Struct Memory

pub struct Memory { /* private fields */ }

A hash-like accessor for environment variables using a fake in-memory store.

Memory offers the same API as other environment variable backends in this crate, but does not access or mutate the underlying system.

This backend is suitable for running in untrusted environments such as a Wasm binary, testing environments, or in embedded contexts.

Examples

Fetching an environment variable:

let env = Memory::new();
// `Memory` backends are initially empty.
assert_eq!(env.get(b"PATH"), Ok(None));

Setting an environment variable:

let mut env = Memory::new();
env.put(b"ENV_BACKEND", Some(b"spinoso_env::Memory"))?;
assert_eq!(
    env.get(b"ENV_BACKEND")?.as_deref(),
    Some(&b"spinoso_env::Memory"[..])
);

Implementations

impl Memory

pub fn new() -> Self

Constructs a new, empty ENV Memory backend.

The resulting environment variable accessor has no access to the underlying host operating system. The returned accessor uses a virtual environment.

Examples

let env = Memory::new();

pub fn get<'a>( &'a self, name: &[u8], ) -> Result<Option<Cow<'a, [u8]>>, ArgumentError>

Retrieves the value for environment variable name.

Returns None if the named variable does not exist.

Examples

let env = Memory::new();
assert_eq!(env.get(b"PATH"), Ok(None));

Errors

If name contains a NUL byte, e.g. b'\0', an error is returned.

pub fn put(&mut self, name: &[u8], value: Option<&[u8]>) -> Result<(), Error>

Sets the environment variable name to value.

If the value given is None the environment variable is deleted.

Examples

let mut env = Memory::new();

env.put(b"RUBY", Some(b"Artichoke"))?;
assert_eq!(env.get(b"RUBY")?.as_deref(), Some(&b"Artichoke"[..]));

env.put(b"RUBY", None)?;
assert_eq!(env.get(b"RUBY")?, None);

Errors

If name contains a NUL byte, e.g. b'\0', an argument error is returned.

If name contains an ‘=’ byte, e.g. b'=', an EINVAL error is returned.

If value is Some and contains a NUL byte, e.g. b'\0', an argument error is returned.

pub fn to_map(&self) -> Result<HashMap<Vec<u8>, Vec<u8>>, ArgumentError>

Serialize the environ to a HashMap.

Map keys are environment variable names and map values are environment variable values.

Examples

let env = Memory::new();
let map = env.to_map()?;
assert!(map.is_empty());

Errors

This function is infallible.

Trait Implementations

impl Clone for Memory

fn clone(&self) -> Memory

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Memory

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

Formats the value using the given formatter.

impl Default for Memory

fn default() -> Memory

Returns the “default value” for a type.

impl PartialEq for Memory

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl Eq for Memory

impl StructuralPartialEq for Memory