From 2bed29253c2cf79b125b57324b48c0a0f917365c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edvard=20Th=C3=B6rnros?= <edvard.thornros@gmail.com>
Date: Tue, 12 Jan 2021 21:14:25 +0100
Subject: Reference counted strings

---
 src/compiler.rs |  3 ++-
 src/vm.rs       | 19 ++++++++++++++-----
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/compiler.rs b/src/compiler.rs
index df094ae..d3fc1fd 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -1,4 +1,5 @@
 use std::path::{Path, PathBuf};
+use std::rc::Rc;
 use std::convert::TryFrom;
 
 use crate::tokenizer::{Token, TokenStream};
@@ -225,7 +226,7 @@ impl Compiler {
             Token::Float(f) => { Value::Float(f) },
             Token::Int(i) => { Value::Int(i) }
             Token::Bool(b) => { Value::Bool(b) }
-            Token::String(s) => { Value::String(s.clone()) }
+            Token::String(s) => { Value::String(Rc::from(s)) }
             _ => { error!(self, "Cannot parse value."); Value::Bool(false) }
         };
         block.add(Op::Constant(value), self.line());
diff --git a/src/vm.rs b/src/vm.rs
index d0b9190..2962b7f 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -1,4 +1,5 @@
 use std::path::{Path, PathBuf};
+use std::rc::Rc;
 use std::collections::HashMap;
 
 use crate::error::{Error, ErrorKind};
@@ -17,7 +18,7 @@ pub enum Value {
     Float(f64),
     Int(i64),
     Bool(bool),
-    String(String),
+    String(Rc<String>),
 }
 
 #[derive(Debug, Clone)]
@@ -153,7 +154,7 @@ impl VM {
     }
 
     pub fn run(&mut self) -> Result<(), Error>{
-        const PRINT_WHILE_RUNNING: bool = false;
+        const PRINT_WHILE_RUNNING: bool = true;
         const PRINT_BLOCK: bool = true;
 
         if PRINT_BLOCK {
@@ -167,8 +168,14 @@ impl VM {
         loop {
             if PRINT_WHILE_RUNNING {
                 print!("    [");
-                for s in self.stack.iter() {
-                    print!("{:?} ", s);
+                for (i, s) in self.stack.iter().enumerate() {
+                    if i != 0 {
+                        print!(" ");
+                    }
+                    match s {
+                        Value::String(rc) => print!("{:?}<{}>", rc, Rc::strong_count(rc)),
+                        _ => print!("{:?}", s),
+                    }
                 }
                 println!("]");
 
@@ -205,7 +212,9 @@ impl VM {
                     match self.pop_twice() {
                         (Value::Float(a), Value::Float(b)) => self.stack.push(Value::Float(b + a)),
                         (Value::Int(a), Value::Int(b)) => self.stack.push(Value::Int(b + a)),
-                        (Value::String(a), Value::String(b)) => self.stack.push(Value::String(format!("{}{}", a, b))),
+                        (Value::String(a), Value::String(b)) => {
+                            self.stack.push(Value::String(Rc::from(format!("{}{}", a, b))))
+                        }
                         (a, b) => error!(self, ErrorKind::TypeError(op.clone(), vec![a, b])),
                     }
                 }
-- 
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