rtree-sql.js/src/worker.coffee

SQLite library with support for opening and writing databases, prepared statements, and more. This SQLite library is in pure javascript (compiled with emscripten).

# Since this is only included in web worker builds, I'm not sure if we need to detect this.
# In fact, it seems like we might want to throw an error if importScripts isn't available.
if typeof importScripts is 'function' # Detect webworker context
    db = null

    createDb = (data) ->
        if db? then db.close()
        db = new SQL.Database data

    sqlModuleReady = initSqlJs();
    self.onmessage = (event) ->
        sqlModuleReady.then ->
            data  = event['data']
            switch data?['action']
                when 'open'
                    buff = data['buffer']
                    createDb (if buff then new Uint8Array(buff) else undefined)
                    postMessage
                        'id': data['id']
                        'ready': true
                when 'exec'
                    if db is null then createDb()
                    if not data['sql'] then throw 'exec: Missing query string'
                    postMessage
                        'id' : data['id']
                        'results': db.exec data['sql']
                when 'each'
                    if db is null then createDb()
                    callback = (row) -> postMessage
                                                'id': data['id']
                                                'row': row
                                                'finished': false
                    done = -> postMessage
                                                'id' : data['id']
                                                'finished': true
                    db.each data['sql'], data['params'], callback, done

                when 'export'
                    buff = db.export()
                    result = {
                        'id' : data['id']
                        'buffer' : buff
                    }
                    try
                        postMessage result, [result]
                    catch err # Some browsers fail when trying to use transferable objects
                        postMessage result
                when 'close'
                    db?.close()
                else
                    throw new 'Invalid action : ' + data?['action']