feat: initial SQL REPL for xarray-sql

Author: RohanDisa

xarray_sql/repl.py

@@ -0,0 +1,58 @@
+"""Simple SQL REPL for xarray-sql.
+
+Run with: python -m xarray_sql.repl
+
+Starts with a demo "air" table (xarray tutorial dataset). Type SQL and see
+results. Commands: .quit or .exit to exit.
+"""
+
+import sys
+
+# Enable up/down arrow history for input() (Unix/Mac built-in; Windows: pip install pyreadline3)
+try:
+  import readline  # noqa: F401
+except ImportError:
+  pass
+
+import xarray as xr
+
+from .sql import XarrayContext
+
+MAX_DISPLAY_ROWS = 100
+
+
+def main():
+  ctx = XarrayContext()
+  # Demo table: streaming path (no read_all); requires _native to be built
+  print("Loading demo table 'air' (xarray tutorial air_temperature)...")
+  air = xr.tutorial.open_dataset("air_temperature").chunk({"time": 240})
+  ctx.from_dataset("air", air)
+  print("Ready. Type SQL or .quit / .exit to exit.\n")
+
+  while True:
+    try:
+      line = input("xarray-sql> ").strip()
+    except EOFError:
+      print()
+      break
+
+    if not line:
+      continue
+    if line in (".quit", ".exit"):
+      break
+
+    try:
+      result = ctx.sql(line).to_pandas()
+      display = result.head(MAX_DISPLAY_ROWS)
+      print(display.to_string())
+      if len(result) > MAX_DISPLAY_ROWS:
+        print(f"... ({len(result) - MAX_DISPLAY_ROWS} more rows)")
+    except Exception as e:
+      print(f"Error: {e}", file=sys.stderr)
+    print()
+
+  sys.exit(0)
+
+
+if __name__ == "__main__":
+  main()