extract AtomEdit and Edit into new ra_text_edit crate

3 files changed, 118 insertions, 0 deletions

diff --git a/crates/ra_text_edit/src/edit.rs b/crates/ra_text_edit/src/edit.rs
new file mode 100644
index 000000000..560cf2bbc
--- /dev/null
+++ b/crates/ra_text_edit/src/edit.rs
@@ -0,0 +1,84 @@
+use crate::AtomEdit;
+use crate::text_utils::contains_offset_nonstrict;
+use text_unit::{TextRange, TextUnit};
+
+#[derive(Debug, Clone)]
+pub struct Edit {
+    atoms: Vec<AtomEdit>,
+}
+
+#[derive(Debug)]
+pub struct EditBuilder {
+    atoms: Vec<AtomEdit>,
+}
+
+impl EditBuilder {
+    pub fn new() -> EditBuilder {
+        EditBuilder { atoms: Vec::new() }
+    }
+    pub fn replace(&mut self, range: TextRange, replace_with: String) {
+        self.atoms.push(AtomEdit::replace(range, replace_with))
+    }
+    pub fn delete(&mut self, range: TextRange) {
+        self.atoms.push(AtomEdit::delete(range))
+    }
+    pub fn insert(&mut self, offset: TextUnit, text: String) {
+        self.atoms.push(AtomEdit::insert(offset, text))
+    }
+    pub fn finish(self) -> Edit {
+        let mut atoms = self.atoms;
+        atoms.sort_by_key(|a| (a.delete.start(), a.delete.end()));
+        for (a1, a2) in atoms.iter().zip(atoms.iter().skip(1)) {
+            assert!(a1.delete.end() <= a2.delete.start())
+        }
+        Edit { atoms }
+    }
+    pub fn invalidates_offset(&self, offset: TextUnit) -> bool {
+        self.atoms
+            .iter()
+            .any(|atom| contains_offset_nonstrict(atom.delete, offset))
+    }
+}
+
+impl Edit {
+    pub fn into_atoms(self) -> Vec<AtomEdit> {
+        self.atoms
+    }
+
+    pub fn apply(&self, text: &str) -> String {
+        let mut total_len = text.len();
+        for atom in self.atoms.iter() {
+            total_len += atom.insert.len();
+            total_len -= u32::from(atom.delete.end() - atom.delete.start()) as usize;
+        }
+        let mut buf = String::with_capacity(total_len);
+        let mut prev = 0;
+        for atom in self.atoms.iter() {
+            let start = u32::from(atom.delete.start()) as usize;
+            let end = u32::from(atom.delete.end()) as usize;
+            if start > prev {
+                buf.push_str(&text[prev..start]);
+            }
+            buf.push_str(&atom.insert);
+            prev = end;
+        }
+        buf.push_str(&text[prev..text.len()]);
+        assert_eq!(buf.len(), total_len);
+        buf
+    }
+
+    pub fn apply_to_offset(&self, offset: TextUnit) -> Option<TextUnit> {
+        let mut res = offset;
+        for atom in self.atoms.iter() {
+            if atom.delete.start() >= offset {
+                break;
+            }
+            if offset < atom.delete.end() {
+                return None;
+            }
+            res += TextUnit::of_str(&atom.insert);
+            res -= atom.delete.len();
+        }
+        Some(res)
+    }
+}
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
new file mode 100644
index 000000000..789471e8a
--- /dev/null
+++ b/crates/ra_text_edit/src/lib.rs
@@ -0,0 +1,29 @@
+mod edit;
+pub mod text_utils;
+
+pub use crate::edit::{Edit, EditBuilder};
+
+use text_unit::{TextRange, TextUnit};
+
+#[derive(Debug, Clone)]
+pub struct AtomEdit {
+    pub delete: TextRange,
+    pub insert: String,
+}
+
+impl AtomEdit {
+    pub fn replace(range: TextRange, replace_with: String) -> AtomEdit {
+        AtomEdit {
+            delete: range,
+            insert: replace_with,
+        }
+    }
+
+    pub fn delete(range: TextRange) -> AtomEdit {
+        AtomEdit::replace(range, String::new())
+    }
+
+    pub fn insert(offset: TextUnit, text: String) -> AtomEdit {
+        AtomEdit::replace(TextRange::offset_len(offset, 0.into()), text)
+    }
+}
diff --git a/crates/ra_text_edit/src/text_utils.rs b/crates/ra_text_edit/src/text_utils.rs
new file mode 100644
index 000000000..e3b4dc4fe
--- /dev/null
+++ b/crates/ra_text_edit/src/text_utils.rs
@@ -0,0 +1,5 @@
+use text_unit::{TextRange, TextUnit};
+
+pub fn contains_offset_nonstrict(range: TextRange, offset: TextUnit) -> bool {
+    range.start() <= offset && offset <= range.end()
+}