From bb5cd07ce5be7bbb420e26296a3592743a9189f5 Mon Sep 17 00:00:00 2001
From: Markus Armbruster <armbru@pond.sub.org>
Date: Tue, 25 Jan 2011 20:13:41 +0100
Subject: [PATCH] New relations_with()

Relations checking with getrel() often needs a special case for "is
same country".  If you forget, you get behavior appropriate for a
neutral foreign country, which is usually very wrong (see commit
16c68eb4 for an example).

Unlike getrel(), relations_with() considers countries allied to
themselves.  Less dangerous.  In fact, allied behavior is typically
just right, so the special case isn't even needed.
---
 include/nat.h        |  1 +
 src/lib/common/nat.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/nat.h b/include/nat.h
index e8c0d736..f44d30d2 100644
--- a/include/nat.h
+++ b/include/nat.h
@@ -170,6 +170,7 @@ extern char *relatename(struct natstr *np, natid other);
 extern char *rejectname(struct natstr *np, natid other);
 extern char *natstate(struct natstr *np);
 extern int getrel(struct natstr *np, natid them);
+extern int relations_with(natid, natid);
 extern int getrejects(natid them, struct natstr *np);
 extern int getcontact(struct natstr *np, natid them);
 extern void putrel(struct natstr *np, natid them, int relate);
diff --git a/src/lib/common/nat.c b/src/lib/common/nat.c
index e71e1cf8..1efc5b19 100644
--- a/src/lib/common/nat.c
+++ b/src/lib/common/nat.c
@@ -104,6 +104,16 @@ getrel(struct natstr *np, natid them)
     return np->nat_relate[them];
 }
 
+/*
+ * Return relations US has with THEM.
+ * Countries are considered allied to themselves.
+ */
+int
+relations_with(natid us, natid them)
+{
+    return us == them ? ALLIED : getrel(getnatp(us), them);
+}
+
 int
 getrejects(natid them, struct natstr *np)
 {