3 files changed, 33 insertions, 46 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 7305d6dd5..1e2fc7851 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1244,7 +1244,7 @@ dependencies = [
  "rowan 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "smol_str 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
- "text_unit 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "text_unit 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1255,7 +1255,7 @@ version = "0.1.0"
 dependencies = [
  "proptest 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
- "text_unit 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "text_unit 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1468,7 +1468,7 @@ dependencies = [
  "colosseum 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "smol_str 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "text_unit 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "text_unit 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1748,12 +1748,12 @@ dependencies = [
  "difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
- "text_unit 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "text_unit 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "text_unit"
-version = "0.1.6"
+version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2193,7 +2193,7 @@ dependencies = [
 "checksum teraron 0.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0d89ad4617d1dec55331067fadaa041e813479e1779616f3d3ce9308bf46184e"
 "checksum termion 1.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "dde0593aeb8d47accea5392b39350015b5eccb12c0d98044d856983d89548dea"
 "checksum termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "72b620c5ea021d75a735c943269bb07d30c9b77d6ac6b236bc8b5c496ef05625"
-"checksum text_unit 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "158bb1c22b638b1da3c95a8ad9f061ea40d4d39fd0301be3a520f92efeeb189e"
+"checksum text_unit 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "019e5bc4c698b63073968610964c8c0869b60455d8f2e303a0ee7ad2e4f6ade4"
 "checksum textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
 "checksum threadpool 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e2f0c90a5f3459330ac8bc0d2f879c693bb7a2f59689c1083fc4ef83834da865"
diff --git a/crates/ra_syntax/Cargo.toml b/crates/ra_syntax/Cargo.toml
index 1f3981f5a..2e521183c 100644
--- a/crates/ra_syntax/Cargo.toml
+++ b/crates/ra_syntax/Cargo.toml
@@ -17,7 +17,7 @@ rowan = "0.5.0"
 
 # ideally, `serde` should be enabled by `ra_lsp_server`, but we enable it here
 # to reduce number of compilations
-text_unit = { version = "0.1.6", features = ["serde"] }
+text_unit = { version = "0.1.8", features = ["serde"] }
 smol_str = { version = "0.1.9", features = ["serde"] }
 
 ra_text_edit = { path = "../ra_text_edit" }
diff --git a/crates/ra_syntax/src/syntax_text.rs b/crates/ra_syntax/src/syntax_text.rs
index 6bb2ff461..b013164c4 100644
--- a/crates/ra_syntax/src/syntax_text.rs
+++ b/crates/ra_syntax/src/syntax_text.rs
@@ -1,4 +1,4 @@
-use std::{fmt, ops};
+use std::{fmt, ops::{self, Bound}};
 
 use crate::{SyntaxNode, TextRange, TextUnit, SyntaxElement};
 
@@ -54,10 +54,31 @@ impl<'a> SyntaxText<'a> {
         self.range.len()
     }
 
-    pub fn slice(&self, range: impl SyntaxTextSlice) -> SyntaxText<'a> {
-        let range = range.restrict(self.range).unwrap_or_else(|| {
-            panic!("invalid slice, range: {:?}, slice: {:?}", self.range, range)
-        });
+    /// NB, the offsets here are absolute, and this probably doesn't make sense!
+    pub fn slice(&self, range: impl ops::RangeBounds<TextUnit>) -> SyntaxText<'a> {
+        let start = match range.start_bound() {
+            Bound::Included(b) => *b,
+            Bound::Excluded(b) => *b + TextUnit::from(1u32),
+            Bound::Unbounded => self.range.start(),
+        };
+        let end = match range.end_bound() {
+            Bound::Included(b) => *b + TextUnit::from(1u32),
+            Bound::Excluded(b) => *b,
+            Bound::Unbounded => self.range.end(),
+        };
+        assert!(
+            start <= end,
+            "invalid slice, range: {:?}, slice: {:?}",
+            self.range,
+            (range.start_bound(), range.end_bound()),
+        );
+        let range = TextRange::from_to(start, end);
+        assert!(
+            range.is_subrange(&self.range),
+            "invalid slice, range: {:?}, slice: {:?}",
+            self.range,
+            range,
+        );
         SyntaxText { node: self.node, range }
     }
 
@@ -88,40 +109,6 @@ impl<'a> fmt::Display for SyntaxText<'a> {
     }
 }
 
-pub trait SyntaxTextSlice: fmt::Debug {
-    fn restrict(&self, range: TextRange) -> Option<TextRange>;
-}
-
-impl SyntaxTextSlice for TextRange {
-    fn restrict(&self, range: TextRange) -> Option<TextRange> {
-        self.intersection(&range)
-    }
-}
-
-impl SyntaxTextSlice for ops::RangeTo<TextUnit> {
-    fn restrict(&self, range: TextRange) -> Option<TextRange> {
-        if !range.contains_inclusive(self.end) {
-            return None;
-        }
-        Some(TextRange::from_to(range.start(), self.end))
-    }
-}
-
-impl SyntaxTextSlice for ops::RangeFrom<TextUnit> {
-    fn restrict(&self, range: TextRange) -> Option<TextRange> {
-        if !range.contains_inclusive(self.start) {
-            return None;
-        }
-        Some(TextRange::from_to(self.start, range.end()))
-    }
-}
-
-impl SyntaxTextSlice for ops::Range<TextUnit> {
-    fn restrict(&self, range: TextRange) -> Option<TextRange> {
-        TextRange::from_to(self.start, self.end).restrict(range)
-    }
-}
-
 impl From<SyntaxText<'_>> for String {
     fn from(text: SyntaxText) -> String {
         text.to_string()