1 files changed, 86 insertions, 0 deletions
diff --git a/src/parse/span.rs b/src/parse/span.rs
new file mode 100644
index 0000000..340a078
--- /dev/null
+++ b/src/parse/span.rs
@@ -0,0 +1,86 @@
+use std::sync::atomic::AtomicU32;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct FileId {
+    id: u32,
+}
+
+impl FileId {
+    pub fn new() -> Self {
+        static GEN: AtomicU32 = AtomicU32::new(0);
+        Self {
+            id: GEN.fetch_add(1, std::sync::atomic::Ordering::SeqCst),
+        }
+    }
+
+    pub fn from(self, start: u32) -> SpanFrom {
+        SpanFrom::new(self, start)
+    }
+
+    pub fn span(self, start: u32, end: u32) -> Span {
+        Span::new(self, start, end)
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct SpanFrom {
+    pub file: FileId,
+    pub start: u32,
+}
+
+impl SpanFrom {
+    pub fn new(file: FileId, start: u32) -> Self {
+        Self { file, start }
+    }
+
+    pub fn to(self, end: u32) -> Span {
+        Span::new(self.file, self.start, end)
+    }
+
+    pub fn with_len(self, len: u32) -> Span {
+        self.to(self.start + len)
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub struct Span {
+    pub file: FileId,
+    pub start: u32,
+    pub end: u32,
+}
+
+/// manual implementation of PartialOrd to ensure shorter Spans are first
+impl PartialOrd for Span {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        match self.file.partial_cmp(&other.file) {
+            Some(core::cmp::Ordering::Equal) => {}
+            ord => return ord,
+        }
+        match self.start.partial_cmp(&other.start) {
+            Some(core::cmp::Ordering::Equal) => {}
+            ord => return ord,
+        }
+        other.end.partial_cmp(&self.end)
+    }
+}
+
+/// manual implementation of Ord to ensure shorter Spans are first
+impl Ord for Span {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        match self.file.cmp(&other.file) {
+            core::cmp::Ordering::Equal => {}
+            ord => return ord,
+        }
+        match self.start.cmp(&other.start) {
+            core::cmp::Ordering::Equal => {}
+            ord => return ord,
+        }
+        other.end.cmp(&self.end)
+    }
+}
+
+impl Span {
+    pub fn new(file: FileId, start: u32, end: u32) -> Self {
+        Self { file, start, end }
+    }
+}