Json doc

Purpose: Parse JSON text.

 json-doc <text> to <json> \
     [ status <status> ] [ length <length> ] [ noencode ] [ no-enum ] \
     [ error-text <error text> ] \
         [ error-position <error position> ] \
         [ error-line <line> ] \
         [ error-char <char> ]

 json-doc  delete <json>

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json-doc will parse JSON <text> into <json> variable, which can be used with read-json to get the data.

The length of <text> may be specified with "length" clause in <length> variable, or if not, it will be the string length of <text>.

The "status" clause specifies the return <status> number, which is GG_OKAY if successful or GG_ERR_JSON if there is an error. The number <error position> in "error-position" clause is the byte position in <text> where error was found (starting with "0"), in which case <error text> in "error-text" clause is the error message. You can also obtain the error's line number (with number <line> in clause "error-line") and the character position within that line (with number <char> in clause "error-char").

"noencode" clause will not encode strings, i.e. convert from JSON Unicode strings to UTF, nor will it perform any validity checks on strings. This may be useful as a performance boost or to pass along strings unencoded, however in most cases it is not needed.

"no-enum" clause will not include indexing of arrays in normalized names (with "[..]"), see read-json. This is useful if you want to check the path of each data element, and not worry about counting them; this happens often when using JSON in a structured way to transfer arrays when data elements repeat in a predictable fashion. Parsing of JSON is also faster with "no-enum".

The maximum depth of nested structures in JSON document (i.e. objects and arrays) is 32, and the maximum length of normalized leaf node name is 1024 (see read-json for more on normalized names). There is no limit on document size.

Deleting

To delete a JSON variable, use "delete" clause with the <json>. This will delete all memory associated with it, and the variable <json> itself.

Examples

Parse the following JSON document and display all keys and values from it. You can use them as they come along, or store them into new-hash or new-tree for instance for searching of large documents. This also demonstrates usage of UTF8 characters:


 // JSON to parse
 set-string jd unquoted = {"menu":\
     {"id": "file",\
     "value": 23091,\
     "active": false,\
     "popup":\
         {"menuitem":\
             [{"value": "New", "onclick": "CreateNewDoc with\uD834\uDD1Emusic"},\
             {"value": "Open", "onclick": "OpenDoc() with \uD834\uDD1E\uD834\uDD1E"},\
             {"value": "Close", "onclick": "\uD834\uDD1ECloseDoc()"}\
             ]\
         }\
     }\
 }

 // Parse JSON
 json-doc jd status st error-text et error-position ep to nj

 // Check parsing okay, if not display error details
 if-true st not-equal GG_OKAY
     @Error [<<p-out et>>] at [<<p-num ep>>]
     exit-handler -1
 end-if

 // Display all data elements in order from top to bottom
 start-loop
     read-json nj key k value v type t next
     if-true t equal GG_JSON_TYPE_NONE
         break-loop
     end-if
     @Key [<<p-out k>>]
     @Value [<<p-out v>>]
     @Type [<<p-num t>>]
     @--------
 end-loop
 @

 // Delete JSON document
 json-doc delete nj

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The output would be:

Key ["menu"."id"]
Value [file]
Type [0]
--------
Key ["menu"."value"]
Value [23091]
Type [1]
--------
Key ["menu"."active"]
Value [false]
Type [3]
--------
Key ["menu"."popup"."menuitem"[0]."value"]
Value [New]
Type [0]
--------
Key ["menu"."popup"."menuitem"[0]."onclick"]
Value [CreateNewDoc with𝄞music]
Type [0]
--------
Key ["menu"."popup"."menuitem"[1]."value"]
Value [Open]
Type [0]
--------
Key ["menu"."popup"."menuitem"[1]."onclick"]
Value [OpenDoc() with 𝄞𝄞]
Type [0]
--------
Key ["menu"."popup"."menuitem"[2]."value"]
Value [Close]
Type [0]
--------
Key ["menu"."popup"."menuitem"[2]."onclick"]
Value [𝄞CloseDoc()]
Type [0]
--------

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Note that if "no-enum" were used in json-doc, then all keys with arrays would not have "[..]", for instance the very last key above would be "menu"."popup"."menuitem"."onclick", i.e. there would be no indexing of arrays.