tanzim-merge

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Third stage of the tanzim pipeline: groups parsed payloads by entry name and merges their values.

The Merge trait

Implement [Merge] to define a custom merge strategy. The output is [Merged] — a HashMap<Option<String>, (Vec<Payload>, LocatedValue)> keyed by entry name, where the Vec<Payload> records which payloads contributed to each merged value.

Grouping key

Payload::maybe_name determines the map key:

• Some("foo") → key Some("foo")
• None → key None (all unnamed payloads share this bucket)

Built-in strategies

Example

use tanzim_merge::{DeepMerge, LastWins, Merge};
use tanzim_load::Payload;
use tanzim_source::Source;
use tanzim_value::{LocatedValue, Location, Map, Value};

let source = Source::parse("env").unwrap();

let make_entry = |name: Option<&str>, key: &str, val: &str| {
    let loc = Location::at("env", "", None, None, None);
    let mut map = Map::new();
    map.insert(key.to_string(), LocatedValue::new(Value::String(val.to_string()), loc.clone()));
    let payload = Payload {
        source: source.clone(),
        maybe_name: name.map(str::to_string),
        maybe_format: Some("env".into()),
        content: vec![],
    };
    (payload, LocatedValue::new(Value::Map(map), loc))
};

let list = vec![
    make_entry(Some("db"), "host", "primary"),
    make_entry(Some("db"), "host", "replica"),
];

// LastWins: second entry fully replaces the first
let merged = LastWins.merge(&list).unwrap();
let db = merged.get(&Some("db".to_string())).unwrap();
let host = db.1.value().as_map().unwrap().get("host").unwrap();
assert_eq!(host.value().as_string().unwrap(), "replica");

Features

No default features. Opt-in logging / tracing emit log messages / trace spans via the log / tracing crates.

Relations

• Consumes LocatedValue from tanzim-parse.
• Uses Payload from tanzim-load (which embeds Source) to track provenance.
• Full pipeline wired in tanzim.