bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/span/src/map.rs')
-rw-r--r--crates/span/src/map.rs81
1 files changed, 81 insertions, 0 deletions
diff --git a/crates/span/src/map.rs b/crates/span/src/map.rs
new file mode 100644
index 0000000000..e69d003c07
--- /dev/null
+++ b/crates/span/src/map.rs
@@ -0,0 +1,81 @@
+//! A map that maps a span to every position in a file. Usually maps a span to some range of positions.
+//! Allows bidirectional lookup.
+
+use std::hash::Hash;
+
+use stdx::{always, itertools::Itertools};
+use syntax::{TextRange, TextSize};
+
+/// Maps absolute text ranges for the corresponding file to the relevant span data.
+#[derive(Debug, PartialEq, Eq, Clone, Hash)]
+pub struct SpanMap<S> {
+ spans: Vec<(TextSize, S)>,
+ // FIXME: Should be
+ // spans: Vec<(TextSize, crate::SyntaxContextId)>,
+}
+
+impl<S: Copy> SpanMap<S> {
+ /// Creates a new empty [`SpanMap`].
+ pub fn empty() -> Self {
+ Self { spans: Vec::new() }
+ }
+
+ /// Finalizes the [`SpanMap`], shrinking its backing storage and validating that the offsets are
+ /// in order.
+ pub fn finish(&mut self) {
+ always!(
+ self.spans.iter().tuple_windows().all(|(a, b)| a.0 < b.0),
+ "spans are not in order"
+ );
+ self.spans.shrink_to_fit();
+ }
+
+ /// Pushes a new span onto the [`SpanMap`].
+ pub fn push(&mut self, offset: TextSize, span: S) {
+ if cfg!(debug_assertions) {
+ if let Some(&(last_offset, _)) = self.spans.last() {
+ assert!(
+ last_offset < offset,
+ "last_offset({last_offset:?}) must be smaller than offset({offset:?})"
+ );
+ }
+ }
+ self.spans.push((offset, span));
+ }
+
+ /// Returns all [`TextRange`]s that correspond to the given span.
+ ///
+ /// Note this does a linear search through the entire backing vector.
+ pub fn ranges_with_span(&self, span: S) -> impl Iterator<Item = TextRange> + '_
+ where
+ S: Eq,
+ {
+ // FIXME: This should ignore the syntax context!
+ self.spans.iter().enumerate().filter_map(move |(idx, &(end, s))| {
+ if s != span {
+ return None;
+ }
+ let start = idx.checked_sub(1).map_or(TextSize::new(0), |prev| self.spans[prev].0);
+ Some(TextRange::new(start, end))
+ })
+ }
+
+ /// Returns the span at the given position.
+ pub fn span_at(&self, offset: TextSize) -> S {
+ let entry = self.spans.partition_point(|&(it, _)| it <= offset);
+ self.spans[entry].1
+ }
+
+ /// Returns the spans associated with the given range.
+ /// In other words, this will return all spans that correspond to all offsets within the given range.
+ pub fn spans_for_range(&self, range: TextRange) -> impl Iterator<Item = S> + '_ {
+ let (start, end) = (range.start(), range.end());
+ let start_entry = self.spans.partition_point(|&(it, _)| it <= start);
+ let end_entry = self.spans[start_entry..].partition_point(|&(it, _)| it <= end); // FIXME: this might be wrong?
+ (&self.spans[start_entry..][..end_entry]).iter().map(|&(_, s)| s)
+ }
+
+ pub fn iter(&self) -> impl Iterator<Item = (TextSize, S)> + '_ {
+ self.spans.iter().copied()
+ }
+}