From 0e82029eaac11db2dbbc01055c7d4e51496f9fd3 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Wed, 24 Dec 2025 19:40:48 -0500
Subject: [PATCH] xo-facet: facet template [WIP]

---
 codegen/abstract_facet.hpp.j2 |  40 ++++++++++++
 codegen/genfacet.py           | 115 ++++++++++++++++++++++++++++++++++
 2 files changed, 155 insertions(+)
 create mode 100644 codegen/abstract_facet.hpp.j2
 create mode 100755 codegen/genfacet.py

diff --git a/codegen/abstract_facet.hpp.j2 b/codegen/abstract_facet.hpp.j2
new file mode 100644
index 0000000..ff9c61f
--- /dev/null
+++ b/codegen/abstract_facet.hpp.j2
@@ -0,0 +1,40 @@
+/** @file {{ abstract_facet_fname }}
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [{{genfacet}}]
+ *     arguments:
+ *       --input [{{genfacet_input}}]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [{{ abstract_facet_hpp_j2 }}]
+ *  3. idl for facet methods
+ *       [{{ idl_fname }}]
+ **/
+
+#pragma once
+
+// includes (via {facet_includes})
+{% for include_fname in facet_includes %}
+#include {{include_fname}}
+{% endfor %}
+
+namespace {{facet_ns1}} {
+namespace {{facet_ns2}} {
+
+/**
+{{abstract_facet_doc}}
+**/
+class {{abstract_facet}} {
+public:
+    {% for method in methods %}
+
+    /** {{method.doc}} **/
+    virtual {{method.return_type}} {{method.name}}({{method.args | args}}) {{method | qualifiers}} = 0;
+
+    {% endfor %}
+}; /*{{abstract_facet}}*/
+
+template <typename DRepr>
+
+} /*namespace {{facet_ns2}}*/
+} /*namespace {{facet_ns1}}*/
diff --git a/codegen/genfacet.py b/codegen/genfacet.py
new file mode 100755
index 0000000..aab098f
--- /dev/null
+++ b/codegen/genfacet.py
@@ -0,0 +1,115 @@
+#! /usr/bin/env python3
+#
+# genfacet.py
+
+import json5
+import argparse
+from pathlib import Path
+from jinja2 import Environment, FileSystemLoader
+
+def load_idl(path):
+    with open(path) as f:
+        return json5.load(f)
+
+def format_method_qualifiers(method):
+    """ Build qualifier string: const noexcept
+    """
+    quals = []
+    if method.get('const', False):
+        quals.append('const')
+    if method.get('noexcept', False):
+        quals.append('noexcept')
+
+    return ' '.join(quals)
+
+def format_args(args, include_names=True):
+    """ Format argument list for a method
+    """
+    if not args:
+        return ''
+    if include_names:
+        return ', '.join(f"{p['type']} {p['name']}" for p in args)
+    else:
+        return ', '.join(p['type'] for p in args)
+
+def format_arg_names(args):
+    """ Format argument names, for forwarding
+    """
+    return ', '.join(p['name'] for p in args)
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--input', required=True, help='input IDL JSON5 file')
+    parser.add_argument('--output', required=True, help='output directory')
+    args = parser.parse_args()
+
+    idl_fname = args.input
+    idl = load_idl(idl_fname)
+    output_dir = Path(args.output)
+    output_dir.mkdir(parents=False, exist_ok=True)
+
+    # setup jinja2
+    template_dir = Path(__file__).parent
+    #template_dir = Path(__file__).parent / 'codegen'
+
+    print(f'template_dir: [{template_dir}]')
+
+    env = Environment(loader = FileSystemLoader(template_dir),
+                      trim_blocks = True,
+                      lstrip_blocks = True)
+
+    # custom filters
+    env.filters['qualifiers'] = format_method_qualifiers
+    env.filters['args'] = format_args
+    env.filters['argnames'] = format_arg_names
+
+    facet_includes = idl['includes']
+    facet_ns1 = idl['namespace1']
+    facet_ns2 = idl['namespace2']
+    facet_name = idl['facet']          # e.g. Sequence
+    facet_brief = idl['brief']
+    facet_doc = '\n'.join(idl['doc'])
+    methods = idl['methods']
+    for method in methods:
+        method['doc'] = '\n'.join(method['doc'])
+
+    abstract_facet = f'A{facet_name}'
+    abstract_facet_fname = f'{abstract_facet}.hpp'
+
+    context = {
+        'genfacet': __file__,
+        'genfacet_input': args.input,
+        #
+        'facet_includes': facet_includes,
+        'facet_ns1': facet_ns1,
+        'facet_ns2': facet_ns2,
+        #'name': facet_name,
+        'idl_fname': idl_fname,
+        #
+        'abstract_facet_hpp_j2': 'abstract_facet.hpp.j2',
+        'abstract_facet': abstract_facet,
+        'abstract_facet_fname': abstract_facet_fname,
+        'abstract_facet_doc': facet_doc,
+        #
+        'methods': methods
+    }
+
+    # generate .hpp files
+
+    templates = {}
+    templates[abstract_facet_fname] = context['abstract_facet_hpp_j2']
+
+    for output_file, template_name in templates.items():
+        print(f'output_file: [{output_file}]')
+        print(f'template_name: [{template_name}]')
+
+        template = env.get_template(template_name)
+        content = template.render(**context)
+        
+        (output_dir / output_file).write_text(content)
+        print(f"Generated {output_dir}/{output_file}")
+
+
+if __name__ == '__main__':
+    main()
+