✨ feat(eval): support .[] iterator for arrays and dicts

[harehare]

• Arrays: .[] returns all elements as an array (identity passthrough)
• Dicts: .[] returns all values as an array
• Handles both args and no-args eval paths

[codspeed-hq]

Merging this PR will not alter performance

✅ 29 untouched benchmarks

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_{Comparing feat/array-dict-iterator-selector (d938219) with main (5151f74)¹}

Footnotes

1. No successful run was found on main (527244e) during the generation of this report, so 5151f74 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Copilot]

Pull request overview

This PR extends mq-lang’s evaluator to treat the selector syntax .[] as an iterator over runtime arrays and dicts (arrays passthrough; dicts yield values), and adds integration tests to validate the new behavior.

Changes:

• Add array indexing support for .[n] in selector evaluation (return element or NONE if out-of-bounds).
• Implement .[] on arrays as an identity/passthrough and .[] on dicts as “values as array” (no-args path).
• Add integration tests covering .[] for arrays/dicts and .[n] indexing.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
crates/mq-lang/src/eval.rs	Adds selector handling for .[n] indexing and .[] iteration semantics in the evaluator.
crates/mq-lang/tests/integration_tests.rs	Adds integration cases verifying .[] and .[n] behavior for arrays and dicts.

Comments suppressed due to low confidence (1)

crates/mq-lang/src/eval.rs:816

• eval_selector_expr_with_args adds .[] identity behavior for arrays (when args are empty), but the Dict branch doesn’t mirror this. As a result, {"a": 1} | .[]() (SelectorCall with empty args) will produce a dict of NONEs instead of returning the dict values as an array, and behavior differs between .[] and .[]() / args vs no-args paths. Consider adding the same Selector::List(None, None) + empty-args special-case in the RuntimeValue::Dict arm here.

                            }
                        }
                        _ if matches!(selector, Selector::List(None, None)) && args.is_empty() => {
                            vec![value.clone()]
                        }
                        RuntimeValue::Dict(_) => {
                            vec![Self::eval_selector_expr_with_args(value, selector, args)]
                        }
                        _ => vec![RuntimeValue::NONE],