path: root/js/games/nluqo.github.io/~bh/v2ch7/match.lg

to match :pat :sen
local [special.var special.pred special.buffer in.list]
if or wordp :pat wordp :sen [output "false]
if emptyp :pat [output emptyp :sen]
if listp first :pat [output special fput "!: :pat :sen]
if memberp first first :pat [? # ! & @ ^] [output special :pat :sen]
if emptyp :sen [output "false]
if equalp first :pat first :sen ~
   [output match butfirst :pat butfirst :sen]
output "false
end

;; Parsing quantifiers

to special :pat :sen
set.special parse.special butfirst first :pat "
output run word "match first first :pat
end

to parse.special :word :var
if emptyp :word [output list :var "always]
if equalp first :word ": [output list :var butfirst :word]
output parse.special butfirst :word word :var first :word
end

to set.special :list
make "special.var first :list
make "special.pred last :list
if emptyp :special.var [make "special.var "special.buffer]
if memberp :special.pred [in anyof] [set.in]
if not emptyp :special.pred [stop]
make "special.pred first butfirst :pat
make "pat fput first :pat butfirst butfirst :pat
end

to set.in
make "in.list first butfirst :pat
make "pat fput first :pat butfirst butfirst :pat
end

;; Exactly one match

to match!
if emptyp :sen [output "false]
if not try.pred [output "false]
make :special.var first :sen
output match butfirst :pat butfirst :sen
end

;; Zero or one match

to match?
make :special.var []
if emptyp :sen [output match butfirst :pat :sen]
if not try.pred [output match butfirst :pat :sen]
make :special.var first :sen
if match butfirst :pat butfirst :sen [output "true]
make :special.var []
output match butfirst :pat :sen
end

;; Zero or more matches

to match#
make :special.var []
output #test #gather :sen
end

to #gather :sen
if emptyp :sen [output :sen]
if not try.pred [output :sen]
make :special.var lput first :sen thing :special.var
output #gather butfirst :sen
end

to #test :sen
if match butfirst :pat :sen [output "true]
if emptyp thing :special.var [output "false]
output #test2 fput last thing :special.var :sen
end

to #test2 :sen
make :special.var butlast thing :special.var
output #test :sen
end

;; One or more matches

to match&
output &test match#
end

to &test :tf
if emptyp thing :special.var [output "false]
output :tf
end

;; Zero or more matches (as few as possible)

to match^
make :special.var []
output ^test :sen
end

to ^test :sen
if match butfirst :pat :sen [output "true]
if emptyp :sen [output "false]
if not try.pred [output "false]
make :special.var lput first :sen thing :special.var
output ^test butfirst :sen
end

;; Match words in a group

to match@
make :special.var :sen
output @test []
end

to @test :sen
if @try.pred [if match butfirst :pat :sen [output "true]]
if emptyp thing :special.var [output "false]
output @test2 fput last thing :special.var :sen
end

to @test2 :sen
make :special.var butlast thing :special.var
output @test :sen
end

;; Applying the predicates

to try.pred
if listp :special.pred [output match :special.pred first :sen]
output run list :special.pred quoted first :sen
end

to quoted :thing
if listp :thing [output :thing]
output word "" :thing
end

to @try.pred
if listp :special.pred [output match :special.pred thing :special.var]
output run list :special.pred thing :special.var
end

;; Special predicates

to always :x
output "true
end

to in :word
output memberp :word :in.list
end

to anyof :sen
output anyof1 :sen :in.list
end

to anyof1 :sen :pats
if emptyp :pats [output "false]
if match first :pats :sen [output "true]
output anyof1 :sen butfirst :pats
end