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I remember searching for a JSON library with minimal dependencies a while ago, and came across this: https://rawgit.com/miloyip/nativejson-benchmark/master/sam

I remember searching for a JSON library with minimal dependencies a while ago, and came across this: https://rawgit.com/miloyip/nativejson-benchmark/master/sample/conformance.html https://rawgit.com/miloyip/nativejson-benchmark/master/sampl... The variance in feature set, design and performance is huge across all of them. I ultimately landed on libjson, written in C: https://github.com/vincenthz/libjson https://github.com/vincenthz/libjson It does a lot for you, but it notably does not build a tree for you and does not try to interpret numbers, which I found perfect for adding to languages with C FFI that have their own collection and number types. It’s also great for partial parsing if you need to do any sort of streaming. It looks like this one can’t currently do partial parsing, but it looks great if C++ maps/vectors are your target.

nwpierce 2y ago
Somehow I didn't run across that one in my searching - I'll check it out. I've been working on a json C library myself: https://github.com/nwpierce/jsb https://github.com/nwpierce/jsb My goal was to convert a stream of JSON to/from a binary stream that is easier to traverse and manipulate.
alex_suzuki 2y ago
Did you try cJSON? Works well for me. https://github.com/DaveGamble/cJSON https://github.com/DaveGamble/cJSON
msarnoff 2y ago
If you want to go extremely lightweight, there’s jsmn: https://github.com/zserge/jsmn https://github.com/zserge/jsmn It does no dynamic memory allocation, which is a plus in constrained IoT/embedded applications. But it’s really only a tokenizer. For example, if you want to parse fields out of a map, you have to write your own wrappers to iterate over key/value pairs. Since no data is copied out of the original buffer, all the “tokens” are given as byte offsets and lengths, not null-terminated strings, so you can’t just do printf(“%s”). If you can’t (or don’t want to) malloc, it gets the job done. Not sure I’d recommend it for other applications though.
- jdougan 2y ago
  Is there a reason you can't do printf("%.*s", strlen, strptr); ?
  - jeffreygoesto 2y ago
    The terminating character is still the closing double quote and not a null, since the library does neither copy out nor alter the input. For example tiny_json replaces the closing quotes to create C strings, but that needs the full file to be in a mutable buffer which can be prohibitive for small controllers reading some config from flash only.
    - jdougan 2y ago
      With the "%.*s" format you need no null at the end. It just counts out the characters: #include <stdio.h> void main() { char buff[10] = {'R', 'o', 'b', 'o', 't', 't', 'y', 'p', 'e', 's'}; printf("=>%.*s<=", 4, ((char *)&buff + 3)); } prints =>otty<=
      - jeffreygoesto 2y ago
        Ah. Ok. Scanning the length before printing is mandatory then.
        ska 2y ago
        You have to do (a variant of) one or the other, no?
        jdougan 2y ago
        @msarnoff had already stipulated that the json lib is returning lengths: all the “tokens” are given as byte offsets and lengths
  - msarnoff 2y ago
    Yes, that’s exactly what I’ve done.

nwpierce 2y ago

Somehow I didn't run across that one in my searching - I'll check it out. I've been working on a json C library myself: https://github.com/nwpierce/jsb https://github.com/nwpierce/jsb My goal was to convert a stream of JSON to/from a binary stream that is easier to traverse and manipulate.

alex_suzuki 2y ago

Did you try cJSON? Works well for me. https://github.com/DaveGamble/cJSON https://github.com/DaveGamble/cJSON

msarnoff 2y ago

If you want to go extremely lightweight, there’s jsmn: https://github.com/zserge/jsmn https://github.com/zserge/jsmn It does no dynamic memory allocation, which is a plus in constrained IoT/embedded applications. But it’s really only a tokenizer. For example, if you want to parse fields out of a map, you have to write your own wrappers to iterate over key/value pairs. Since no data is copied out of the original buffer, all the “tokens” are given as byte offsets and lengths, not null-terminated strings, so you can’t just do printf(“%s”). If you can’t (or don’t want to) malloc, it gets the job done. Not sure I’d recommend it for other applications though.

jdougan 2y ago
Is there a reason you can't do printf("%.*s", strlen, strptr); ?
- jeffreygoesto 2y ago
  The terminating character is still the closing double quote and not a null, since the library does neither copy out nor alter the input. For example tiny_json replaces the closing quotes to create C strings, but that needs the full file to be in a mutable buffer which can be prohibitive for small controllers reading some config from flash only.
  - jdougan 2y ago
    With the "%.*s" format you need no null at the end. It just counts out the characters: #include <stdio.h> void main() { char buff[10] = {'R', 'o', 'b', 'o', 't', 't', 'y', 'p', 'e', 's'}; printf("=>%.*s<=", 4, ((char *)&buff + 3)); } prints =>otty<=
    - jeffreygoesto 2y ago
      Ah. Ok. Scanning the length before printing is mandatory then.
      - ska 2y ago
        You have to do (a variant of) one or the other, no?
      - jdougan 2y ago
        @msarnoff had already stipulated that the json lib is returning lengths: all the “tokens” are given as byte offsets and lengths
- msarnoff 2y ago
  Yes, that’s exactly what I’ve done.