Make utf8 default, implement utf16 in terms of it

crates/ide/src/lib.rs

@@ -95,7 +95,7 @@ pub use ide_db::{
     },
     call_info::CallInfo,
     label::Label,
-    line_index::{LineColUtf16, LineIndex},
+    line_index::{LineCol, LineColUtf16, LineIndex},
     search::{ReferenceAccess, SearchScope},
     source_change::{FileSystemEdit, SourceChange},
     symbol_index::Query,

crates/ide_db/src/line_index.rs

@@ -22,6 +22,14 @@ pub struct LineColUtf16 {
     pub col: u32,
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct LineCol {
+    /// Zero-based
+    pub line: u32,
+    /// Zero-based utf8 offset
+    pub col: u32,
+}
+
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub(crate) struct Utf16Char {
     /// Start offset of a character inside a line, zero-based
@@ -88,18 +96,25 @@ impl LineIndex {
         LineIndex { newlines, utf16_lines }
     }
 
-    pub fn line_col(&self, offset: TextSize) -> LineColUtf16 {
+    pub fn line_col(&self, offset: TextSize) -> LineCol {
         let line = partition_point(&self.newlines, |&it| it <= offset) - 1;
         let line_start_offset = self.newlines[line];
         let col = offset - line_start_offset;
-
-        LineColUtf16 { line: line as u32, col: self.utf8_to_utf16_col(line as u32, col) as u32 }
+        LineCol { line: line as u32, col: col.into() }
     }
 
-    pub fn offset(&self, line_col: LineColUtf16) -> TextSize {
-        //FIXME: return Result
+    pub fn offset(&self, line_col: LineCol) -> TextSize {
+        self.newlines[line_col.line as usize] + TextSize::from(line_col.col)
+    }
+
+    pub fn to_utf16(&self, line_col: LineCol) -> LineColUtf16 {
+        let col = self.utf8_to_utf16_col(line_col.line, line_col.col.into());
+        LineColUtf16 { line: line_col.line, col: col as u32 }
+    }
+
+    pub fn to_utf8(&self, line_col: LineColUtf16) -> LineCol {
         let col = self.utf16_to_utf8_col(line_col.line, line_col.col);
-        self.newlines[line_col.line as usize] + col
+        LineCol { line: line_col.line, col: col.into() }
     }
 
     pub fn lines(&self, range: TextRange) -> impl Iterator<Item = TextRange> + '_ {

crates/ide_db/src/line_index/tests.rs

@@ -17,14 +17,14 @@ fn test_line_index() {
 
     let index = LineIndex::new(text);
     for &(offset, line, col) in &table {
-        assert_eq!(index.line_col(offset.into()), LineColUtf16 { line, col });
+        assert_eq!(index.line_col(offset.into()), LineCol { line, col });
     }
 
     let text = "\nhello\nworld";
     let table = [(0, 0, 0), (1, 1, 0), (2, 1, 1), (6, 1, 5), (7, 2, 0)];
     let index = LineIndex::new(text);
     for &(offset, line, col) in &table {
-        assert_eq!(index.line_col(offset.into()), LineColUtf16 { line, col });
+        assert_eq!(index.line_col(offset.into()), LineCol { line, col });
     }
 }
 

crates/rust-analyzer/src/cli/analysis_bench.rs

@@ -5,7 +5,7 @@ use std::{env, path::PathBuf, str::FromStr, sync::Arc, time::Instant};
 use anyhow::{bail, format_err, Result};
 use hir::PrefixKind;
 use ide::{
-    Analysis, AnalysisHost, Change, CompletionConfig, DiagnosticsConfig, FilePosition, LineColUtf16,
+    Analysis, AnalysisHost, Change, CompletionConfig, DiagnosticsConfig, FilePosition, LineCol,
 };
 use ide_db::{
     base_db::{
@@ -97,7 +97,7 @@ impl BenchCmd {
                 let offset = host
                     .analysis()
                     .file_line_index(file_id)?
-                    .offset(LineColUtf16 { line: pos.line - 1, col: pos.column });
+                    .offset(LineCol { line: pos.line - 1, col: pos.column });
                 let file_position = FilePosition { file_id, offset };
 
                 if is_completion {

crates/rust-analyzer/src/from_proto.rs

@@ -19,6 +19,7 @@ pub(crate) fn vfs_path(url: &lsp_types::Url) -> Result<vfs::VfsPath> {
 
 pub(crate) fn offset(line_index: &LineIndex, position: lsp_types::Position) -> TextSize {
     let line_col = LineColUtf16 { line: position.line as u32, col: position.character as u32 };
+    let line_col = line_index.to_utf8(line_col);
     line_index.offset(line_col)
 }
 

crates/rust-analyzer/src/to_proto.rs

@@ -22,6 +22,7 @@ use crate::{
 
 pub(crate) fn position(line_index: &LineIndex, offset: TextSize) -> lsp_types::Position {
     let line_col = line_index.line_col(offset);
+    let line_col = line_index.to_utf16(line_col);
     lsp_types::Position::new(line_col.line, line_col.col)
 }