antirez' tiny JSON selector library

Nov 27, 2023

Salvatore Sanfilippo, aka antirez released a telegram bot library in C recently. While I'm not at all interested in a telegram bot library, I always like to read Salvatore's code, which is uniformly superb.

The bit of code that caught my eye in this release is in this file, which implements a simple selector library on top of the json library he's using. In about 100 lines of code, it implements a function that parses and executes a tiny jq-like language:

/* You can select things like this:
 * cJSON *json = cJSON_Parse(myjson_string);
 * cJSON *width = cJSON_Select(json,".features.screens[*].width",4);
 * cJSON *height = cJSON_Select(json,".features.screens[4].*","height");
 * cJSON *price = cJSON_Select(json,".features.screens[4].price_*",
 *                  price_type == EUR ? "eur" : "usd");

It's a really nice example of just how simple you can make a parser for a tiny language.

I think it'd be fun to re-implement this in another language to understand it better, and I might give it a go at some point.

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