src/file.bend source

src/file.bend on the hub · documented module

# src/file: a file's text, read whole, or None when it cannot be opened.import Base# the handle closed, and whatever was gathereddef file.slurp.end(file: File, acc: String) -> IO(String):  do IO<String>:    File.close(file)    return acc# an empty chunk means the end of the filedef file.slurp.cut(chunk: String, file: File, acc: String, rest: File -> String -> IO(String)) -> IO(String):  match chunk:    case SNil{}:      file.slurp.end(file, acc)    case SCon{c, t}:      rest(file, acc ++ SCon{c, t})# a failed read ends the file as surely as an empty onedef file.slurp.more(  res: Result<&1, &1, U32 & String, String>,  file: File,  acc: String,  rest: File -> String -> IO(String)) -> IO(String):  match res:    case Fail{_e}:      file.slurp.end(file, acc)    case Done{chunk}:      file.slurp.cut(chunk, file, acc, rest)# the handle comes back paired with what it readdef file.slurp.next(  got: File & Result<&1, &1, U32 & String, String>,  acc: String,  rest: File -> String -> IO(String)) -> IO(String):  (file, res) = got  file.slurp.more(res, file, acc, rest)# the whole file, read in chunks until one is empty, or the fuel isdef file.slurp(fuel: Nat, file: File, acc: String) -> IO(String):  match fuel:    case 0n:      file.slurp.end(file, acc)    case 1n+f:      do IO<String>:        got : File & Result<&1, &1, U32 & String, String> <- File.read(file, 65536)        file.slurp.next(got, acc, fl => a => file.slurp(f, fl, a))# the reads a file with no size to go by may take: a pipe, a device or a# /proc file reports 0 bytes and a file past 4 GiB fails to report, so these# are read until they end, up to 100000 reads of 64 KiBdef file.unsized() -> Nat:  U32.to_nat(100000)# a size of 0 is no size to go by; any other is read todef file.reads.given(none: Bool, bytes: U32) -> Nat:  match none:    case True{}:      file.unsized()    case False{}:      U32.to_nat(U32.add(U32.div(bytes, 65536), 2))# the reads a file of this many bytes takes: one for every 64 KiB, one for# the part past the last whole 64 KiB, and one to spare for a short readdef file.reads(+bytes: U32) -> Nat:  file.reads.given(U32.is_zero(bytes), bytes)# the reads the size the host reported allowsdef file.reads.of(res: Result<&1, &1, U32 & String, U32>) -> Nat:  match res:    case Fail{_e}:      file.unsized()    case Done{bytes}:      file.reads(bytes)# a file read whole, with fuel enough for the size it reporteddef file.read.sized(got: File & Result<&1, &1, U32 & String, U32>) -> IO(String):  (file, res) = got  file.slurp(file.reads.of(res), file, "")# what an opened file holds, or nothing when it would not opendef file.read.opened(res: Result<&1, &1, U32 & String, File>) -> IO(Maybe<&2, String>):  match res:    case Fail{_e}:      IO.pure(Maybe<&2, String>, None{})    case Done{file}:      do IO<Maybe<&2, String>>:        got : File & Result<&1, &1, U32 & String, U32> <- File.size(file)        text : String <- file.read.sized(got)        return Some{text}# a file's text, or None when it cannot be openeddef file.read(path: String) -> IO(Maybe<&2, String>):  do IO<Maybe<&2, String>>:    res : Result<&1, &1, U32 & String, File> <- File.open(path, "r")    file.read.opened(res)# a file's text, or "" when there is nonedef file.text_of(got: Maybe<&2, String>) -> String:  match got:    case None{}:      ""    case Some{s}:      s