1 //! See [`AssistContext`]. 2 3 use std::mem; 4 5 use hir::Semantics; 6 use ide_db::{ 7 base_db::{AnchoredPathBuf, FileId, FileRange}, 8 helpers::SnippetCap, 9 }; 10 use ide_db::{ 11 label::Label, 12 source_change::{FileSystemEdit, SourceChange}, 13 RootDatabase, 14 }; 15 use syntax::{ 16 algo::{self, find_node_at_offset, find_node_at_range}, 17 AstNode, AstToken, Direction, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxNodePtr, 18 SyntaxToken, TextRange, TextSize, TokenAtOffset, 19 }; 20 use text_edit::{TextEdit, TextEditBuilder}; 21 22 use crate::{ 23 assist_config::AssistConfig, Assist, AssistId, AssistKind, AssistResolveStrategy, GroupLabel, 24 }; 25 26 /// `AssistContext` allows to apply an assist or check if it could be applied. 27 /// 28 /// Assists use a somewhat over-engineered approach, given the current needs. 29 /// The assists workflow consists of two phases. In the first phase, a user asks 30 /// for the list of available assists. In the second phase, the user picks a 31 /// particular assist and it gets applied. 32 /// 33 /// There are two peculiarities here: 34 /// 35 /// * first, we ideally avoid computing more things then necessary to answer "is 36 /// assist applicable" in the first phase. 37 /// * second, when we are applying assist, we don't have a guarantee that there 38 /// weren't any changes between the point when user asked for assists and when 39 /// they applied a particular assist. So, when applying assist, we need to do 40 /// all the checks from scratch. 41 /// 42 /// To avoid repeating the same code twice for both "check" and "apply" 43 /// functions, we use an approach reminiscent of that of Django's function based 44 /// views dealing with forms. Each assist receives a runtime parameter, 45 /// `resolve`. It first check if an edit is applicable (potentially computing 46 /// info required to compute the actual edit). If it is applicable, and 47 /// `resolve` is `true`, it then computes the actual edit. 48 /// 49 /// So, to implement the original assists workflow, we can first apply each edit 50 /// with `resolve = false`, and then applying the selected edit again, with 51 /// `resolve = true` this time. 52 /// 53 /// Note, however, that we don't actually use such two-phase logic at the 54 /// moment, because the LSP API is pretty awkward in this place, and it's much 55 /// easier to just compute the edit eagerly :-) 56 pub(crate) struct AssistContext<'a> { 57 pub(crate) config: &'a AssistConfig, 58 pub(crate) sema: Semantics<'a, RootDatabase>, 59 frange: FileRange, 60 trimmed_range: TextRange, 61 source_file: SourceFile, 62 } 63 64 impl<'a> AssistContext<'a> { new( sema: Semantics<'a, RootDatabase>, config: &'a AssistConfig, frange: FileRange, ) -> AssistContext<'a>65 pub(crate) fn new( 66 sema: Semantics<'a, RootDatabase>, 67 config: &'a AssistConfig, 68 frange: FileRange, 69 ) -> AssistContext<'a> { 70 let source_file = sema.parse(frange.file_id); 71 72 let start = frange.range.start(); 73 let end = frange.range.end(); 74 let left = source_file.syntax().token_at_offset(start); 75 let right = source_file.syntax().token_at_offset(end); 76 let left = 77 left.right_biased().and_then(|t| algo::skip_whitespace_token(t, Direction::Next)); 78 let right = 79 right.left_biased().and_then(|t| algo::skip_whitespace_token(t, Direction::Prev)); 80 let left = left.map(|t| t.text_range().start().clamp(start, end)); 81 let right = right.map(|t| t.text_range().end().clamp(start, end)); 82 83 let trimmed_range = match (left, right) { 84 (Some(left), Some(right)) if left <= right => TextRange::new(left, right), 85 // Selection solely consists of whitespace so just fall back to the original 86 _ => frange.range, 87 }; 88 89 AssistContext { config, sema, frange, source_file, trimmed_range } 90 } 91 db(&self) -> &RootDatabase92 pub(crate) fn db(&self) -> &RootDatabase { 93 self.sema.db 94 } 95 96 // NB, this ignores active selection. offset(&self) -> TextSize97 pub(crate) fn offset(&self) -> TextSize { 98 self.frange.range.start() 99 } 100 file_id(&self) -> FileId101 pub(crate) fn file_id(&self) -> FileId { 102 self.frange.file_id 103 } 104 has_empty_selection(&self) -> bool105 pub(crate) fn has_empty_selection(&self) -> bool { 106 self.trimmed_range.is_empty() 107 } 108 109 /// Returns the selected range trimmed for whitespace tokens, that is the range will be snapped 110 /// to the nearest enclosed token. selection_trimmed(&self) -> TextRange111 pub(crate) fn selection_trimmed(&self) -> TextRange { 112 self.trimmed_range 113 } 114 token_at_offset(&self) -> TokenAtOffset<SyntaxToken>115 pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> { 116 self.source_file.syntax().token_at_offset(self.offset()) 117 } find_token_syntax_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken>118 pub(crate) fn find_token_syntax_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> { 119 self.token_at_offset().find(|it| it.kind() == kind) 120 } find_token_at_offset<T: AstToken>(&self) -> Option<T>121 pub(crate) fn find_token_at_offset<T: AstToken>(&self) -> Option<T> { 122 self.token_at_offset().find_map(T::cast) 123 } find_node_at_offset<N: AstNode>(&self) -> Option<N>124 pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> { 125 find_node_at_offset(self.source_file.syntax(), self.offset()) 126 } find_node_at_range<N: AstNode>(&self) -> Option<N>127 pub(crate) fn find_node_at_range<N: AstNode>(&self) -> Option<N> { 128 find_node_at_range(self.source_file.syntax(), self.trimmed_range) 129 } find_node_at_offset_with_descend<N: AstNode>(&self) -> Option<N>130 pub(crate) fn find_node_at_offset_with_descend<N: AstNode>(&self) -> Option<N> { 131 self.sema.find_node_at_offset_with_descend(self.source_file.syntax(), self.offset()) 132 } 133 /// Returns the element covered by the selection range, this excludes trailing whitespace in the selection. covering_element(&self) -> SyntaxElement134 pub(crate) fn covering_element(&self) -> SyntaxElement { 135 self.source_file.syntax().covering_element(self.selection_trimmed()) 136 } 137 } 138 139 pub(crate) struct Assists { 140 file: FileId, 141 resolve: AssistResolveStrategy, 142 buf: Vec<Assist>, 143 allowed: Option<Vec<AssistKind>>, 144 } 145 146 impl Assists { new(ctx: &AssistContext, resolve: AssistResolveStrategy) -> Assists147 pub(crate) fn new(ctx: &AssistContext, resolve: AssistResolveStrategy) -> Assists { 148 Assists { 149 resolve, 150 file: ctx.frange.file_id, 151 buf: Vec::new(), 152 allowed: ctx.config.allowed.clone(), 153 } 154 } 155 finish(mut self) -> Vec<Assist>156 pub(crate) fn finish(mut self) -> Vec<Assist> { 157 self.buf.sort_by_key(|assist| assist.target.len()); 158 self.buf 159 } 160 add( &mut self, id: AssistId, label: impl Into<String>, target: TextRange, f: impl FnOnce(&mut AssistBuilder), ) -> Option<()>161 pub(crate) fn add( 162 &mut self, 163 id: AssistId, 164 label: impl Into<String>, 165 target: TextRange, 166 f: impl FnOnce(&mut AssistBuilder), 167 ) -> Option<()> { 168 let mut f = Some(f); 169 self.add_impl(None, id, label.into(), target, &mut |it| f.take().unwrap()(it)) 170 } 171 add_group( &mut self, group: &GroupLabel, id: AssistId, label: impl Into<String>, target: TextRange, f: impl FnOnce(&mut AssistBuilder), ) -> Option<()>172 pub(crate) fn add_group( 173 &mut self, 174 group: &GroupLabel, 175 id: AssistId, 176 label: impl Into<String>, 177 target: TextRange, 178 f: impl FnOnce(&mut AssistBuilder), 179 ) -> Option<()> { 180 let mut f = Some(f); 181 self.add_impl(Some(group), id, label.into(), target, &mut |it| f.take().unwrap()(it)) 182 } 183 add_impl( &mut self, group: Option<&GroupLabel>, id: AssistId, label: String, target: TextRange, f: &mut dyn FnMut(&mut AssistBuilder), ) -> Option<()>184 fn add_impl( 185 &mut self, 186 group: Option<&GroupLabel>, 187 id: AssistId, 188 label: String, 189 target: TextRange, 190 f: &mut dyn FnMut(&mut AssistBuilder), 191 ) -> Option<()> { 192 if !self.is_allowed(&id) { 193 return None; 194 } 195 196 let source_change = if self.resolve.should_resolve(&id) { 197 let mut builder = AssistBuilder::new(self.file); 198 f(&mut builder); 199 Some(builder.finish()) 200 } else { 201 None 202 }; 203 204 let label = Label::new(label); 205 let group = group.cloned(); 206 self.buf.push(Assist { id, label, group, target, source_change }); 207 Some(()) 208 } 209 is_allowed(&self, id: &AssistId) -> bool210 fn is_allowed(&self, id: &AssistId) -> bool { 211 match &self.allowed { 212 Some(allowed) => allowed.iter().any(|kind| kind.contains(id.1)), 213 None => true, 214 } 215 } 216 } 217 218 pub(crate) struct AssistBuilder { 219 edit: TextEditBuilder, 220 file_id: FileId, 221 source_change: SourceChange, 222 223 /// Maps the original, immutable `SyntaxNode` to a `clone_for_update` twin. 224 mutated_tree: Option<TreeMutator>, 225 } 226 227 pub(crate) struct TreeMutator { 228 immutable: SyntaxNode, 229 mutable_clone: SyntaxNode, 230 } 231 232 impl TreeMutator { new(immutable: &SyntaxNode) -> TreeMutator233 pub(crate) fn new(immutable: &SyntaxNode) -> TreeMutator { 234 let immutable = immutable.ancestors().last().unwrap(); 235 let mutable_clone = immutable.clone_for_update(); 236 TreeMutator { immutable, mutable_clone } 237 } 238 make_mut<N: AstNode>(&self, node: &N) -> N239 pub(crate) fn make_mut<N: AstNode>(&self, node: &N) -> N { 240 N::cast(self.make_syntax_mut(node.syntax())).unwrap() 241 } 242 make_syntax_mut(&self, node: &SyntaxNode) -> SyntaxNode243 pub(crate) fn make_syntax_mut(&self, node: &SyntaxNode) -> SyntaxNode { 244 let ptr = SyntaxNodePtr::new(node); 245 ptr.to_node(&self.mutable_clone) 246 } 247 } 248 249 impl AssistBuilder { new(file_id: FileId) -> AssistBuilder250 pub(crate) fn new(file_id: FileId) -> AssistBuilder { 251 AssistBuilder { 252 edit: TextEdit::builder(), 253 file_id, 254 source_change: SourceChange::default(), 255 mutated_tree: None, 256 } 257 } 258 edit_file(&mut self, file_id: FileId)259 pub(crate) fn edit_file(&mut self, file_id: FileId) { 260 self.commit(); 261 self.file_id = file_id; 262 } 263 commit(&mut self)264 fn commit(&mut self) { 265 if let Some(tm) = self.mutated_tree.take() { 266 algo::diff(&tm.immutable, &tm.mutable_clone).into_text_edit(&mut self.edit) 267 } 268 269 let edit = mem::take(&mut self.edit).finish(); 270 if !edit.is_empty() { 271 self.source_change.insert_source_edit(self.file_id, edit); 272 } 273 } 274 make_mut<N: AstNode>(&mut self, node: N) -> N275 pub(crate) fn make_mut<N: AstNode>(&mut self, node: N) -> N { 276 self.mutated_tree.get_or_insert_with(|| TreeMutator::new(node.syntax())).make_mut(&node) 277 } 278 /// Returns a copy of the `node`, suitable for mutation. 279 /// 280 /// Syntax trees in rust-analyzer are typically immutable, and mutating 281 /// operations panic at runtime. However, it is possible to make a copy of 282 /// the tree and mutate the copy freely. Mutation is based on interior 283 /// mutability, and different nodes in the same tree see the same mutations. 284 /// 285 /// The typical pattern for an assist is to find specific nodes in the read 286 /// phase, and then get their mutable couterparts using `make_mut` in the 287 /// mutable state. make_syntax_mut(&mut self, node: SyntaxNode) -> SyntaxNode288 pub(crate) fn make_syntax_mut(&mut self, node: SyntaxNode) -> SyntaxNode { 289 self.mutated_tree.get_or_insert_with(|| TreeMutator::new(&node)).make_syntax_mut(&node) 290 } 291 292 /// Remove specified `range` of text. delete(&mut self, range: TextRange)293 pub(crate) fn delete(&mut self, range: TextRange) { 294 self.edit.delete(range) 295 } 296 /// Append specified `text` at the given `offset` insert(&mut self, offset: TextSize, text: impl Into<String>)297 pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) { 298 self.edit.insert(offset, text.into()) 299 } 300 /// Append specified `snippet` at the given `offset` insert_snippet( &mut self, _cap: SnippetCap, offset: TextSize, snippet: impl Into<String>, )301 pub(crate) fn insert_snippet( 302 &mut self, 303 _cap: SnippetCap, 304 offset: TextSize, 305 snippet: impl Into<String>, 306 ) { 307 self.source_change.is_snippet = true; 308 self.insert(offset, snippet); 309 } 310 /// Replaces specified `range` of text with a given string. replace(&mut self, range: TextRange, replace_with: impl Into<String>)311 pub(crate) fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) { 312 self.edit.replace(range, replace_with.into()) 313 } 314 /// Replaces specified `range` of text with a given `snippet`. replace_snippet( &mut self, _cap: SnippetCap, range: TextRange, snippet: impl Into<String>, )315 pub(crate) fn replace_snippet( 316 &mut self, 317 _cap: SnippetCap, 318 range: TextRange, 319 snippet: impl Into<String>, 320 ) { 321 self.source_change.is_snippet = true; 322 self.replace(range, snippet); 323 } replace_ast<N: AstNode>(&mut self, old: N, new: N)324 pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) { 325 algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit) 326 } create_file(&mut self, dst: AnchoredPathBuf, content: impl Into<String>)327 pub(crate) fn create_file(&mut self, dst: AnchoredPathBuf, content: impl Into<String>) { 328 let file_system_edit = FileSystemEdit::CreateFile { dst, initial_contents: content.into() }; 329 self.source_change.push_file_system_edit(file_system_edit); 330 } move_file(&mut self, src: FileId, dst: AnchoredPathBuf)331 pub(crate) fn move_file(&mut self, src: FileId, dst: AnchoredPathBuf) { 332 let file_system_edit = FileSystemEdit::MoveFile { src, dst }; 333 self.source_change.push_file_system_edit(file_system_edit); 334 } 335 finish(mut self) -> SourceChange336 fn finish(mut self) -> SourceChange { 337 self.commit(); 338 mem::take(&mut self.source_change) 339 } 340 } 341