Initial commit.

src/l0/ast.rs

@@ -0,0 +1,63 @@
+use std::vec::{Vec};
+
+pub type Var = String;
+
+pub type Atom = String;
+
+#[derive(Debug)]
+pub enum TopLevel {
+    Fact(Term),
+    Query(Term)
+}
+
+#[derive(Debug)]
+pub enum Term {
+    Atom(Atom),
+    Clause(Atom, Vec<Box<Term>>),
+    Var(Var)
+}
+
+impl Term {
+    pub fn name(&self) -> &Atom {
+        match self {
+            &Term::Atom(ref atom) => atom,
+            &Term::Var(ref var)   => var,
+            &Term::Clause(ref atom, _) => atom
+        }
+    }
+
+    pub fn is_variable(&self) -> bool {
+        if let &Term::Var(_) = self {
+            return true;
+        }
+
+        return false;
+    }
+}
+
+#[derive(Clone)]
+pub enum MachineInstruction {
+    GetStructure(Atom, usize, usize),
+    PutStructure(Atom, usize, usize),
+    SetVariable(usize),
+    SetValue(usize),
+    UnifyVariable(usize),
+    UnifyValue(usize)
+}
+
+pub type Program = Vec<MachineInstruction>;
+
+#[derive(Clone, Copy, PartialEq)]    
+pub enum Addr {
+    HeapCell(usize),
+    RegNum(usize)
+}
+
+impl Addr {
+    pub fn heap_offset(&self) -> usize {
+        match self {
+            &Addr::HeapCell(hc) => hc,
+            &Addr::RegNum(reg)  => reg
+        }
+    }
+}