Base_bigstring
SourceString type based on Bigarray
, for use in I/O and C-bindings.
Type of bigstrings
Type of bigstrings which support hashing. Note that mutation invalidates previous hashes.
val hash_fold_t_frozen :
Ppx_hash_lib.Std.Hash.state ->
t_frozen ->
Ppx_hash_lib.Std.Hash.state
include Base.Equal.S with type t := t
init n ~f
creates a bigstring t
of length n
, with t.{i} = f i
.
of_string ?pos ?len str
of_bytes ?pos ?len str
to_string ?pos ?len bstr
to_bytes ?pos ?len bstr
check_args ~loc ~pos ~len bstr
checks the position and length arguments pos
and len
for bigstrings bstr
.
unsafe_get t pos
returns the character at pos
, without bounds checks.
unsafe_set t pos
sets the character at pos
, without bounds checks.
blit ~src ?src_pos ?src_len ~dst ?dst_pos ()
blits src_len
characters from src
starting at position src_pos
to dst
at position dst_pos
.
include Base.Blit.S with type t := t
memset t ~pos ~len c
fills t
with c
within the range [pos, pos + len)
.
unsafe_memset t ~pos ~len c
fills t
with c
within the range [pos, pos + len)
, without bounds checks.
Memcmp
memcmp t1 ~pos1 t2 ~pos2 ~len
is like compare t1 t2
except performs the comparison on the subregions of t1
and t2
defined by pos1
, pos2
, and len
.
find ?pos ?len char t
returns Some i
for the smallest i >= pos
such that t.{i} = char
, or None
if there is no such i
.
Same as find
, but does no bounds checking, and returns a negative value instead of None
if char
is not found.
Binary_packing
These are in Bigstring
rather than a separate module because:
1. Existing Binary_packing
requires copies and does not work with bigstring
s. 2. The accessors rely on the implementation of bigstring
, and hence should change should the implementation of bigstring
move away from Bigarray
. 3. Bigstring
already has some external C functions, so it didn't require many changes to the jbuild
^_^.
In a departure from Binary_packing
, the naming conventions are chosen to be close to C99 stdint types, as it's a more standard description and it is somewhat useful in making compact macros for the implementations. The accessor names contain endian-ness to allow for branch-free implementations
<accessor> ::= <unsafe><operation><type><endian> <unsafe> ::= unsafe_ | '' <operation> ::= get_ | set_ <type> ::= int8 | uint8 | int16 | uint16 | int32 | uint32 | int64 | uint64 <endian> ::= _le | _be | ''
The unsafe_
prefix indicates that these functions do no bounds checking and silently truncate out-of-range numeric arguments.
Similar to the usage in binary_packing, the below methods are treating the value being read (or written), as an ocaml immediate integer, as such it is actually 63 bits. If the user is confident that the range of values used in practice will not require 64-bit precision (i.e. Less than Max_Long), then we can avoid allocation and use an immediate. If the user is wrong, an exception will be thrown (for get).
These are alternatives to to_string
that follow the conventions of the int accessors, and in particular avoid optional arguments.