2 files changed, 121 insertions, 0 deletions

diff --git a/crates/ra_ide_db/src/lib.rs b/crates/ra_ide_db/src/lib.rs
index e6f2d36e9..52fcd7b6f 100644
--- a/crates/ra_ide_db/src/lib.rs
+++ b/crates/ra_ide_db/src/lib.rs
@@ -10,6 +10,7 @@ pub mod change;
 pub mod defs;
 pub mod search;
 pub mod imports_locator;
+pub mod source_change;
 mod wasm_shims;
 
 use std::sync::Arc;
diff --git a/crates/ra_ide_db/src/source_change.rs b/crates/ra_ide_db/src/source_change.rs
new file mode 100644
index 000000000..4dd01b312
--- /dev/null
+++ b/crates/ra_ide_db/src/source_change.rs
@@ -0,0 +1,120 @@
+//! This modules defines type to represent changes to the source code, that flow
+//! from the server to the client.
+//!
+//! It can be viewed as a dual for `AnalysisChange`.
+
+use ra_db::{FileId, FilePosition, RelativePathBuf, SourceRootId};
+use ra_text_edit::{TextEdit, TextSize};
+
+#[derive(Debug)]
+pub struct SourceChange {
+    /// For display in the undo log in the editor
+    pub label: String,
+    pub source_file_edits: Vec<SourceFileEdit>,
+    pub file_system_edits: Vec<FileSystemEdit>,
+    pub cursor_position: Option<FilePosition>,
+}
+
+impl SourceChange {
+    /// Creates a new SourceChange with the given label
+    /// from the edits.
+    pub fn from_edits<L: Into<String>>(
+        label: L,
+        source_file_edits: Vec<SourceFileEdit>,
+        file_system_edits: Vec<FileSystemEdit>,
+    ) -> Self {
+        SourceChange {
+            label: label.into(),
+            source_file_edits,
+            file_system_edits,
+            cursor_position: None,
+        }
+    }
+
+    /// Creates a new SourceChange with the given label,
+    /// containing only the given `SourceFileEdits`.
+    pub fn source_file_edits<L: Into<String>>(label: L, edits: Vec<SourceFileEdit>) -> Self {
+        let label = label.into();
+        assert!(label.starts_with(char::is_uppercase));
+        SourceChange {
+            label: label,
+            source_file_edits: edits,
+            file_system_edits: vec![],
+            cursor_position: None,
+        }
+    }
+
+    /// Creates a new SourceChange with the given label,
+    /// containing only the given `FileSystemEdits`.
+    pub(crate) fn file_system_edits<L: Into<String>>(label: L, edits: Vec<FileSystemEdit>) -> Self {
+        SourceChange {
+            label: label.into(),
+            source_file_edits: vec![],
+            file_system_edits: edits,
+            cursor_position: None,
+        }
+    }
+
+    /// Creates a new SourceChange with the given label,
+    /// containing only a single `SourceFileEdit`.
+    pub fn source_file_edit<L: Into<String>>(label: L, edit: SourceFileEdit) -> Self {
+        SourceChange::source_file_edits(label, vec![edit])
+    }
+
+    /// Creates a new SourceChange with the given label
+    /// from the given `FileId` and `TextEdit`
+    pub fn source_file_edit_from<L: Into<String>>(
+        label: L,
+        file_id: FileId,
+        edit: TextEdit,
+    ) -> Self {
+        SourceChange::source_file_edit(label, SourceFileEdit { file_id, edit })
+    }
+
+    /// Creates a new SourceChange with the given label
+    /// from the given `FileId` and `TextEdit`
+    pub fn file_system_edit<L: Into<String>>(label: L, edit: FileSystemEdit) -> Self {
+        SourceChange::file_system_edits(label, vec![edit])
+    }
+
+    /// Sets the cursor position to the given `FilePosition`
+    pub fn with_cursor(mut self, cursor_position: FilePosition) -> Self {
+        self.cursor_position = Some(cursor_position);
+        self
+    }
+
+    /// Sets the cursor position to the given `FilePosition`
+    pub fn with_cursor_opt(mut self, cursor_position: Option<FilePosition>) -> Self {
+        self.cursor_position = cursor_position;
+        self
+    }
+}
+
+#[derive(Debug)]
+pub struct SourceFileEdit {
+    pub file_id: FileId,
+    pub edit: TextEdit,
+}
+
+#[derive(Debug)]
+pub enum FileSystemEdit {
+    CreateFile { source_root: SourceRootId, path: RelativePathBuf },
+    MoveFile { src: FileId, dst_source_root: SourceRootId, dst_path: RelativePathBuf },
+}
+
+pub struct SingleFileChange {
+    pub label: String,
+    pub edit: TextEdit,
+    pub cursor_position: Option<TextSize>,
+}
+
+impl SingleFileChange {
+    pub fn into_source_change(self, file_id: FileId) -> SourceChange {
+        SourceChange {
+            label: self.label,
+            source_file_edits: vec![SourceFileEdit { file_id, edit: self.edit }],
+            file_system_edits: Vec::new(),
+            cursor_position: self.cursor_position.map(|offset| FilePosition { file_id, offset }),
+        }
+    }
+}