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Module type
Parameter
Class
Class type
Library
Module
Module type
Parameter
Class
Class type
include module type of struct include Yojson.Safe end
type t = [
| `Null
| `Bool of bool
| `Int of int
| `Intlit of string
| `Float of float
| `String of string
| `Assoc of (string * t) list
| `List of t list
| `Tuple of t list
| `Variant of string * t option
]
All possible cases defined in Yojson:
("abc", 123)
.<"Foo">
or <"Bar":123>
.val pp : Format.formatter -> t -> unit
Pretty printer, useful for debugging
val show : t -> string
Convert value to string, useful for debugging
equal a b
is the monomorphic equality. Determines whether two JSON values are considered equal. In the case of JSON objects, the order of the keys does not matter, except for duplicate keys which will be considered equal as long as they are in the same input order.
val to_basic : t -> Yojson.Basic.t
Tuples are converted to JSON arrays, Variants are converted to JSON strings or arrays of a string (constructor) and a json value (argument). Long integers are converted to JSON strings.
Examples:
`Tuple [ `Int 1; `Float 2.3 ] -> `List [ `Int 1; `Float 2.3 ] `Variant ("A", None) -> `String "A" `Variant ("B", Some x) -> `List [ `String "B", x ] `Intlit "12345678901234567890" -> `String "12345678901234567890"
val to_channel :
?buf:Buffer.t ->
?len:int ->
?suf:string ->
?std:bool ->
out_channel ->
t ->
unit
Write a compact JSON value to a channel. Note: the out_channel
is not flushed by this function.
See to_string
for the role of the optional arguments and raised exceptions.
val to_output :
?buf:Buffer.t ->
?len:int ->
?suf:string ->
?std:bool ->
< output : string -> int -> int -> int.. > ->
t ->
unit
Write a compact JSON value to an OO channel.
See to_string
for the role of the optional arguments and raised exceptions.
val to_file : ?len:int -> ?std:bool -> ?suf:string -> string -> t -> unit
Write a compact JSON value to a file. See to_string
for the role of the optional arguments and raised exceptions.
Write a compact JSON value to an existing buffer. See to_string
for the role of the optional argument and raised exceptions.
Write a sequence of suf
-suffixed compact one-line JSON values to a string.
val seq_to_channel :
?buf:Buffer.t ->
?len:int ->
?suf:string ->
?std:bool ->
out_channel ->
t Seq.t ->
unit
Write a sequence of suf
-suffixed compact one-line JSON values to a channel.
Write a sequence of suf
-suffixed compact one-line JSON values to a file.
Write a sequence of suf
-suffixed compact one-line JSON values to an existing buffer.
Write the given JSON value to the given buffer. Provided as a writer function for atdgen.
Sort object fields (stable sort, comparing field names and treating them as byte sequences)
val pretty_print : ?std:bool -> Format.formatter -> t -> unit
Pretty-print into a Format.formatter
. See to_string
for the role of the optional std
argument.
val pretty_to_string : ?std:bool -> t -> string
Pretty-print into a string. See to_string
for the role of the optional std
argument. See pretty_print
for raised exceptions.
val pretty_to_channel : ?std:bool -> out_channel -> t -> unit
Pretty-print to a channel. See to_string
for the role of the optional std
argument. See pretty_print
for raised exceptions.
Combined parser and pretty-printer. See to_string
for the role of the optional std
argument and raised exceptions.
Combined parser and printer. See to_string
for the role of the optional std
argument and raised exceptions.
Read a JSON value from a string.
val from_channel :
?buf:Buffer.t ->
?fname:string ->
?lnum:int ->
in_channel ->
t
Read a JSON value from a channel. See from_string
for the meaning of the optional arguments and raised exceptions.
Read a JSON value from a file. See from_string
for the meaning of the optional arguments and raised exceptions.
type lexer_state = {
buf : Buffer.t;
mutable lnum : int;
mutable bol : int;
mutable fname : string option;
}
This alias is provided for backward compatibility. New code should refer to Yojson.lexer_state
directly.
val init_lexer :
?buf:Buffer.t ->
?fname:string ->
?lnum:int ->
unit ->
lexer_state
This alias is provided for backward compatibility. New code should use Yojson.init_lexer
directly.
val from_lexbuf : lexer_state -> ?stream:bool -> Lexing.lexbuf -> t
Read a JSON value from a lexbuf. A valid initial lexer_state
can be created with init_lexer
. See from_string
for the meaning of the optional arguments and raised exceptions.
Input a sequence of JSON values from a string. Whitespace between JSON values is fine but not required. See from_string
for the meaning of the optional arguments and raised exceptions.
val seq_from_channel :
?buf:Buffer.t ->
?fin:(unit -> unit) ->
?fname:string ->
?lnum:int ->
in_channel ->
t Seq.t
Input a sequence of JSON values from a channel. Whitespace between JSON values is fine but not required.
Input a sequence of JSON values from a file. Whitespace between JSON values is fine but not required.
See from_string
for the meaning of the optional arguments and raised exceptions.
val seq_from_lexbuf :
lexer_state ->
?fin:(unit -> unit) ->
Lexing.lexbuf ->
t Seq.t
Input a sequence of JSON values from a lexbuf. A valid initial lexer_state
can be created with init_lexer
. Whitespace between JSON values is fine but not required.
The type of values resulting from a parsing attempt of a JSON value.
val lineseq_from_channel :
?buf:Buffer.t ->
?fin:(unit -> unit) ->
?fname:string ->
?lnum:int ->
in_channel ->
json_line Seq.t
Input a sequence of JSON values, one per line, from a channel. Exceptions raised when reading malformed lines are caught and represented using `Exn
.
See seq_from_channel
for the meaning of the optional fin
argument. See from_string
for the meaning of the other optional arguments and raised exceptions.
Input a sequence of JSON values, one per line, from a file. Exceptions raised when reading malformed lines are caught and represented using `Exn
.
See seq_from_channel
for the meaning of the optional fin
argument. See from_string
for the meaning of the other optional arguments and raised exceptions.
val read_t : lexer_state -> Lexing.lexbuf -> t
Read a JSON value from the given lexer_state and lexing buffer and return it. Provided as a reader function for atdgen.
module Util = Yojson.Safe.Util
This module provides combinators for extracting fields from JSON values.
include module type of struct include Util end
This module provides combinators for extracting fields from JSON values.
Raised when the JSON value is not of the correct type to support an operation, e.g. member
on an `Int
. The string message explains the mismatch.
Raised when the equivalent JavaScript operation on the JSON value would return undefined. Currently this only happens when an array index is out of bounds.
member k obj
returns the value associated with the key k
in the JSON object obj
, or `Null
if k
is not present in obj
.
index i arr
returns the value at index i
in the JSON array arr
. Negative indices count from the end of the list (so -1 is the last element).
map f arr
calls the function f
on each element of the JSON array arr
, and returns a JSON array containing the results.
Return None
if the JSON value is null or map the JSON value to Some
value using the provided function.
Extract Some
boolean value, return None
if the value is null.
Extract Some
number, return None
if the value is null.
Extract a float value. to_number
is generally preferred as it also works with int literals.
Extract Some
float value, return None
if the value is null. to_number_option
is generally preferred as it also works with int literals.
Extract Some
int from a JSON int, return None
if the value is null.
Extract Some
string from a JSON string, return None
if the value is null.
The conversion functions above cannot be used with map
, because they do not return JSON values. This convenience function convert_each to_f arr
is equivalent to List.map to_f (to_list arr)
.
The following functions operate on lists of JSON nodes. None of them raises an exception when a certain kind of node is expected but no node or the wrong kind of node is found. Instead of raising an exception, nodes that are not as expected are simply ignored.
filter_map f l
maps each element of the list l
to an optional value using function f
and unwraps the resulting values.
Expects JSON arrays and returns all their elements as a single list. flatten l
is equivalent to List.flatten (filter_list l)
.
Expects JSON arrays and returns all their elements existing at the given position.
Expects JSON arrays and unwraps them.
Expects JSON objects and returns all the fields of the given name (at most one field per object).
Expects JSON objects and unwraps them.
Expects JSON integers (`Int
nodes) and unwraps them.
Expects JSON floats (`Float
nodes) and unwraps them.
Expects JSON numbers (`Int
or `Float
) and unwraps them. Ints are converted to floats.