syntax/word.bend source

syntax/word.bend on the hub · documented module

# syntax/word: the name under a (line, col), both 0-based. A name is letters,# digits, `_` and `.` (dots are just characters in a Bend name, and a module# alias rides in front: `Frame.decode`). A position right after a name counts# as on it, as editors put the cursor there.import Baseimport ../lazy/lazy.bend as Lazy# i: the column of the next char; start: where the current run began; run: the# current name, reversed; hit: the name foundtype W is Data:  W{i: U32, start: U32, run: List<&2, Char>, hit: Maybe<&2, String>}# a char a name may hold: letters, digits, `_` and `.`def is_name(+c: Char) -> Bool:  Bool.or(Bool.or(Char.is_alpha(c), Char.is_digit(c)), Bool.or(Char.is_eq(c, '_'), Char.is_eq(c, '.')))# the run's chars (reversed) as a stringdef text(run: List<&2, Char>) -> String:  String.from_list(List.reverse(&2, Char, run))# a run that ends at column i holds col when start <= col <= idef close(+i: U32, +start: U32, +run: List<&2, Char>, +hit: Maybe<&2, String>, +col: U32) -> Maybe<&2, String>:  Bool.pick(Maybe<&2, String>,    Bool.and(Bool.and(Maybe.is_none(&2, String, hit), Bool.not(List.is_empty(&2, Char, run))),      Bool.and(U32.is_le(start, col), U32.is_le(col, i))),    Some{text(run)}, hit)# one char: it extends the run of name chars, or ends it (a run holding the# column is the answer)def step(+c: Char, st: W, +col: U32) -> W:  W{+i, +start, +run, +hit} = st  Bool.pick(W, is_name(c),    W{(i + 1 : U32), start, c <> run, hit},    W{(i + 1 : U32), (i + 1 : U32), [], close(i, start, run, hit, col)})# every char, in orderdef scan(cs: List<&2, Char>, st: W, +col: U32) -> W:  match cs:    case Nil{}:      st    case Con{c, t}:      scan(t, step(c, st, col), col)# the run that held the column, else ""def finish(st: W, col: U32) -> String:  W{i, start, run, hit} = st  Maybe.default(&2, String, close(i, start, run, hit, col), "")# the name at a column of a linedef in_line(line: String, +col: U32) -> String:  finish(scan(String.to_list(line), W{0, 0, [], None{}}, col), col)# the name under a (line, col) of a source, "" when nonedef at(source: String, line: U32, col: U32) -> String:  in_line(Maybe.default(&2, String, List.get(&2, String, String.lines(source), U32.to_nat(line)), ""), col)# `Alias.rest` cut at its first dot: ("Alias", "rest"); no dot: (name, "")def cut.go(cs: List<&2, Char>, acc: List<&2, Char>) -> String & String:  match cs:    case Nil{}:      (text(acc), "")    case Con{'.', t}:      (text(acc), String.from_list(t))    case Con{c, t}:      cut.go(t, c <> acc)# `Alias.rest` cut at its first dot: ("Alias", "rest"); no dot: (name, "")def cut(name: String) -> String & String:  cut.go(String.to_list(name), [])# a pair's firstdef fst(p: String & String) -> String:  (h, r) = p  h# a pair's seconddef snd(p: String & String) -> String:  (h, r) = p  r# the part before the first dotdef head(name: String) -> String:  fst(cut(name))# the part after the first dot, "" when there is nonedef rest(name: String) -> String:  snd(cut(name))# the leading run of name charsdef run_of(cs: List<&2, Char>) -> List<&2, Char>:  match cs:    case Nil{}:      Nil{}    case Con{+c, t}:      Lazy.stop(List<&2, Char>, Bool.not(is_name(c)), Nil{}, _u => c <> run_of(t))# the name that ends at (line, col): what is being typed, for completiondef before(source: String, line: U32, col: U32) -> String:  text(run_of(List.reverse(&2, Char, String.to_list(String.take(    Maybe.default(&2, String, List.get(&2, String, String.lines(source), U32.to_nat(line)), ""),    U32.to_nat(col))))))