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The Span module provides an unboxed span type that references regions of buffers using offset and length. Spans use int16# internally since the maximum buffer size is 32KB, enabling zero-allocation buffer operations.

​
Type Definition

​
t
record
The span type representing an offset and length into a buffer.
​
off
int16#
Offset into the buffer (unboxed int16)
​
len
int16#
Length of the span (unboxed int16)

​
Construction

​
make

val make : off:int16# -> len:int16# -> t
Create a span from int16# offset and length.
​
off
int16#
required
The offset into the buffer
​
len
int16#
required
The length of the span
Example: 
let span = Span.make ~off:(Span.of_int 10) ~len:(Span.of_int 5)

​
Conversion Functions

​
of_int

val of_int : int -> int16#
Convert int to int16# for use in span construction.
​
n
int
required
The integer value to convert

​
to_int

val to_int : int16# -> int
Convert int16# to int for regular operations.
​
n
int16#
required
The unboxed int16 value to convert

​
Accessors

​
off16

val off16 : t -> int16#
Get offset as int16# (unboxed).
​
span
t
required
The span to get the offset from

​
len16

val len16 : t -> int16#
Get length as int16# (unboxed).
​
span
t
required
The span to get the length from

​
off

val off : t -> int
Get offset as int (for array indexing).
​
span
t
required
The span to get the offset from
Example: 
let offset = Span.off span in
let byte = Bigstringaf.get buffer offset

​
len

val len : t -> int
Get length as int (for comparisons with String.length etc).
​
span
t
required
The span to get the length from

​
Comparison Functions

​
equal

val equal : local_ Base_bigstring.t -> t -> string -> bool
Case-sensitive comparison of span contents with a string.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span to compare
​
str
string
required
The string to compare against
Example: 
if Span.equal buffer method_span "GET" then
  (* Handle GET request *)
  ...

​
equal_caseless

val equal_caseless : local_ Base_bigstring.t -> t -> string -> bool
Case-insensitive comparison of span contents with a string.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span to compare
​
str
string
required
The string to compare against (case-insensitive)
Example: 
if Span.equal_caseless buffer header_value "chunked" then
  (* Handle chunked encoding *)
  ...

​
Parsing Functions

​
parse_int64

val parse_int64 : local_ Base_bigstring.t -> t -> int64#
Parse decimal integer from span. Returns -1L on error.
This does NOT check for overflow. Use parse_int64_limited for security-critical parsing.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span containing the decimal digits
Example: 
let content_length = Span.parse_int64 buffer length_span in
if Int64.compare content_length (Int64.of_int (-1)) = 0 then
  (* Invalid number *)
  ...

​
parse_int64_limited

val parse_int64_limited : local_ Base_bigstring.t -> t -> max_value:int64# -> #(int64# * bool)
Parse decimal integer from span with overflow protection and maximum value limit. Returns unboxed tuple #(value, overflow_flag) where:
  • value: parsed value or -1L if empty/invalid
  • overflow_flag: true if value exceeds max_value or has too many digits
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span containing the decimal digits
​
max_value
int64#
required
Maximum allowed value (returns overflow flag if exceeded)
Example: 
let max_content_length = Int64.of_int 10_000_000 in
let #(length, overflow) = 
  Span.parse_int64_limited buffer length_span ~max_value:max_content_length in
if overflow then
  (* Content-Length too large *)
  raise (Error Content_length_overflow)

​
Conversion to Allocated Types

​
to_string

val to_string : local_ Base_bigstring.t -> t -> string
Copy span contents to a string. Allocates memory.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span to copy
Example: 
let path = Span.to_string buffer request.target_span in
printf "Request path: %s\n" path

​
to_bytes

val to_bytes : local_ Base_bigstring.t -> t -> bytes
Copy span contents to bytes. Allocates memory.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
span
t
required
The span to copy

​
Pretty Printing

​
pp_with_buf

val pp_with_buf : local_ Base_bigstring.t -> Stdlib.Format.formatter -> t -> unit
Pretty-print span contents using buffer.
​
buf
local_ Base_bigstring.t
required
The buffer containing the span data
​
formatter
Stdlib.Format.formatter
required
The formatter to print to
​
span
t
required
The span to print

​
pp

val pp : Stdlib.Format.formatter -> t -> unit
Pretty-print span structure (offset and length).
​
formatter
Stdlib.Format.formatter
required
The formatter to print to
​
span
t
required
The span to print
Example: 
Format.printf "Span: %a@." Span.pp span
(* Output: Span: {off=10; len=5} *)

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