From c97dd145b9edd2fce58eb71e665c2b1305a3ee74 Mon Sep 17 00:00:00 2001
From: Martin Atkins <mart@degeneration.co.uk>
Date: Thu, 3 May 2018 10:33:02 -0700
Subject: [PATCH] addrs: Module.Call method

This is a helper for splitting a non-root module path into a callee and
call pair, similar to the method of the same name on ModuleInstance.
---
 addrs/module.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/addrs/module.go b/addrs/module.go
index 8e30f1b16..6420c6301 100644
--- a/addrs/module.go
+++ b/addrs/module.go
@@ -52,3 +52,24 @@ func (m Module) Parent() Module {
 	}
 	return m[:len(m)-1]
 }
+
+// Call returns the module call address that corresponds to the given module
+// instance, along with the address of the module that contains it.
+//
+// There is no call for the root module, so this method will panic if called
+// on the root module address.
+//
+// In practice, this just turns the last element of the receiver into a
+// ModuleCall and then returns a slice of the receiever that excludes that
+// last part. This is just a convenience for situations where a call address
+// is required, such as when dealing with *Reference and Referencable values.
+func (m Module) Call() (Module, ModuleCall) {
+	if len(m) == 0 {
+		panic("cannot produce ModuleCall for root module")
+	}
+
+	caller, callName := m[:len(m)-1], m[len(m)-1]
+	return caller, ModuleCall{
+		Name: callName,
+	}
+}