Files
road-compiler/.trellis/scripts/common/io.py
que01 c7425f5ed4 feat: make crosswalk and stop-line offsets solvable
Step 1 of the control-marking task, and deliberately server-only: no handle is
drawn yet. This project already shipped a range handle for `profile.interval`,
which compileGeometry ignores, so the control dragged and changed nothing. The
consumer comes first now.

Two kinds join the taxonomy — `junction-crosswalk-inset` and
`junction-stop-line-offset`, both on the existing `junction-approach` anchor. The
solver writes them onto the approach entry, `applyDirectJunctionPlans` carries
them onto the compiled approach, and `compileControlMarkings` reads them in place
of the module constants it used for every junction. They move markings without
reshaping the junction, so unlike width and cutback they deliberately do not
trigger a boundary recompute.

`applyJunctionConstraint` becomes an explicit switch. Its trailing `else` had
meant every kind that was not approach-width fell through to the cutback
validator, so a new kind would have been silently validated and written as a
cutback. The same non-exhaustive shape in the test fixture's `valueFor` is fixed
the same way, and now throws for an unnamed kind rather than answering with a
corner radius.

design.md's taxonomy is updated with it — a test asserts the two cannot drift,
which is what caught the omission.

Measured on a 41-road workspace with 8 crossings: both constraints change their
marking geometry, neither drags the other, and out-of-range blocks instead of
clamping. That measurement is not in the suite: the synthetic junction resolves
`junction_inset_m` to 0 because its crossing never binds to a plan, and the
committed OSM fixture has no crossings at all. The tests assert the wiring the
handles will depend on — values reaching the approach entry, distinct branches,
blocking diagnostics — and the gap is recorded in the test itself.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-28 15:01:36 +08:00

62 lines
1.6 KiB
Python
Executable File

"""
JSON file I/O utilities.
Provides read_json and write_json as the single source of truth
for JSON file operations across all Trellis scripts.
"""
from __future__ import annotations
import json
import os
import tempfile
from pathlib import Path
def read_json(path: Path) -> dict | None:
"""Read and parse a JSON file.
Returns None if the file doesn't exist, is invalid JSON, or can't be read.
"""
try:
return json.loads(path.read_text(encoding="utf-8"))
except (FileNotFoundError, json.JSONDecodeError, OSError):
return None
def write_json(path: Path, data: dict) -> bool:
"""Write dict to JSON file with pretty formatting.
The write is atomic: content goes to a temp file in the same directory
and is then renamed over the target. A crash or Ctrl-C mid-write leaves
the existing file intact rather than truncated, so a corrupted task.json
can never make a task silently vanish from `task.py list`.
Returns True on success, False on error.
"""
payload = json.dumps(data, indent=2, ensure_ascii=False)
try:
fd, tmp = tempfile.mkstemp(
dir=str(path.parent), prefix=f".{path.name}.", suffix=".tmp"
)
except OSError:
return False
try:
try:
f = os.fdopen(fd, "w", encoding="utf-8")
except OSError:
# fdopen never took ownership of fd; close it ourselves.
os.close(fd)
raise
with f:
f.write(payload)
os.replace(tmp, path)
return True
except OSError:
try:
os.unlink(tmp)
except OSError:
pass
return False