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1//! See `AssistContext`
2
3use algo::find_covering_element;
4use hir::Semantics;
5use ra_db::{FileId, FileRange};
6use ra_fmt::{leading_indent, reindent};
7use ra_ide_db::{
8 source_change::{SingleFileChange, SourceChange},
9 RootDatabase,
10};
11use ra_syntax::{
12 algo::{self, find_node_at_offset, SyntaxRewriter},
13 AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
14 TokenAtOffset,
15};
16use ra_text_edit::TextEditBuilder;
17
18use crate::{Assist, AssistId, GroupLabel, ResolvedAssist};
19
20/// `AssistContext` allows to apply an assist or check if it could be applied.
21///
22/// Assists use a somewhat over-engineered approach, given the current needs.
23/// The assists workflow consists of two phases. In the first phase, a user asks
24/// for the list of available assists. In the second phase, the user picks a
25/// particular assist and it gets applied.
26///
27/// There are two peculiarities here:
28///
29/// * first, we ideally avoid computing more things then necessary to answer "is
30/// assist applicable" in the first phase.
31/// * second, when we are applying assist, we don't have a guarantee that there
32/// weren't any changes between the point when user asked for assists and when
33/// they applied a particular assist. So, when applying assist, we need to do
34/// all the checks from scratch.
35///
36/// To avoid repeating the same code twice for both "check" and "apply"
37/// functions, we use an approach reminiscent of that of Django's function based
38/// views dealing with forms. Each assist receives a runtime parameter,
39/// `resolve`. It first check if an edit is applicable (potentially computing
40/// info required to compute the actual edit). If it is applicable, and
41/// `resolve` is `true`, it then computes the actual edit.
42///
43/// So, to implement the original assists workflow, we can first apply each edit
44/// with `resolve = false`, and then applying the selected edit again, with
45/// `resolve = true` this time.
46///
47/// Note, however, that we don't actually use such two-phase logic at the
48/// moment, because the LSP API is pretty awkward in this place, and it's much
49/// easier to just compute the edit eagerly :-)
50pub(crate) struct AssistContext<'a> {
51 pub(crate) sema: Semantics<'a, RootDatabase>,
52 pub(crate) db: &'a RootDatabase,
53 pub(crate) frange: FileRange,
54 source_file: SourceFile,
55}
56
57impl<'a> AssistContext<'a> {
58 pub fn new(sema: Semantics<'a, RootDatabase>, frange: FileRange) -> AssistContext<'a> {
59 let source_file = sema.parse(frange.file_id);
60 let db = sema.db;
61 AssistContext { sema, db, frange, source_file }
62 }
63
64 // NB, this ignores active selection.
65 pub(crate) fn offset(&self) -> TextSize {
66 self.frange.range.start()
67 }
68
69 pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
70 self.source_file.syntax().token_at_offset(self.offset())
71 }
72 pub(crate) fn find_token_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> {
73 self.token_at_offset().find(|it| it.kind() == kind)
74 }
75 pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> {
76 find_node_at_offset(self.source_file.syntax(), self.offset())
77 }
78 pub(crate) fn find_node_at_offset_with_descend<N: AstNode>(&self) -> Option<N> {
79 self.sema.find_node_at_offset_with_descend(self.source_file.syntax(), self.offset())
80 }
81 pub(crate) fn covering_element(&self) -> SyntaxElement {
82 find_covering_element(self.source_file.syntax(), self.frange.range)
83 }
84 // FIXME: remove
85 pub(crate) fn covering_node_for_range(&self, range: TextRange) -> SyntaxElement {
86 find_covering_element(self.source_file.syntax(), range)
87 }
88}
89
90pub(crate) struct Assists {
91 resolve: bool,
92 file: FileId,
93 buf: Vec<(Assist, Option<SourceChange>)>,
94}
95
96impl Assists {
97 pub(crate) fn new_resolved(ctx: &AssistContext) -> Assists {
98 Assists { resolve: true, file: ctx.frange.file_id, buf: Vec::new() }
99 }
100 pub(crate) fn new_unresolved(ctx: &AssistContext) -> Assists {
101 Assists { resolve: false, file: ctx.frange.file_id, buf: Vec::new() }
102 }
103
104 pub(crate) fn finish_unresolved(self) -> Vec<Assist> {
105 assert!(!self.resolve);
106 self.finish()
107 .into_iter()
108 .map(|(label, edit)| {
109 assert!(edit.is_none());
110 label
111 })
112 .collect()
113 }
114
115 pub(crate) fn finish_resolved(self) -> Vec<ResolvedAssist> {
116 assert!(self.resolve);
117 self.finish()
118 .into_iter()
119 .map(|(label, edit)| ResolvedAssist { assist: label, source_change: edit.unwrap() })
120 .collect()
121 }
122
123 pub(crate) fn add(
124 &mut self,
125 id: AssistId,
126 label: impl Into<String>,
127 target: TextRange,
128 f: impl FnOnce(&mut AssistBuilder),
129 ) -> Option<()> {
130 let label = Assist::new(id, label.into(), None, target);
131 self.add_impl(label, f)
132 }
133 pub(crate) fn add_group(
134 &mut self,
135 group: &GroupLabel,
136 id: AssistId,
137 label: impl Into<String>,
138 target: TextRange,
139 f: impl FnOnce(&mut AssistBuilder),
140 ) -> Option<()> {
141 let label = Assist::new(id, label.into(), Some(group.clone()), target);
142 self.add_impl(label, f)
143 }
144 fn add_impl(&mut self, label: Assist, f: impl FnOnce(&mut AssistBuilder)) -> Option<()> {
145 let change_label = label.label.clone();
146 let source_change = if self.resolve {
147 let mut builder = AssistBuilder::new(self.file);
148 f(&mut builder);
149 Some(builder.finish(change_label))
150 } else {
151 None
152 };
153
154 self.buf.push((label, source_change));
155 Some(())
156 }
157
158 fn finish(mut self) -> Vec<(Assist, Option<SourceChange>)> {
159 self.buf.sort_by_key(|(label, _edit)| label.target.len());
160 self.buf
161 }
162}
163
164pub(crate) struct AssistBuilder {
165 edit: TextEditBuilder,
166 cursor_position: Option<TextSize>,
167 file: FileId,
168}
169
170impl AssistBuilder {
171 pub(crate) fn new(file: FileId) -> AssistBuilder {
172 AssistBuilder { edit: TextEditBuilder::default(), cursor_position: None, file }
173 }
174
175 /// Remove specified `range` of text.
176 pub(crate) fn delete(&mut self, range: TextRange) {
177 self.edit.delete(range)
178 }
179 /// Append specified `text` at the given `offset`
180 pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) {
181 self.edit.insert(offset, text.into())
182 }
183 /// Replaces specified `range` of text with a given string.
184 pub(crate) fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) {
185 self.edit.replace(range, replace_with.into())
186 }
187 pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) {
188 algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit)
189 }
190 /// Replaces specified `node` of text with a given string, reindenting the
191 /// string to maintain `node`'s existing indent.
192 // FIXME: remove in favor of ra_syntax::edit::IndentLevel::increase_indent
193 pub(crate) fn replace_node_and_indent(
194 &mut self,
195 node: &SyntaxNode,
196 replace_with: impl Into<String>,
197 ) {
198 let mut replace_with = replace_with.into();
199 if let Some(indent) = leading_indent(node) {
200 replace_with = reindent(&replace_with, &indent)
201 }
202 self.replace(node.text_range(), replace_with)
203 }
204 pub(crate) fn rewrite(&mut self, rewriter: SyntaxRewriter) {
205 let node = rewriter.rewrite_root().unwrap();
206 let new = rewriter.rewrite(&node);
207 algo::diff(&node, &new).into_text_edit(&mut self.edit)
208 }
209
210 /// Specify desired position of the cursor after the assist is applied.
211 pub(crate) fn set_cursor(&mut self, offset: TextSize) {
212 self.cursor_position = Some(offset)
213 }
214 // FIXME: better API
215 pub(crate) fn set_file(&mut self, assist_file: FileId) {
216 self.file = assist_file;
217 }
218
219 // FIXME: kill this API
220 /// Get access to the raw `TextEditBuilder`.
221 pub(crate) fn text_edit_builder(&mut self) -> &mut TextEditBuilder {
222 &mut self.edit
223 }
224
225 fn finish(self, change_label: String) -> SourceChange {
226 let edit = self.edit.finish();
227 if edit.is_empty() && self.cursor_position.is_none() {
228 panic!("Only call `add_assist` if the assist can be applied")
229 }
230 SingleFileChange { label: change_label, edit, cursor_position: self.cursor_position }
231 .into_source_change(self.file)
232 }
233}