wic: add BitbakeVars class

Moved code of getting bitbake variables into separate class.

Created singleton object of this class in the module namespace.

Preserved existing API get_bitbake_var.

(From OE-Core rev: 3229d37993e315c9ca1902849746b9f50f35845c)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/utils/oe/misc.py

@@ -124,48 +124,63 @@ def exec_native_cmd(cmd_and_args, native_sysroot, catch=3):
 
 BOOTDD_EXTRA_SPACE = 16384
 
-_BITBAKE_VARS = defaultdict(dict)
+class BitbakeVars(defaultdict):
+    """
+    Container for Bitbake variables.
+    """
+    def __init__(self):
+        defaultdict.__init__(self, dict)
+
+    def get_var(self, var, image=None):
+        """
+        Get bitbake variable value lazy way, i.e. run
+        'bitbake -e' only when variable is requested.
+        """
+        if image not in self:
+            # Get bitbake -e output
+            cmd = "bitbake -e"
+            if image:
+                cmd += " %s" % image
+
+            log_level = msger.get_loglevel()
+            msger.set_loglevel('normal')
+            ret, lines = _exec_cmd(cmd)
+            msger.set_loglevel(log_level)
+
+            if ret:
+                print "Couldn't get '%s' output." % cmd
+                print "Bitbake failed with error:\n%s\n" % lines
+                return
+
+            # Parse bitbake -e output
+            for line in lines.split('\n'):
+                if "=" not in line:
+                    continue
+                try:
+                    key, val = line.split("=")
+                except ValueError:
+                    continue
+                key = key.strip()
+                val = val.strip()
+                if key.replace('_', '').isalnum():
+                    self[image][key] = val.strip('"')
+
+            # Make first image a default set of variables
+            images = [key for key in self if key]
+            if len(images) == 1:
+                self[None] = self[image]
+
+        return self[image].get(var)
+
+# Create BB_VARS singleton
+BB_VARS = BitbakeVars()
 
 def get_bitbake_var(var, image=None):
     """
-    Get bitbake variable value lazy way, i.e. run
-    'bitbake -e' only when variable is requested.
+    Provide old get_bitbake_var API by wrapping
+    get_var method of BB_VARS singleton.
     """
-    if image not in _BITBAKE_VARS:
-        # Get bitbake -e output
-        cmd = "bitbake -e"
-        if image:
-            cmd += " %s" % image
-
-        log_level = msger.get_loglevel()
-        msger.set_loglevel('normal')
-        ret, lines = _exec_cmd(cmd)
-        msger.set_loglevel(log_level)
-
-        if ret:
-            print "Couldn't get '%s' output." % cmd
-            print "Bitbake failed with error:\n%s\n" % lines
-            return
-
-        # Parse bitbake -e output
-        for line in lines.split('\n'):
-            if "=" not in line:
-                continue
-            try:
-                key, val = line.split("=")
-            except ValueError:
-                continue
-            key = key.strip()
-            val = val.strip()
-            if key.replace('_', '').isalnum():
-                _BITBAKE_VARS[image][key] = val.strip('"')
-
-        # Make first image a default set of variables
-        images = [key for key in _BITBAKE_VARS if key]
-        if len(images) == 1:
-            _BITBAKE_VARS[None] = _BITBAKE_VARS[image]
-
-    return _BITBAKE_VARS[image].get(var)
+    return BB_VARS.get_var(var, image)
 
 def parse_sourceparams(sourceparams):
     """