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 RIM_OKAY if successful or RIM_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.

Surrogate UTF8

JSON uses surrogate UTF8 pairs to represent the full 32-bit UTF characters. In general UTF8, a "\UXXXXXXXX" notation is used instead.

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 (\uD834\uDD1E for a G Clef symbol):


// 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, and with non-surrogate character \u21d7"},\
            {"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 RIM_OKAY
    @Error [<<print-out et>>] at [<<print-out 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 RIM_JSON_TYPE_NONE
        break-loop
    end-if
    @Key [<<print-out k>>]
    @Value [<<print-out v>>]
    @Type [<<print-out 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 𝄞𝄞, and with non-surrogate character ⇗]
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.