BaseTools:Fix GenFds issue for BuildOption replace GenFdsOption

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2455

BuildOption is used by TargetTxtClassObj.py
GenFdsOption is used by GenFds.py
When the GenFds tool is used alone (e.g. python3 -m GenFds.GenFds -h)
With the OptionParser function, the first detected function
prints the help message

import TargetTxtClassObj to GenFds,
The BuildOption will be executed and replace GenFdsOption

We removed all objects associated with this problem that
were created directly during the import process
(e.g. BuildOption, BuildTarget = MyOptionParser(),
 TargetTxt = TargetTxtDict())

The Patch is going to fix this issue

Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/AutoGen/BuildEngine.py

@@ -20,7 +20,7 @@ from Common.BuildToolError import *
 from Common.Misc import tdict, PathClass
 from Common.StringUtils import NormPath
 from Common.DataType import *
-from Common.TargetTxtClassObject import TargetTxt
+from Common.TargetTxtClassObject import TargetTxtDict
 gDefaultBuildRuleFile = 'build_rule.txt'
 AutoGenReqBuildRuleVerNum = '0.1'
 
@@ -588,24 +588,42 @@ class BuildRule:
         _UnknownSection    : SkipSection,
     }
 
-def GetBuildRule():
-    BuildRuleFile = None
-    if TAB_TAT_DEFINES_BUILD_RULE_CONF in TargetTxt.TargetTxtDictionary:
-        BuildRuleFile = TargetTxt.TargetTxtDictionary[TAB_TAT_DEFINES_BUILD_RULE_CONF]
-    if not BuildRuleFile:
-        BuildRuleFile = gDefaultBuildRuleFile
-    RetVal = BuildRule(BuildRuleFile)
-    if RetVal._FileVersion == "":
-        RetVal._FileVersion = AutoGenReqBuildRuleVerNum
-    else:
-        if RetVal._FileVersion < AutoGenReqBuildRuleVerNum :
-            # If Build Rule's version is less than the version number required by the tools, halting the build.
-            EdkLogger.error("build", AUTOGEN_ERROR,
-                            ExtraData="The version number [%s] of build_rule.txt is less than the version number required by the AutoGen.(the minimum required version number is [%s])"\
-                             % (RetVal._FileVersion, AutoGenReqBuildRuleVerNum))
-    return RetVal
+class ToolBuildRule():
 
-BuildRuleObj = GetBuildRule()
+    def __new__(cls, *args, **kw):
+        if not hasattr(cls, '_instance'):
+            orig = super(ToolBuildRule, cls)
+            cls._instance = orig.__new__(cls, *args, **kw)
+        return cls._instance
+
+    def __init__(self):
+        if not hasattr(self, 'ToolBuildRule'):
+            self._ToolBuildRule = None
+
+    @property
+    def ToolBuildRule(self):
+        if not self._ToolBuildRule:
+            self._GetBuildRule()
+        return self._ToolBuildRule
+
+    def _GetBuildRule(self):
+        BuildRuleFile = None
+        TargetObj = TargetTxtDict()
+        TargetTxt = TargetObj.Target
+        if TAB_TAT_DEFINES_BUILD_RULE_CONF in TargetTxt.TargetTxtDictionary:
+            BuildRuleFile = TargetTxt.TargetTxtDictionary[TAB_TAT_DEFINES_BUILD_RULE_CONF]
+        if not BuildRuleFile:
+            BuildRuleFile = gDefaultBuildRuleFile
+        RetVal = BuildRule(BuildRuleFile)
+        if RetVal._FileVersion == "":
+            RetVal._FileVersion = AutoGenReqBuildRuleVerNum
+        else:
+            if RetVal._FileVersion < AutoGenReqBuildRuleVerNum :
+                # If Build Rule's version is less than the version number required by the tools, halting the build.
+                EdkLogger.error("build", AUTOGEN_ERROR,
+                                ExtraData="The version number [%s] of build_rule.txt is less than the version number required by the AutoGen.(the minimum required version number is [%s])"\
+                                 % (RetVal._FileVersion, AutoGenReqBuildRuleVerNum))
+        self._ToolBuildRule = RetVal
 
 # This acts like the main() function for the script, unless it is 'import'ed into another
 # script.