Comparison and examples

Compare documents

Document::compare reports effective-key differences between two documents. Each document uses its own dialect for duplicates and lookup participation.

Difference kinds:

• value changed;
• assignment state changed, such as assigned, empty or bare;
• key exists only on the left;
• key exists only on the right;
• export state changed.

#![allow(unused)]
fn main() {
use adotenv::{parse_strict, DifferenceKind};

let left = parse_strict("A=1\nB=\nC=3\n").unwrap();
let right = parse_strict("A=2\nB\nD=4\n").unwrap();
let changes: Vec<_> = left
    .compare(&right)
    .differences()
    .iter()
    .map(|entry| (entry.key.as_str(), entry.kind))
    .collect();

assert_eq!(
    changes,
    [
        ("A", DifferenceKind::Value),
        ("B", DifferenceKind::State),
        ("C", DifferenceKind::OnlyLeft),
        ("D", DifferenceKind::OnlyRight),
    ]
);
}

Comparison is literal. It does not expand values, read files, inspect the environment or run commands.

Generate an example

Document::example replaces assigned values while preserving:

• comments and blank lines;
• keys, export prefixes and formatting;
• line endings and a BOM;
• the assignment state of bare declarations.

Malformed statements and empty-key entries become indentation-preserving comments. Value text from those forms cannot leak into the output.

#![allow(unused)]
fn main() {
let source = "# app\nA=1\nB=\"two\" # note\nBARE\nBAD KEY=secret\n";
assert_eq!(
    adotenv::parse(source).0.example(),
    "# app\nA=\nB= # note\nBARE\n#\n"
);
}

Empty quoted values keep a placeholder when needed to keep an inline comment attached. The result is intended for examples and documentation, not for use as a runtime configuration.