Low memory parsing of JSON with the JSONPath language
This project is still in the prototype stage, but the workflow is
# compile the Ragel state machine for the Ruby host language
# creating file main.rb
$ ragel -R main.rl
# run the compiled state machine against the example.json file
$ ruby test.rb > out.txt
This produces a bunch of state information on stdout that I've been using to track the state of the parser; the output lines are all prefixed with a string associating them with an action function in main.rl. The most important output line is the one that produces some serialized JSON associated with the specified JSONPath of "$.store.book[2]"
$ grep "yield_value" out.txt
# a_end_array_value: yield_value "{ \"category\": \"fiction\",\n \"author\": \"Herman # Melville\",\n \"title\": \"Moby Dick\",\n \"isbn\": \"0-553-21311-3\",\n # \"price\": 8.99\n },"
I am extending this proof of concept to support the full JSONPath language.