[gnome-builder] cargo: hoist cargo lookup into helper function

[Christian Hergert <chergert src gnome org>]

commit 1d72dac8daafac3dbb1ac757bb600bc17c734d61
Author: Christian Hergert <chergert redhat com>
Date:   Wed Nov 22 16:48:06 2017 -0800

    cargo: hoist cargo lookup into helper function
    
    So that we can use this later when necessary outside of the
    build pipeline.

 src/plugins/cargo/cargo_plugin.py |   22 +++++++++++++++-------
 1 files changed, 15 insertions(+), 7 deletions(-)
---
diff --git a/src/plugins/cargo/cargo_plugin.py b/src/plugins/cargo/cargo_plugin.py
index 6c82a45..abf501a 100644
--- a/src/plugins/cargo/cargo_plugin.py
+++ b/src/plugins/cargo/cargo_plugin.py
@@ -71,6 +71,20 @@ class CargoBuildSystem(Ide.Object, Ide.BuildSystem, Gio.AsyncInitable):
     def do_get_priority(self):
         return 300
 
+def locate_cargo_from_config(config):
+    cargo = _CARGO
+
+    if config:
+        runtime = config.get_runtime()
+        if config.getenv('CARGO'):
+            cargo = config.getenv('CARGO')
+        elif not runtime or not runtime.contains_program_in_path(_CARGO):
+            cargo_in_home = os.path.expanduser('~/.cargo/bin/cargo')
+            if os.path.exists(cargo_in_home):
+                cargo = cargo_in_home
+
+    return cargo
+
 class CargoPipelineAddin(Ide.Object, Ide.BuildPipelineAddin):
     """
     The CargoPipelineAddin is responsible for creating the necessary build
@@ -92,13 +106,7 @@ class CargoPipelineAddin(Ide.Object, Ide.BuildPipelineAddin):
         runtime = config.get_runtime()
 
         # We might need to use cargo from ~/.cargo/bin
-        cargo = _CARGO
-        if config.getenv('CARGO'):
-            cargo = config.getenv('CARGO')
-        elif not runtime.contains_program_in_path(_CARGO):
-            cargo_in_home = os.path.expanduser('~/.cargo/bin/cargo')
-            if os.path.exists(cargo_in_home):
-                cargo = cargo_in_home
+        cargo = locate_cargo_from_config(config)
 
         # Fetch dependencies so that we no longer need network access
         fetch_launcher = pipeline.create_launcher()