specs: switch from YAML to JSON

Fix failing CI on MacOS:

      File "/Users/runner/work/gopro-lib-node.gl/gopro-lib-node.gl/venv/lib/python3.11/site-packages/setuptools/wheel.py", line 162, in _convert_metadata
        os.rename(dist_info, egg_info)
    OSError: [Errno 66] Directory not empty: '/Users/runner/work/gopro-lib-node.gl/gopro-lib-node.gl/pynodegl/.eggs/PyYAML-6.0-py3.11-macosx-10.9-universal2.egg/PyYAML-6.0.dist-info' -> '/Users/runner/work/gopro-lib-node.gl/gopro-lib-node.gl/pynodegl/.eggs/PyYAML-6.0-py3.11-macosx-10.9-universal2.egg/EGG-INFO'

Python 3.11 works locally on Linux, so it's likely something broken in
PyYAML wheel.

Similarly, trying ruamel.yaml fails on Windows:

    ImportError: cannot import name 'YAML' from 'ruamel.yaml' (d:\a\gopro-lib-node.gl\gopro-lib-node.gl\pynodegl\.eggs\ruamel.yaml.clib-0.2.7-py3.8-win-amd64.egg\ruamel\yaml\__init__.py)

It is thus decided to simplify the build by using a JSON specs instead
of YAML.

CHANGELOG.md

@@ -11,6 +11,9 @@ Versioning](https://semver.org/spec/v2.0.0.html) for `libnodegl`.
 ### Fixed
 - Color channel difference in `ngl-diff` is now done in linear space
 
+### Changed
+- The installed `nodes.specs` is now in `JSON` instead of `YAML`
+
 ## [2022.8] [libnodegl 0.6.1] - 2022-09-22
 ### Fixed
 - Crash with specific draw time sequences in some time filtered diamond-tree

doc/dev/expl/pynodegl.md

@@ -44,7 +44,7 @@ graph
 
 ### libnodegl → nodes.specs
 
-`libnodegl` writes the [nodes.specs][specs] specifications in YAML using a
+`libnodegl` writes the [nodes.specs][specs] specifications in JSON using a
 dedicated tool ([gen_specs.c][gen-specs-c]) crawling the internal node C
 definitions.
 
@@ -59,13 +59,13 @@ generated `Makefile`) is installed on the system or targeted environment by the
 
 In its [setup.py][pynodegl-setup], `pynodegl` uses `pkg-config` to query the
 `libnodegl` installation data directory, in order to obtain the path to the
-installed `nodes.specs` file. The file is then loaded as YAML file.
+installed `nodes.specs` file. The file is then loaded as JSON file.
 
 [pynodegl-setup]: /pynodegl/setup.py
 
 ### pynodegl → nodes_def.pyx
 
-Using the loaded `nodes.specs` as YAML, `setup.py` writes the Cython code
+Using the loaded `nodes.specs` as JSON, `setup.py` writes the Cython code
 definitions into a `nodes_def.pyx` file.
 
 ### nodes_def.pyx ← Cython

libnodegl/gen_specs.c

@@ -33,23 +33,26 @@ extern const struct param_specs ngli_params_specs[];
 
 static void print_node_params(const char *name, const struct node_param *p)
 {
-    printf("%s:\n", name);
+    printf("  \"%s\": [\n", name);
     if (p) {
         while (p->key) {
-            printf("    - [%s, %s, \"%s%s%s\"]\n", p->key, ngli_params_specs[p->type].name,
+            printf("    [\"%s\", \"%s\", \"%s%s%s\"]%s\n", p->key, ngli_params_specs[p->type].name,
                    (p->flags & NGLI_PARAM_FLAG_ALLOW_LIVE_CHANGE) ? "L" : "",  /* [L]ive */
                    (p->flags & NGLI_PARAM_FLAG_ALLOW_NODE)        ? "N" : "",  /* [N]ode */
-                   (p->flags & NGLI_PARAM_FLAG_NON_NULL)          ? "M" : ""); /* [M]andatory */
+                   (p->flags & NGLI_PARAM_FLAG_NON_NULL)          ? "M" : "",  /* [M]andatory */
+                   (p + 1)->key ? "," : ""
+            );
             p++;
         }
     }
-    printf("\n");
+    printf("  ]");
 }
 
 #define CLASS_COMMALIST(type_name, cls) &cls,
 
 int main(void)
 {
+    printf("{\n");
     print_node_params("_Node", ngli_base_node_params);
 
     static const struct node_class *node_classes[] = {
@@ -74,16 +77,20 @@ int main(void)
             if (mapped_param) {
                 ngli_assert(mapped_param == p);
             } else {
+                printf(",\n");
                 print_node_params(pname, p);
                 ngli_hmap_set(params_map, c->params_id, (void *)p);
             }
-            printf("%s: %s\n\n", c->name, pname);
+            printf(",\n");
+            printf("  \"%s\": \"%s\"", c->name, pname);
             ngli_free(pname);
         } else {
+            printf(",\n");
             print_node_params(c->name, p);
         }
     }
 
     ngli_hmap_freep(&params_map);
+    printf("\n}\n");
     return 0;
 }