Move `Fragment` into library

3 files changed, 85 insertions, 1 deletions

diff --git a/library/src/layout/fragment.rs b/library/src/layout/fragment.rs
new file mode 100644
index 00000000..d1f6b524
--- /dev/null
+++ b/library/src/layout/fragment.rs
@@ -0,0 +1,82 @@
+use crate::prelude::*;
+
+/// A partial layout result.
+#[derive(Clone)]
+pub struct Fragment(Vec<Frame>);
+
+impl Fragment {
+    /// Create a fragment from a single frame.
+    pub fn frame(frame: Frame) -> Self {
+        Self(vec![frame])
+    }
+
+    /// Create a fragment from multiple frames.
+    pub fn frames(frames: Vec<Frame>) -> Self {
+        Self(frames)
+    }
+
+    /// The number of frames in the fragment.
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Extract the first and only frame.
+    ///
+    /// Panics if there are multiple frames.
+    #[track_caller]
+    pub fn into_frame(self) -> Frame {
+        assert_eq!(self.0.len(), 1, "expected exactly one frame");
+        self.0.into_iter().next().unwrap()
+    }
+
+    /// Extract the frames.
+    pub fn into_frames(self) -> Vec<Frame> {
+        self.0
+    }
+
+    /// Iterate over the contained frames.
+    pub fn iter(&self) -> std::slice::Iter<Frame> {
+        self.0.iter()
+    }
+
+    /// Iterate over the contained frames.
+    pub fn iter_mut(&mut self) -> std::slice::IterMut<Frame> {
+        self.0.iter_mut()
+    }
+}
+
+impl Debug for Fragment {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self.0.as_slice() {
+            [frame] => frame.fmt(f),
+            frames => frames.fmt(f),
+        }
+    }
+}
+
+impl IntoIterator for Fragment {
+    type Item = Frame;
+    type IntoIter = std::vec::IntoIter<Frame>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.into_iter()
+    }
+}
+
+impl<'a> IntoIterator for &'a Fragment {
+    type Item = &'a Frame;
+    type IntoIter = std::slice::Iter<'a, Frame>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.iter()
+    }
+}
+
+impl<'a> IntoIterator for &'a mut Fragment {
+    type Item = &'a mut Frame;
+    type IntoIter = std::slice::IterMut<'a, Frame>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0.iter_mut()
+    }
+}
diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index ab5ebaf8..61fcfd44 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -6,6 +6,7 @@ mod container;
 #[path = "enum.rs"]
 mod enum_;
 mod flow;
+mod fragment;
 mod grid;
 mod hide;
 mod list;
@@ -25,6 +26,7 @@ pub use self::columns::*;
 pub use self::container::*;
 pub use self::enum_::*;
 pub use self::flow::*;
+pub use self::fragment::*;
 pub use self::grid::*;
 pub use self::hide::*;
 pub use self::list::*;
diff --git a/library/src/prelude.rs b/library/src/prelude.rs
index b8f6025a..98ec1ccb 100644
--- a/library/src/prelude.rs
+++ b/library/src/prelude.rs
@@ -28,6 +28,6 @@ pub use typst::util::{format_eco, EcoString};
 pub use typst::World;
 
 #[doc(no_inline)]
-pub use crate::layout::{Inline, Layout, Regions};
+pub use crate::layout::{Fragment, Inline, Layout, Regions};
 #[doc(no_inline)]
 pub use crate::shared::{Behave, Behaviour, ContentExt, StyleMapExt};