angstrom 0.16.0 · OCaml Package

Unsafe Operations on Angstrom's Internal Buffer

These functions are considered unsafe as they expose the input buffer to client code without any protections against modification, or leaking references. They are exposed to support performance-sensitive parsers that want to avoid allocation at all costs. Client code should take care to write the input buffer callback functions such that they:

do not modify the input buffer outside of the range [off, off + len);
do not modify the input buffer inside of the range [off, off + len) if the parser might backtrack; and
do not return any direct or indirect references to the input buffer.

If the input buffer callback functions do not do any of these things, then the client may consider their use safe.

val take : int -> (bigstring -> off:int -> len:int -> 'a) -> 'a t

take n f accepts exactly n characters of input into the parser's internal buffer then calls f buffer ~off ~len. buffer is the parser's internal buffer. off is the offset from the start of buffer containing the requested content. len is the length of the requested content. len is guaranteed to be equal to n.

val take_while : 
  (char -> bool) ->
  (bigstring -> off:int -> len:int -> 'a) ->
  'a t

take_while check f accepts input into the parser's interal buffer as long as check returns true then calls f buffer ~off ~len. buffer is the parser's internal buffer. off is the offset from the start of buffer containing the requested content. len is the length of the content matched by check.

This parser does not fail. If check returns false on the first character, len will be 0.

val take_while1 : 
  (char -> bool) ->
  (bigstring -> off:int -> len:int -> 'a) ->
  'a t

take_while1 check f accepts input into the parser's interal buffer as long as check returns true then calls f buffer ~off ~len. buffer is the parser's internal buffer. off is the offset from the start of buffer containing the requested content. len is the length of the content matched by check.

This parser requires that f return true for at least one character of input, and will fail otherwise.

val take_till : 
  (char -> bool) ->
  (bigstring -> off:int -> len:int -> 'a) ->
  'a t

take_till check f accepts input into the parser's interal buffer as long as check returns false then calls f buffer ~off ~len. buffer is the parser's internal buffer. off is the offset from the start of buffer containing the requested content. len is the length of the content matched by check.

This parser does not fail. If check returns true on the first character, len will be 0.

val peek : int -> (bigstring -> off:int -> len:int -> 'a) -> 'a t

peek n ~f accepts exactly n characters and calls f buffer ~off ~len with len = n. If there is not enough input, it will fail.

This parser does not advance the input. Use it for lookahead.

package angstrom