JSON parser - Printable Version

JSON parser - Printable Version

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JSON parser - simon - 28-07-2016

Hi Guys,

FYI I have developed a very small JSON parser that works good on simple JSON file structure

Here is the code (composed of two functions)

Code:
Function ParseSimpleJson$($inputJson$, $key$, $CollectionIndex%)

      $StartIndex% = 1

      FOR $i% = 0 TO 10000

        $StartBracketPos% = INSTR $StartIndex%, $inputJson$, '{'

        IF $StartBracketPos% = 0 THEN 

          $ParseSimpleJson$ = "ELEMENT DOES NOT EXIST"

          RETURN

        ENDIF

        IF $CollectionIndex% > 0 THEN

          $CollectionIndex% = $CollectionIndex% - 1

          $StartIndex% = $StartBracketPos% + 1 

          //Find next element

        ELSE          

            IF $StartBracketPos% = 0 THEN

              $ParseSimpleJson$ = "JSON FORMAT NOT VALID"

              RETURN

            ELSE        

              $EndBracketPos% = INSTR $StartBracketPos%, $inputJson$, '}'

              $ELEMENTString$ = $inputJson$($StartBracketPos% TO $EndBracketPos%)

              $ParseSimpleJson$ = @ExtractKeyValue$($ELEMENTString$, $key$)

              RETURN

            ENDIF            

        ENDIF 

      NEXT $i%   

EndFn

Function ExtractKeyValue$($ElementString$, $Key$)

   $StartPosKey% = INSTR 1,$ElementString$, $key$

   $StartPosKeyColumn% = INSTR $StartPosKey% ,$ElementString$, ":"

   $EndPosKeyColumn% = INSTR $StartPosKeyColumn% ,$ElementString$, ','

   $StartPosKeyColumn% = $StartPosKeyColumn% + 1

   $EndPosKeyColumn% = $EndPosKeyColumn% - 1

   IF $EndPosKeyColumn% = -1 THEN //Last key

     $EndPosKeyColumn% = LEN $ElementString$ - 1

   ENDIF

   $KeyValue$ = $ElementString$($StartPosKeyColumn% TO $EndPosKeyColumn%)

   $KeyValue$ = LTRIM $KeyValue$

   $KeyValue$ = RTRIM $KeyValue$

   IF $KeyValue$(1) = '"' THEN //is a string value -> remove quote

     $EndKeyValue = LEN $KeyValue$ - 1

     $ExtractKeyValue$ = $KeyValue$(2 TO $EndKeyValue)

   ELSE

     $ExtractKeyValue$ = $KeyValue$  

   ENDIF

EndFn

And an example of how to use it :

Code:
ParseFile:

InputStr$ = '[{"opna":"PROXIMUS        ","opid":"  20601","stat":"="},{"opna":"B mobistar      ","opid":"  20610","stat":"-"},{"opna":"BASE            ","opid":"  20620","stat":"-"}]'

indexElement% = 0

Loop:

  A$ = @ParseSimpleJson$(InputStr$,"opna",indexElement%)

  IF A$ = "ELEMENT DOES NOT EXIST" THEN GOTO EndLoop

  PRINT A$

  PRINT @ParseSimpleJson$(InputStr$,"opid",indexElement%)

  PRINT @ParseSimpleJson$(InputStr$,"stat",indexElement%)

  indexElement% = indexElement% +1

IF indexElement% < 100 THEN GOTO Loop:

EndLoop:

RE: JSON parser - polishglider - 12-10-2016

(28-07-2016, 04:09 PM)Simon Wrote: Hi Guys,

FYI I have developed a very small JSON parser that works good on simple JSON file structure

Here is the code (composed of two functions)

Code:
Function ParseSimpleJson$($inputJson$, $key$, $CollectionIndex%) $StartIndex% = 1 FOR $i% = 0 TO 10000 $StartBracketPos% = INSTR $StartIndex%, $inputJson$, '{' IF $StartBracketPos% = 0 THEN $ParseSimpleJson$ = "ELEMENT DOES NOT EXIST" RETURN ENDIF IF $CollectionIndex% > 0 THEN $CollectionIndex% = $CollectionIndex% - 1 $StartIndex% = $StartBracketPos% + 1 //Find next element ELSE IF $StartBracketPos% = 0 THEN $ParseSimpleJson$ = "JSON FORMAT NOT VALID" RETURN ELSE $EndBracketPos% = INSTR $StartBracketPos%, $inputJson$, '}' $ELEMENTString$ = $inputJson$($StartBracketPos% TO $EndBracketPos%) $ParseSimpleJson$ = @ExtractKeyValue$($ELEMENTString$, $key$) RETURN ENDIF ENDIF NEXT $i% EndFn Function ExtractKeyValue$($ElementString$, $Key$) $StartPosKey% = INSTR 1,$ElementString$, $key$ $StartPosKeyColumn% = INSTR $StartPosKey% ,$ElementString$, ":" $EndPosKeyColumn% = INSTR $StartPosKeyColumn% ,$ElementString$, ',' $StartPosKeyColumn% = $StartPosKeyColumn% + 1 $EndPosKeyColumn% = $EndPosKeyColumn% - 1 IF $EndPosKeyColumn% = -1 THEN //Last key $EndPosKeyColumn% = LEN $ElementString$ - 1 ENDIF $KeyValue$ = $ElementString$($StartPosKeyColumn% TO $EndPosKeyColumn%) IF $KeyValue$(1) = '"' THEN //is a string value -> remove quote $EndKeyValue = LEN $KeyValue$ - 1 $ExtractKeyValue$ = $KeyValue$(2 TO $EndKeyValue) ELSE $ExtractKeyValue$ = $KeyValue$ ENDIF EndFn

And an example of how to use it :

Code:
ParseFile: InputStr$ = '[{"opna":"PROXIMUS ","opid":" 20601","stat":"="},{"opna":"B mobistar ","opid":" 20610","stat":"-"},{"opna":"BASE ","opid":" 20620","stat":"-"}]' indexElement% = 0 Loop: A$ = @ParseSimpleJson$(InputStr$,"opna",indexElement%) IF A$ = "ELEMENT DOES NOT EXIST" THEN GOTO EndLoop PRINT A$ PRINT @ParseSimpleJson$(InputStr$,"opid",indexElement%) PRINT @ParseSimpleJson$(InputStr$,"stat",indexElement%) indexElement% = indexElement% +1 IF indexElement% < 100 THEN GOTO Loop: EndLoop:

Hi Simon

I used this example to extract from a web page.

I'm a member of Blitzortung Network (World Lightning Detection Network), and I've got access to the entire lightning detection database (because I've got a Strike Detector). With this long range detector, I used an DIY Strike Detector (As3935 Module on Arduino and Ethernet Shield), which communicate with a Flexy in Modbus Ethernet. When a strike occurs, the DIY Module send to the flexy the distance of the strike (up to 50km).Then, the "Parse" script is launch to request the last 10 strikes in my area, save data on txt file. This file contain the GPS positions, and the timestamp of each strike. The basic script extract all the data, read the timestamp, and compare it with realtime hour (and keep only the last hour strikes), and send them to an array on a Allen Bradley Flexlogix PLC. The PLC calculate the distance of every strike, and send the minus one to the ewon, which send me an SMS. All positions are displayed on a map, thanks to markers on a PCVue Application. Every 15 minutes, the script connect to the lightning servers to check if no strike occurs near.