rust-analyzer/crates/ra_ide_api/src/completion/complete_pattern.rs

use crate::completion::{CompletionContext, Completions};

/// Completes constats and paths in patterns.
pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
    if !ctx.is_pat_binding {
        return;
    }
    // TODO: ideally, we should look at the type we are matching against and
    // suggest variants + auto-imports
    let names = ctx.resolver.all_names(ctx.db);
    for (name, res) in names.into_iter() {
        let r = res.as_ref();
        let def = match r.take_types().or(r.take_values()) {
            Some(hir::Resolution::Def(def)) => def,
            _ => continue,
        };
        match def {
            hir::ModuleDef::Enum(..)
            | hir::ModuleDef::EnumVariant(..)
            | hir::ModuleDef::Const(..)
            | hir::ModuleDef::Module(..) => (),
            _ => continue,
        }
        acc.add_resolution(ctx, name.to_string(), &res)
    }
}

#[cfg(test)]
mod tests {
    use insta::assert_debug_snapshot_matches;
    use crate::completion::{CompletionItem, CompletionKind, do_completion};

    fn complete(code: &str) -> Vec<CompletionItem> {
        do_completion(code, CompletionKind::Reference)
    }

    #[test]
    fn completes_enum_variants_and_modules() {
        let completions = complete(
            r"
            enum E { X }
            use self::E::X;
            const Z: E = E::X;
            mod m {}

            static FOO: E = E::X;
            struct Bar { f: u32 }

            fn foo() {
               match E::X {
                   <|>
               }
            }
            ",
        );
        assert_debug_snapshot_matches!(completions, @r###"[
    CompletionItem {
        label: "E",
        source_range: [246; 246),
        delete: [246; 246),
        insert: "E",
        kind: Enum
    },
    CompletionItem {
        label: "X",
        source_range: [246; 246),
        delete: [246; 246),
        insert: "X",
        kind: EnumVariant
    },
    CompletionItem {
        label: "Z",
        source_range: [246; 246),
        delete: [246; 246),
        insert: "Z",
        kind: Const
    },
    CompletionItem {
        label: "m",
        source_range: [246; 246),
        delete: [246; 246),
        insert: "m",
        kind: Module
    }
]"###);
    }
}