add Provides generator

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

cargo-deps.py

@@ -0,0 +1,28 @@
+#!/usr/bin/python
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import argparse
+import json
+import subprocess
+import sys
+
+def get_metadata(path):
+    # --no-deps is to disable recursive scanning of deps
+    metadata = subprocess.check_output(["cargo", "metadata", "--no-deps",
+                                        "--manifest-path={}".format(path)])
+    return json.loads(metadata)["packages"][0]
+
+parser = argparse.ArgumentParser()
+group = parser.add_mutually_exclusive_group(required=True)
+group.add_argument("-P", "--provides", action="store_true", help="Print Provides")
+parser.add_argument("file", nargs="*", help="Path(s) to Cargo.toml")
+args = parser.parse_args()
+
+files = args.file or sys.stdin.readlines()
+
+for f in files:
+    f = f.rstrip()
+    md = get_metadata(f)
+    if args.provides:
+        print("crate({}) = {}".format(md["name"], md["version"]))

cargo.attr

@@ -0,0 +1,2 @@
+%__cargo_provides  %{_rpmconfigdir}/cargo-deps.py --provides
+%__cargo_path      ^%{cargo_registry}/[^/]+/Cargo\\.toml$