diff --git a/src/data.rs b/src/data.rs
index 91093b7..2449565 100644
--- a/src/data.rs
+++ b/src/data.rs
@@ -1,4 +1,5 @@
 use core::cmp::Ordering;
+use core::fmt::{Debug, Formatter};
 use crate::upcast::IntoUsize;
 
 //noinspection SpellCheckingInspection
@@ -87,4 +88,62 @@ pub fn iterate<T: pointer_iterator::Pointer>(pointer: T) -> T::IterType {
 
 pub fn fill_with<T, F: FnMut(usize) -> T>(slice: &mut [T], mut func: F) {
     slice.iter_mut().enumerate().for_each(|(i,v)|*v = func(i))
+}
+
+pub struct FixedVec<const MAX_LEN: usize, T> {
+    length: usize,
+    buffer: [core::mem::MaybeUninit<T>;MAX_LEN],
+}
+
+impl<const MAX_LEN: usize, T: Sized> FixedVec<MAX_LEN, T> {
+    pub fn push(&mut self, value: T) -> Option<()> {
+        if self.length >= MAX_LEN { return None }
+        unsafe { *self.buffer[self.length].as_mut_ptr() = value };
+        self.length += 1;
+        Some(())
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        if self.length == 0 { return None }
+        self.length -= 1;
+        Some(unsafe { self.buffer[self.length].assume_init_read() })
+    }
+
+    pub fn extend<Iter: Iterator<Item=T>>(&mut self, mut iter: Iter) -> Result<usize, usize> {
+        let mut count = 0;
+        loop {
+            if self.length == MAX_LEN {
+                return Err(count);
+            }
+            match iter.next() {
+                None => return Ok(count),
+                Some(value) => {
+                    unsafe { *self.buffer[self.length].as_mut_ptr() = value };
+                    self.length += 1;
+                    count += 1;
+                }
+            }
+
+        }
+    }
+
+    pub fn as_slice(&self) -> &[T] {
+        // length can't be larger than MaxLen, use unsafe to dodge the panic
+        unsafe { core::slice::from_raw_parts(self.buffer.as_ptr() as *const T, self.length) }
+    }
+
+}
+
+impl<const MAX_LEN: usize, T: Debug> Debug for FixedVec<MAX_LEN, T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        Debug::fmt(self.as_slice(), f)
+    }
+}
+
+impl<const MAX_LEN: usize, T> Drop for FixedVec<MAX_LEN, T> {
+    fn drop(&mut self) {
+        for e in &mut self.buffer[..self.length] {
+            unsafe { e.assume_init_drop() }
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/iter_tools/mod.rs b/src/iter_tools/mod.rs
new file mode 100644
index 0000000..52585b8
--- /dev/null
+++ b/src/iter_tools/mod.rs
@@ -0,0 +1,18 @@
+
+mod take_until;
+pub use take_until::*;
+
+pub trait IterTools: Iterator {
+
+    #[inline]
+    fn take_until<P>(self, predicate: P) -> TakeUntil<Self, P>
+        where
+            Self: Sized,
+            P: FnMut(&Self::Item) -> bool,
+    {
+        TakeUntil::new(self, predicate)
+    }
+
+}
+
+impl<T: Iterator> IterTools for T {}
diff --git a/src/iter_tools/take_until.rs b/src/iter_tools/take_until.rs
new file mode 100644
index 0000000..b40b190
--- /dev/null
+++ b/src/iter_tools/take_until.rs
@@ -0,0 +1,50 @@
+
+use core::fmt;
+
+
+#[derive(Clone)]
+pub struct TakeUntil<I, P> {
+    iter: I,
+    flag: bool,
+    predicate: P,
+}
+
+impl<I, P> TakeUntil<I, P> {
+    pub(in super) fn new(iter: I, predicate: P) -> TakeUntil<I, P> {
+        TakeUntil { iter, flag: false, predicate }
+    }
+}
+
+impl<I: Iterator, P> Iterator for TakeUntil<I, P>
+    where
+        P: FnMut(&I::Item) -> bool,
+{
+    type Item = I::Item;
+
+    #[inline]
+    fn next(&mut self) -> Option<I::Item> {
+        if self.flag {
+            None
+        } else {
+            let x = self.iter.next()?;
+            if (self.predicate)(&x) {
+                Some(x)
+            } else {
+                self.flag = true;
+                Some(x)
+            }
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.flag {
+            (0, Some(0))
+        } else {
+            let (_, upper) = self.iter.size_hint();
+            (0, upper) // can't know a lower bound, due to the predicate
+        }
+    }
+}
+
+
diff --git a/src/lib.rs b/src/lib.rs
index b6d8532..2116162 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -42,4 +42,7 @@ mod hash;
 pub use hash::*;
 
 mod strings;
-pub use strings::*;
\ No newline at end of file
+pub use strings::*;
+
+mod iter_tools;
+pub use iter_tools::*;
\ No newline at end of file