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This results in nearly 8x speedup of JSON parsing when keys don't have spaces. On my reference JSON, based on yours bet extended slightly and made much larger, the original simpleJSONParser takes 4705 ms to parse it 10 times. This new version takes 871 ms. And that's with a penalty because of a space in the name of one of the keys (more on that below).
When keys have spaces, a performance penalty is imposed, but it's a fairly static penalty, and it's only imposed once for each set of spaces in a key, for the key with the most spaces. That can be optimized away somewhat at the cost of a slightly more complex regex, but it's pretty fast now. Basically it's just trading regex complexity for algorithm complexity, but since the regexes are all highly optimized C, that's a good trade.
I build the key space removing regex out of variables for readability. While the regex object supports the /x flag for readability, without line spanning strings it's less useful than it could be. The actual regex I'm using to remove a space from a quoted key is
This can be optimized slightly to remove more than one space at a time by utilizing empty match vars, but only as much as we add in. We can replace two spaces at a time, or three spaces at a time, etc, and still replace a single space, but the extra complexity on an already ugly regex just makes me cringe. Plus, I'm tired.
If you don't mind, I'll add the JSON lib to librokudev. Instead of "simple", the prefix would be "rd" to match the library naming structure. I would of course to include comments crediting the original source (meaning both you and hoffmcs).
P.S. This started out as me thinking that caching the regex objects as globals would be a simple optimization, but PCRE seems to already cache regex objects requested so the second request doesn't incur a regex compile penalty, which is nice.
Function simpleJSONParser( jsonString As String ) As Object
q = chr(34)
beforeKey = "[,{]"
keyFiller = "[^:]*?"
keyNospace = "[-_\w\d]+"
valueStart = "[" +q+ "\d\[{]|true|false|null"
reReplaceKeySpaces = "("+beforeKey+")\s*"+q+"("+keyFiller+")("+keyNospace+")\s+("+keyNospace+")\s*"+q+"\s*:\s*(" + valueStart + ")"
regexKeyUnquote = CreateObject( "roRegex", q + "([a-zA-Z0-9_\-\s]*)" + q + "\:", "i" )
regexKeyUnspace = CreateObject( "roRegex", reReplaceKeySpaces, "i" )
regexQuote = CreateObject( "roRegex", "\\" + q, "i" )
' setup "null" variable
null = invalid
' Replace escaped quotes
jsonString = regexQuote.ReplaceAll( jsonString, q + " + q + " + q )
while regexKeyUnspace.isMatch( jsonString )
jsonString = regexKeyUnspace.ReplaceAll( jsonString, "\1\2\3\4: \5" )
end while
jsonString = regexKeyUnquote.ReplaceAll( jsonString, "\1:" )
jsonObject = invalid
' Eval the BrightScript formatted JSON string
Eval( "jsonObject = " + jsonString )
Return jsonObject
End Function
When keys have spaces, a performance penalty is imposed, but it's a fairly static penalty, and it's only imposed once for each set of spaces in a key, for the key with the most spaces. That can be optimized away somewhat at the cost of a slightly more complex regex, but it's pretty fast now. Basically it's just trading regex complexity for algorithm complexity, but since the regexes are all highly optimized C, that's a good trade.
I build the key space removing regex out of variables for readability. While the regex object supports the /x flag for readability, without line spanning strings it's less useful than it could be. The actual regex I'm using to remove a space from a quoted key is
([,{])\s*"([^:]*?)([-_\w\d]+)\s+([-_\w\d]+)\s*"\s*:\s*(["\d\[{]|true|false|null)
This can be optimized slightly to remove more than one space at a time by utilizing empty match vars, but only as much as we add in. We can replace two spaces at a time, or three spaces at a time, etc, and still replace a single space, but the extra complexity on an already ugly regex just makes me cringe. Plus, I'm tired.
If you don't mind, I'll add the JSON lib to librokudev. Instead of "simple", the prefix would be "rd" to match the library naming structure. I would of course to include comments crediting the original source (meaning both you and hoffmcs).
P.S. This started out as me thinking that caching the regex objects as globals would be a simple optimization, but PCRE seems to already cache regex objects requested so the second request doesn't incur a regex compile penalty, which is nice.
I know just enough regex to confuse the hell out of myself every time I look back at an expression I've written, so if you say your's is more efficient, you won't get an argument from me! 
Your function, however, doesn't work with the actual JSON strings I'm working with. I have some keys with multiple (non-contiguous) spaces, which your function doesn't seem to be taking into account.
Here's an example of one of the JSON strings that fails to parse with your code:
Your function, however, doesn't work with the actual JSON strings I'm working with. I have some keys with multiple (non-contiguous) spaces, which your function doesn't seem to be taking into account.
Here's an example of one of the JSON strings that fails to parse with your code:
{"params":["",["serverstatus","0","999"]],"method":"slim.request","id":1,"result":{"other player count":0,"info total albums":"1658","player count":0,"version":"7.5.1","uuid":"f8c06881-02a6-4e2e-bae3-4ca9e08fe66d","sn player count":0,"info total artists":"1711","info total songs":"20179","lastscan":"1284783999","info total genres":"69"}}
