gobject-introspection: GIR: tries to find .gir in a current vocabulary's directory, in system gir-1.0 (/usr/share/gir-1.0, /usr/local/share/gir-1.0)

or user-defined (GIR_DIRS env. variable) directories;

basis/gobject-introspection/gobject-introspection.factor

@@ -1,15 +1,47 @@
 ! Copyright (C) 2010 Anton Gorenko.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors combinators gobject-introspection.common
+USING: accessors combinators environment gobject-introspection.common
 gobject-introspection.ffi gobject-introspection.loader
-gobject-introspection.types kernel lexer locals namespaces parser
-sequences xml ;
+gobject-introspection.types io io.files io.pathnames kernel lexer
+locals make namespaces parser sequences splitting summary vocabs
+vocabs.parser xml ;
 IN: gobject-introspection
 
+ERROR: gir-not-found name paths ;
+
+M: gir-not-found summary
+    [ name>> "“" "” file not found on paths:\n" surround ]
+    [ paths>> "\n" join ] bi
+    "\n\nUse the existing path or declare GIR_DIRS environment variable"
+    3append ;
+
 <PRIVATE
 
-:: define-gir-vocab ( file-name -- )
-    file-name file>xml xml>repository
+: system-gir-dirs ( -- dirs )
+    "XDG_DATA_DIRS" os-env "/usr/local/share/:/usr/share/" or
+    ":" split [ "gir-1.0" append-path ] map ;
+
+: custom-gir-dirs ( -- dirs )
+    "GIR_DIRS" os-env ":" split ;
+
+: current-vocab-dirs ( -- dirs )
+    [
+        current-vocab vocab-name "." split "/" join dup ,
+        dup file-name "ffi" = [ parent-directory , ] [ drop ] if
+    ] { } make ;
+
+:: resolve-gir-path ( path -- path )
+    path exists?
+    [ path ] [
+        current-vocab-dirs custom-gir-dirs system-gir-dirs
+        3append sift :> paths
+        paths [ path append-path exists? ] find nip
+        [ path append-path ] [ path paths gir-not-found ] if*
+    ] if ;
+
+: define-gir-vocab ( path -- )
+    resolve-gir-path dup "  loading " write print
+    file>xml xml>repository
     {
         [ namespace>> name>> current-namespace-name set-global ]
         [ def-ffi-repository ]