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REMOVE_STRING Best practice
mjones2620
Posts: 86
Help.
I guess I still don't have the best understanding of how to effectively parse a buffer without destroying it. I thought the buffer remained the same as you pass through each condition but that doesn't seem the case here. The first variable works, the rest does not. Any advice would be great. Thanks.
string:
parse function:
I guess I still don't have the best understanding of how to effectively parse a buffer without destroying it. I thought the buffer remained the same as you pass through each condition but that doesn't seem the case here. The first variable works, the rest does not. Any advice would be great. Thanks.
string:
{"current_time": 1426595891, "items": [{ "bus": "bus1","stop": "lobby7","modifier": "","time": 1426595881.08877}, { "bus": "bus1","stop": "lobby1","modifier": "","time": 1426595981.6541}, { "bus": "bus1","stop": "ss2mp","modifier": "","time": 1426596043.26716}, { "bus": "bus1","stop": "sl2mp","modifier": "","time": 1426596105.19317}, { "bus": "bus1","stop": "mp1","modifier": "","time": 1426596203.61697}, { "bus": "bus1","stop": "ss2mp5","modifier": "","time": 1426596255.84008}, { "bus": "bus1","stop": "mp5","modifier": "","time": 1426596283.88472}, { "bus": "bus1","stop": "mp4","modifier": "","time": 1426596365.64478}, { "bus": "bus1","stop": "mp6","modifier": "","time": 1426596457.76979}, { "bus": "bus1","stop": "sl2l7","modifier": "","time": 1426596534.33809}, { "bus": "bus5","stop": "lobby1south","modifier": "","time": 1426596043.43202}, { "bus": "bus5","stop": "b26","modifier": "","time": 1426596114.69907}, { "bus": "bus5","stop": "ss2b23","modifier": "","time": 1426596138.91473}, { "bus": "bus5","stop": "b23","modifier": "","time": 1426596239.65891}, { "bus": "bus5","stop": "ss2b200","modifier": "","time": 1426596318.22645}, { "bus": "bus5","stop": "sl2b200","modifier": "","time": 1426596400.11884}, { "bus": "bus5","stop": "b200","modifier": "","time": 1426595912.1329}, { "bus": "bus5","stop": "ss2l1","modifier": "","time": 1426595974.02958}, { "bus": "bus2","stop": "mp6","modifier": "","time": 1426594740}, { "bus": "bus2","stop": "lobby7","modifier": "","time": 1426594920}, { "bus": "bus2","stop": "lobby1","modifier": "","time": 1426595040}, { "bus": "bus2","stop": "b200","modifier": "","time": 1426595160}], "buses": {"bus1": {"lat": 39.164114,"lon": -76.896467,"loopTime": 754.3380870042, "stop": "lobby7"}, "bus5": {"lat": 39.159872,"lon": -76.898317,"loopTime": 548.118844121}, "bus2": {"lat": 39.170054,"lon": -76.89581,"loopTime": 0}, "bus4": {"lat": 39.167839,"lon": -76.898051,"loopTime": 0}}}
parse function:
DEFINE_FUNCTION fnPARSE_BUS_BUFFER()
{
LOCAL_VAR CHAR FULL[50]
LOCAL_VAR CHAR EXPRESS[50]
LOCAL_VAR CHAR SOUTH[50]
LOCAL_VAR INTEGER B1LOBBY7
LOCAL_VAR INTEGER B2LOBBY7
LOCAL_VAR INTEGER B1MP6
LOCAL_VAR INTEGER B2MP6
LOCAL_VAR INTEGER MP1
LOCAL_VAR INTEGER MP4
LOCAL_VAR INTEGER B1LOBBY1
LOCAL_VAR INTEGER B2LOBBY1
LOCAL_VAR INTEGER BL200
LOCAL_VAR CHAR cCURRENT_TIME[20]
WHILE(FIND_STRING(cBUS_BUFFER, "'{"current_time": '", 1))
{
cCURRENT_TIME = REMOVE_STRING(cBUS_BUFFER, '{"current_time": ', 1)
cCURRENT_TIME = LEFT_STRING(cBUS_BUFFER, 10)
IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "lobby7","modifier": "","time": '", 1)) //Bus 1, Lobby 7
{
FULL = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "lobby7","modifier": "","time": '", 1)
FULL = LEFT_STRING(cBUS_BUFFER, 16)
B1LOBBY7 = fnCONVERT_BUS_TIME(FULL, cCURRENT_TIME)
IF(B1LOBBY7 > 0)
{
uBUSES[1].FULL_ETA = "ITOA(B1LOBBY7), ' Minutes'"
}
ELSE IF(B1LOBBY7 == 0)
{
uBUSES[1].FULL_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "lobby1","modifier": "","time": '", 1))//Bus 1, Lobby 1
{
FULL = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "lobby1","modifier": "","time": '", 1)
FULL = LEFT_STRING(cBUS_BUFFER, 16)
B1LOBBY1 = fnCONVERT_BUS_TIME(FULL, cCURRENT_TIME)
IF(B1LOBBY1 > 0)
{
uBUSES[2].FULL_ETA = "ITOA(B1LOBBY1), ' Minutes'"
}
ELSE IF(B1LOBBY1 == 0)
{
uBUSES[2].FULL_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp1","modifier": "","time": '", 1)) //Bus 1, MP1
{
FULL = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp1","modifier": "","time": '", 1)
FULL = LEFT_STRING(cBUS_BUFFER, 16)
MP1 = fnCONVERT_BUS_TIME(FULL, cCURRENT_TIME)
IF(MP1 > 0)
{
uBUSES[3].FULL_ETA = "ITOA(MP1), ' Minutes'"
}
ELSE IF(MP1 == 0)
{
uBUSES[3].FULL_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp4","modifier": "","time": '", 1)) //Bus 1, MP4
{
FULL = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp4","modifier": "","time": '", 1)
FULL = LEFT_STRING(cBUS_BUFFER, 16)
MP4 = fnCONVERT_BUS_TIME(FULL, cCURRENT_TIME)
IF(MP4 > 0)
{
uBUSES[4].FULL_ETA = "ITOA(MP4), ' Minutes'"
}
ELSE IF(MP4 == 0)
{
uBUSES[4].FULL_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp6","modifier": "","time": '", 1)) //Bus 1, MP6
{
FULL = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus1","stop": "mp6","modifier": "","time": '", 1)
FULL = LEFT_STRING(cBUS_BUFFER, 16)
B1MP6 = fnCONVERT_BUS_TIME(FULL, cCURRENT_TIME)
IF(B1MP6 > 0)
{
uBUSES[5].FULL_ETA = "ITOA(B1MP6), ' Minutes'"
}
ELSE IF(B1MP6 == 0)
{
uBUSES[5].FULL_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "lobby7","modifier": "","time": '", 1)) //Bus 2, Lobby 7
{
EXPRESS = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "lobby7","modifier": "","time": '", 1)
EXPRESS = LEFT_STRING(cBUS_BUFFER, 16)
B2LOBBY7 = fnCONVERT_BUS_TIME(EXPRESS, cCURRENT_TIME)
IF(B2LOBBY7 > 0)
{
uBUSES[1].EXPRESS_ETA = "ITOA(B2LOBBY7), ' Minutes'"
}
ELSE IF(B2LOBBY7 == 0)
{
uBUSES[1].EXPRESS_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "lobby1","modifier": "","time": '", 1)) //Bus 2, Lobby 1
{
EXPRESS = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "lobby1","modifier": "","time": '", 1)
EXPRESS = LEFT_STRING(cBUS_BUFFER, 16)
B2LOBBY1 = fnCONVERT_BUS_TIME(EXPRESS, cCURRENT_TIME)
IF(B2LOBBY1 > 0)
{
uBUSES[2].EXPRESS_ETA = "ITOA(B2LOBBY1), ' Minutes'"
}
ELSE IF(B2LOBBY1 == 0)
{
uBUSES[2].EXPRESS_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "b200","modifier": "","time": '", 1)) //Bus 2, Building 200
{
EXPRESS = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "b200","modifier": "","time": '", 1)
EXPRESS = LEFT_STRING(cBUS_BUFFER, 16)
BL200 = fnCONVERT_BUS_TIME(EXPRESS, cCURRENT_TIME)
IF(BL200 > 0)
{
uBUSES[6].EXPRESS_ETA = "ITOA(BL200), ' Minutes'"
}
ELSE IF(BL200 == 0)
{
uBUSES[6].EXPRESS_ETA = "'BOARDING'"
}
}
ELSE IF(FIND_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "mp6","modifier": "","time": '", 1)) //Bus 2, MP6
{
EXPRESS = REMOVE_STRING(cBUS_BUFFER, "'{ "bus": "bus2","stop": "mp6","modifier": "","time": '", 1)
EXPRESS = LEFT_STRING(cBUS_BUFFER, 16)
B2MP6 = fnCONVERT_BUS_TIME(EXPRESS, cCURRENT_TIME)
IF(B2MP6 > 0)
{
uBUSES[5].EXPRESS_ETA = "ITOA(B2MP6), ' Minutes'"
}
ELSE IF(B2MP6 == 0)
{
uBUSES[5].EXPRESS_ETA = "'BOARDING'"
}
}
}
}
0
Comments
if you want to parse the whole string in a loop I would suggest removing from the buffer based on the end of the string, possibly "}}}". That way you know you have the whole string before you start parsing.
Hello Jason,
I am calling the function in the Data_Event for the bus port, under string... is this not the best application? I got it to work now, but it took a few minutes after coming online to start parsing correctly.
I've treid to get into the habit of going ahead and building my own string buffers and not relying upon data.text and/or create_buffer to tell me when a string is done. It's really pretty simple to do, it doesn't add that many lines of code and is waaaaay more reliable.
A simple way to do this is to just tag any incmoing data.text stuff on the end of a buffer and quickly search for the end delimiter. Here's a simple example:
data_event[MySillyString_Device]] string:{ MySillyString_Buffer="MySillyString_Buffer,data.text" while(find_string(MySillyString_Buffer,13,1))){ fn_Parse_My_String(remove_string(MySillyString_Buffer,13,1)); } } }// d_eHere again, not exactly how I'd do it but the concept is simple.
keep adding any strings coming onto the end of the buffer.
Then sit and spin on the while loop, peeling off messages that end in the delimiter. (In this example, the end of message is a LineFeed (13)). So, just peel off a message and process.
If your sputtery device sends something like:
" Message One<LF> Message Two <LF> Mes"
and then sputters but finishes with...
"sage Three<LF>"
This example might generate two data events.
If you just relaied upon data.text it could get goofed up. Depending upon how you code you might even ignore the second message and the third message will not parse correctly. If seen this a lot in code I get.
So, I'd suggest bulding your own routine to put the buffer together that doesn't rely on the timing of either the device or the AMX master's idea of what a message should look like.
Yes that is where I would call the function. I was just verifying that is where it was being called for my own thought process.
If you do use a while loop to process your buffer (I generally do) make sure there is a way to exit that loop if you don't get the results you expect or the string is not long enough (usually this is more of a concern with a protocol which uses a length byte and a checksum as opposed to a clear delimiter). An endless while loop will severely affect processor performance!
Back in those halcyon days when dinosaurs roamed the Earth (When I took Prog II class) we were told them not to use the While loop for the very reason that it was possible to lock yourself up. I do use it as well; gamling on it not locking me up. Iv'e yet to be bitten by it. But I do need to make good n sure I'll never get bit by it.
In casese where I'm not so sure I go ahead and create a really fast timeline that can run endlessly if need be but won't lock me up. I can then watch the thing and if it's running on and on, I can just kill it and clear the messy buffer.
DEFINE_FUNCTION CHAR[500] fnJSONGetKey(CHAR sArgJSON[], CHAR sArgKEY[]) {(* //////////////////////////////////////////////////////////////////////////////////////// This function returns the JSON Value associated with the key sArgKEY from the JSON data sArgJSON This function is non-destructive to the data inputs /////////////////////////////////////////////////////////////////////////////////////// *) STACK_VAR INTEGER nMyBegin STACK_VAR INTEGER nMyValueLength STACK_VAR INTEGER nMyKeyLength STACK_VAR CHAR sMyValue[500] // get the length of the key nMyKeyLength=LENGTH_STRING(sArgKEY)+3 // get the begning of the value nMyBegin=FIND_STRING(sArgJSON,"'"',sArgKEY,'":'",1) // if the key exists IF(nMyBegin) { // get the length of the value nMyValueLength=FIND_STRING(sArgJSON,',',nMyBegin+nMyKeyLength) // get the value sMyValue = MID_STRING(sArgJSON,nMyBegin+nMyKeyLength,nMyValueLength-nMyBegin-nMyKeyLength) // if the value is not a key/value pair itself IF(!FIND_STRING(sMyValue,'{',1)) { // if it was the last value of an array, it will have a closing bracket IF(FIND_STRING(sMyValue,']',1)) { // get rid of the closing bracket SET_LENGTH_STRING(sMyValue,LENGTH_STRING(sMyValue)-1) } // if it was the last value it will have a closing bracket IF(FIND_STRING(sMyValue,'}',1)) { // get rid of the closing bracket SET_LENGTH_STRING(sMyValue,LENGTH_STRING(sMyValue)-1) } // text string with quotes around it IF(FIND_STRING(sMyValue,'"',1)) { STACK_VAR INTEGER nMyLength // get the length of the value nMyLength=LENGTH_STRING(sMyValue) // get the 2nd through 2nd to last characters sMyValue=MID_STRING(sMyValue,2,nMyLength-2) } } } // return the value RETURN sMyValue; }