1	# ez/start: what `ez check`, `ez build` and `ez run` start, decided from the
2	# ledger they read and the words they were given. Each starts one bend on
3	# the entry the ledger names, or refuses and starts nothing when there is no
4	# ez.toml or it does not parse, as cargo refuses a directory with no
5	# Cargo.toml. The interpreter (`ez/cmd.bend`) reads ez.toml, puts the
6	# project's BEND_LIB in front of the line (`Env.line`), runs it and exits;
7	# that it does so faithfully is EZ-TRUST-2.
8	import Base
9	import ../ledger/manifest.bend as M
10	import ../share/args.bend as Args
11	
12	# which of the three commands is asking, with what it was told: where a
13	# build goes, and every word of the line for a run
14	type Ask is Data:
15	  Check{}
16	  Build{out: String}
17	  Run{as: List<&2, String>}
18	
19	# what a command does: refuse with a reason, having started nothing, or start
20	# bend with this line
21	type Start is Data:
22	  Refused{why: String}
23	  Starts{line: List<&2, String>}
24	
25	# what each command is for, in the words a refusal says it with
26	def does(ask: Ask) -> String:
27	  match ask:
28	    case Check{}:
29	      "ez check checks a project's entry"
30	    case Build{_out}:
31	      "ez build builds a project's entry"
32	    case Run{_as}:
33	      "ez run runs a project's entry"
34	
35	# why a directory with no ez.toml is refused
36	def none(ask: Ask) -> String:
37	  "ez: no ez.toml here; " ++ does(ask) ++ ", and ez init makes one"
38	
39	# the entry file a ledger names, or "main.bend" when it names none
40	def entry.or(+file: String) -> String:
41	  Bool.pick(String, String.is_empty(file), "main.bend", file)
42	
43	# the entry file of a ledger that parsed
44	def entry(ledger: M.Manifest) -> String:
45	  M.Manifest{_n, e, _b, _h, _pa, _pv, _ds, _ts} = ledger
46	  entry.or(e)
47	
48	# the name a ledger that parsed gives the package
49	def named(ledger: M.Manifest) -> String:
50	  M.Manifest{n, _e, _b, _h, _pa, _pv, _ds, _ts} = ledger
51	  n
52	
53	# where a build lands when nothing said: `bin/<package name>.out`. The name
54	# and not the entry file, because the entry is where a program starts and the
55	# name is what it is called: a package named `bolt` with its entry at
56	# `bolt/main.bend` builds `bin/bolt.out` and not `bin/main.out`.
57	def build.named(+name: String) -> String:
58	  "bin/" ++ name ++ ".out"
59	
60	# where a build lands: what was asked for, or the default
61	def build.out(+at: String, +name: String) -> String:
62	  Bool.pick(String, String.is_empty(at), build.named(name), at)
63	
64	# the line each command starts bend with, over a ledger that parsed: the
65	# entry checked into `.ez/check.js` and never run, built to a native binary,
66	# or run with every word after `run` (EZ-TOOL-9)
67	def line(ask: Ask, +ledger: M.Manifest) -> List<&2, String>:
68	  match ask:
69	    case Check{}:
70	      ["bend", entry(ledger), "-o", ".ez/check.js"]
71	    case Build{+out}:
72	      ["bend", entry(ledger), "-o", build.out(out, named(ledger))]
73	    case Run{as}:
74	      Args.run.line(entry(ledger), as)
75	
76	# what a command does with the ledger it read
77	def read(+ask: Ask, ledger: M.Read) -> Start:
78	  match ledger:
79	    case M.Bad{why}:
80	      Refused{"ez: " ++ M.show(M.Bad{why})}
81	    case M.Good{+m}:
82	      Starts{line(ask, m)}
83	
84	# what a command does with ez.toml's text, None when there is none
85	def start(+ask: Ask, text: Maybe<&2, String>) -> Start:
86	  match text:
87	    case None{}:
88	      Refused{none(ask)}
89	    case Some{t}:
90	      read(ask, M.parse(t))
91	
92	# the status `ez run` exits with, given the status of the program it started
93	# (EZ-OUT-1): 1 for a refusal, which started none, and the program's own
94	# status otherwise, as `cargo run` exits. `ez check` and `ez build` end on
95	# what bend printed instead (`ez/ends.bend`).
96	def code(start: Start, program: U32) -> U32:
97	  match start:
98	    case Refused{_why}:
99	      1
100	    case Starts{_line}:
101	      program
102	
103	# why a command refused, or "" when it started bend
104	def why(start: Start) -> String:
105	  match start:
106	    case Refused{w}:
107	      w
108	    case Starts{_line}:
109	      ""