crates/ide_completion/src/completions/attribute/derive.rs

   1 //! Completion for derives
   2 use hir::{HasAttrs, MacroDef, MacroKind};
   3 use ide_db::helpers::FamousDefs;
   4 use itertools::Itertools;
   5 use rustc_hash::FxHashSet;
   6 use syntax::ast;
   7
   8 use crate::{
   9     context::CompletionContext,
  10     item::{CompletionItem, CompletionItemKind, CompletionKind},
  11     Completions,
  12 };
  13
  14 pub(super) fn complete_derive(
  15     acc: &mut Completions,
  16     ctx: &CompletionContext,
  17     existing_derives: &[ast::Path],
  18 ) {
  19     let core = FamousDefs(&ctx.sema, ctx.krate).core();
  20     let existing_derives: FxHashSet<_> = existing_derives
  21         .into_iter()
  22         .filter_map(|path| ctx.scope.speculative_resolve_as_mac(&path))
  23         .filter(|mac| mac.kind() == MacroKind::Derive)
  24         .collect();
  25
  26     for (name, mac) in get_derives_in_scope(ctx) {
  27         if existing_derives.contains(&mac) {
  28             continue;
  29         }
  30
  31         let name = name.to_smol_str();
  32         let label;
  33         let (label, lookup) = match core.zip(mac.module(ctx.db).map(|it| it.krate())) {
  34             // show derive dependencies for `core`/`std` derives
  35             Some((core, mac_krate)) if core == mac_krate => {
  36                 if let Some(derive_completion) = DEFAULT_DERIVE_DEPENDENCIES
  37                     .iter()
  38                     .find(|derive_completion| derive_completion.label == name)
  39                 {
  40                     let mut components = vec![derive_completion.label];
  41                     components.extend(derive_completion.dependencies.iter().filter(
  42                         |&&dependency| {
  43                             !existing_derives
  44                                 .iter()
  45                                 .filter_map(|it| it.name(ctx.db))
  46                                 .any(|it| it.to_smol_str() == dependency)
  47                         },
  48                     ));
  49                     let lookup = components.join(", ");
  50                     label = components.iter().rev().join(", ");
  51                     (label.as_str(), Some(lookup))
  52                 } else {
  53                     (&*name, None)
  54                 }
  55             }
  56             _ => (&*name, None),
  57         };
  58
  59         let mut item = CompletionItem::new(CompletionKind::Attribute, ctx.source_range(), label);
  60         item.kind(CompletionItemKind::Attribute);
  61         if let Some(docs) = mac.docs(ctx.db) {
  62             item.documentation(docs);
  63         }
  64         if let Some(lookup) = lookup {
  65             item.lookup_by(lookup);
  66         }
  67         item.add_to(acc);
  68     }
  69 }
  70
  71 fn get_derives_in_scope(ctx: &CompletionContext) -> Vec<(hir::Name, MacroDef)> {
  72     let mut result = Vec::default();
  73     ctx.process_all_names(&mut |name, scope_def| {
  74         if let hir::ScopeDef::MacroDef(mac) = scope_def {
  75             if mac.kind() == hir::MacroKind::Derive {
  76                 result.push((name, mac));
  77             }
  78         }
  79     });
  80     result
  81 }
  82
  83 struct DeriveDependencies {
  84     label: &'static str,
  85     dependencies: &'static [&'static str],
  86 }
  87
  88 /// Standard Rust derives that have dependencies
  89 /// (the dependencies are needed so that the main derive don't break the compilation when added)
  90 const DEFAULT_DERIVE_DEPENDENCIES: &[DeriveDependencies] = &[
  91     DeriveDependencies { label: "Copy", dependencies: &["Clone"] },
  92     DeriveDependencies { label: "Eq", dependencies: &["PartialEq"] },
  93     DeriveDependencies { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
  94     DeriveDependencies { label: "PartialOrd", dependencies: &["PartialEq"] },
  95 ];