1 files changed, 123 insertions, 0 deletions
diff --git a/src/gen/well_known_types.rs b/src/gen/well_known_types.rs
new file mode 100644
index 0000000..6b0b389
--- /dev/null
+++ b/src/gen/well_known_types.rs
@@ -0,0 +1,123 @@
+use protobuf_parse::ProtobufAbsPath;
+use protobuf_parse::ProtobufRelPath;
+use protobuf_parse::ProtobufRelPathRef;
+
+use crate::compiler_plugin;
+use crate::gen::code_writer::CodeWriter;
+use crate::gen::paths::proto_path_to_rust_mod;
+
+pub(crate) static WELL_KNOWN_TYPES_PROTO_FILE_NAMES: &[&str] = &[
+    "any.proto",
+    "api.proto",
+    "duration.proto",
+    "empty.proto",
+    "field_mask.proto",
+    "source_context.proto",
+    "struct.proto",
+    "timestamp.proto",
+    "type.proto",
+    "wrappers.proto",
+];
+
+pub(crate) static WELL_KNOWN_TYPES_PROTO_FILE_FULL_NAMES: &[&str] = &[
+    "google/protobuf/any.proto",
+    "google/protobuf/api.proto",
+    "google/protobuf/duration.proto",
+    "google/protobuf/empty.proto",
+    "google/protobuf/field_mask.proto",
+    "google/protobuf/source_context.proto",
+    "google/protobuf/struct.proto",
+    "google/protobuf/timestamp.proto",
+    "google/protobuf/type.proto",
+    "google/protobuf/wrappers.proto",
+];
+
+static NAMES: &'static [&'static str] = &[
+    "Any",
+    "Api",
+    "BoolValue",
+    "BytesValue",
+    "DoubleValue",
+    "Duration",
+    "Empty",
+    "Enum",
+    "EnumValue",
+    "Field",
+    "Field.Cardinality",
+    "Field.Kind",
+    "FieldMask",
+    "FloatValue",
+    "Int32Value",
+    "Int64Value",
+    "ListValue",
+    "Method",
+    "Mixin",
+    "NullValue",
+    "Option",
+    "SourceContext",
+    "StringValue",
+    "Struct",
+    "Syntax",
+    "Timestamp",
+    "Type",
+    "UInt32Value",
+    "UInt64Value",
+    "Value",
+];
+
+fn is_well_known_type(name: &ProtobufRelPathRef) -> bool {
+    NAMES.iter().any(|&n| n == format!("{}", name))
+}
+
+pub(crate) fn is_well_known_type_full(name: &ProtobufAbsPath) -> Option<ProtobufRelPath> {
+    if let Some(rem) = name.remove_prefix(&ProtobufAbsPath::from(".google.protobuf")) {
+        if is_well_known_type(rem) {
+            Some(rem.to_owned())
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+pub(crate) fn gen_well_known_types_mod() -> compiler_plugin::GenResult {
+    let v = CodeWriter::with_no_error(|w| {
+        w.comment("This file is generated. Do not edit");
+        w.comment("@generated");
+        w.mod_doc("Generated code for \"well known types\"");
+        w.mod_doc("");
+        w.mod_doc("[This document](https://developers.google.com/protocol-buffers/docs/reference/google.protobuf) describes these types.");
+
+        w.write_line("");
+        w.write_line("#![allow(unused_attributes)]");
+        w.write_line("#![cfg_attr(rustfmt, rustfmt::skip)]");
+
+        w.write_line("");
+        for m in WELL_KNOWN_TYPES_PROTO_FILE_NAMES {
+            w.write_line(&format!("pub mod {};", proto_path_to_rust_mod(m)));
+        }
+    });
+
+    compiler_plugin::GenResult {
+        name: "well_known_types_mod.rs".to_string(),
+        content: v.into_bytes(),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_is_well_known_type_full() {
+        assert_eq!(
+            Some(ProtobufRelPath::from("BoolValue")),
+            is_well_known_type_full(&ProtobufAbsPath::from(".google.protobuf.BoolValue"))
+        );
+        assert_eq!(
+            None,
+            is_well_known_type_full(&ProtobufAbsPath::from(".google.protobuf.Fgfg"))
+        );
+    }
+}