Make generate.py a bit smarter about determining the ZCL definition file.

If the ZCL definition file is not specified, it tries to look in the ZAP file
provided, but falls back to our in-tree zcl.json if the ZAP file has nothing
specified.

This change just uses the fallback if neither the ZCL definition file _nor_ the
ZAP file are specified, which allows simpler codegen command lines for
client-side things that don't have a specific ZAP file attached to them.

Author: bzbarsky-apple

scripts/tools/zap/generate.py

@@ -90,20 +90,21 @@ def detectZclFile(zapFile):
     prefix_chip_root_dir = True
     path = 'src/app/zap-templates/zcl/zcl.json'
 
-    data = json.load(open(zapFile))
-    for package in data["package"]:
-        if package["type"] != "zcl-properties":
-            continue
-
-        prefix_chip_root_dir = (package["pathRelativity"] != "resolveEnvVars")
-        # found the right path, try to figure out the actual path
-        if package["pathRelativity"] == "relativeToZap":
-            path = os.path.abspath(os.path.join(
-                os.path.dirname(zapFile), package["path"]))
-        elif package["pathRelativity"] == "resolveEnvVars":
-            path = os.path.expandvars(package["path"])
-        else:
-            path = package["path"]
+    if zapFile:
+        data = json.load(open(zapFile))
+        for package in data["package"]:
+            if package["type"] != "zcl-properties":
+                continue
+
+            prefix_chip_root_dir = (package["pathRelativity"] != "resolveEnvVars")
+            # found the right path, try to figure out the actual path
+            if package["pathRelativity"] == "relativeToZap":
+                path = os.path.abspath(os.path.join(
+                    os.path.dirname(zapFile), package["path"]))
+            elif package["pathRelativity"] == "resolveEnvVars":
+                path = os.path.expandvars(package["path"])
+            else:
+                path = package["path"]
 
     return getFilePath(path, prefix_chip_root_dir)