tools/fidl/fidlgen_rust/codegen/union.tmpl

{{/*
// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
*/}}

{{- define "UnionDeclaration" }}
{{- range .DocComments }}
///{{ . }}
{{- end }}
{{- if .IsFlexible }}
{{ .Derives.RemoveCustom "PartialEq" }}
{{- else }}
{{ .Derives }}
{{- end }}
pub enum {{ .Name }} {
    {{- range .Members }}
    {{- range .DocComments }}
    ///{{ . }}
    {{- end }}
    {{ .Name }}({{ .Type.Owned }}),
    {{- end }}
    {{- if .IsFlexible }}
    #[deprecated = "Use `{{ .Name }}::unknown()` to construct and `{{ .Name }}Unknown!()` to exhaustively match."]
    #[doc(hidden)]
    #[non_exhaustive]
    __Unknown {
        ordinal: u64,
    },
    {{- end }}
}

{{- if .IsFlexible }}
/// Pattern that matches an unknown `{{ .Name }}` member.
#[macro_export]
macro_rules! {{ .Name }}Unknown {
    () => { _ };
}

// Custom PartialEq so that unknown variants are not equal to themselves.
impl PartialEq for {{ .Name }} {
    fn eq(&self, other: &Self) -> bool {
        match (self, other) {
            {{- range .Members }}
            (Self::{{ .Name }}(x), Self::{{ .Name }}(y)) => *x == *y,
            {{- end }}
            _ => false,
        }
    }
}
{{- end }}

impl {{ .Name }} {
    #[inline]
    pub fn ordinal(&self) -> u64 {
        match *self {
{{- range .Members }}
            Self::{{ .Name }}(_) => {{ .Ordinal }},
{{- end }}
{{- if .IsFlexible }}
            #[allow(deprecated)]
            Self::__Unknown { ordinal } => ordinal,
{{- end }}
        }
    }

{{- if .IsStrict }}
    #[deprecated = "Strict unions should not use `is_unknown`"]
    #[inline]
    pub fn is_unknown(&self) -> bool {
        false
    }
{{- end }}

{{- if .IsFlexible }}
    #[inline]
    pub fn unknown_variant_for_testing() -> Self {
        #[allow(deprecated)]
        Self::__Unknown { ordinal: 0 }
    }

    #[inline]
    pub fn is_unknown(&self) -> bool {
        match self {
            #[allow(deprecated)]
            Self::__Unknown { .. } => true,
            {{- if .Members }}
            _ => false,
            {{- end }}
        }
    }
{{- end }}
}

{{- if .IsResourceType }}
impl fidl::Standalone for {{ .Name }} {}
{{- else }}
impl fidl::Persistable for {{ .Name }} {}
{{- end }}

fidl_union! {
    name: {{ .Name }},
    {{- if .IsResourceType }}
    resource: true,
    {{- end }}
    members: [
    {{- range .Members }}
        {{ .Name }} {
            ty: {{ .Type.Fidl }},
            {{- if .Type.IsResourceType }}
            resource: true,
            {{- end }}
            ordinal: {{ .Ordinal }},
        },
    {{- end }}
    ],
    {{- if .IsFlexible }}
    unknown_member: __Unknown,
    {{- end }}
}
{{- end }}