Auto merge of #15269 - DropDemBits:structured-snippets-deferred-rendering, r=Veykril

internal: Defer structured snippet rendering to allow escaping snippet bits

Since we know exactly where snippets are, we can transparently escape snippet bits to the exact text edits that need it, and not have to do it for anything other text edits.

Also will eventually fix #11006 once all assists are migrated. This comes as a side-effect of text edits that don't have snippets get marked as having no insert formatting at all.

8 files changed, 956 insertions, 233 deletions

diff --git a/crates/ide-assists/src/tests.rs b/crates/ide-assists/src/tests.rs
index 344f2bfcce1..cc3e251a8f2 100644
--- a/crates/ide-assists/src/tests.rs
+++ b/crates/ide-assists/src/tests.rs
@@ -132,8 +132,13 @@ fn check_doc_test(assist_id: &str, before: &str, after: &str) {
             .filter(|it| !it.source_file_edits.is_empty() || !it.file_system_edits.is_empty())
             .expect("Assist did not contain any source changes");
         let mut actual = before;
-        if let Some(source_file_edit) = source_change.get_source_edit(file_id) {
+        if let Some((source_file_edit, snippet_edit)) =
+            source_change.get_source_and_snippet_edit(file_id)
+        {
             source_file_edit.apply(&mut actual);
+            if let Some(snippet_edit) = snippet_edit {
+                snippet_edit.apply(&mut actual);
+            }
         }
         actual
     };
@@ -191,9 +196,12 @@ fn check_with_config(
                 && source_change.file_system_edits.len() == 0;
 
             let mut buf = String::new();
-            for (file_id, edit) in source_change.source_file_edits {
+            for (file_id, (edit, snippet_edit)) in source_change.source_file_edits {
                 let mut text = db.file_text(file_id).as_ref().to_owned();
                 edit.apply(&mut text);
+                if let Some(snippet_edit) = snippet_edit {
+                    snippet_edit.apply(&mut text);
+                }
                 if !skip_header {
                     let sr = db.file_source_root(file_id);
                     let sr = db.source_root(sr);
@@ -485,18 +493,21 @@ pub fn test_some_range(a: int) -> bool {
                         source_file_edits: {
                             FileId(
                                 0,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "let $0var_name = 5;\n    ",
-                                        delete: 45..45,
-                                    },
-                                    Indel {
-                                        insert: "var_name",
-                                        delete: 59..60,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "let $0var_name = 5;\n    ",
+                                            delete: 45..45,
+                                        },
+                                        Indel {
+                                            insert: "var_name",
+                                            delete: 59..60,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                         },
                         file_system_edits: [],
                         is_snippet: true,
@@ -544,18 +555,21 @@ pub fn test_some_range(a: int) -> bool {
                         source_file_edits: {
                             FileId(
                                 0,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "let $0var_name = 5;\n    ",
-                                        delete: 45..45,
-                                    },
-                                    Indel {
-                                        insert: "var_name",
-                                        delete: 59..60,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "let $0var_name = 5;\n    ",
+                                            delete: 45..45,
+                                        },
+                                        Indel {
+                                            insert: "var_name",
+                                            delete: 59..60,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                         },
                         file_system_edits: [],
                         is_snippet: true,
@@ -581,18 +595,21 @@ pub fn test_some_range(a: int) -> bool {
                         source_file_edits: {
                             FileId(
                                 0,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "fun_name()",
-                                        delete: 59..60,
-                                    },
-                                    Indel {
-                                        insert: "\n\nfn $0fun_name() -> i32 {\n    5\n}",
-                                        delete: 110..110,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "fun_name()",
+                                            delete: 59..60,
+                                        },
+                                        Indel {
+                                            insert: "\n\nfn $0fun_name() -> i32 {\n    5\n}",
+                                            delete: 110..110,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                         },
                         file_system_edits: [],
                         is_snippet: true,
diff --git a/crates/ide-db/src/source_change.rs b/crates/ide-db/src/source_change.rs
index fad0ca51a02..39763479c65 100644
--- a/crates/ide-db/src/source_change.rs
+++ b/crates/ide-db/src/source_change.rs
@@ -7,17 +7,17 @@ use std::{collections::hash_map::Entry, iter, mem};
 
 use crate::SnippetCap;
 use base_db::{AnchoredPathBuf, FileId};
+use itertools::Itertools;
 use nohash_hasher::IntMap;
 use stdx::never;
 use syntax::{
-    algo, ast, ted, AstNode, SyntaxElement, SyntaxNode, SyntaxNodePtr, SyntaxToken, TextRange,
-    TextSize,
+    algo, AstNode, SyntaxElement, SyntaxNode, SyntaxNodePtr, SyntaxToken, TextRange, TextSize,
 };
 use text_edit::{TextEdit, TextEditBuilder};
 
 #[derive(Default, Debug, Clone)]
 pub struct SourceChange {
-    pub source_file_edits: IntMap<FileId, TextEdit>,
+    pub source_file_edits: IntMap<FileId, (TextEdit, Option<SnippetEdit>)>,
     pub file_system_edits: Vec<FileSystemEdit>,
     pub is_snippet: bool,
 }
@@ -26,7 +26,7 @@ impl SourceChange {
     /// Creates a new SourceChange with the given label
     /// from the edits.
     pub fn from_edits(
-        source_file_edits: IntMap<FileId, TextEdit>,
+        source_file_edits: IntMap<FileId, (TextEdit, Option<SnippetEdit>)>,
         file_system_edits: Vec<FileSystemEdit>,
     ) -> Self {
         SourceChange { source_file_edits, file_system_edits, is_snippet: false }
@@ -34,7 +34,7 @@ impl SourceChange {
 
     pub fn from_text_edit(file_id: FileId, edit: TextEdit) -> Self {
         SourceChange {
-            source_file_edits: iter::once((file_id, edit)).collect(),
+            source_file_edits: iter::once((file_id, (edit, None))).collect(),
             ..Default::default()
         }
     }
@@ -42,12 +42,31 @@ impl SourceChange {
     /// Inserts a [`TextEdit`] for the given [`FileId`]. This properly handles merging existing
     /// edits for a file if some already exist.
     pub fn insert_source_edit(&mut self, file_id: FileId, edit: TextEdit) {
+        self.insert_source_and_snippet_edit(file_id, edit, None)
+    }
+
+    /// Inserts a [`TextEdit`] and potentially a [`SnippetEdit`] for the given [`FileId`].
+    /// This properly handles merging existing edits for a file if some already exist.
+    pub fn insert_source_and_snippet_edit(
+        &mut self,
+        file_id: FileId,
+        edit: TextEdit,
+        snippet_edit: Option<SnippetEdit>,
+    ) {
         match self.source_file_edits.entry(file_id) {
             Entry::Occupied(mut entry) => {
-                never!(entry.get_mut().union(edit).is_err(), "overlapping edits for same file");
+                let value = entry.get_mut();
+                never!(value.0.union(edit).is_err(), "overlapping edits for same file");
+                never!(
+                    value.1.is_some() && snippet_edit.is_some(),
+                    "overlapping snippet edits for same file"
+                );
+                if value.1.is_none() {
+                    value.1 = snippet_edit;
+                }
             }
             Entry::Vacant(entry) => {
-                entry.insert(edit);
+                entry.insert((edit, snippet_edit));
             }
         }
     }
@@ -56,7 +75,10 @@ impl SourceChange {
         self.file_system_edits.push(edit);
     }
 
-    pub fn get_source_edit(&self, file_id: FileId) -> Option<&TextEdit> {
+    pub fn get_source_and_snippet_edit(
+        &self,
+        file_id: FileId,
+    ) -> Option<&(TextEdit, Option<SnippetEdit>)> {
         self.source_file_edits.get(&file_id)
     }
 
@@ -70,7 +92,18 @@ impl SourceChange {
 
 impl Extend<(FileId, TextEdit)> for SourceChange {
     fn extend<T: IntoIterator<Item = (FileId, TextEdit)>>(&mut self, iter: T) {
-        iter.into_iter().for_each(|(file_id, edit)| self.insert_source_edit(file_id, edit));
+        self.extend(iter.into_iter().map(|(file_id, edit)| (file_id, (edit, None))))
+    }
+}
+
+impl Extend<(FileId, (TextEdit, Option<SnippetEdit>))> for SourceChange {
+    fn extend<T: IntoIterator<Item = (FileId, (TextEdit, Option<SnippetEdit>))>>(
+        &mut self,
+        iter: T,
+    ) {
+        iter.into_iter().for_each(|(file_id, (edit, snippet_edit))| {
+            self.insert_source_and_snippet_edit(file_id, edit, snippet_edit)
+        });
     }
 }
 
@@ -82,6 +115,8 @@ impl Extend<FileSystemEdit> for SourceChange {
 
 impl From<IntMap<FileId, TextEdit>> for SourceChange {
     fn from(source_file_edits: IntMap<FileId, TextEdit>) -> SourceChange {
+        let source_file_edits =
+            source_file_edits.into_iter().map(|(file_id, edit)| (file_id, (edit, None))).collect();
         SourceChange { source_file_edits, file_system_edits: Vec::new(), is_snippet: false }
     }
 }
@@ -94,6 +129,65 @@ impl FromIterator<(FileId, TextEdit)> for SourceChange {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct SnippetEdit(Vec<(u32, TextRange)>);
+
+impl SnippetEdit {
+    pub fn new(snippets: Vec<Snippet>) -> Self {
+        let mut snippet_ranges = snippets
+            .into_iter()
+            .zip(1..)
+            .with_position()
+            .map(|pos| {
+                let (snippet, index) = match pos {
+                    itertools::Position::First(it) | itertools::Position::Middle(it) => it,
+                    // last/only snippet gets index 0
+                    itertools::Position::Last((snippet, _))
+                    | itertools::Position::Only((snippet, _)) => (snippet, 0),
+                };
+
+                let range = match snippet {
+                    Snippet::Tabstop(pos) => TextRange::empty(pos),
+                    Snippet::Placeholder(range) => range,
+                };
+                (index, range)
+            })
+            .collect_vec();
+
+        snippet_ranges.sort_by_key(|(_, range)| range.start());
+
+        // Ensure that none of the ranges overlap
+        let disjoint_ranges = snippet_ranges
+            .iter()
+            .zip(snippet_ranges.iter().skip(1))
+            .all(|((_, left), (_, right))| left.end() <= right.start() || left == right);
+        stdx::always!(disjoint_ranges);
+
+        SnippetEdit(snippet_ranges)
+    }
+
+    /// Inserts all of the snippets into the given text.
+    pub fn apply(&self, text: &mut String) {
+        // Start from the back so that we don't have to adjust ranges
+        for (index, range) in self.0.iter().rev() {
+            if range.is_empty() {
+                // is a tabstop
+                text.insert_str(range.start().into(), &format!("${index}"));
+            } else {
+                // is a placeholder
+                text.insert(range.end().into(), '}');
+                text.insert_str(range.start().into(), &format!("${{{index}:"));
+            }
+        }
+    }
+
+    /// Gets the underlying snippet index + text range
+    /// Tabstops are represented by an empty range, and placeholders use the range that they were given
+    pub fn into_edit_ranges(self) -> Vec<(u32, TextRange)> {
+        self.0
+    }
+}
+
 pub struct SourceChangeBuilder {
     pub edit: TextEditBuilder,
     pub file_id: FileId,
@@ -152,24 +246,19 @@ impl SourceChangeBuilder {
     }
 
     fn commit(&mut self) {
-        // Render snippets first so that they get bundled into the tree diff
-        if let Some(mut snippets) = self.snippet_builder.take() {
-            // Last snippet always has stop index 0
-            let last_stop = snippets.places.pop().unwrap();
-            last_stop.place(0);
-
-            for (index, stop) in snippets.places.into_iter().enumerate() {
-                stop.place(index + 1)
-            }
-        }
+        let snippet_edit = self.snippet_builder.take().map(|builder| {
+            SnippetEdit::new(
+                builder.places.into_iter().map(PlaceSnippet::finalize_position).collect_vec(),
+            )
+        });
 
         if let Some(tm) = self.mutated_tree.take() {
-            algo::diff(&tm.immutable, &tm.mutable_clone).into_text_edit(&mut self.edit)
+            algo::diff(&tm.immutable, &tm.mutable_clone).into_text_edit(&mut self.edit);
         }
 
         let edit = mem::take(&mut self.edit).finish();
-        if !edit.is_empty() {
-            self.source_change.insert_source_edit(self.file_id, edit);
+        if !edit.is_empty() || snippet_edit.is_some() {
+            self.source_change.insert_source_and_snippet_edit(self.file_id, edit, snippet_edit);
         }
     }
 
@@ -275,6 +364,16 @@ impl SourceChangeBuilder {
 
     pub fn finish(mut self) -> SourceChange {
         self.commit();
+
+        // Only one file can have snippet edits
+        stdx::never!(self
+            .source_change
+            .source_file_edits
+            .iter()
+            .filter(|(_, (_, snippet_edit))| snippet_edit.is_some())
+            .at_most_one()
+            .is_err());
+
         mem::take(&mut self.source_change)
     }
 }
@@ -296,6 +395,13 @@ impl From<FileSystemEdit> for SourceChange {
     }
 }
 
+pub enum Snippet {
+    /// A tabstop snippet (e.g. `$0`).
+    Tabstop(TextSize),
+    /// A placeholder snippet (e.g. `${0:placeholder}`).
+    Placeholder(TextRange),
+}
+
 enum PlaceSnippet {
     /// Place a tabstop before an element
     Before(SyntaxElement),
@@ -306,57 +412,11 @@ enum PlaceSnippet {
 }
 
 impl PlaceSnippet {
-    /// Places the snippet before or over an element with the given tab stop index
-    fn place(self, order: usize) {
-        // ensure the target element is still attached
-        match &self {
-            PlaceSnippet::Before(element)
-            | PlaceSnippet::After(element)
-            | PlaceSnippet::Over(element) => {
-                // element should still be in the tree, but if it isn't
-                // then it's okay to just ignore this place
-                if stdx::never!(element.parent().is_none()) {
-                    return;
-                }
-            }
-        }
-
+    fn finalize_position(self) -> Snippet {
         match self {
-            PlaceSnippet::Before(element) => {
-                ted::insert_raw(ted::Position::before(&element), Self::make_tab_stop(order));
-            }
-            PlaceSnippet::After(element) => {
-                ted::insert_raw(ted::Position::after(&element), Self::make_tab_stop(order));
-            }
-            PlaceSnippet::Over(element) => {
-                let position = ted::Position::before(&element);
-                element.detach();
-
-                let snippet = ast::SourceFile::parse(&format!("${{{order}:_}}"))
-                    .syntax_node()
-                    .clone_for_update();
-
-                let placeholder =
-                    snippet.descendants().find_map(ast::UnderscoreExpr::cast).unwrap();
-                ted::replace(placeholder.syntax(), element);
-
-                ted::insert_raw(position, snippet);
-            }
+            PlaceSnippet::Before(it) => Snippet::Tabstop(it.text_range().start()),
+            PlaceSnippet::After(it) => Snippet::Tabstop(it.text_range().end()),
+            PlaceSnippet::Over(it) => Snippet::Placeholder(it.text_range()),
         }
     }
-
-    fn make_tab_stop(order: usize) -> SyntaxNode {
-        let stop = ast::SourceFile::parse(&format!("stop!(${order})"))
-            .syntax_node()
-            .descendants()
-            .find_map(ast::TokenTree::cast)
-            .unwrap()
-            .syntax()
-            .clone_for_update();
-
-        stop.first_token().unwrap().detach();
-        stop.last_token().unwrap().detach();
-
-        stop
-    }
 }
diff --git a/crates/ide-diagnostics/src/tests.rs b/crates/ide-diagnostics/src/tests.rs
index 4ac9d0a9fb7..ee0e0354906 100644
--- a/crates/ide-diagnostics/src/tests.rs
+++ b/crates/ide-diagnostics/src/tests.rs
@@ -49,8 +49,11 @@ fn check_nth_fix(nth: usize, ra_fixture_before: &str, ra_fixture_after: &str) {
         let file_id = *source_change.source_file_edits.keys().next().unwrap();
         let mut actual = db.file_text(file_id).to_string();
 
-        for edit in source_change.source_file_edits.values() {
+        for (edit, snippet_edit) in source_change.source_file_edits.values() {
             edit.apply(&mut actual);
+            if let Some(snippet_edit) = snippet_edit {
+                snippet_edit.apply(&mut actual);
+            }
         }
         actual
     };
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 0ad4c6c47e6..bf77d55d58e 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -127,7 +127,7 @@ pub use ide_db::{
     label::Label,
     line_index::{LineCol, LineIndex},
     search::{ReferenceCategory, SearchScope},
-    source_change::{FileSystemEdit, SourceChange},
+    source_change::{FileSystemEdit, SnippetEdit, SourceChange},
     symbol_index::Query,
     RootDatabase, SymbolKind,
 };
diff --git a/crates/ide/src/rename.rs b/crates/ide/src/rename.rs
index e10c4638102..5c4beb7dd50 100644
--- a/crates/ide/src/rename.rs
+++ b/crates/ide/src/rename.rs
@@ -367,7 +367,7 @@ mod tests {
                 let mut file_id: Option<FileId> = None;
                 for edit in source_change.source_file_edits {
                     file_id = Some(edit.0);
-                    for indel in edit.1.into_iter() {
+                    for indel in edit.1 .0.into_iter() {
                         text_edit_builder.replace(indel.delete, indel.insert);
                     }
                 }
@@ -895,14 +895,17 @@ mod foo$0;
                     source_file_edits: {
                         FileId(
                             1,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo2",
-                                    delete: 4..7,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo2",
+                                        delete: 4..7,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -944,24 +947,30 @@ use crate::foo$0::FooContent;
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "quux",
-                                    delete: 8..11,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "quux",
+                                        delete: 8..11,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                         FileId(
                             2,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "quux",
-                                    delete: 11..14,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "quux",
+                                        delete: 11..14,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -997,14 +1006,17 @@ mod fo$0o;
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo2",
-                                    delete: 4..7,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo2",
+                                        delete: 4..7,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveDir {
@@ -1047,14 +1059,17 @@ mod outer { mod fo$0o; }
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "bar",
-                                    delete: 16..19,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "bar",
+                                        delete: 16..19,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -1120,24 +1135,30 @@ pub mod foo$0;
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo2",
-                                    delete: 27..30,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo2",
+                                        delete: 27..30,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                         FileId(
                             1,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo2",
-                                    delete: 8..11,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo2",
+                                        delete: 8..11,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -1187,14 +1208,17 @@ mod quux;
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo2",
-                                    delete: 4..7,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo2",
+                                        delete: 4..7,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -1325,18 +1349,21 @@ pub fn baz() {}
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "r#fn",
-                                    delete: 4..7,
-                                },
-                                Indel {
-                                    insert: "r#fn",
-                                    delete: 22..25,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "r#fn",
+                                        delete: 4..7,
+                                    },
+                                    Indel {
+                                        insert: "r#fn",
+                                        delete: 22..25,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
@@ -1395,18 +1422,21 @@ pub fn baz() {}
                     source_file_edits: {
                         FileId(
                             0,
-                        ): TextEdit {
-                            indels: [
-                                Indel {
-                                    insert: "foo",
-                                    delete: 4..8,
-                                },
-                                Indel {
-                                    insert: "foo",
-                                    delete: 23..27,
-                                },
-                            ],
-                        },
+                        ): (
+                            TextEdit {
+                                indels: [
+                                    Indel {
+                                        insert: "foo",
+                                        delete: 4..8,
+                                    },
+                                    Indel {
+                                        insert: "foo",
+                                        delete: 23..27,
+                                    },
+                                ],
+                            },
+                            None,
+                        ),
                     },
                     file_system_edits: [
                         MoveFile {
diff --git a/crates/ide/src/ssr.rs b/crates/ide/src/ssr.rs
index deaf3c9c416..d8d81869a2f 100644
--- a/crates/ide/src/ssr.rs
+++ b/crates/ide/src/ssr.rs
@@ -126,14 +126,17 @@ mod tests {
                         source_file_edits: {
                             FileId(
                                 0,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "3",
-                                        delete: 33..34,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "3",
+                                            delete: 33..34,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                         },
                         file_system_edits: [],
                         is_snippet: false,
@@ -163,24 +166,30 @@ mod tests {
                         source_file_edits: {
                             FileId(
                                 0,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "3",
-                                        delete: 33..34,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "3",
+                                            delete: 33..34,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                             FileId(
                                 1,
-                            ): TextEdit {
-                                indels: [
-                                    Indel {
-                                        insert: "3",
-                                        delete: 11..12,
-                                    },
-                                ],
-                            },
+                            ): (
+                                TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "3",
+                                            delete: 11..12,
+                                        },
+                                    ],
+                                },
+                                None,
+                            ),
                         },
                         file_system_edits: [],
                         is_snippet: false,
diff --git a/crates/rust-analyzer/src/handlers/request.rs b/crates/rust-analyzer/src/handlers/request.rs
index aad74b7466a..5f1f731cffb 100644
--- a/crates/rust-analyzer/src/handlers/request.rs
+++ b/crates/rust-analyzer/src/handlers/request.rs
@@ -353,7 +353,8 @@ pub(crate) fn handle_on_type_formatting(
     };
 
     // This should be a single-file edit
-    let (_, text_edit) = edit.source_file_edits.into_iter().next().unwrap();
+    let (_, (text_edit, snippet_edit)) = edit.source_file_edits.into_iter().next().unwrap();
+    stdx::never!(snippet_edit.is_none(), "on type formatting shouldn't use structured snippets");
 
     let change = to_proto::snippet_text_edit_vec(&line_index, edit.is_snippet, text_edit);
     Ok(Some(change))
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 7a89533a5e9..7b32180e3eb 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -10,8 +10,8 @@ use ide::{
     CompletionItemKind, CompletionRelevance, Documentation, FileId, FileRange, FileSystemEdit,
     Fold, FoldKind, Highlight, HlMod, HlOperator, HlPunct, HlRange, HlTag, Indel, InlayHint,
     InlayHintLabel, InlayHintLabelPart, InlayKind, Markup, NavigationTarget, ReferenceCategory,
-    RenameError, Runnable, Severity, SignatureHelp, SourceChange, StructureNodeKind, SymbolKind,
-    TextEdit, TextRange, TextSize,
+    RenameError, Runnable, Severity, SignatureHelp, SnippetEdit, SourceChange, StructureNodeKind,
+    SymbolKind, TextEdit, TextRange, TextSize,
 };
 use itertools::Itertools;
 use serde_json::to_value;
@@ -22,7 +22,7 @@ use crate::{
     config::{CallInfoConfig, Config},
     global_state::GlobalStateSnapshot,
     line_index::{LineEndings, LineIndex, PositionEncoding},
-    lsp_ext,
+    lsp_ext::{self, SnippetTextEdit},
     lsp_utils::invalid_params_error,
     semantic_tokens::{self, standard_fallback_type},
 };
@@ -885,16 +885,136 @@ fn outside_workspace_annotation_id() -> String {
     String::from("OutsideWorkspace")
 }
 
+fn merge_text_and_snippet_edits(
+    line_index: &LineIndex,
+    edit: TextEdit,
+    snippet_edit: SnippetEdit,
+) -> Vec<SnippetTextEdit> {
+    let mut edits: Vec<SnippetTextEdit> = vec![];
+    let mut snippets = snippet_edit.into_edit_ranges().into_iter().peekable();
+    let mut text_edits = edit.into_iter();
+
+    while let Some(current_indel) = text_edits.next() {
+        let new_range = {
+            let insert_len =
+                TextSize::try_from(current_indel.insert.len()).unwrap_or(TextSize::from(u32::MAX));
+            TextRange::at(current_indel.delete.start(), insert_len)
+        };
+
+        // insert any snippets before the text edit
+        for (snippet_index, snippet_range) in
+            snippets.take_while_ref(|(_, range)| range.end() < new_range.start())
+        {
+            let snippet_range = if !stdx::always!(
+                snippet_range.is_empty(),
+                "placeholder range {:?} is before current text edit range {:?}",
+                snippet_range,
+                new_range
+            ) {
+                // only possible for tabstops, so make sure it's an empty/insert range
+                TextRange::empty(snippet_range.start())
+            } else {
+                snippet_range
+            };
+
+            let range = range(&line_index, snippet_range);
+            let new_text = format!("${snippet_index}");
+
+            edits.push(SnippetTextEdit {
+                range,
+                new_text,
+                insert_text_format: Some(lsp_types::InsertTextFormat::SNIPPET),
+                annotation_id: None,
+            })
+        }
+
+        if snippets.peek().is_some_and(|(_, range)| new_range.intersect(*range).is_some()) {
+            // at least one snippet edit intersects this text edit,
+            // so gather all of the edits that intersect this text edit
+            let mut all_snippets = snippets
+                .take_while_ref(|(_, range)| new_range.intersect(*range).is_some())
+                .collect_vec();
+
+            // ensure all of the ranges are wholly contained inside of the new range
+            all_snippets.retain(|(_, range)| {
+                    stdx::always!(
+                        new_range.contains_range(*range),
+                        "found placeholder range {:?} which wasn't fully inside of text edit's new range {:?}", range, new_range
+                    )
+                });
+
+            let mut text_edit = text_edit(line_index, current_indel);
+
+            // escape out snippet text
+            stdx::replace(&mut text_edit.new_text, '\\', r"\\");
+            stdx::replace(&mut text_edit.new_text, '$', r"\$");
+
+            // ...and apply!
+            for (index, range) in all_snippets.iter().rev() {
+                let start = (range.start() - new_range.start()).into();
+                let end = (range.end() - new_range.start()).into();
+
+                if range.is_empty() {
+                    text_edit.new_text.insert_str(start, &format!("${index}"));
+                } else {
+                    text_edit.new_text.insert(end, '}');
+                    text_edit.new_text.insert_str(start, &format!("${{{index}:"));
+                }
+            }
+
+            edits.push(SnippetTextEdit {
+                range: text_edit.range,
+                new_text: text_edit.new_text,
+                insert_text_format: Some(lsp_types::InsertTextFormat::SNIPPET),
+                annotation_id: None,
+            })
+        } else {
+            // snippet edit was beyond the current one
+            // since it wasn't consumed, it's available for the next pass
+            edits.push(snippet_text_edit(line_index, false, current_indel));
+        }
+    }
+
+    // insert any remaining tabstops
+    edits.extend(snippets.map(|(snippet_index, snippet_range)| {
+        let snippet_range = if !stdx::always!(
+            snippet_range.is_empty(),
+            "found placeholder snippet {:?} without a text edit",
+            snippet_range
+        ) {
+            TextRange::empty(snippet_range.start())
+        } else {
+            snippet_range
+        };
+
+        let range = range(&line_index, snippet_range);
+        let new_text = format!("${snippet_index}");
+
+        SnippetTextEdit {
+            range,
+            new_text,
+            insert_text_format: Some(lsp_types::InsertTextFormat::SNIPPET),
+            annotation_id: None,
+        }
+    }));
+
+    edits
+}
+
 pub(crate) fn snippet_text_document_edit(
     snap: &GlobalStateSnapshot,
     is_snippet: bool,
     file_id: FileId,
     edit: TextEdit,
+    snippet_edit: Option<SnippetEdit>,
 ) -> Cancellable<lsp_ext::SnippetTextDocumentEdit> {
     let text_document = optional_versioned_text_document_identifier(snap, file_id);
     let line_index = snap.file_line_index(file_id)?;
-    let mut edits: Vec<_> =
-        edit.into_iter().map(|it| snippet_text_edit(&line_index, is_snippet, it)).collect();
+    let mut edits = if let Some(snippet_edit) = snippet_edit {
+        merge_text_and_snippet_edits(&line_index, edit, snippet_edit)
+    } else {
+        edit.into_iter().map(|it| snippet_text_edit(&line_index, is_snippet, it)).collect()
+    };
 
     if snap.analysis.is_library_file(file_id)? && snap.config.change_annotation_support() {
         for edit in &mut edits {
@@ -974,8 +1094,14 @@ pub(crate) fn snippet_workspace_edit(
         let ops = snippet_text_document_ops(snap, op)?;
         document_changes.extend_from_slice(&ops);
     }
-    for (file_id, edit) in source_change.source_file_edits {
-        let edit = snippet_text_document_edit(snap, source_change.is_snippet, file_id, edit)?;
+    for (file_id, (edit, snippet_edit)) in source_change.source_file_edits {
+        let edit = snippet_text_document_edit(
+            snap,
+            source_change.is_snippet,
+            file_id,
+            edit,
+            snippet_edit,
+        )?;
         document_changes.push(lsp_ext::SnippetDocumentChangeOperation::Edit(edit));
     }
     let mut workspace_edit = lsp_ext::SnippetWorkspaceEdit {
@@ -1414,7 +1540,9 @@ pub(crate) fn rename_error(err: RenameError) -> crate::LspError {
 
 #[cfg(test)]
 mod tests {
+    use expect_test::{expect, Expect};
     use ide::{Analysis, FilePosition};
+    use ide_db::source_change::Snippet;
     use test_utils::extract_offset;
     use triomphe::Arc;
 
@@ -1484,6 +1612,481 @@ fn bar(_: usize) {}
         assert!(!docs.contains("use crate::bar"));
     }
 
+    fn check_rendered_snippets(edit: TextEdit, snippets: SnippetEdit, expect: Expect) {
+        let text = r#"/* place to put all ranges in */"#;
+        let line_index = LineIndex {
+            index: Arc::new(ide::LineIndex::new(text)),
+            endings: LineEndings::Unix,
+            encoding: PositionEncoding::Utf8,
+        };
+
+        let res = merge_text_and_snippet_edits(&line_index, edit, snippets);
+        expect.assert_debug_eq(&res);
+    }
+
+    #[test]
+    fn snippet_rendering_only_tabstops() {
+        let edit = TextEdit::builder().finish();
+        let snippets = SnippetEdit::new(vec![
+            Snippet::Tabstop(0.into()),
+            Snippet::Tabstop(0.into()),
+            Snippet::Tabstop(1.into()),
+            Snippet::Tabstop(1.into()),
+        ]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "$1",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "$2",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 1,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 1,
+                        },
+                    },
+                    new_text: "$3",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 1,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 1,
+                        },
+                    },
+                    new_text: "$0",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_only_text_edits() {
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), "abc".to_owned());
+        edit.insert(3.into(), "def".to_owned());
+        let edit = edit.finish();
+        let snippets = SnippetEdit::new(vec![]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "abc",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 3,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 3,
+                        },
+                    },
+                    new_text: "def",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_tabstop_after_text_edit() {
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), "abc".to_owned());
+        let edit = edit.finish();
+        let snippets = SnippetEdit::new(vec![Snippet::Tabstop(7.into())]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "abc",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 7,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 7,
+                        },
+                    },
+                    new_text: "$0",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_tabstops_before_text_edit() {
+        let mut edit = TextEdit::builder();
+        edit.insert(2.into(), "abc".to_owned());
+        let edit = edit.finish();
+        let snippets =
+            SnippetEdit::new(vec![Snippet::Tabstop(0.into()), Snippet::Tabstop(0.into())]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+                [
+                    SnippetTextEdit {
+                        range: Range {
+                            start: Position {
+                                line: 0,
+                                character: 0,
+                            },
+                            end: Position {
+                                line: 0,
+                                character: 0,
+                            },
+                        },
+                        new_text: "$1",
+                        insert_text_format: Some(
+                            Snippet,
+                        ),
+                        annotation_id: None,
+                    },
+                    SnippetTextEdit {
+                        range: Range {
+                            start: Position {
+                                line: 0,
+                                character: 0,
+                            },
+                            end: Position {
+                                line: 0,
+                                character: 0,
+                            },
+                        },
+                        new_text: "$0",
+                        insert_text_format: Some(
+                            Snippet,
+                        ),
+                        annotation_id: None,
+                    },
+                    SnippetTextEdit {
+                        range: Range {
+                            start: Position {
+                                line: 0,
+                                character: 2,
+                            },
+                            end: Position {
+                                line: 0,
+                                character: 2,
+                            },
+                        },
+                        new_text: "abc",
+                        insert_text_format: None,
+                        annotation_id: None,
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_tabstops_between_text_edits() {
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), "abc".to_owned());
+        edit.insert(7.into(), "abc".to_owned());
+        let edit = edit.finish();
+        let snippets =
+            SnippetEdit::new(vec![Snippet::Tabstop(4.into()), Snippet::Tabstop(4.into())]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "abc",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 4,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 4,
+                        },
+                    },
+                    new_text: "$1",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 4,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 4,
+                        },
+                    },
+                    new_text: "$0",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 7,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 7,
+                        },
+                    },
+                    new_text: "abc",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_multiple_tabstops_in_text_edit() {
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), "abcdefghijkl".to_owned());
+        let edit = edit.finish();
+        let snippets = SnippetEdit::new(vec![
+            Snippet::Tabstop(0.into()),
+            Snippet::Tabstop(5.into()),
+            Snippet::Tabstop(12.into()),
+        ]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "$1abcde$2fghijkl$0",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_multiple_placeholders_in_text_edit() {
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), "abcdefghijkl".to_owned());
+        let edit = edit.finish();
+        let snippets = SnippetEdit::new(vec![
+            Snippet::Placeholder(TextRange::new(0.into(), 3.into())),
+            Snippet::Placeholder(TextRange::new(5.into(), 7.into())),
+            Snippet::Placeholder(TextRange::new(10.into(), 12.into())),
+        ]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "${1:abc}de${2:fg}hij${0:kl}",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
+    #[test]
+    fn snippet_rendering_escape_snippet_bits() {
+        // only needed for snippet formats
+        let mut edit = TextEdit::builder();
+        edit.insert(0.into(), r"abc\def$".to_owned());
+        edit.insert(8.into(), r"ghi\jkl$".to_owned());
+        let edit = edit.finish();
+        let snippets =
+            SnippetEdit::new(vec![Snippet::Placeholder(TextRange::new(0.into(), 3.into()))]);
+
+        check_rendered_snippets(
+            edit,
+            snippets,
+            expect![[r#"
+            [
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 0,
+                        },
+                    },
+                    new_text: "${0:abc}\\\\def\\$",
+                    insert_text_format: Some(
+                        Snippet,
+                    ),
+                    annotation_id: None,
+                },
+                SnippetTextEdit {
+                    range: Range {
+                        start: Position {
+                            line: 0,
+                            character: 8,
+                        },
+                        end: Position {
+                            line: 0,
+                            character: 8,
+                        },
+                    },
+                    new_text: "ghi\\jkl$",
+                    insert_text_format: None,
+                    annotation_id: None,
+                },
+            ]
+        "#]],
+        );
+    }
+
     // `Url` is not able to parse windows paths on unix machines.
     #[test]
     #[cfg(target_os = "windows")]