn from_static(s: &'static str) -> Self

Create a FastString from a static string. The string may contain non-ASCII characters, and if so, will take the slower path when used in v8.

pub const fn ensure_static_ascii(s: &'static str) -> Self

Create a FastString from a static string. If the string contains non-ASCII characters, the compiler will abort.

pub fn into_cheap_copy(self) -> (Self, Self)

Creates a cheap copy of this FastString, potentially transmuting it to a faster form. Note that this is not a clone operation as it consumes the old FastString.

pub fn try_clone(&self) -> Option<Self>

If this FastString is cheaply cloneable, returns a clone.

pub const fn try_static_ascii(&self) -> Option<&'static [u8]>

pub fn as_bytes(&self) -> &[u8]

pub fn as_str(&self) -> &str

pub fn v8<'a>(&self, scope: &mut HandleScope<'a>) -> Local<'a, String>

Create a v8 string from this FastString. If the string is static and contains only ASCII characters, an external one-byte static is created.

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

Truncates a FastString value, possibly re-allocating or memcpy’ing. May be slow.

Trait Implementations

impl AsRef<str> for FastString

fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<str> for FastString

fn borrow(&self) -> &str

Immutably borrows from an owned value.

impl Debug for FastString

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

Formats the value using the given formatter.

impl Default for FastString

fn default() -> Self

Returns the “default value” for a type.

impl From<Arc<str>> for FastString

FastString can be made cheaply from Arc<str> as we know it’s shared and don’t need to do an ASCII check.

fn from(value: Arc<str>) -> Self

Converts to this type from the input type.

impl From<String> for FastString

FastString can be made cheaply from String as we know it’s owned and don’t need to do an ASCII check.

fn from(value: String) -> Self

Converts to this type from the input type.

impl From<Url> for FastString

FastString can be made cheaply from Url as we know it’s owned and don’t need to do an ASCII check.

fn from(value: Url) -> Self

Converts to this type from the input type.

impl Hash for FastString

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for FastString

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for FastString