Overlay.qll: Streamline discardable entities into one Discardable superclass

Author: d10c

python/ql/lib/semmle/python/Overlay.qll

@@ -14,30 +14,71 @@ overlay[local]
 predicateisOverlay(){databaseMetadata("isOverlay","true")}
 
 overlay[local]
-privatestringgetRawPathForLocation(@location loc){
+privatestringgetPathForLocation(@location loc){
 exists(@file file|locations_default(loc,file, _, _, _, _)|files(file,result))
 or
-exists(@py_Module mod|locations_ast(loc,mod, _, _, _, _)|result=getRawPathForModule(mod))
+exists(@py_Module mod|locations_ast(loc,mod, _, _, _, _)|result=getPathForModule(mod))
 }
 
 overlay[local]
-privatestringgetRawPathForModule(@py_Module mod){
+privatestringgetPathForModule(@py_Module mod){
 exists(@container fileOrFolder|py_module_path(mod,fileOrFolder)|
-result=getRawPathForContainer(fileOrFolder)
+result=getPathForContainer(fileOrFolder)
 )
 }
 
 overlay[local]
-privatestringgetRawPathForContainer(@container fileOrFolder){
+privatestringgetPathForContainer(@container fileOrFolder){
 files(fileOrFolder,result)orfolders(fileOrFolder,result)
 }
 
-/*- Source elements -*/
+/*- Discardable entities and their discard predicates -*/
+overlay[local]
+privateclassDiscardable_= @py_source_element or @py_flow_node or @py_base_var or @location;
+
+overlay[discard_entity]
+privatepredicatediscardEntity(@py_source_element el){
+// Within `@py_source_element`, only `@py_Module` and `@container`
+// use named IDs; the rest use *-ids.
+exists(Discardabled|d=el|
+overlayChangedFiles(d.getPath())and
+d.existsInBase()and
+notd.existsInOverlay()
+)
+}
+
+overlay[discard_entity]
+privatepredicatediscardCfgNode(@py_flow_node n){
+// `@py_flow_node`s use *-ids, so cannot exist both in base and overlay.
+exists(Discardabled|d=n|
+overlayChangedFiles(d.getPath())and
+d.existsInBase()
+)
+}
+
+overlay[discard_entity]
+privatepredicatediscardVar(@py_base_var n){
+// `@py_base_var`s use *-ids, so cannot exist both in base and overlay.
+exists(Discardabled|d=n|
+overlayChangedFiles(d.getPath())and
+d.existsInBase()
+)
+}
+
+overlay[discard_entity]
+privatepredicatediscardLocation(@location loc){
+// Locations use *-ids, so cannot exist both in base and overlay.
+exists(Discardabled|d=loc|
+overlayChangedFiles(d.getPath())and
+d.existsInBase()
+)
+}
+
 /**
  * An abstract base class for all elements that can be discarded from the base.
  */
 overlay[local]
-abstractprivateclassDiscardableextends@py_source_element{
+abstractprivateclassDiscardableextendsDiscardable_{
 /** Gets the path to the file in which this element occurs. */
 abstractstringgetPath();
 
@@ -51,98 +92,51 @@ abstract private class Discardable extends @py_source_element{
 stringtoString(){none()}
 }
 
-overlay[discard_entity]
-privatepredicatediscardEntity(@py_source_element el){
-exists(Discardabled|d=el|
-overlayChangedFiles(d.getPath())and
-d.existsInBase()and
-notd.existsInOverlay()
-)
-}
-
 /**
- * Discard all locatable AST nodes (`@py_location_parent`) in modified files
- * since they use *-ids and hence cannot be referenced across TRAP files.
+ * Discardable locatable AST nodes (`@py_location_parent`).
  */
 overlay[local]
 finalprivateclassDiscardableLocatableextendsDiscardableinstanceof @py_location_parent {
 overridestringgetPath(){
-exists(@location loc|py_locations(loc,this)|result=getRawPathForLocation(loc))
+exists(@location loc|py_locations(loc,this)|result=getPathForLocation(loc))
 }
 }
 
 /**
- * Discard scopes (classes, functions, modules) that were deleted in the overlay.
+ * Discardable scopes (classes, functions, modules).
  */
 overlay[local]
 finalprivateclassDiscardableScopeextendsDiscardableinstanceof @py_scope {
 overridestringgetPath(){
-exists(@location loc|py_scope_location(loc,this)|result=getRawPathForLocation(loc))
+exists(@location loc|py_scope_location(loc,this)|result=getPathForLocation(loc))
 or
-result=getRawPathForModule(this)
+result=getPathForModule(this)
 }
 }
 
 /**
- * Discard files and folders that were deleted in the overlay.
+ * Discardable files and folders.
  */
 overlay[local]
 finalprivateclassDiscardableContainerextendsDiscardableinstanceof @container {
-overridestringgetPath(){result=getRawPathForContainer(this)}
+overridestringgetPath(){result=getPathForContainer(this)}
 }
 
-/*- CFG Nodes -*/
 /** Discardable control flow nodes */
 overlay[local]
-finalprivateclassDiscardableCfgNodeinstanceof @py_flow_node {
-stringgetPath(){
+finalprivateclassDiscardableCfgNodeextendsDiscardableinstanceof @py_flow_node {
+overridestringgetPath(){
 exists(Discardabled|result=d.getPath()|
 py_flow_bb_node(this,d.(@py_ast_node), _, _)
 or
 py_scope_flow(this,d.(@py_scope), _)
 )
 }
-
-predicateexistsInBase(){notisOverlay()andexists(this)}
-
-predicateexistsInOverlay(){isOverlay()andexists(this)}
-
-stringtoString(){none()}
-}
-
-overlay[discard_entity]
-privatepredicatediscardCfgNode(@py_flow_node n){
-exists(DiscardableCfgNoded|d=n|
-overlayChangedFiles(d.getPath())and
-d.existsInBase()and
-notd.existsInOverlay()
-)
-}
-
-/*- Variables -*/
-/** Discardable (normal and SSA) variables */
-overlay[local]
-abstractprivateclassDiscardableBaseVarinstanceof @py_base_var {
-abstractstringgetPath();
-
-predicateexistsInBase(){notisOverlay()andexists(this)}
-
-predicateexistsInOverlay(){isOverlay()andexists(this)}
-
-stringtoString(){none()}
-}
-
-overlay[discard_entity]
-privatepredicatediscardVar(@py_base_var n){
-exists(DiscardableVard|d=n|
-overlayChangedFiles(d.getPath())and
-d.existsInBase()and
-notd.existsInOverlay()
-)
 }
 
+/** Discardable Python variables. */
 overlay[local]
-finalprivateclassDiscardableVarextendsDiscardableBaseVarinstanceof @py_variable {
+finalprivateclassDiscardableVarextendsDiscardableinstanceof @py_variable {
 overridestringgetPath(){
 exists(Discardableparent|result=parent.getPath()|
 variable(this,parent.(@py_scope), _)
@@ -152,8 +146,9 @@ final private class DiscardableVar extends DiscardableBaseVar instanceof @py_var
 }
 }
 
+/** Discardable SSA variables. */
 overlay[local]
-finalprivateclassDiscardableSsaVarextendsDiscardableBaseVarinstanceof @py_ssa_var {
+finalprivateclassDiscardableSsaVarextendsDiscardableinstanceof @py_ssa_var {
 overridestringgetPath(){
 exists(DiscardableSsaVarother|result=other.getPath()|
 py_ssa_phi(this,other.(@py_ssa_var))
@@ -169,18 +164,10 @@ final private class DiscardableSsaVar extends DiscardableBaseVar instanceof @py_
 }
 }
 
-/*- Locations -*/
+/** Discardable locations. */
 overlay[local]
-privatepredicatelocationExistsInBase(@location loc){notisOverlay()andexists(loc)}
-
-overlay[local]
-privatepredicatelocationExistsInOverlay(@location loc){isOverlay()andexists(loc)}
-
-overlay[discard_entity]
-privatepredicatediscardLocation(@location loc){
-overlayChangedFiles(getRawPathForLocation(loc))and
-locationExistsInBase(loc)and
-notlocationExistsInOverlay(loc)
+finalprivateclassDiscardableLocationextendsDiscardableinstanceof @location {
+overridestringgetPath(){result=getPathForLocation(this)}
 }
 
 /*- XML -*/