Macro transpose_tuple 

macro_rules! transpose_tuple {
    (Option; $first:expr, $($rest:expr),+ $(,)?) => { ... };
    (Result; $first:expr, $($rest:expr),+ $(,)?) => { ... };
    ($first:expr, $($rest:expr),+ $(,)?) => { ... };
}

Transposes an arbitrary length of tuple of Options/Results into an Option/Result of a tuple.

Syntax:

• Option-variant: transpose_tuple!(Option; e1, e2, ..., eN) … transposes a tuple of Options.
  • You can omit Option; part, like: transpose_tuple!(e1, e2, ..., eN).
• Result-variant: transpose_tuple!(Result; e1, e2, ..., eN)… transposes a tuple of valq::Results.

Note: Result-variant is meant to be used with valq::Result (return type of query_value_result! macro). It doesn’t support other error types for now.

Examples

// Options
use serde_json::json;
use valq::{query_value, transpose_tuple};

let valq = json!({
    "name": "valq",
    "keywords": ["macro", "query", "serde"],
    "author": {
        "name": "jiftechnify",
        "age": 31
    }
});

let picks = transpose_tuple!(
    query_value!(valq.name -> str),
    query_value!(valq.keywords[1] -> str),
    query_value!(valq.author.age -> u64),
);
assert_eq!(picks, Some(("valq", "query", 31u64)));

let wrong_picks = transpose_tuple!(
    query_value!(valq.name -> str),
    query_value!(valq.keywords[10] -> str), // out of bounds
);
assert_eq!(wrong_picks, None);

// Results
use valq::{query_value_result, transpose_tuple};

let picks = transpose_tuple!(
    Result; // don't forget this!
    query_value_result!(valq.name -> str),
    query_value_result!(valq.keywords[1] -> str),
    query_value_result!(valq.author.age -> u64),
);
assert!(matches!(picks, Ok(("valq", "query", 31u64))));

let wrong_picks = transpose_tuple!(
    Result;
    query_value_result!(valq.name -> str),
    query_value_result!(valq.secrets), // non-existent path
);
assert!(matches!(wrong_picks, Err(valq::Error::ValueNotFoundAtPath(_))));