1	# no_unused/imports: an import that nothing in its file uses.
2	# Fix: deletes the import's line.
3	# Heuristics: a use is a name written through the import's alias, or, for Base, a name that only Base
4	# declares (Imported in lint.bend).
5	import Base
6	import bend-lint-api@0.2.2.0/linter/lint.bend as Lint
7	import bend-lint-api@0.2.2.0/shared/lists.bend as Lists
8	import bend-lint-api@0.2.2.0/shared/strings.bend as Strings
9	
10	# The fix that deletes the import's line.
11	def deleted(+text: String, path: String, at: U32) -> List<&2, Lint.Fix>:
12	  +beg = Strings.line_start(text, at)
13	  [
14	    Lint.Fix{
15	      "Remove the import",
16	      [Lint.Replace{Lint.Span{path, beg, Strings.line_end(text, beg)}, ""}]
17	    }
18	  ]
19	
20	def unused(text: String, d: Lint.Declaration) -> List<&2, Lint.Finding>:
21	  match d:
22	    case Lint.Declaration{
23	      Lint.Node{Lint.Import{t}, name, Some{Lint.Span{+path, +beg, end}}, k, f},
24	      Nil{}
25	    }:
26	      [
27	        Lint.Finding{
28	          Lint.Warning{},
29	          Lint.Span{path, beg, end},
30	          "Remove the import " ++ name ++ ": nothing uses it.",
31	          deleted(text, path, beg)
32	        }
33	      ]
34	    case _:
35	      []
36	
37	def findings(
38	  declarations: List<&2, Lint.Declaration>,
39	  +text: String,
40	  out: List<&2, Lint.Finding>
41	) -> List<&2, Lint.Finding>:
42	  match declarations:
43	    case Nil{}:
44	      List.reverse(&2, Lint.Finding, out)
45	    case Con{d, rest}:
46	      findings(rest, text, Lists.onto(&2, Lint.Finding, unused(text, d), out))
47	
48	def run(+here: Lint.Here) -> Lint.Ask(List<&2, Lint.Finding>):
49	  Lint.done(findings(Lint.Here.declarations(here), Lint.Here.text(here), []))
50	
51	def rule() -> Lint.Rule:
52	  Lint.Rule{Lint.Needs{False{}, True{}}, [], Lint.OnFile{run}}