1	import Base
2	
3	# Quote-aware scanning of a line (spec appendix B.3): where the first unquoted
4	# colon or delimiter is, and how to cut a row on its delimiter.
5	
6	# Scanner state: 0 outside quotes, 1 inside, 2 inside after a backslash.
7	def sel.u(+b: Bool, +x: U32, +y: U32) -> U32:
8	  match b:
9	    case True{}:
10	      x
11	    case False{}:
12	      y
13	
14	def qnext.pick(+st: U32, +quote: Bool, +bslash: Bool) -> U32:
15	  sel.u(U32.is_eq(st, 0), sel.u(quote, 1, 0),
16	  sel.u(U32.is_eq(st, 1), sel.u(bslash, 2, sel.u(quote, 0, 1)), 1))
17	
18	def qnext(+st: U32, +c: U32) -> U32:
19	  qnext.pick(st, U32.is_eq(c, 34), U32.is_eq(c, 92))
20	
21	# Sentinel index for "not found".
22	def none() -> U32:
23	  4294967295
24	
25	def found(+hit: Bool, +i: U32, +later: U32) -> U32:
26	  sel.u(hit, i, later)
27	
28	# Index of the first `target` outside quotes, or `none()`.
29	def find_unq(+s: String, +target: U32, +st: U32, +i: U32) -> U32:
30	  match s:
31	    case SNil{}:
32	      none()
33	    case SCon{Chr{c}, t}:
34	      found(U32.is_eq(st, 0) && U32.is_eq(c, target), i, find_unq(t, target, qnext(st, c), (i + 1 : U32)))
35	
36	# Put a character in front of the token being built, or start a new token.
37	def split.put(+c: U32, +sep: Bool, +r: List<&2, String>) -> List<&2, String>:
38	  match sep:
39	    case True{}:
40	      Con{SNil{}, r}
41	    case False{}:
42	      match r:
43	        case Con{h, rest}:
44	          Con{SCon{Chr{c}, h}, rest}
45	        case Nil{}:
46	          Nil{}
47	
48	def split.go(+s: String, +d: U32, +st: U32) -> List<&2, String>:
49	  match s:
50	    case SNil{}:
51	      Con{SNil{}, Nil{}}
52	    case SCon{Chr{c}, t}:
53	      split.put(c, U32.is_eq(st, 0) && U32.is_eq(c, d), split.go(t, d, qnext(st, c)))
54	
55	# Cut on the delimiter `d` outside quotes. Always at least one token.
56	def split(+s: String, +d: U32) -> List<&2, String>:
57	  split.go(s, d, 0)
58	
59	# Index of the first `target`, ignoring quotes, or `none()`.
60	def find(+s: String, +target: U32, +i: U32) -> U32:
61	  match s:
62	    case SNil{}:
63	      none()
64	    case SCon{Chr{c}, t}:
65	      found(U32.is_eq(c, target), i, find(t, target, (i + 1 : U32)))