Improve route level parser

[ties]

Summary

This PR improves the route-level parser by changing route iteration from eager per-prefix rows to route batches with shared parsed state. The new batching model avoids repeatedly cloning shared data such as AS paths and delays NLRI prefix parsing until route rows are actually consumed.

A routebatch maps cleanly on one BGP message. Main question is if it improves performance, current API is more ergonomic.

What Changed

• into_route_iter() now yields RouteBatch values instead of direct BgpRouteElem rows.
• Added RouteBatch::routes() for filtered route iteration and RouteBatch::all_routes() for unfiltered iteration.
• Changed BgpRouteElem into a borrowed route row, BgpRouteElem<'a>, with as_path: Option<&'a AsPath>.
• Added BgpRouteElemOwned and BgpRouteElem::into_owned() for callers that need rows to outlive the containing batch.
• Updated FallibleRouteIterator to yield Result<RouteBatch, ParserErrorWithBytes>.
• Reworked route-level MP_REACH/MP_UNREACH and standard NLRI handling to store raw Bytes and parse prefixes lazily.
• Preserved AS path sharing across all announced prefixes in the same route batch.
• Updated route filtering to work against borrowed route rows inside each batch.
• Updated the route-level parsing example to consume batches and iterate routes explicitly.

Behavior Notes

This is a public API change for route-level parsing callers. Existing code like:

for route in parser.into_route_iter() {
    // use route
}

now needs to iterate through each batch:

for batch in parser.into_route_iter() {
    for route in batch.routes() {
        let route = route?;
        // use route
    }
}

Use batch.all_routes() when applying custom filters manually or when unfiltered batch contents are needed.

[codecov]

Codecov Report

❌ Patch coverage is 93.27354% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.03%. Comparing base (d9889d1) to head (4ba8326).

Files with missing lines	Patch %	Lines
src/parser/iters/route.rs	92.85%	30 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #287      +/-   ##
==========================================
+ Coverage   89.69%   90.03%   +0.33%     
==========================================
  Files          86       86              
  Lines       18334    18657     +323     
==========================================
+ Hits        16444    16797     +353     
+ Misses       1890     1860      -30     

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[Copilot]

Pull request overview

This PR refactors the route-level parsing API to iterate by BGP message/record “batches” with shared parsed state, enabling lazy NLRI prefix parsing and reducing repeated cloning (notably AS paths) across per-prefix route rows.

Changes:

• into_route_iter() now yields RouteBatch (one batch per route-bearing record / UPDATE), with RouteBatch::routes() and RouteBatch::all_routes() producing per-prefix rows lazily.
• BgpRouteElem becomes a borrowed row (BgpRouteElem<'a>) borrowing &AsPath, with BgpRouteElemOwned + into_owned() for ownership.
• Route-level MP_REACH/MP_UNREACH and standard NLRI handling is reworked to store raw Bytes and parse prefixes on-demand; filter plumbing updated accordingly.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/parser/utils.rs	Exposes try_parse_prefix within the crate to support lazy NLRI parsing.
src/parser/iters/route.rs	Implements RouteBatch + lazy NLRI parsing/iteration and updates route-level iterators to yield batches.
src/parser/iters/mod.rs	Re-exports new batch types and updates route-iterator docs to match the new API.
src/parser/filter.rs	Updates filtering traits/implementations to work with borrowed BgpRouteElem<'_>.
src/models/bgp/elem.rs	Converts BgpRouteElem into a borrowed type and introduces BgpRouteElemOwned.
examples/route_level_parsing.rs	Updates the example to consume batches and then iterate routes within each batch.

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[ties]

I think this might be a performance regression. In an application, compared to baseline:

ingest_mrt/load_mrt_file/rrc13_bview_20260403_0000
                        time:   [2.4200 s 2.4230 s 2.4264 s]
                        change: [+24.610% +24.911% +25.241%] (p = 0.00 < 0.05)
                        Performance has regressed.