Adventure Game Studio

jsonparser version 0.1.0
(https://ci.appveyor.com/api/projects/status/ub23w5v2ga96us0m/branch/main?svg=true) (https://ci.appveyor.com/project/ericoporto/jsonparser/branch/main)

Get Latest Release jsonparser.scm (https://github.com/ericoporto/jsonparser/releases/download/0.1.0/jsonparser.scm) | GitHub Repo (https://github.com/ericoporto/jsonparser) | Demo Windows (https://github.com/ericoporto/jsonparser/releases/download/0.1.0/jsonparser_demo_windows.zip) | Demo Linux (https://github.com/ericoporto/jsonparser/releases/download/0.1.0/jsonparser_demo_linux.tar.gz) | Download project .zip  (https://github.com/ericoporto/jsonparser/archive/0.1.0.zip)

I recently found a cool unrelated tool that I wanted to add to my workflow, but the tool output was a json file. There's no good object to represent a JSON object in AGS and I was too lazy to make a plugin.
So I made a parser! This is a JSON minimal parser for Adventure Game Studio. It's based on JSMN, which is a C JSON parser that had an easy to read code.

It's not well tested, but I thought to "formally" release it here in case someone had a need that it would be enough for it. I probably need to work on a better demo and write better docs for it too. But hey, first release!

Usage

If you wish to handle things more manually, you can use a thiner parser that is also faster:

String json_string = "{ \"name\":\"John\", \"age\":30, \"car\":null }";
JsonParser* parser = new JsonParser;

int token_count = 8;
JsonToken* t[] = JsonToken.NewArray(token_count);

int r = parser.Parse(json_string, t, token_count);

// now that you have the Tokens, you can use them to parse as you wish!
if (r < 0) Display("Failed to parse JSON: %d\n", r);
if (r < 1 || t[0].type != eJSON_Tok_OBJECT) Display("Object expected\n");

for(int i=0; i<r  ; i++){
  JsonToken* tok = t[i];
  Display(String.Format("%d ; %s ; %d ; %s ; %d ; %d ; %d",
    i, tok.ToString(json_string), tok.size , tok.TypeAsString,  tok.start ,  tok.end ,  tok.parent ));
}

Display("JSON Parsing has FINISHED for string\n\n%s", json_string);
You can find here an example in-game usage of the parsing (https://github.com/ericoporto/manamatch/blob/32d4300039d03c743db0bc1ca59ee92d2b0b5f15/manamatch/Board.asc#L131), which may be useful for giving ideas.

This module also packs a more approacheable (but less tested, probably buggy) parser:

String json_string = ""; json_string = json_string.Append("{\"squadName\":\"Super squad\",\"formed\":2016,\"active\":true,\"members\":[");
json_string = json_string.Append("{\"name\":\"Molecule Man\",\"age\":29,\"secretIdentity\":\"Dan Jukes\",\"powers\":[\"Radiation resistance\",\"Radiation blast\"]},");
json_string = json_string.Append("{\"name\":\"Madam Uppercut\",\"age\":39,\"secretIdentity\":\"Jane Wilson\",\"powers\":[\"Million punch\",\"Super reflexes\"]},");
json_string = json_string.Append("{\"name\":\"Eternal Flame\",\"age\":100,\"secretIdentity\":\"Unknown\",\"powers\":[\"Immortality\",\"Heat Immunity\",\"Interdimensional jump\"]}]}");

MiniJsonParser jp;
jp.Init(json_string); // parse json_string and internally generate the tokens

while(jp.NextToken()) // advance the current token and exit when there are no tokens left
{   
  if(jp.CurrentTokenIsLeaf)  // usually the interesting information is on the leafs
  {
    Display(String.Format("%s: %s", jp.CurrentFullKey, jp.CurrentTokenAsString));
  }   
}

Display("JSON Parsing has FINISHED for string\n\n%s", json_string);
Script API

JsonParser
JsonParser.Parse
int JsonParser.Parse(String json_string, JsonToken *tokens[], int num_tokens)Parses a JSON data string into and array of tokens, each describing a single JSON object. Negative return is a JsonError, otherwise it's the number of used tokens.

You need to preallocate a number of tokens to be used by this method before calling it. Use JsonToken.NewArray(count) to help you.

JsonParser.Reset
void JsonParser.Reset()Marks the parser for reset, useful if you want to use it again with a different file. Reset only actually happens when Parse is called.

JsonParser.pos
int JsonParser.posoffset in the JSON string

JsonParser.toknext
int JsonParser.toknextnext token to allocate

JsonParser.toksuper
int JsonParser.toksupersuperior token node, e.g. parent object or array

JsonToken
JsonToken.NewArray
static JsonToken* [] JsonToken.NewArray(int count)Static helper to ease Token Array creation. Ex: JsonToken* t[] = JsonToken.NewArray(token_count);

JsonToken.ToString
String JsonToken.ToString(String json_string)pass the json_string that was parsed and generated this token to recover the string this token refers to

JsonToken.type
JsonTokenType JsonToken.typeThe type of the token: object, array, string etc.

JsonToken.start
int JsonToken.startThe start position in JSON data string.

JsonToken.end
int JsonToken.endThe end position in JSON data string.

JsonToken.size
int JsonToken.sizeThe size tells about the direct children of the token, 0 if it's a leaf value, 1 or bigger if it's a key or object/array.

JsonToken.parent
int JsonToken.parentIf it's a child, is the index position of the parent in the token array.

JsonToken.TypeAsString
readonly attribute String JsonToken.TypeAsStringUtility function for debugging, returns the type of the token in a String format.

JsonTokenType
- eJSON_Tok_UNDEFINED, a valid token should never have this type.
- eJSON_Tok_OBJECT, an object, it holds keys and values, values can be any other type.
- eJSON_Tok_ARRAY, an array, the token will contain direct ordered children.
- eJSON_Tok_STRING, the token is a string, could be a key, could be a value, context is needed.
- eJSON_Tok_PRIMITIVE, the token is either a number (float or integer), a boolean (true or false) or null.

JsonError
Used to check parse results.
- eJSON_Error_InsuficientTokens, Not enough tokens were provided. Please use more tokens.
- eJSON_Error_InvalidCharacter, Invalid character inside JSON string.
- eJSON_Error_Partial, The string is not a full JSON packet, more bytes expected.

MiniJsonParser
MiniJsonParser.Init
void MiniJsonParser.Init(String json_string)Initialize the parser passing a JSON as a string. Common usage is: MiniJsonParser jp; jp.Init(json_string);.

MiniJsonParser.NextToken
bool MiniJsonParser.NextToken()Advances to the next token. Returns false if no tokens left.

MiniJsonParser.CurrentTokenAsString
readonly attribute String MiniJsonParser.CurrentTokenAsStringThe current token content, as a String.

MiniJsonParser.CurrentTokenType
readonly attribute JsonTokenType MiniJsonParser.CurrentTokenTypeThe current token type.

MiniJsonParser.CurrentTokenSize
readonly attribute int MiniJsonParser.CurrentTokenSizeThe current token size, 0 if it's a leaf value, 1 or bigger if it's a key or object/array.

MiniJsonParser.CurrentState
readonly attribute MiniJsonParserState MiniJsonParser.CurrentStateThe current state of our mini parser. Helps understanding the JSON tokens we got when parsing.

MiniJsonParser.CurrentFullKey
readonly attribute String MiniJsonParser.CurrentFullKeyGets the current dot separated key.

MiniJsonParser.CurrentTokenIsLeaf
readonly attribute bool MiniJsonParser.CurrentTokenIsLeafChecks if the state and key type currently are a leaf. True if it's, usually leafs are the interesting tokens we want when parsing.

MiniJsonParserState
- eJP_State_START, The parser just started.
- eJP_State_KEY, The current token is key in an object.
- eJP_State_VALUE, The current token is a value in an object.
- eJP_State_ARRVALUE, The current token is a value in an array.
- eJP_State_STOP, Don't parse anything in this state, but the parser is not necessarily done.


License

This code is made by eri0o and is licensed with MIT LICENSE (https://github.com/ericoporto/jsonparser/blob/main/LICENSE). The code on this module is based on Serge's JSMN, which is also MIT licensed and is referenced in the license.

That's pretty cool! Thanks.