rust/crates/hir-expand/src/span.rs

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//! Spanmaps allow turning absolute ranges into relative ranges for incrementality purposes as well
//! as associating spans with text ranges in a particular file.
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use base_db::{
span::{ErasedFileAstId, SpanAnchor, SpanData, SyntaxContextId, ROOT_ERASED_FILE_AST_ID},
FileId,
};
use syntax::{ast::HasModuleItem, AstNode, TextRange, TextSize};
use triomphe::Arc;
use crate::db::ExpandDatabase;
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pub type ExpansionSpanMap = mbe::SpanMap<SpanData>;
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/// Spanmap for a macro file or a real file
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#[derive(Clone, Debug, PartialEq, Eq)]
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pub enum SpanMap {
/// Spanmap for a macro file
ExpansionSpanMap(Arc<ExpansionSpanMap>),
/// Spanmap for a real file
RealSpanMap(Arc<RealSpanMap>),
}
#[derive(Copy, Clone)]
pub enum SpanMapRef<'a> {
/// Spanmap for a macro file
ExpansionSpanMap(&'a ExpansionSpanMap),
/// Spanmap for a real file
RealSpanMap(&'a RealSpanMap),
}
impl mbe::SpanMapper<SpanData> for SpanMap {
fn span_for(&self, range: TextRange) -> SpanData {
self.span_for_range(range)
}
}
impl mbe::SpanMapper<SpanData> for SpanMapRef<'_> {
fn span_for(&self, range: TextRange) -> SpanData {
self.span_for_range(range)
}
}
impl mbe::SpanMapper<SpanData> for RealSpanMap {
fn span_for(&self, range: TextRange) -> SpanData {
self.span_for_range(range)
}
}
impl SpanMap {
pub fn span_for_range(&self, range: TextRange) -> SpanData {
match self {
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Self::ExpansionSpanMap(span_map) => span_map.span_at(range.start()),
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Self::RealSpanMap(span_map) => span_map.span_for_range(range),
}
}
pub fn as_ref(&self) -> SpanMapRef<'_> {
match self {
Self::ExpansionSpanMap(span_map) => SpanMapRef::ExpansionSpanMap(span_map),
Self::RealSpanMap(span_map) => SpanMapRef::RealSpanMap(span_map),
}
}
}
impl SpanMapRef<'_> {
pub fn span_for_range(self, range: TextRange) -> SpanData {
match self {
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Self::ExpansionSpanMap(span_map) => span_map.span_at(range.start()),
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Self::RealSpanMap(span_map) => span_map.span_for_range(range),
}
}
}
#[derive(PartialEq, Eq, Hash, Debug)]
pub struct RealSpanMap {
file_id: FileId,
/// Invariant: Sorted vec over TextSize
// FIXME: SortedVec<(TextSize, ErasedFileAstId)>?
pairs: Box<[(TextSize, ErasedFileAstId)]>,
}
impl RealSpanMap {
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/// Creates a real file span map that returns absolute ranges (relative ranges to the root ast id).
pub fn absolute(file_id: FileId) -> Self {
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RealSpanMap { file_id, pairs: Box::from([(TextSize::new(0), ROOT_ERASED_FILE_AST_ID)]) }
}
pub fn from_file(db: &dyn ExpandDatabase, file_id: FileId) -> Self {
let mut pairs = vec![(TextSize::new(0), ROOT_ERASED_FILE_AST_ID)];
let ast_id_map = db.ast_id_map(file_id.into());
pairs.extend(
db.parse(file_id)
.tree()
.items()
.map(|item| (item.syntax().text_range().start(), ast_id_map.ast_id(&item).erase())),
);
RealSpanMap { file_id, pairs: pairs.into_boxed_slice() }
}
pub fn span_for_range(&self, range: TextRange) -> SpanData {
let start = range.start();
let idx = self
.pairs
.binary_search_by(|&(it, _)| it.cmp(&start).then(std::cmp::Ordering::Less))
.unwrap_err();
let (offset, ast_id) = self.pairs[idx - 1];
SpanData {
range: range - offset,
anchor: SpanAnchor { file_id: self.file_id, ast_id },
ctx: SyntaxContextId::ROOT,
}
}
}