Merge pull request #118 from TheSignPainter98/context/rc-file-contents

Use `Rc<str>` for file contents

crates/emblem_core/src/context/file_content.rs

@@ -0,0 +1,157 @@
+use std::{
+    borrow::Borrow,
+    fmt::Display,
+    ops::{Bound, Range, RangeBounds},
+    rc::Rc,
+};
+
+pub trait FileSlice: AsRef<str> {
+    fn slice<R: RangeBounds<usize>>(&self, index: R) -> FileContentSlice;
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct FileContent {
+    inner: Rc<str>,
+}
+
+impl FileContent {
+    pub(crate) fn new(contents: &str) -> Self {
+        Self {
+            inner: contents.into(),
+        }
+    }
+}
+
+impl Default for FileContent {
+    fn default() -> Self {
+        Self::new("")
+    }
+}
+
+impl FileSlice for FileContent {
+    fn slice<R: RangeBounds<usize>>(&self, index: R) -> FileContentSlice {
+        let start = match index.start_bound() {
+            Bound::Included(i) => *i,
+            Bound::Excluded(_) => panic!("internal error: excluded left lower bound"),
+            Bound::Unbounded => 0,
+        };
+        let end = match index.end_bound() {
+            Bound::Included(i) => *i + 1,
+            Bound::Excluded(i) => *i,
+            Bound::Unbounded => self.as_ref().len(),
+        };
+        FileContentSlice {
+            raw: self.clone(),
+            range: start..end,
+        }
+    }
+}
+
+impl AsRef<str> for FileContent {
+    fn as_ref(&self) -> &str {
+        self.inner.as_ref()
+    }
+}
+
+impl Borrow<str> for FileContent {
+    fn borrow(&self) -> &str {
+        self.inner.borrow()
+    }
+}
+
+impl PartialEq<&str> for FileContent {
+    fn eq(&self, other: &&str) -> bool {
+        self.inner.as_ref() == *other
+    }
+}
+
+impl PartialEq<FileContent> for &str {
+    fn eq(&self, other: &FileContent) -> bool {
+        *self == other.inner.as_ref()
+    }
+}
+
+impl PartialEq<&str> for &FileContent {
+    fn eq(&self, other: &&str) -> bool {
+        self.inner.as_ref() == *other
+    }
+}
+
+impl PartialEq<&FileContent> for &str {
+    fn eq(&self, other: &&FileContent) -> bool {
+        *self == other.inner.as_ref()
+    }
+}
+
+impl Display for FileContent {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct FileContentSlice {
+    raw: FileContent,
+    range: Range<usize>,
+}
+
+impl FileSlice for FileContentSlice {
+    fn slice<R: RangeBounds<usize>>(&self, index: R) -> FileContentSlice {
+        let start = self.range.start
+            + match index.start_bound() {
+                Bound::Included(i) => *i,
+                Bound::Excluded(_) => panic!("internal error: excluded left lower bound"),
+                Bound::Unbounded => 0,
+            };
+        let end = self.range.end
+            + match index.end_bound() {
+                Bound::Included(i) => *i + 1,
+                Bound::Excluded(i) => *i,
+                Bound::Unbounded => self.as_ref().len(),
+            };
+        Self {
+            raw: self.raw.clone(),
+            range: start..end,
+        }
+    }
+}
+
+impl AsRef<str> for FileContentSlice {
+    fn as_ref(&self) -> &str {
+        &self.raw.as_ref()[self.range.clone()]
+    }
+}
+
+impl Display for FileContentSlice {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.as_ref().fmt(f)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn slice_unbounded() {
+        let original = "hello big world";
+        let content = FileContent::new(original);
+        assert_eq!(original, content.slice(..).as_ref());
+    }
+
+    #[test]
+    fn slice_exclusive() {
+        let original = "hello big world";
+        let content = FileContent::new(original);
+        let range = 1..10;
+        assert_eq!(&original[range.clone()], content.slice(range).as_ref());
+    }
+
+    #[test]
+    fn slice_inclusive() {
+        let original = "hello big world";
+        let content = FileContent::new(original);
+        let range = 1..=10;
+        assert_eq!(&original[range.clone()], content.slice(range).as_ref());
+    }
+}

crates/emblem_core/src/context/mod.rs

@@ -1,3 +1,4 @@
+pub(crate) mod file_content;
 pub(crate) mod file_name;
 mod module;
 mod resource_limit;

crates/emblem_core/src/lib.rs

@@ -27,7 +27,11 @@ pub use crate::{
         },
         Builder,
     },
-    context::{file_name::FileName, Context, ResourceLimit, SandboxLevel},
+    context::{
+        file_content::{FileContent, FileContentSlice},
+        file_name::FileName,
+        Context, ResourceLimit, SandboxLevel,
+    },
     explain::Explainer,
     extensions::ExtensionState,
     lint::Linter,