Merge #325

325: implement translate_offset_with_edit r=matklad a=vemoo

- Implement `translate_offset_with_edit` to resolve #105 
- Add proptest impls for text, offsets and edits and use them in tests for `translate_offset_with_edit` and `LineIndex`
- Added benchmark for `translate_offset_with_edit`

Co-authored-by: Bernardo <[email protected]>

4 files changed, 98 insertions, 6 deletions

diff --git a/crates/ra_text_edit/Cargo.toml b/crates/ra_text_edit/Cargo.toml
index 3c4157a4e..e0db49688 100644
--- a/crates/ra_text_edit/Cargo.toml
+++ b/crates/ra_text_edit/Cargo.toml
@@ -7,6 +7,7 @@ publish = false
 
 [dependencies]
 text_unit = "0.1.5"
+proptest = "0.8.7"
 
 [dev-dependencies]
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
index 13e20f6fb..8acf10448 100644
--- a/crates/ra_text_edit/src/lib.rs
+++ b/crates/ra_text_edit/src/lib.rs
@@ -1,12 +1,15 @@
 mod text_edit;
 pub mod text_utils;
+pub mod test_utils;
 
 pub use crate::text_edit::{TextEdit, TextEditBuilder};
 
 use text_unit::{TextRange, TextUnit};
 
+/// Must not overlap with other `AtomTextEdit`s
 #[derive(Debug, Clone)]
 pub struct AtomTextEdit {
+    /// Refers to offsets in the original text
     pub delete: TextRange,
     pub insert: String,
 }
diff --git a/crates/ra_text_edit/src/test_utils.rs b/crates/ra_text_edit/src/test_utils.rs
new file mode 100644
index 000000000..745f21c93
--- /dev/null
+++ b/crates/ra_text_edit/src/test_utils.rs
@@ -0,0 +1,85 @@
+use proptest::prelude::*;
+use text_unit::{TextUnit, TextRange};
+use crate::{AtomTextEdit, TextEdit};
+
+pub fn arb_text() -> proptest::string::RegexGeneratorStrategy<String> {
+    // generate multiple newlines
+    proptest::string::string_regex("(.*\n?)*").unwrap()
+}
+
+fn text_offsets(text: &str) -> Vec<TextUnit> {
+    text.char_indices()
+        .map(|(i, _)| TextUnit::from_usize(i))
+        .collect()
+}
+
+pub fn arb_offset(text: &str) -> BoxedStrategy<TextUnit> {
+    let offsets = text_offsets(text);
+    // this is necessary to avoid "Uniform::new called with `low >= high`" panic
+    if offsets.is_empty() {
+        Just(TextUnit::from(0)).boxed()
+    } else {
+        prop::sample::select(offsets).boxed()
+    }
+}
+
+pub fn arb_text_edit(text: &str) -> BoxedStrategy<TextEdit> {
+    if text.is_empty() {
+        // only valid edits
+        return Just(vec![])
+            .boxed()
+            .prop_union(
+                arb_text()
+                    .prop_map(|text| vec![AtomTextEdit::insert(TextUnit::from(0), text)])
+                    .boxed(),
+            )
+            .prop_map(TextEdit::from_atoms)
+            .boxed();
+    }
+
+    let offsets = text_offsets(text);
+    let max_cuts = 7.min(offsets.len());
+
+    proptest::sample::subsequence(offsets, 0..max_cuts)
+        .prop_flat_map(|cuts| {
+            let strategies: Vec<_> = cuts
+                .chunks(2)
+                .map(|chunk| match chunk {
+                    &[from, to] => {
+                        let range = TextRange::from_to(from, to);
+                        Just(AtomTextEdit::delete(range))
+                            .boxed()
+                            .prop_union(
+                                arb_text()
+                                    .prop_map(move |text| AtomTextEdit::replace(range, text))
+                                    .boxed(),
+                            )
+                            .boxed()
+                    }
+                    &[x] => arb_text()
+                        .prop_map(move |text| AtomTextEdit::insert(x, text))
+                        .boxed(),
+                    _ => unreachable!(),
+                })
+                .collect();
+            strategies
+        })
+        .prop_map(TextEdit::from_atoms)
+        .boxed()
+}
+
+#[derive(Debug, Clone)]
+pub struct ArbTextWithEdit {
+    pub text: String,
+    pub edit: TextEdit,
+}
+
+pub fn arb_text_with_edit() -> BoxedStrategy<ArbTextWithEdit> {
+    let text = arb_text();
+    text.prop_flat_map(|s| {
+        let edit = arb_text_edit(&s);
+        (Just(s), edit)
+    })
+    .prop_map(|(text, edit)| ArbTextWithEdit { text, edit })
+    .boxed()
+}
diff --git a/crates/ra_text_edit/src/text_edit.rs b/crates/ra_text_edit/src/text_edit.rs
index 392968d63..0881f3e1c 100644
--- a/crates/ra_text_edit/src/text_edit.rs
+++ b/crates/ra_text_edit/src/text_edit.rs
@@ -26,12 +26,7 @@ impl TextEditBuilder {
         self.atoms.push(AtomTextEdit::insert(offset, text))
     }
     pub fn finish(self) -> TextEdit {
-        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())
-        }
-        TextEdit { atoms }
+        TextEdit::from_atoms(self.atoms)
     }
     pub fn invalidates_offset(&self, offset: TextUnit) -> bool {
         self.atoms
@@ -41,6 +36,14 @@ impl TextEditBuilder {
 }
 
 impl TextEdit {
+    pub(crate) fn from_atoms(mut atoms: Vec<AtomTextEdit>) -> TextEdit {
+        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())
+        }
+        TextEdit { atoms }
+    }
+
     pub fn as_atoms(&self) -> &[AtomTextEdit] {
         &self.atoms
     }