add string table, StringList representation

src/prolog/machine/machine_state.rs

@@ -6,6 +6,7 @@ use prolog::machine::machine_errors::*;
 use prolog::num::{BigInt, BigUint, Zero, One};
 use prolog::or_stack::*;
 use prolog::read::*;
+use prolog::string_list::*;
 use prolog::tabled_rc::*;
 
 use downcast::Any;
@@ -288,6 +289,7 @@ impl Default for MachineFlags {
 
 pub struct MachineState {
     pub(crate) atom_tbl: TabledData<Atom>,
+    pub(crate) string_tbl: TabledData<StringListWrapper>,
     pub(super) s: usize,
     pub(super) p: CodePtr,
     pub(super) b: usize,

src/prolog/machine/machine_state_impl.rs

@@ -9,8 +9,8 @@ use prolog::num::{Integer, Signed, ToPrimitive, Zero};
 use prolog::num::bigint::{BigInt, BigUint};
 use prolog::num::rational::Ratio;
 use prolog::or_stack::*;
-use prolog::tabled_rc::*;
 
+use std::cell::RefCell;
 use std::cmp::{max, Ordering};
 use std::collections::{HashMap, HashSet};
 use std::rc::Rc;
@@ -28,9 +28,10 @@ macro_rules! try_or_fail {
 }
 
 impl MachineState {
-    pub(super) fn new(atom_tbl: TabledData<Atom>) -> MachineState {
+    pub(super) fn new() -> Self {
         MachineState {
-            atom_tbl,
+            atom_tbl: Rc::new(RefCell::new(HashSet::new())),
+            string_tbl: Rc::new(RefCell::new(HashSet::new())),
             s: 0,
             p: CodePtr::default(),
             b: 0,

src/prolog/machine/mod.rs

@@ -1,6 +1,7 @@
 use prolog::ast::*;
 use prolog::compile::*;
 use prolog::heap_print::*;
+use prolog::string_list::StringListWrapper;
 use prolog::tabled_rc::*;
 
 mod machine_errors;
@@ -11,8 +12,7 @@ mod system_calls;
 
 use prolog::machine::machine_state::*;
 
-use std::cell::RefCell;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::mem::swap;
 use std::ops::Index;
 use std::rc::Rc;
@@ -99,7 +99,7 @@ static QUEUES: &str  = include_str!("../lib/queues.pl");
 impl Machine {
     pub fn new() -> Self {
         let mut wam = Machine {
-            ms: MachineState::new(Rc::new(RefCell::new(HashSet::new()))),
+            ms: MachineState::new(),
             call_policy: Box::new(DefaultCallPolicy {}),
             cut_policy: Box::new(DefaultCutPolicy {}),
             code: Code::new(),
@@ -177,6 +177,10 @@ impl Machine {
         self.ms.atom_tbl.clone()
     }
 
+    pub fn string_tbl(&self) -> TabledData<StringListWrapper> {
+        self.ms.string_tbl.clone()
+    }
+    
     pub fn use_qualified_module_in_toplevel(&mut self, name: ClauseName, exports: Vec<PredicateKey>)
                                             -> EvalSession
     {