1	import Base
2	
3	# Logical keys and the physical MyLSM key layout. All keys are ASCII with
4	# "/" separators so prefix scan stays possible at the storage layer.
5	type LogicalKey is Data:
6	  Make{namespace_name: String, record_identifier: String}
7	
8	# Renders a key as "namespace/record".
9	def encode_logical_key(logical_key: LogicalKey) -> String:
10	  match logical_key:
11	    case Make{namespace_name, record_identifier}:
12	      namespace_name ++ "/" ++ record_identifier
13	
14	# Addresses a content-addressed object by its hash.
15	def build_object_storage_key(content_hash: String) -> String:
16	  "object/" ++ content_hash
17	
18	# Addresses a persisted state tree by its hash.
19	def build_tree_storage_key(tree_hash_value: String) -> String:
20	  "tree/" ++ tree_hash_value
21	
22	# Addresses a persisted commit by its identifier.
23	def build_commit_storage_key(commit_identifier: String) -> String:
24	  "commit/" ++ commit_identifier
25	
26	# Addresses one versioned index entry: value hash or TOMBSTONE.
27	def build_index_storage_key(namespace_name: String, record_identifier: String, commit_identifier: String) -> String:
28	  "index/" ++ namespace_name ++ "/" ++ record_identifier ++ "/" ++ commit_identifier
29	
30	# Addresses one uncommitted staged value.
31	def build_stage_storage_key(session_identifier: String, namespace_name: String, record_identifier: String) -> String:
32	  "stage/" ++ session_identifier ++ "/" ++ namespace_name ++ "/" ++ record_identifier
33	
34	# Same version-index layout for callers holding "namespace/record" as one string.
35	def build_version_index_key(combined_key: String, commit_identifier: String) -> String:
36	  "index/" ++ combined_key ++ "/" ++ commit_identifier
37	
38	# Same stage layout for callers holding "namespace/record" as one string.
39	def build_stage_storage_key_combined(session_identifier: String, combined_key: String) -> String:
40	  "stage/" ++ session_identifier ++ "/" ++ combined_key
41	
42	# Scans for the first "/"; the head match is on a pattern-bound variable.
43	def split_scan(remaining_text: String, namespace_accum: String) -> LogicalKey:
44	  match remaining_text:
45	    case SNil{}:
46	      Make{namespace_accum, ""}
47	    case SCon{head_char, remaining_chars}:
48	      match head_char:
49	        case '/':
50	          Make{namespace_accum, remaining_chars}
51	        case _:
52	          split_scan(remaining_chars, String.append(namespace_accum, SCon{head_char, SNil{}}))
53	
54	# Inverse of encode_logical_key: splits at the FIRST "/".
55	def split_combined_key(combined_key: String) -> LogicalKey:
56	  split_scan(combined_key, "")