add json2nix script

scripts/json2nix.py

@@ -0,0 +1,84 @@
+"""Converts JSON objects into nix (hackishly)."""
+
+import sys
+import json
+
+
+INDENT = " " * 2
+
+
+def strip_comments(t):
+    # fixme: doesn't work if JSON strings contain //
+    return "\n".join(l.partition("//")[0] for l in t.split("\n"))
+
+
+def indent(s):
+    return "\n".join(INDENT + i for i in s.split("\n"))
+
+
+def nix_stringify(s):
+    # fixme: this doesn't handle string interpolation and possibly has more bugs
+    return json.dumps(s)
+
+
+def sanitize_key(s):
+    if s and s.isalnum() and not s[0].isdigit():
+        return s
+    return nix_stringify(s)
+
+
+def flatten_obj_item(k, v):
+    keys = [k]
+    val = v
+    while isinstance(val, dict) and len(val) == 1:
+        k = next(iter(val.keys()))
+        keys.append(k)
+        val = val[k]
+    return keys, val
+
+
+def fmt_object(obj, flatten):
+    fields = []
+    for k, v in obj.items():
+        if flatten:
+            keys, val = flatten_obj_item(k, v)
+            formatted_key = ".".join(sanitize_key(i) for i in keys)
+        else:
+            formatted_key = sanitize_key(k)
+            val = v
+        fields.append(f"{formatted_key} = {fmt_any(val, flatten)};")
+
+    return "{\n" + indent("\n".join(fields)) + "\n}"
+
+
+def fmt_array(o, flatten):
+    body = indent("\n".join(fmt_any(i, flatten) for i in o))
+    return f"[\n{body}\n]"
+
+
+def fmt_any(o, flatten):
+    if isinstance(o, str) or isinstance(o, bool) or isinstance(o, int):
+        return json.dumps(o)
+    if isinstance(o, list):
+        return fmt_array(o, flatten)
+    if isinstance(o, dict):
+        return fmt_object(o, flatten)
+    raise TypeError(f"Unknown type {type(o)!r}")
+
+
+def main():
+    flatten = "--flatten" in sys.argv
+    args = [a for a in sys.argv[1:] if not a.startswith("--")]
+
+    if len(args) < 1:
+        print(f"Usage: {sys.argv[0]} [--flatten] <file.json>", file=sys.stderr)
+        sys.exit(1)
+
+    with open(args[0], "r") as f:
+        data = json.loads(strip_comments(f.read()))
+
+    print(fmt_any(data, flatten=flatten))
+
+
+if __name__ == "__main__":
+    main()