.TH JSON 2.SH NAMEjson: readjson, writejson, JValue \- read, write and represent values in JavaScript Object Notation.SH SYNOPSIS.EXinclude "json.m";json := load JSON JSON->PATH; JValue: adt {    pick{    Object =>        mem:   cyclic list of (string, ref JValue);    Array =>        a:     cyclic array of ref JValue;    String =>        s:     string;    Int =>        value: big;    Real =>        value: real;    True or    False or    Null =>    }    isarray:   fn(v: self ref JValue): int;    isfalse:   fn(v: self ref JValue): int;    isint:     fn(v: self ref JValue): int;    isnull:    fn(v: self ref JValue): int;    isnumber:  fn(v: self ref JValue): int;    isobject:  fn(v: self ref JValue): int;    isreal:    fn(v: self ref JValue): int;    isstring:  fn(v: self ref JValue): int;    istrue:    fn(v: self ref JValue): int;    copy:      fn(v: self ref JValue): ref Jvalue;    eq:        fn(v: self ref JValue, v: ref JValue): int;    get:       fn(v: self ref JValue, mem: string): ref JValue;    set:       fn(v: self ref JValue, mem: string, value: ref JValue);    text:      fn(v: self ref JValue): string;}; init:      fn(bufio: Bufio);readjson:  fn(input: ref Bufio->Iobuf): (ref JValue, string);writejson: fn(output: ref Bufio->Iobuf, val: ref JValue): int; jvarray:   fn(a: array of ref JValue): ref JValue.Array;jvbig:     fn(b: big): ref JValue.Int;jvfalse:   fn(): ref JValue.False;jvint:     fn(i: int): ref JValue.Int;jvnull:    fn(): ref JValue.Null;jvobject:  fn(m: list of (string, ref JValue)): ref JValue.Object;jvreal:    fn(r: real): ref JValue.Real;jvstring:  fn(s: string): ref JValue.String;jvtrue:    fn(): ref JValue.True;.EE.SH DESCRIPTION.B JSONprovides value representations, and encoding and decoding operations for the JavaScript Object Notation (JSON)described by Internet RFC4627and summarised in.IR json (6)..PP.B Initmust be called before invoking any other operation of the module.The.I bufioparameter must refer to the instance of.IR bufio (2)that provides the.B Iobufparameters used for input and output..PP.B JValueis the internal representation of values transmitted by the JSON encoding.They are distinguished in a pick adt:.TP.B JValue.FalseRepresents the value.BR false ..TP.B JValue.NullRepresents a null value of any type..TP.B JValue.TrueRepresents the value.BR true ..TP.B JValue.IntRepresents as a Limbo.B biga JavaScript number with no fractional part..TP.B JValue.RealRepresents as a Limbo.B reala JavaScript number with a fractional part..TP.B JValue.StringRepresents a JavaScript string of Unicode characters from.B +U'0000'to.BR +U'FFFF' ..TP.B JValue.ArrayRepresents a JavaScript array of values of any type..TP.B JValue.ObjectRepresents a tuple of (member/property name, value) pairs corresponding to the value of a JavaScript object,or an associative array or table, indexed by strings.The member names must be unique within a value..PP.B Readjsonreads a single value in JSONformat from the.I inputstream and returns a tuple.BI ( val,\ err ).On success,.I valis a.B JValuethat represents the value successfully read.If an error occurs,.I valis nil and.I errcontains a diagnostic..PP.B Writejsonwrites to the.I outputstream in JSON format arepresentation of the value.IR v .It returns 0 on success and -1 on error (setting the system error string)..PPThe easiest way to create a new.B JValuefor subsequent output is with one of the module-level functions.BR jvarray ,.BR jvint ,.BR jvobject ,.BR jvstring ,and so on.As values of a pick adt, a.B JValuecan be inspected using Limbo's.B tagofoperator and the appropriate variant accessed using a.B pickstatement..B JValuealso supports several groups of common operations, for smaller, tidier code.First, the set of enquiry functions.IB v .is X ()return true if the value.I vis an instance of the JavaScript type.I X.RI ( array ,.IR int ,.IR object ,.IR real ,.IR string ,etc).A.I numericvalue is either.I intor.IR real .The other operations are:.TP.IB v .copy()Return a (reference to) a copy of value.IR v .The copying is not recursive..TP.IB v .eq( w )Return true if the values of.I vand.I ware equal, including the values of corresponding subcomponents, recursively.TP.IB v .get( mem )Return the value associated with the member named.I memin.IR v ;return null if there is none..TP.IB v .set( mem,\ value )Adds or changes the.I valueassociated with the member named.I memin.IR v ,which must be a.BR JValue.Object (raises exception.B "json: set non-object"otherwise)..TP.IB v .text()Return a string containing the JSON representation of.IR v ..SH SOURCE.B /appl/lib/json.b.SH SEE ALSO.IR sexprs (2),.IR ubfa (2) ,.IR json (6),.IR sexprs (6),.IR ubfa (6).brD Crockford, ``The application/json Media Type for JavaScript Object Notation (JSON)'',.IR RFC4627 .