add a flag for generating variant traits for flags/enums

book/src/config_api.md

@@ -24,6 +24,13 @@ single_version_file = true
 # which do not have an override for `generate_display_trait`
 # (defaults to "true")
 generate_display_trait = true
+# Generation of Variant serialization traits enabled for all enums and flags which do not
+# have an override for `generate_variant_traits`. Generates traits for StaticVariantType,
+# ToVariant, FromVariant, and Into<Variant>. Can be "none" to skip generating traits,
+# "repr" to serialize to INT (for enums) and UINT (for flags), or "string" to serialize to
+# string values.
+# (defaults to "none")
+generate_variant_traits = "repr"
 # Trust the nullability information about return values. If this is disabled
 # then any pointer return type is assumed to be nullable unless there is an
 # explicit override for it.
@@ -110,6 +117,8 @@ version = "3.12"
 cfg_condition = "mycond"
 # if you want to override default option Ex. for write your own Display implementation
 generate_display_trait = false
+# if you want to override default option Ex. for write your own Variant serialization
+generate_variant_traits = "none"
 # if you want to generate builder with name SomeClassBuilder
 generate_builder = true
 # trust return value nullability annotations for this specific type.

src/codegen/enums.rs

@@ -13,9 +13,9 @@ use crate::{
             cfg_deprecated, derives, doc_alias, version_condition, version_condition_no_doc,
             version_condition_string,
         },
-        generate_default_impl,
+        generate_default_impl, generate_variant_impls,
     },
-    config::gobjects::GObject,
+    config::{config::VariantTraitMode, gobjects::GObject},
     env::Env,
     file_saver,
     library::*,
@@ -387,14 +387,14 @@ impl FromGlib<{sys_crate_name}::{ffi_name}> for {name} {{
         )?;
     }
 
+    let configured_functions = config.functions.matched("get_type");
+    let version = std::iter::once(enum_.version)
+        .chain(configured_functions.iter().map(|f| f.version))
+        .max()
+        .flatten();
+
     // Generate StaticType trait implementation.
     if let Some(ref get_type) = enum_.glib_get_type {
-        let configured_functions = config.functions.matched("get_type");
-        let version = std::iter::once(enum_.version)
-            .chain(configured_functions.iter().map(|f| f.version))
-            .max()
-            .flatten();
-
         version_condition(w, env, None, version, false, 0)?;
         cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
         allow_deprecated(w, enum_.deprecated_version, false, 0)?;
@@ -506,5 +506,47 @@ impl FromGlib<{sys_crate_name}::{ffi_name}> for {name} {{
         },
     )?;
 
+    match config.generate_variant_traits {
+        VariantTraitMode::Repr => generate_variant_impls(
+            w,
+            env,
+            config,
+            &enum_.name,
+            version,
+            enum_.deprecated_version,
+            "i",
+            "match unsafe { FromGlib::from_glib(variant.get::<i32>()?) } {
+            Self::__Unknown(_) => None,
+            value => Some(value),
+        }",
+            "self.into_glib().to_variant()",
+        )?,
+        VariantTraitMode::String => {
+            let enumclass = use_glib_type(env, "EnumClass");
+            generate_variant_impls(
+                w,
+                env,
+                config,
+                &enum_.name,
+                version,
+                enum_.deprecated_version,
+                "s",
+                &format!(
+                    "if !variant.is::<String>() {{
+            return None;
+        }}
+        let enum_class = {enumclass}::new(<Self as StaticType>::static_type()).unwrap();
+        let value = enum_class.value_by_nick(variant.str()?)?.value();
+        Some(unsafe {{ FromGlib::from_glib(value) }})",
+                        ),
+                &format!(
+                    "let enum_class = {enumclass}::new(<Self as StaticType>::static_type()).unwrap();
+        enum_class.value(self.into_glib()).unwrap().nick().to_variant()",
+                        )
+            )?
+        }
+        _ => {}
+    }
+
     Ok(())
 }

src/codegen/flags.rs

@@ -12,9 +12,9 @@ use crate::{
             cfg_deprecated, derives, doc_alias, version_condition, version_condition_doc,
             version_condition_no_doc, version_condition_string,
         },
-        generate_default_impl,
+        generate_default_impl, generate_variant_impls,
     },
-    config::gobjects::GObject,
+    config::{config::VariantTraitMode, gobjects::GObject},
     env::Env,
     file_saver,
     library::*,
@@ -258,13 +258,13 @@ impl FromGlib<{sys_crate_name}::{ffi_name}> for {name} {{
         assert = assert
     )?;
 
-    if let Some(ref get_type) = flags.glib_get_type {
-        let configured_functions = config.functions.matched("get_type");
-        let version = std::iter::once(flags.version)
-            .chain(configured_functions.iter().map(|f| f.version))
-            .max()
-            .flatten();
+    let configured_functions = config.functions.matched("get_type");
+    let version = std::iter::once(flags.version)
+        .chain(configured_functions.iter().map(|f| f.version))
+        .max()
+        .flatten();
 
+    if let Some(ref get_type) = flags.glib_get_type {
         version_condition(w, env, None, version, false, 0)?;
         cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
         allow_deprecated(w, flags.deprecated_version, false, 0)?;
@@ -357,5 +357,43 @@ impl FromGlib<{sys_crate_name}::{ffi_name}> for {name} {{
         writeln!(w)?;
     }
 
+    match config.generate_variant_traits {
+        VariantTraitMode::Repr => generate_variant_impls(
+            w,
+            env,
+            config,
+            &flags.name,
+            version,
+            flags.deprecated_version,
+            "u",
+            "Some(Self::from_bits(variant.get::<u32>()?)?)",
+            "self.into_glib().to_variant()",
+        )?,
+        VariantTraitMode::String => {
+            let flagsclass = use_glib_type(env, "FlagsClass");
+            generate_variant_impls(
+                w,
+                env,
+                config,
+                &flags.name,
+                version,
+                flags.deprecated_version,
+                "s",
+                &format!(
+                    "if !variant.is::<String>() {{
+            return None;
+        }}
+        let flags_class = {flagsclass}::new(<Self as StaticType>::static_type()).unwrap();
+        Self::from_bits(flags_class.from_nick_string(variant.str()?).ok()?)",
+                        ),
+                &format!(
+                    "let flags_class = {flagsclass}::new(<Self as StaticType>::static_type()).unwrap();
+        flags_class.to_nick_string(self.into_glib()).to_variant()",
+                        )
+            )?
+        }
+        _ => {}
+    }
+
     Ok(())
 }

src/codegen/mod.rs

@@ -11,6 +11,7 @@ use crate::{
     env::Env,
     file_saver::*,
     library::Member,
+    nameutil::use_glib_type,
     version::Version,
 };
 
@@ -43,6 +44,8 @@ mod trampoline;
 mod trampoline_from_glib;
 mod visibility;
 pub use visibility::Visibility;
+
+use self::general::{allow_deprecated, cfg_condition_no_doc};
 mod trampoline_to_glib;
 pub mod translate_from_glib;
 pub mod translate_to_glib;
@@ -168,3 +171,82 @@ pub fn generate_default_impl<
         Ok(())
     }
 }
+
+pub fn generate_variant_impls(
+    w: &mut dyn Write,
+    env: &Env,
+    config: &GObject,
+    type_name: &str,
+    type_version: Option<Version>,
+    deprecated_version: Option<Version>,
+    static_variant_type_str: &str,
+    from_variant_impl: &str,
+    to_variant_impl: &str,
+) -> Result<()> {
+    let assert = if env.config.generate_safety_asserts {
+        "skip_assert_initialized!();\n\t\t"
+    } else {
+        ""
+    };
+    let gvariant = use_glib_type(env, "Variant");
+    let tovariant = use_glib_type(env, "ToVariant");
+
+    version_condition(w, env, None, type_version, false, 0)?;
+    cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
+    allow_deprecated(w, deprecated_version, false, 0)?;
+    writeln!(
+        w,
+        "impl {staticvarianttype} for {type_name} {{
+    fn static_variant_type() -> std::borrow::Cow<'static, {variantty}> {{
+        {assert}std::borrow::Cow::Borrowed(unsafe {{
+            {variantty}::from_str_unchecked(\"{static_variant_type_str}\")
+        }})
+    }}
+}}",
+        staticvarianttype = use_glib_type(env, "StaticVariantType"),
+        variantty = use_glib_type(env, "VariantTy"),
+    )?;
+    writeln!(w)?;
+
+    version_condition(w, env, None, type_version, false, 0)?;
+    cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
+    allow_deprecated(w, deprecated_version, false, 0)?;
+    writeln!(
+        w,
+        "impl {fromvariant} for {type_name} {{
+    fn from_variant(variant: &{gvariant}) -> Option<Self> {{
+        {assert}{from_variant_impl}
+    }}
+}}",
+        fromvariant = use_glib_type(env, "FromVariant"),
+    )?;
+    writeln!(w)?;
+
+    version_condition(w, env, None, type_version, false, 0)?;
+    cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
+    allow_deprecated(w, deprecated_version, false, 0)?;
+    writeln!(
+        w,
+        "impl {tovariant} for {type_name} {{
+    fn to_variant(&self) -> {gvariant} {{
+        {assert}{to_variant_impl}
+    }}
+}}"
+    )?;
+    writeln!(w)?;
+
+    version_condition(w, env, None, type_version, false, 0)?;
+    cfg_condition_no_doc(w, config.cfg_condition.as_ref(), false, 0)?;
+    allow_deprecated(w, deprecated_version, false, 0)?;
+    writeln!(
+        w,
+        "impl From<{type_name}> for {gvariant} {{
+    fn from(v: {type_name}) -> Self {{
+        {assert}{tovariant}::to_variant(&v)
+    }}
+}}",
+    )?;
+    writeln!(w)?;
+
+    Ok(())
+}

src/config/config.rs

@@ -90,6 +90,38 @@ impl GirVersion {
     }
 }
 
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
+pub enum VariantTraitMode {
+    #[default]
+    None,
+    Repr,
+    String,
+}
+
+impl VariantTraitMode {
+    pub fn is_none(self) -> bool {
+        self == Self::None
+    }
+    pub fn is_repr(self) -> bool {
+        self == Self::Repr
+    }
+    pub fn is_string(self) -> bool {
+        self == Self::String
+    }
+}
+
+impl FromStr for VariantTraitMode {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "none" => Ok(Self::None),
+            "repr" => Ok(Self::Repr),
+            "string" => Ok(Self::String),
+            e => Err(format!("Wrong variant trait mode: \"{}\"", e)),
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct Config {
     pub work_mode: WorkMode,
@@ -113,6 +145,7 @@ pub struct Config {
     pub concurrency: library::Concurrency,
     pub single_version_file: Option<PathBuf>,
     pub generate_display_trait: bool,
+    pub generate_variant_traits: VariantTraitMode,
     pub trust_return_value_nullability: bool,
     pub docs_rs_features: Vec<String>,
     pub disable_format: bool,
@@ -255,6 +288,13 @@ impl Config {
             None => true,
         };
 
+        let generate_variant_traits = match toml.lookup("options.generate_variant_traits") {
+            Some(v) => v
+                .as_result_str("options.generate_variant_traits")?
+                .parse()?,
+            None => Default::default(),
+        };
+
         let trust_return_value_nullability =
             match toml.lookup("options.trust_return_value_nullability") {
                 Some(v) => v.as_result_bool("options.trust_return_value_nullability")?,
@@ -281,6 +321,7 @@ impl Config {
                     t,
                     concurrency,
                     generate_display_trait,
+                    generate_variant_traits,
                     generate_builder,
                     trust_return_value_nullability,
                 )
@@ -291,6 +332,7 @@ impl Config {
             &toml,
             concurrency,
             generate_display_trait,
+            generate_variant_traits,
             generate_builder,
             trust_return_value_nullability,
         );
@@ -367,6 +409,7 @@ impl Config {
             concurrency,
             single_version_file,
             generate_display_trait,
+            generate_variant_traits,
             trust_return_value_nullability,
             docs_rs_features,
             disable_format,