Starting the rust version of gats.

1 files changed, 131 insertions, 0 deletions

diff --git a/rust/src/lib.rs b/rust/src/lib.rs
new file mode 100644
index 0000000..9b177a1
--- /dev/null
+++ b/rust/src/lib.rs
@@ -0,0 +1,131 @@
+use std::collections::HashMap;
+use std::vec::Vec;
+use std::io::{Write,Read};
+use std::num::FpCategory;
+
+pub enum Value {
+    Integer(i64),
+    ByteString(Vec<u8>),
+    Boolean(bool),
+    List(Vec<Value>),
+    Dictionary(HashMap<String, Value>),
+    Float(f64),
+    Nothing,
+}
+
+// const FLOAT_DIVISOR: f64 = (256_f64).ln();
+
+fn write_packed_int( x: i64 ) -> Vec<u8>
+{
+    let mut w = Vec::<u8>::with_capacity(10);
+    let mut v = x;
+    let mut bb = if x < 0 {
+        v = -v;
+        0x40_u8
+    } else {
+        0x00_u8
+    } | if v > (v & 0x3F) { 0x80_u8 } else { 0x00_u8 };
+    w.push(bb);
+    v = v >> 6;
+    while v > 0 {
+        bb = (v & 0x7F) as u8 | if v > (v & 0x7F) { 0x80_u8 } else { 0x00_u8 };
+        w.push(bb);
+        v = v >> 7;
+    }
+
+    w
+}
+
+fn read_packed_int<R: Read>( r: &mut R ) -> Result<i64, std::io::Error> {
+    let mut out : i64;
+    let mut bb = [0u8];
+    r.read( &mut bb )?;
+    let negative = (bb[0]&0x40_u8) == 0x40_u8;
+    out = (bb[0]&0x3F_u8) as i64;
+    let mut c = 0;
+    while (bb[0]&0x80_u8) != 0 {
+        r.read( &mut bb )?;
+        out |= ((bb[0]&0x7F_u8) as i64) << (6+7*c);
+        c += 1;
+    }
+
+    if negative {
+        Ok(-out)
+    } else {
+        Ok(out)
+    }
+}
+
+impl Value {
+    pub fn write<W: Write>(&self, w: &mut W) -> Result<(), std::io::Error> {
+        match self {
+            Self::Integer(x) => {
+                let mut bb = [0u8];
+                bb[0] = 'i' as u8;
+                w.write_all(&bb)?;
+                w.write_all(&write_packed_int( *x ))?;
+            },
+            Self::ByteString(s) => {
+                let mut bb = [0u8];
+                bb[0] = 's' as u8;
+                w.write_all(&bb)?;
+                w.write_all(&write_packed_int( s.len() as i64 ))?;
+                w.write_all( &s )?;
+            },
+            Self::Boolean(b) => {
+                let mut bb = [0u8];
+                bb[0] = if *b { '1' } else { '0' } as u8;
+                w.write_all( &bb )?;
+            },
+            Self::List(l) => {
+            },
+            Self::Dictionary(d) => {
+            },
+            Self::Float(f) => {
+                let mut bb = ['F' as u8, 0u8];
+                match f.classify() {
+                    FpCategory::Nan => {
+                        bb[1] = if f.is_sign_negative() { 'N' } else { 'n' } as u8;
+                        w.write_all( &bb )?;
+                    },
+                    FpCategory::Infinite => {
+                        bb[1] = if f.is_sign_negative() { 'I' } else { 'i' } as u8;
+                        w.write_all( &bb )?;
+                    },
+                    FpCategory::Zero => {
+                        bb[1] = if f.is_sign_negative() { 'Z' } else { 'z' } as u8;
+                        w.write_all( &bb )?;
+                    },
+                    FpCategory::Subnormal => {
+                        // The format doesn't account for these...uh...make them zero?
+                        bb[1] = if f.is_sign_negative() { 'Z' } else { 'z' } as u8;
+                        w.write_all( &bb )?;
+                    },
+                    FpCategory::Normal => {
+                        let div = 256f64.ln();
+                        todo!();
+
+                    },
+                }
+            },
+            Self::Nothing => {
+            },
+        }
+        Ok(())
+    }
+}
+
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}