1	# files/disk: the real file system. Reads bytes and decodes them itself, as a
2	# chunk may end inside a UTF-8 char.
3	import Base
4	import ./service.bend as S
5	import ../frame.bend as Frame
6	import ../../walk/disk.bend as WalkDisk
7	
8	def slurp.end(file: File, acc: List<&2, U32>) -> IO(Maybe<&2, String>):
9	  do IO<Maybe<&2, String>>:
10	    File.close(file)
11	    return Some{Frame.decode(acc)}
12	
13	def slurp.cut(
14	  bytes: List<&2, U32>,
15	  file: File,
16	  acc: List<&2, U32>,
17	  rest: File -> List<&2, U32> -> IO(Maybe<&2, String>)
18	) -> IO(Maybe<&2, String>):
19	  match bytes:
20	    case Nil{}:
21	      slurp.end(file, acc)
22	    case Con{b, t}:
23	      rest(file, List.append(&2, U32, acc, b <> t))
24	
25	def slurp.more(
26	  rr: Result<&1, &1, U32 & String, List<&2, U32>>,
27	  file: File,
28	  acc: List<&2, U32>,
29	  rest: File -> List<&2, U32> -> IO(Maybe<&2, String>)
30	) -> IO(Maybe<&2, String>):
31	  match rr:
32	    case Fail{e}:
33	      slurp.end(file, acc)
34	    case Done{bytes}:
35	      slurp.cut(bytes, file, acc, rest)
36	
37	def slurp.next(
38	  got: File & Result<&1, &1, U32 & String, List<&2, U32>>,
39	  acc: List<&2, U32>,
40	  rest: File -> List<&2, U32> -> IO(Maybe<&2, String>)
41	) -> IO(Maybe<&2, String>):
42	  (file, r) = got
43	  slurp.more(r, file, acc, rest)
44	
45	# the whole file, read in chunks until one is empty, or the fuel is
46	def slurp(fuel: Nat, file: File, acc: List<&2, U32>) -> IO(Maybe<&2, String>):  # noqa: L001 disk effect
47	  match fuel:
48	    case 0n:
49	      slurp.end(file, acc)
50	    case 1n+f:
51	      do IO<Maybe<&2, String>>:
52	        got : File & Result<&1, &1, U32 & String, List<&2, U32>> <- File.read_bytes(file, 65536)
53	        slurp.next(got, acc, fl => a => slurp(f, fl, a))
54	
55	def read.opened(rr: Result<&1, &1, U32 & String, File>) -> IO(Maybe<&2, String>):
56	  match rr:
57	    case Fail{e}:
58	      IO.pure(Maybe<&2, String>, None{})
59	    case Done{file}:
60	      slurp(U32.to_nat(100000), file, [])
61	
62	# a file's text, or None when it cannot be opened
63	def read(path: String) -> IO(Maybe<&2, String>):  # noqa: L001 disk effect
64	  do IO<Maybe<&2, String>>:
65	    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")
66	    read.opened(r)
67	
68	def base_path.of(rr: Result<&1, &1, U32 & String, String>) -> IO(String):
69	  match rr:
70	    case Fail{e}:
71	      IO.pure(String, "")
72	    case Done{home}:
73	      IO.pure(String, home ++ "/.bend/current/bend2/base.bend")
74	
75	# Base, where bend's installer puts it
76	def base_path(_u: Unit) -> IO(String):  # noqa: L001 disk effect
77	  do IO<String>:
78	    r : Result<&1, &1, U32 & String, String> <- IO.get_env("HOME")
79	    base_path.of(r)
80	
81	# the working directory, as the lint's walk names it
82	def cwd(_u: Unit) -> IO(String):  # noqa: L001 disk effect
83	  WalkDisk.cwd()
84	
85	# the real file system
86	def new() -> S.Files:  # noqa: L001 effect record
87	  S.Files{read, base_path, cwd}