Swift SIL: add Type.getIndexOfEnumCase(withName:)

... to get the enum case index with a given name.

Author: eeckstein

SwiftCompilerSources/Sources/SIL/Type.swift

@@ -42,7 +42,14 @@ public struct Type : CustomStringConvertible, CustomReflectable {
   public func getNominalFields(in function: Function) -> NominalFieldsArray {
     NominalFieldsArray(type: self, function: function)
   }
-  
+
+  public func getIndexOfEnumCase(withName name: String) -> Int? {
+    let idx = name.withBridgedStringRef {
+      SILType_getCaseIdxOfEnumType(bridged, $0)
+    }
+    return idx >= 0 ? idx : nil
+  }
+
   public var description: String { SILType_debugDescription(bridged).takeString() }
 
   public var customMirror: Mirror { Mirror(self, children: []) }

include/swift/SIL/SILBridging.h

@@ -252,6 +252,8 @@ BridgedType SILType_getNominalFieldType(BridgedType type, SwiftInt index,
                                         BridgedFunction function);
 SwiftInt SILType_getFieldIdxOfNominalType(BridgedType type,
                                           BridgedStringRef fieldName);
+SwiftInt SILType_getCaseIdxOfEnumType(BridgedType type,
+                                      BridgedStringRef caseName);
 
 BridgedSubstitutionMap SubstitutionMap_getEmpty();
 

lib/SIL/Utils/SILBridging.cpp

@@ -489,6 +489,23 @@ SwiftInt SILType_getFieldIdxOfNominalType(BridgedType type,
   return -1;
 }
 
+SwiftInt SILType_getCaseIdxOfEnumType(BridgedType type,
+                                      BridgedStringRef caseName) {
+  SILType ty = castToSILType(type);
+  auto *enumDecl = ty.getEnumOrBoundGenericEnum();
+  if (!enumDecl)
+    return -1;
+
+  SwiftInt idx = 0;
+  for (EnumElementDecl *elem : enumDecl->getAllElements()) {
+    if (elem->getNameStr() == getStringRef(caseName))
+      return idx;
+    idx++;
+  }
+  return -1;
+}
+
+
 //===----------------------------------------------------------------------===//
 //                            SubstitutionMap
 //===----------------------------------------------------------------------===//