Struct LayeredEnvSource 

pub struct LayeredEnvSource { /* private fields */ }

An EnvSource that overlays a small map of override entries on top of a base source.

A lookup returns the override value when the name is present and non-empty; otherwise it delegates to the base source. This lets a caller inject one or two synthetic variables (e.g. a short-lived credential minted at runtime) so that env-driven code paths — scope-availability probes, token resolvers — observe the injected value without mutating the process environment or discarding the base source’s other variables.

An empty override string is treated as “not set” and falls through to the base, matching how the rest of the codebase treats an empty credential (is_some_and(|t| !t.is_empty())): overlaying ("X", "") cannot mask a real base value.

use std::sync::Arc;
use anodizer_core::{EnvSource, LayeredEnvSource, MapEnvSource};

let base: Arc<dyn EnvSource> = Arc::new(MapEnvSource::new().with("A", "base-a"));
let layered = LayeredEnvSource::new(base, [("A", "override-a"), ("B", "override-b")]);
assert_eq!(layered.var("A"), Some("override-a".to_string())); // override wins
assert_eq!(layered.var("B"), Some("override-b".to_string())); // override-only key
assert_eq!(layered.var("MISSING"), None);                     // neither has it

Implementations

impl LayeredEnvSource

pub fn new<I, K, V>(base: Arc<dyn EnvSource>, overrides: I) -> Self

where I: IntoIterator<Item = (K, V)>, K: Into<String>, V: Into<String>,

Wrap base with the given (name, value) overrides. Empty override values are retained but treated as absent by LayeredEnvSource::var (they fall through to the base).

Trait Implementations

impl Clone for LayeredEnvSource

fn clone(&self) -> LayeredEnvSource

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl EnvSource for LayeredEnvSource

fn var(&self, name: &str) -> Option<String>

Look up name and return its value, or None if unset.

fn vars(&self) -> Vec<(String, String)>

Snapshot every (name, value) pair this source can enumerate.