1 files changed, 139 insertions, 0 deletions
diff --git a/toolkit/components/glean/build_scripts/glean_parser_ext/cpp.py b/toolkit/components/glean/build_scripts/glean_parser_ext/cpp.py
new file mode 100644
index 0000000000..003ae4997c
--- /dev/null
+++ b/toolkit/components/glean/build_scripts/glean_parser_ext/cpp.py
@@ -0,0 +1,139 @@
+# -*- coding: utf-8 -*-
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+Outputter to generate C++ code for metrics.
+"""
+
+import json
+
+import jinja2
+from glean_parser import metrics, util
+from util import generate_metric_ids, generate_ping_ids, get_metrics
+
+
+def cpp_datatypes_filter(value):
+    """
+    A Jinja2 filter that renders C++ literals.
+
+    Based on Python's JSONEncoder, but overrides:
+      - lists to array literals {}
+      - strings to "value"
+    """
+
+    class CppEncoder(json.JSONEncoder):
+        def iterencode(self, value):
+            if isinstance(value, list):
+                yield "{"
+                first = True
+                for subvalue in list(value):
+                    if not first:
+                        yield ", "
+                    yield from self.iterencode(subvalue)
+                    first = False
+                yield "}"
+            elif isinstance(value, str):
+                yield '"' + value + '"'
+            else:
+                yield from super().iterencode(value)
+
+    return "".join(CppEncoder().iterencode(value))
+
+
+def type_name(obj):
+    """
+    Returns the C++ type to use for a given metric object.
+    """
+
+    if getattr(obj, "labeled", False):
+        class_name = util.Camelize(obj.type[8:])  # strips "labeled_" off the front.
+        label_enum = "DynamicLabel"
+        if obj.labels and len(obj.labels):
+            label_enum = f"{util.Camelize(obj.name)}Label"
+        return f"Labeled<impl::{class_name}Metric, {label_enum}>"
+    generate_enums = getattr(obj, "_generate_enums", [])  # Extra Keys? Reasons?
+    if len(generate_enums):
+        for name, _ in generate_enums:
+            if not len(getattr(obj, name)) and isinstance(obj, metrics.Event):
+                return util.Camelize(obj.type) + "Metric<NoExtraKeys>"
+            else:
+                # we always use the `extra` suffix,
+                # because we only expose the new event API
+                suffix = "Extra"
+                return "{}Metric<{}>".format(
+                    util.Camelize(obj.type), util.Camelize(obj.name) + suffix
+                )
+    return util.Camelize(obj.type) + "Metric"
+
+
+def extra_type_name(typ: str) -> str:
+    """
+    Returns the corresponding Rust type for event's extra key types.
+    """
+
+    if typ == "boolean":
+        return "bool"
+    elif typ == "string":
+        return "nsCString"
+    elif typ == "quantity":
+        return "uint32_t"
+    else:
+        return "UNSUPPORTED"
+
+
+def output_cpp(objs, output_fd, options={}):
+    """
+    Given a tree of objects, output C++ code to the file-like object `output_fd`.
+
+    :param objs: A tree of objects (metrics and pings) as returned from
+    `parser.parse_objects`.
+    :param output_fd: Writeable file to write the output to.
+    :param options: options dictionary.
+    """
+
+    # Monkeypatch util.snake_case for the templates to use
+    util.snake_case = lambda value: value.replace(".", "_").replace("-", "_")
+    # Monkeypatch util.get_jinja2_template to find templates nearby
+
+    def get_local_template(template_name, filters=()):
+        env = jinja2.Environment(
+            loader=jinja2.PackageLoader("cpp", "templates"),
+            trim_blocks=True,
+            lstrip_blocks=True,
+        )
+        env.filters["camelize"] = util.camelize
+        env.filters["Camelize"] = util.Camelize
+        for filter_name, filter_func in filters:
+            env.filters[filter_name] = filter_func
+        return env.get_template(template_name)
+
+    util.get_jinja2_template = get_local_template
+    get_metric_id = generate_metric_ids(objs)
+    get_ping_id = generate_ping_ids(objs)
+
+    if "pings" in objs:
+        template_filename = "cpp_pings.jinja2"
+        if objs.get("tags"):
+            del objs["tags"]
+    else:
+        template_filename = "cpp.jinja2"
+        objs = get_metrics(objs)
+
+    template = util.get_jinja2_template(
+        template_filename,
+        filters=(
+            ("cpp", cpp_datatypes_filter),
+            ("snake_case", util.snake_case),
+            ("type_name", type_name),
+            ("extra_type_name", extra_type_name),
+            ("metric_id", get_metric_id),
+            ("ping_id", get_ping_id),
+            ("Camelize", util.Camelize),
+        ),
+    )
+
+    output_fd.write(template.render(all_objs=objs))
+    output_fd.write("\n")