dimensioned export (gwy, HDF5)

backend/exporters/table.py

@@ -0,0 +1,44 @@
+"""
+Exporter for RECORD_TABLE and DATA_TABLE values.
+
+Both types are list-of-dict; the Save node currently accepts plain lists in
+this slot too, which is preserved here. CSV auto-derives its column set from
+the first row's keys (and any additional keys that appear later), matching
+the prior behavior.
+"""
+
+from __future__ import annotations
+
+import csv
+import json
+from pathlib import Path
+
+from backend.exporters._base import FormatSpec
+
+accepted_types: tuple[str, ...] = ("RECORD_TABLE", "DATA_TABLE")
+
+FORMATS: dict[str, FormatSpec] = {
+    "CSV":  FormatSpec(ext=".csv",  round_trip=True, label="CSV"),
+    "JSON": FormatSpec(ext=".json", round_trip=True, label="JSON"),
+}
+
+
+def save(path: Path, value: list, format_name: str, **_opts) -> None:
+    rows = list(value)
+    if format_name == "JSON":
+        path.write_text(json.dumps(rows, indent=2), encoding="utf-8")
+        return
+    if format_name == "CSV":
+        columns: list[str] = []
+        for row in rows:
+            if isinstance(row, dict):
+                for key in row.keys():
+                    if key not in columns:
+                        columns.append(str(key))
+        with path.open("w", newline="", encoding="utf-8") as fh:
+            writer = csv.DictWriter(fh, fieldnames=columns)
+            writer.writeheader()
+            for row in rows:
+                writer.writerow(row if isinstance(row, dict) else {"value": row})
+        return
+    raise ValueError(f"Format {format_name!r} is not supported for table inputs.")