package csexp
Library
Module
Module type
Parameter
Class
Class type
Canonical S-expressions
This module provides minimal support for reading and writing S-expressions in canonical form.
https://en.wikipedia.org/wiki/Canonical_S-expressions
Note that because the canonical representation of S-expressions is so simple, this module doesn't go out of his way to provide a fully generic parser and printer and instead just provides a few simple functions. If you are using fancy input sources, simply copy the parser and adapt it. The format is so simple that it's pretty difficult to get it wrong by accident.
To avoid a dependency on a particular S-expression library, the only module of this library is parameterised by the type of S-expressions.
let rec print = function
| Atom str -> Printf.printf "%d:%s" (String.length s)
| List l -> List.iter print l
module type Sexp = sig ... end
module type S = sig ... end
include S with type sexp := t
val parse_string : string -> (t, int * string) Result.t
parse_string s
parses a single S-expression encoded in canonical form in s
. It is an error for s
to contain a S-expression followed by more data. In case of error, the offset of the error as well as an error message is returned.
val parse_string_many : string -> (t list, int * string) Result.t
parse_string s
parses a sequence of S-expressions encoded in canonical form in s
val input : Stdlib.in_channel -> (t, string) Result.t
Read exactly one canonical S-expressions from the given channel. Note that this function never raises End_of_file
. Instead, it returns Error
.
val input_opt : Stdlib.in_channel -> (t option, string) Result.t
Same as input
but returns Ok None
if the end of file has already been reached. If some more characters are available but the end of file is reached before reading a complete S-expression, this function returns Error
.
val input_many : Stdlib.in_channel -> (t list, string) Result.t
Read many S-expressions until the end of input is reached.
Serialising
val serialised_length : t -> int
The length of the serialised representation of a S-expression
val to_string : t -> string
to_string sexp
converts S-expression sexp
to a string in canonical form.
val to_buffer : Stdlib.Buffer.t -> t -> unit
to_buffer buf sexp
outputs the S-expression sexp
converted to its canonical form to buffer buf
.
val to_channel : Stdlib.out_channel -> t -> unit
output oc sexp
outputs the S-expression sexp
converted to its canonical form to channel oc
.
Low level parser
For efficiently parsing from sources other than strings or input channel. For instance in Lwt or Async programs.
module Parser : sig ... end
The Parser
module offers an API that is a balance between sharing the common logic of parsing canonical S-expressions while allowing to write parsers that are as efficient as possible, both in terms of speed and allocations. A carefully written parser using this API will be:
Deprecated low-level parser
The above are deprecated as the Input
signature does not allow to distinguish between IO errors and end of input conditions. Additionally, the use of monads tend to produce parsers that allocates a lot.
It is recommended to use the Parser
module instead.
module type Input = sig ... end
module Make_parser (Input : Input) : sig ... end