feat: composition (#13)

Author: jjcfrancisco

src/composition.rs

@@ -0,0 +1,95 @@
+use std::io::Cursor;
+
+use crate::cursor::IncrementCursor;
+use crate::integer_codec::IntegerCodec;
+use crate::{Compressor, FastPForResult};
+
+pub struct Composition {
+    c1: IntegerCodec,
+    c2: IntegerCodec,
+}
+
+impl Composition {
+    pub fn new<C1, C2>(c1: C1, c2: C2) -> Self
+    where
+        C1: Into<IntegerCodec>,
+        C2: Into<IntegerCodec>,
+    {
+        Composition {
+            c1: c1.into(),
+            c2: c2.into(),
+        }
+    }
+
+    pub fn compress(
+        &mut self,
+        input: &[i32],
+        mut input_length: i32,
+        input_offset: &mut Cursor<i32>,
+        output: &mut [i32],
+        output_offset: &mut Cursor<i32>,
+    ) -> FastPForResult<()> {
+        if input_length == 0 {
+            // Return early if there is no data to compress
+            return Ok(());
+        }
+        let inpos_init = input_offset.position();
+        let outpos_init = output_offset.position();
+        self.c1
+            .compress(input, input_length, input_offset, output, output_offset)?;
+        if output_offset.position() == outpos_init {
+            output[outpos_init as usize] = 0;
+            output_offset.increment();
+        }
+        input_length -= input_offset.position() as i32 - inpos_init as i32;
+        self.c2
+            .compress(input, input_length, input_offset, output, output_offset)
+    }
+
+    pub fn uncompress(
+        &mut self,
+        input: &[i32],
+        mut input_length: i32,
+        input_offset: &mut Cursor<i32>,
+        output: &mut [i32],
+        output_offset: &mut Cursor<i32>,
+    ) -> FastPForResult<()> {
+        if input_length == 0 {
+            // Return early if there is no data to compress
+            return Ok(());
+        }
+        let final_init = input_offset.position() as i32;
+        self.c1
+            .uncompress(input, input_length, input_offset, output, output_offset)?;
+        input_length -= input_offset.position() as i32 - final_init;
+        self.c2
+            .uncompress(input, input_length, input_offset, output, output_offset)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::fastpfor::FastPFOR;
+    use crate::variable_byte::VariableByte;
+
+    #[test]
+    fn test_composition() {
+        let fastpfor = FastPFOR::default();
+        let vb = VariableByte::new();
+        let mut comp = Composition::new(fastpfor, vb);
+        let input = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+        let mut output = vec![0; 10];
+        let mut input_offset = Cursor::new(0);
+        let mut output_offset = Cursor::new(0);
+        let input_length = 10;
+        comp.compress(
+            &input,
+            input_length,
+            &mut input_offset,
+            &mut output,
+            &mut output_offset,
+        )
+        .expect("Failed to compress");
+    }
+}

src/compressor.rs

@@ -0,0 +1,23 @@
+use std::io::Cursor;
+
+use crate::FastPForResult;
+
+pub trait Compressor<T> {
+    fn compress(
+        &mut self,
+        input: &[i32],
+        input_length: i32,
+        input_offset: &mut Cursor<i32>,
+        output: &mut [T],
+        output_offset: &mut Cursor<i32>,
+    ) -> FastPForResult<()>;
+
+    fn uncompress(
+        &mut self,
+        input: &[T],
+        input_length: i32,
+        input_offset: &mut Cursor<i32>,
+        output: &mut [i32],
+        output_offset: &mut Cursor<i32>,
+    ) -> FastPForResult<()>;
+}