site_data.py

Go to the documentation of this file.

"""site_data.py - IL sim's own tiny RailML reader.
 
Independently re-parses safeAPIRBC2oo2SA/etc/site/ab_site.railml.xml -
see TrainRBCSim/src/train/site_data.py's own header for the full "why a
FOURTH independent reader, not a shared library call" rationale (matches
the no-pipeline-coupling convention safeAPIRBC2oo2GP's/GA's own RailML
generators already established).
 
Unlike Train's own reader, this is genuinely NEW ground for IL - today's
il_sim.py hardcodes no route data at all (every ROUTE_ADD's own
start_signal/end_signal/route_len is entirely test/command-supplied, see
that file's own header doc). This module gives IL its own real route
table (id/name/start_signal/end_signal/length_m), the same shape
safeAPIRBC2oo2GA/etc/scripts/generate_ab_site_ga.py's own
ab_site_ga_route_layout_t table already carries and the SAME positional-
id convention it uses (route/signal ids assigned by RailML document
order, not parsed from the element's own @id string) - so a route id
this module reports lines up numerically with what GP/GA's own C code
means by that same id.
"""
 
import logging
import os
import xml.etree.ElementTree as ET
 
_RAILML_NS = "https://www.railml.org/schemas/3.3"
_SAPI_NS = "https://safeapirbc2oo2.example/schemas/sapi-ext/1"
_NS = {"r": _RAILML_NS, "sapi": _SAPI_NS}
 
# ILRBCSim/src/il/ -> up 3 (il, src, ILRBCSim) -> the SAPI workspace root
# -> safeAPIRBC2oo2SA's own sibling checkout - same convention
# TrainRBCSim/src/train/site_data.py's own DEFAULT_RAILML_PATH uses.
_WORKSPACE_ROOT = os.path.abspath(os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "..", ".."))
DEFAULT_RAILML_PATH = os.path.join(_WORKSPACE_ROOT, "safeAPIRBC2oo2SA", "etc", "site", "ab_site.railml.xml")
 
 
def routes(railml_path=None):
    """@return a list of {"id", "name", "start_signal", "end_signal",
    "length_m"} dicts, one per <route>, ordered and id-numbered exactly
    the way generate_ab_site_ga.py's own parse_railml() derives them
    (signal/route ids by document-order position, length_m read directly
    from each route's own sapi:routeDescription/@lengthM extension - no
    segment-length summation needed, that field is already explicit).
    Raises on a genuinely missing/malformed RailML file - unlike Train's
    balise_names() (a pure log-decoration convenience), a route table
    this sim doesn't have at all today is real, load-bearing IL data
    (this is what Phase D's own periodic route-status broadcast iterates
    over) - a silent empty-table fallback here would make IL announce
    "there are zero routes," which is materially wrong, not just
    cosmetically incomplete like a missing balise name would be."""
    path = railml_path or os.environ.get("SAPI_RAILML_PATH") or DEFAULT_RAILML_PATH
    tree = ET.parse(path)
    root = tree.getroot()
    infra = root.find("r:infrastructure", _NS)
    fi = infra.find("r:functionalInfrastructure", _NS)
    il = root.find("r:interlocking", _NS)
    afi = il.find("r:assetsForInterlockings/r:assetsForInterlocking", _NS)
    routes_el = afi.find("r:routes", _NS)
 
    signal_list = fi.find("r:signalsIS", _NS).findall("r:signalIS", _NS)
    sig_pos_by_xmlid = {sig.get("id"): i for i, sig in enumerate(signal_list, start=1)}
 
    result = []
    for i, rt in enumerate(routes_el.findall("r:route", _NS), start=1):
        entry = rt.find("r:routeEntry", _NS).get("refersTo")
        exit_ = rt.find("r:routeExit", _NS).get("refersTo")
        rext = rt.find("r:extensions/sapi:routeDescription", _NS)
        result.append({
            "id": i,
            "name": rt.get("designator", rt.get("id", f"Route_{i}")),
            "start_signal": sig_pos_by_xmlid[entry],
            "end_signal": sig_pos_by_xmlid[exit_],
            "length_m": int(rext.get("lengthM")),
        })
    if not result:
        raise ValueError(f"RailML file at {path!r} parsed but yielded zero routes")
    return result