Factor out `pick_best_token` ide pattern into `ide_db`

9 files changed, 62 insertions, 101 deletions

diff --git a/crates/ide/src/call_hierarchy.rs b/crates/ide/src/call_hierarchy.rs
index 5cd186565..7bf35d2b3 100644
--- a/crates/ide/src/call_hierarchy.rs
+++ b/crates/ide/src/call_hierarchy.rs
@@ -3,8 +3,7 @@
 use indexmap::IndexMap;
 
 use hir::Semantics;
-use ide_db::call_info::FnCallNode;
-use ide_db::RootDatabase;
+use ide_db::{call_info::FnCallNode, RootDatabase};
 use syntax::{ast, AstNode, TextRange};
 
 use crate::{
diff --git a/crates/ide/src/doc_links.rs b/crates/ide/src/doc_links.rs
index 7ac0118fe..dfab8d313 100644
--- a/crates/ide/src/doc_links.rs
+++ b/crates/ide/src/doc_links.rs
@@ -16,11 +16,10 @@ use hir::{
 };
 use ide_db::{
     defs::{Definition, NameClass, NameRefClass},
+    helpers::pick_best_token,
     RootDatabase,
 };
-use syntax::{
-    ast, match_ast, AstNode, SyntaxKind::*, SyntaxNode, SyntaxToken, TextRange, TokenAtOffset, T,
-};
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxNode, TextRange, T};
 
 use crate::{FilePosition, Semantics};
 
@@ -102,7 +101,12 @@ pub(crate) fn external_docs(
 ) -> Option<DocumentationLink> {
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id).syntax().clone();
-    let token = pick_best(file.token_at_offset(position.offset))?;
+    let token = pick_best_token(file.token_at_offset(position.offset), |kind| match kind {
+        IDENT | INT_NUMBER => 3,
+        T!['('] | T![')'] => 2,
+        kind if kind.is_trivia() => 0,
+        _ => 1,
+    })?;
     let token = sema.descend_into_macros(token);
 
     let node = token.parent()?;
@@ -522,18 +526,6 @@ fn get_symbol_fragment(db: &dyn HirDatabase, field_or_assoc: &FieldOrAssocItem)
     })
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            IDENT | INT_NUMBER => 3,
-            T!['('] | T![')'] => 2,
-            kind if kind.is_trivia() => 0,
-            _ => 1,
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
diff --git a/crates/ide/src/expand_macro.rs b/crates/ide/src/expand_macro.rs
index 12a091ac4..854d54b71 100644
--- a/crates/ide/src/expand_macro.rs
+++ b/crates/ide/src/expand_macro.rs
@@ -1,11 +1,8 @@
 use std::iter;
 
 use hir::Semantics;
-use ide_db::RootDatabase;
-use syntax::{
-    ast, ted, AstNode, NodeOrToken, SyntaxKind, SyntaxKind::*, SyntaxNode, SyntaxToken,
-    TokenAtOffset, WalkEvent, T,
-};
+use ide_db::{helpers::pick_best_token, RootDatabase};
+use syntax::{ast, ted, AstNode, NodeOrToken, SyntaxKind, SyntaxKind::*, SyntaxNode, WalkEvent, T};
 
 use crate::FilePosition;
 
@@ -29,7 +26,10 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id);
 
-    let tok = pick_best(file.syntax().token_at_offset(position.offset))?;
+    let tok = pick_best_token(file.syntax().token_at_offset(position.offset), |kind| match kind {
+        SyntaxKind::IDENT => 1,
+        _ => 0,
+    })?;
     let mut expanded = None;
     let mut name = None;
     for node in tok.ancestors() {
@@ -57,16 +57,6 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
     Some(ExpandedMacro { name: name?, expansion })
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            IDENT => 1,
-            _ => 0,
-        }
-    }
-}
-
 fn expand_macro_recur(
     sema: &Semantics<RootDatabase>,
     macro_call: &ast::MacroCall,
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index d8e0dc4d5..df6c35780 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -5,11 +5,10 @@ use hir::{AsAssocItem, InFile, ModuleDef, Semantics};
 use ide_db::{
     base_db::{AnchoredPath, FileId, FileLoader},
     defs::{Definition, NameClass, NameRefClass},
+    helpers::pick_best_token,
     RootDatabase,
 };
-use syntax::{
-    ast, match_ast, AstNode, AstToken, SyntaxKind::*, SyntaxToken, TextRange, TokenAtOffset, T,
-};
+use syntax::{ast, match_ast, AstNode, AstToken, SyntaxKind::*, SyntaxToken, TextRange, T};
 
 use crate::{
     display::TryToNav,
@@ -34,7 +33,12 @@ pub(crate) fn goto_definition(
 ) -> Option<RangeInfo<Vec<NavigationTarget>>> {
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id).syntax().clone();
-    let original_token = pick_best(file.token_at_offset(position.offset))?;
+    let original_token =
+        pick_best_token(file.token_at_offset(position.offset), |kind| match kind {
+            IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] | COMMENT => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        })?;
     let token = sema.descend_into_macros(original_token.clone());
     let parent = token.parent()?;
     if let Some(_) = ast::Comment::cast(token.clone()) {
@@ -128,17 +132,6 @@ fn try_find_trait_item_definition(db: &RootDatabase, def: &Definition) -> Option
         .find_map(|itm| (itm.name(db)? == name).then(|| itm.try_to_nav(db)).flatten())
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] | COMMENT => 2,
-            kind if kind.is_trivia() => 0,
-            _ => 1,
-        }
-    }
-}
-
 pub(crate) fn reference_definition(
     sema: &Semantics<RootDatabase>,
     name_ref: Either<&ast::Lifetime, &ast::NameRef>,
diff --git a/crates/ide/src/goto_type_definition.rs b/crates/ide/src/goto_type_definition.rs
index 43cffefe5..6263d3d4f 100644
--- a/crates/ide/src/goto_type_definition.rs
+++ b/crates/ide/src/goto_type_definition.rs
@@ -1,6 +1,7 @@
 use ide_db::base_db::Upcast;
+use ide_db::helpers::pick_best_token;
 use ide_db::RootDatabase;
-use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, T};
 
 use crate::{display::TryToNav, FilePosition, NavigationTarget, RangeInfo};
 
@@ -22,7 +23,12 @@ pub(crate) fn goto_type_definition(
     let sema = hir::Semantics::new(db);
 
     let file: ast::SourceFile = sema.parse(position.file_id);
-    let token: SyntaxToken = pick_best(file.syntax().token_at_offset(position.offset))?;
+    let token: SyntaxToken =
+        pick_best_token(file.syntax().token_at_offset(position.offset), |kind| match kind {
+            IDENT | INT_NUMBER | T![self] => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        })?;
     let token: SyntaxToken = sema.descend_into_macros(token);
 
     let (ty, node) = sema.token_ancestors_with_macros(token).find_map(|node| {
@@ -56,17 +62,6 @@ pub(crate) fn goto_type_definition(
     Some(RangeInfo::new(node.text_range(), vec![nav]))
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            IDENT | INT_NUMBER | T![self] => 2,
-            kind if kind.is_trivia() => 0,
-            _ => 1,
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use ide_db::base_db::FileRange;
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index c6d6bb74a..0eeea4efb 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -5,16 +5,13 @@ use ide_db::{
     defs::{Definition, NameClass, NameRefClass},
     helpers::{
         generated_lints::{CLIPPY_LINTS, DEFAULT_LINTS, FEATURES},
-        FamousDefs,
+        pick_best_token, FamousDefs,
     },
     RootDatabase,
 };
 use itertools::Itertools;
 use stdx::format_to;
-use syntax::{
-    algo, ast, match_ast, AstNode, AstToken, Direction, SyntaxKind::*, SyntaxToken, TokenAtOffset,
-    T,
-};
+use syntax::{algo, ast, match_ast, AstNode, AstToken, Direction, SyntaxKind::*, SyntaxToken, T};
 
 use crate::{
     display::{macro_label, TryToNav},
@@ -80,7 +77,12 @@ pub(crate) fn hover(
 ) -> Option<RangeInfo<HoverResult>> {
     let sema = hir::Semantics::new(db);
     let file = sema.parse(position.file_id).syntax().clone();
-    let token = pick_best(file.token_at_offset(position.offset))?;
+    let token = pick_best_token(file.token_at_offset(position.offset), |kind| match kind {
+        IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] | T![super] | T![crate] => 3,
+        T!['('] | T![')'] => 2,
+        kind if kind.is_trivia() => 0,
+        _ => 1,
+    })?;
     let token = sema.descend_into_macros(token);
 
     let mut res = HoverResult::default();
@@ -519,19 +521,6 @@ fn find_std_module(famous_defs: &FamousDefs, name: &str) -> Option<hir::Module>
         .find(|module| module.name(db).map_or(false, |module| module.to_string() == name))
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] | T![super] | T![crate] => 3,
-            T!['('] | T![')'] => 2,
-            kind if kind.is_trivia() => 0,
-            _ => 1,
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index b978e36af..ca14533f3 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -439,7 +439,7 @@ impl Analysis {
         self.with_db(|db| call_hierarchy::incoming_calls(db, position))
     }
 
-    /// Computes incoming calls for the given file position.
+    /// Computes outgoing calls for the given file position.
     pub fn outgoing_calls(&self, position: FilePosition) -> Cancellable<Option<Vec<CallItem>>> {
         self.with_db(|db| call_hierarchy::outgoing_calls(db, position))
     }
diff --git a/crates/ide/src/move_item.rs b/crates/ide/src/move_item.rs
index 246f10a0a..1223c2810 100644
--- a/crates/ide/src/move_item.rs
+++ b/crates/ide/src/move_item.rs
@@ -1,12 +1,9 @@
 use std::{iter::once, mem};
 
 use hir::Semantics;
-use ide_db::{base_db::FileRange, RootDatabase};
+use ide_db::{base_db::FileRange, helpers::pick_best_token, RootDatabase};
 use itertools::Itertools;
-use syntax::{
-    algo, ast, match_ast, AstNode, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange,
-    TokenAtOffset,
-};
+use syntax::{algo, ast, match_ast, AstNode, SyntaxElement, SyntaxKind, SyntaxNode, TextRange};
 use text_edit::{TextEdit, TextEditBuilder};
 
 #[derive(Copy, Clone, Debug)]
@@ -36,7 +33,14 @@ pub(crate) fn move_item(
     let file = sema.parse(range.file_id);
 
     let item = if range.range.is_empty() {
-        SyntaxElement::Token(pick_best(file.syntax().token_at_offset(range.range.start()))?)
+        SyntaxElement::Token(pick_best_token(
+            file.syntax().token_at_offset(range.range.start()),
+            |kind| match kind {
+                SyntaxKind::IDENT | SyntaxKind::LIFETIME_IDENT => 2,
+                kind if kind.is_trivia() => 0,
+                _ => 1,
+            },
+        )?)
     } else {
         file.syntax().covering_element(range.range)
     };
@@ -170,18 +174,6 @@ fn replace_nodes<'a>(
     edit.finish()
 }
 
-fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
-    return tokens.max_by_key(priority);
-
-    fn priority(n: &SyntaxToken) -> usize {
-        match n.kind() {
-            SyntaxKind::IDENT | SyntaxKind::LIFETIME_IDENT => 2,
-            kind if kind.is_trivia() => 0,
-            _ => 1,
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use crate::fixture;
diff --git a/crates/ide_db/src/helpers.rs b/crates/ide_db/src/helpers.rs
index d96028cbc..bc21977e3 100644
--- a/crates/ide_db/src/helpers.rs
+++ b/crates/ide_db/src/helpers.rs
@@ -10,7 +10,10 @@ use std::collections::VecDeque;
 use base_db::FileId;
 use either::Either;
 use hir::{Crate, Enum, ItemInNs, MacroDef, Module, ModuleDef, Name, ScopeDef, Semantics, Trait};
-use syntax::ast::{self, make};
+use syntax::{
+    ast::{self, make},
+    SyntaxKind, SyntaxToken, TokenAtOffset,
+};
 
 use crate::RootDatabase;
 
@@ -22,6 +25,14 @@ pub fn item_name(db: &RootDatabase, item: ItemInNs) -> Option<Name> {
     }
 }
 
+/// Picks the token with the highest rank returned by the passed in function.
+pub fn pick_best_token(
+    tokens: TokenAtOffset<SyntaxToken>,
+    f: impl Fn(SyntaxKind) -> usize,
+) -> Option<SyntaxToken> {
+    tokens.max_by_key(move |t| f(t.kind()))
+}
+
 /// Converts the mod path struct into its ast representation.
 pub fn mod_path_to_ast(path: &hir::ModPath) -> ast::Path {
     let _p = profile::span("mod_path_to_ast");