implement simplify using idx versions

src/algorithm/geo/simplify.rs

@@ -4,9 +4,11 @@ use crate::array::*;
 use crate::chunked_array::ChunkedGeometryArray;
 use crate::datatypes::GeoDataType;
 use crate::error::{GeoArrowError, Result};
+use crate::scalar::linestring::scalar::TakeLineString;
+use crate::trait_::GeometryScalarTrait;
 use crate::GeometryArrayTrait;
 use arrow_array::OffsetSizeTrait;
-use geo::Simplify as _Simplify;
+use geo::{Simplify as _Simplify, SimplifyIdx};
 
 /// Simplifies a geometry.
 ///
@@ -96,7 +98,26 @@ macro_rules! iter_geo_impl {
     };
 }
 
-iter_geo_impl!(LineStringArray<O>, geo::LineString);
+impl<O: OffsetSizeTrait> Simplify for LineStringArray<O> {
+    type Output = Self;
+
+    fn simplify(&self, epsilon: &f64) -> Self {
+        let geoms = self
+            .iter()
+            .map(|maybe_g| {
+                if let Some(geom) = maybe_g {
+                    let idxs = geom.to_geo().simplify_idx(epsilon);
+                    Some(TakeLineString::new(geom, idxs))
+                } else {
+                    None
+                }
+            })
+            .collect::<Vec<_>>();
+        LineStringBuilder::from_nullable_line_strings(geoms.as_slice(), Default::default()).finish()
+    }
+}
+
+// iter_geo_impl!(LineStringArray<O>, geo::LineString);
 iter_geo_impl!(PolygonArray<O>, geo::Polygon);
 iter_geo_impl!(MultiLineStringArray<O>, geo::MultiLineString);
 iter_geo_impl!(MultiPolygonArray<O>, geo::MultiPolygon);

src/array/linestring/capacity.rs

@@ -1,4 +1,4 @@
-use std::ops::Add;
+use std::ops::{Add, AddAssign};
 
 use arrow_array::OffsetSizeTrait;
 
@@ -52,6 +52,12 @@ impl LineStringCapacity {
         };
         Ok(())
     }
+
+    #[inline]
+    pub fn add_null(&mut self) {
+        self.geom_capacity += 1;
+    }
+
     pub fn coord_capacity(&self) -> usize {
         self.coord_capacity
     }
@@ -94,3 +100,10 @@ impl Add for LineStringCapacity {
         Self::new(coord_capacity, geom_capacity)
     }
 }
+
+impl AddAssign for LineStringCapacity {
+    fn add_assign(&mut self, rhs: Self) {
+        self.coord_capacity += rhs.coord_capacity;
+        self.geom_capacity += rhs.geom_capacity;
+    }
+}

src/scalar/linestring/mod.rs

@@ -1,6 +1,6 @@
 pub mod iterator;
 mod owned;
-mod scalar;
+pub(crate) mod scalar;
 
 pub use iterator::LineStringIterator;
 pub use owned::OwnedLineString;

src/scalar/linestring/scalar.rs

@@ -180,6 +180,42 @@ impl<O: OffsetSizeTrait> PartialEq for LineString<'_, O> {
     }
 }
 
+/// A LineString where specific indices of the geometry are selected
+///
+/// Primarily used in the Simplify trait
+pub(crate) struct TakeLineString<'a, O: OffsetSizeTrait> {
+    line_string: LineString<'a, O>,
+    idxs: Vec<usize>,
+}
+
+impl<'a, O: OffsetSizeTrait> TakeLineString<'a, O> {
+    pub fn new(line_string: LineString<'a, O>, idxs: Vec<usize>) -> Self {
+        Self { line_string, idxs }
+    }
+}
+
+impl<'a, O: OffsetSizeTrait> LineStringTrait for TakeLineString<'a, O> {
+    type T = f64;
+    type ItemType<'b> = Point<'a> where Self: 'b;
+    type Iter<'b> = LineStringIterator<'a, O> where Self: 'b;
+
+    fn coords(&self) -> Self::Iter<'_> {
+        todo!()
+    }
+
+    fn num_coords(&self) -> usize {
+        self.idxs.len()
+    }
+
+    fn coord(&self, i: usize) -> Option<Self::ItemType<'_>> {
+        if i > self.num_coords() {
+            return None;
+        }
+
+        self.line_string.coord(self.idxs[i])
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::array::LineStringArray;

src/scalar/mod.rs

@@ -5,7 +5,7 @@ pub use binary::WKB;
 pub use coord::{Coord, InterleavedCoord, SeparatedCoord};
 pub use geometry::Geometry;
 pub use geometrycollection::GeometryCollection;
-pub use linestring::{LineString, OwnedLineString};
+pub use linestring::{LineString, LineStringIterator, OwnedLineString};
 pub use multilinestring::{MultiLineString, OwnedMultiLineString};
 pub use multipoint::{MultiPoint, OwnedMultiPoint};
 pub use multipolygon::{MultiPolygon, OwnedMultiPolygon};
@@ -17,7 +17,7 @@ mod binary;
 mod coord;
 mod geometry;
 mod geometrycollection;
-mod linestring;
+pub(crate) mod linestring;
 mod multilinestring;
 mod multipoint;
 mod multipolygon;