refactor to actual modules

src/prolog/machine/or_stack.rs

@@ -0,0 +1,126 @@
+use prolog::machine::machine_indices::*;
+
+use std::ops::{Index, IndexMut};
+use std::vec::Vec;
+
+pub struct Frame {
+    pub global_index: usize,
+    pub e: usize,
+    pub cp: LocalCodePtr,
+    pub attr_var_init_b: usize,
+    pub b: usize,    
+    pub bp: CodePtr,
+    pub tr: usize,
+    pub pstr_tr: usize,
+    pub h: usize,
+    pub b0: usize,
+    args: Vec<Addr>
+}
+
+impl Frame {
+    fn new(global_index: usize,
+           e: usize,
+           cp: LocalCodePtr,
+           attr_var_init_b: usize,
+           b: usize,
+           bp: CodePtr,
+           tr: usize,
+           pstr_tr: usize,
+           h: usize,
+           b0: usize,
+           n: usize)
+           -> Self
+    {
+        Frame {
+            global_index,
+            e,
+            cp,
+            attr_var_init_b,
+            b,
+            bp,
+            tr,
+            pstr_tr,
+            h,
+            b0,
+            args: vec![Addr::HeapCell(0); n]
+        }
+    }
+
+    pub fn num_args(&self) -> usize {
+        self.args.len()
+    }
+}
+
+pub struct OrStack(Vec<Frame>);
+
+impl OrStack {
+    pub fn new() -> Self {
+        OrStack(Vec::new())
+    }
+
+    pub fn push(&mut self,
+                global_index: usize,
+                e: usize,
+                cp: LocalCodePtr,
+                attr_var_init_b: usize,
+                b: usize,
+                bp: CodePtr,
+                tr: usize,
+                pstr_tr: usize,
+                h: usize,
+                b0: usize,
+                n: usize)
+    {
+        self.0.push(Frame::new(global_index, e, cp, attr_var_init_b, b, bp, tr, pstr_tr, h, b0, n));
+    }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn clear(&mut self) {
+        self.0.clear()
+    }
+    
+    pub fn top(&self) -> Option<&Frame> {
+        self.0.last()
+    }
+
+    // truncate expects a 1-indexed new_b, ie.
+    // the value b of MachineState.
+    pub fn truncate(&mut self, new_b: usize) {
+        self.0.truncate(new_b);
+    }
+    
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+impl Index<usize> for OrStack {
+    type Output = Frame;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        self.0.index(index)
+    }
+}
+
+impl IndexMut<usize> for OrStack {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        self.0.index_mut(index)
+    }
+}
+
+impl Index<usize> for Frame {
+    type Output = Addr;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        self.args.index(index - 1)
+    }
+}
+
+impl IndexMut<usize> for Frame {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        self.args.index_mut(index - 1)
+    }
+}