Module Bi_inbuf

Input buffer

type t = {
mutable i_s : bytes;

This is the buffer string. It can be accessed for reading but should normally only be written to or replaced only by the i_refill function.

mutable i_pos : int;

This is the current position in the input buffer. All data before that may be erased at anytime.

mutable i_len : int;

This is the position of the first byte of invalid input data. Data starting at i_pos and ending at i_len-1 is considered valid input data that is available to the user. Beware that calls to try_preread, read and other read functions may move data around and therefore modify the values of i_pos and i_len in order to keep pointing to the correct data segment.

mutable i_offs : int;

Length of data read and discarded from the buffer. This indicates the position in the input stream of the first byte of the buffer. The current position in the input stream is i_offs + i_pos. The total length of input stream data put into the buffer is i_offs + i_len.

mutable i_max_len : int;

This is the length of i_s.

i_refill : t -> int -> unit;

Function called when not enough data is available in the buffer. The int argument is the total number of bytes that must be available starting at position i_pos when the function returns. This function typically does nothing if all input data already has been placed into the buffer. The i_pos and i_len fields can be modified the i_refill function, as long as the available data that was starting from i_pos still starts from the new value of i_pos. All the other fields can be modified as well.

i_shared : Bi_share.Rd.tbl;

Hash table used to map positions in the input stream to shared objects (if any).

}
exception End_of_input

Exception raised by all the functions of this module when it is not possible to return a valid result because there is not enough data to read from the buffer.

val try_preread : t -> int -> int

try_preread ib n make at least n bytes available for reading in ib.i_s, unless the end of the input is reached. The result indicates how many bytes were made available. If smaller than n, the result indicates that the end of the input was reached. ib.i_pos is set to point to the first available byte.

val read : t -> int -> int

read ib n makes at least n bytes available for reading or raises the End_of_input exception. The result is the position of the first available byte. ib.i_pos is moved to point to the next position after the n bytes.

raises End_of_input

if there is less than n bytes before the end of input.

val read_char : t -> char

Read just one byte.

raises End_of_input

if the end of input has already been reached.

val peek : t -> char

Return the next byte without moving forward.

raises End_of_input

if the end of input has already been reached.

val from_string : ?⁠pos:int -> ?⁠shrlen:int -> string -> t

Create an input buffer from a string.

parameter pos

position to start from. Default: 0.

parameter shrlen

initial length of the table used to store shared values.

val from_bytes : ?⁠pos:int -> ?⁠shrlen:int -> bytes -> t

Create an input buffer from bytes.

parameter pos

position to start from. Default: 0.

parameter shrlen

initial length of the table used to store shared values.

since
1.2.0
val from_channel : ?⁠len:int -> ?⁠shrlen:int -> Stdlib.in_channel -> t

Create an input buffer from an in_channel. Such a buffer is not extensible and read requests may not exceed len.

parameter len

buffer length.

parameter shrlen

initial length of the table used to store shared values.