factoring of some ZAM header files for better modularity

src/script_opt/ZAM/Frame.h

@@ -0,0 +1,43 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+// Management of the ZAM frame used to hold low-level local variables.
+
+#pragma once
+
+namespace zeek::detail {
+
+using AttributesPtr = IntrusivePtr<Attributes>;
+
+// Maps ZAM frame slots to associated identifiers. These are the simplest
+// types of frames, where each identifier has its own slot.
+using FrameMap = std::vector<const ID*>;
+
+// Maps ZAM frame slots to information for sharing the slot across
+// multiple script variables.
+class FrameSharingInfo {
+public:
+    // The variables sharing the slot.  ID's need to be non-const so we
+    // can manipulate them, for example by changing their interpreter
+    // frame offset.
+    std::vector<const ID*> ids;
+
+    // A parallel vector, only used for fully compiled code, which
+    // gives the names of the identifiers.  When in use, the above
+    // "ids" member variable may be empty.
+    std::vector<const char*> names;
+
+    // The ZAM instruction number where a given identifier starts its
+    // scope, parallel to "ids".
+    std::vector<zeek_uint_t> id_start;
+
+    // The current end of the frame slot's scope.  Gets updated as
+    // new IDs are added to share the slot.
+    int scope_end = -1;
+
+    // Whether this is a managed slot.
+    bool is_managed = false;
+};
+
+using FrameReMap = std::vector<FrameSharingInfo>;
+
+} // namespace zeek::detail