Add vm::builtins mod as a place for builtin functions to live

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/vm/builtins.rs

@@ -0,0 +1,83 @@
+use crate::object::{BuiltinExit, Int, Value};
+use crate::vm::{error::RuntimeError, machine::MachineBuilder};
+
+impl MachineBuilder {
+    /// Registers all builtins for calling on the machine.
+    pub(super) fn register_builtins(&mut self) {
+        self.scope_stack.push_scope();
+
+        //
+        // panic
+        //
+        self.register_builtin_fun("panic", |machine, _| {
+            println!("!!! panic");
+            println!("!!! top of stack");
+            for (i, value) in machine.stack().iter().enumerate().rev() {
+                println!("!!!   {}. {:?}", i, value);
+            }
+            println!("!!! bottom of stack");
+            panic!();
+        });
+
+        //
+        // if
+        //
+        self.register_builtin_fun("if", |machine, _| {
+            let if_false = machine.stack_pop()?;
+            let if_true = machine.stack_pop()?;
+            let condition = machine.stack_pop()?;
+            let value = if condition.is_truthy() {
+                if_true
+            } else {
+                if_false
+            };
+
+            if let Value::Quote(quote) = value {
+                Ok(BuiltinExit::Call(quote))
+            } else {
+                return Err(RuntimeError::CannotCall(
+                    "if statement requires quote value".to_string(),
+                )
+                .into());
+            }
+        });
+
+        //
+        // print
+        //
+        self.register_builtin_fun("print", |machine, _| {
+            let value = machine.stack_pop()?;
+            print!("{}", value);
+            Ok(BuiltinExit::Return)
+        });
+
+        //
+        // println
+        //
+        self.register_builtin_fun("println", |machine, _| {
+            let value = machine.stack_pop()?;
+            println!("{}", value);
+            Ok(BuiltinExit::Return)
+        });
+
+        //
+        // ==
+        //
+        self.register_builtin_fun("==", |machine, _| {
+            let rhs = machine.stack_pop()?;
+            let lhs = machine.stack_pop()?;
+            machine.stack_push(Value::Int((lhs == rhs) as Int))?;
+            Ok(BuiltinExit::Return)
+        });
+
+        //
+        // ~=
+        //
+        self.register_builtin_fun("~=", |machine, _| {
+            let rhs = machine.stack_pop()?;
+            let lhs = machine.stack_pop()?;
+            machine.stack_push(Value::Int((lhs != rhs) as Int))?;
+            Ok(BuiltinExit::Return)
+        });
+    }
+}

src/vm/machine.rs

@@ -318,10 +318,10 @@ impl Machine {
 
 #[derive(Debug, Default)]
 pub struct MachineBuilder {
-    globals: BTreeMap<Word, Value>,
-    scope_stack: ScopeStack,
-    max_stack_size: Option<usize>,
-    max_arena_objects: Option<usize>,
+    pub(super) globals: BTreeMap<Word, Value>,
+    pub(super) scope_stack: ScopeStack,
+    pub(super) max_stack_size: Option<usize>,
+    pub(super) max_arena_objects: Option<usize>,
 }
 
 impl MachineBuilder {
@@ -335,53 +335,7 @@ impl MachineBuilder {
         self
     }
 
-    /// Registers all builtins for calling on the machine.
-    fn register_builtins(&mut self) {
-        self.scope_stack.push_scope();
-        self.register_builtin_fun("panic", |machine, _| {
-            println!("!!! panic");
-            println!("!!! top of stack");
-            for (i, value) in machine.stack().iter().enumerate().rev() {
-                println!("!!!   {}. {:?}", i, value);
-            }
-            println!("!!! bottom of stack");
-            panic!();
-        });
-
-        self.register_builtin_fun("if", |machine, _| {
-            let if_false = machine.stack_pop()?;
-            let if_true = machine.stack_pop()?;
-            let condition = machine.stack_pop()?;
-            let value = if condition.is_truthy() {
-                if_true
-            } else {
-                if_false
-            };
-
-            if let Value::Quote(quote) = value {
-                Ok(BuiltinExit::Call(quote))
-            } else {
-                return Err(RuntimeError::CannotCall(
-                    "if statement requires quote value".to_string(),
-                )
-                .into());
-            }
-        });
-
-        self.register_builtin_fun("print", |machine, _| {
-            let value = machine.stack_pop()?;
-            print!("{}", value);
-            Ok(BuiltinExit::Return)
-        });
-
-        self.register_builtin_fun("println", |machine, _| {
-            let value = machine.stack_pop()?;
-            println!("{}", value);
-            Ok(BuiltinExit::Return)
-        });
-    }
-
-    fn register_builtin_fun(
+    pub(super) fn register_builtin_fun(
         &mut self,
         name: &str,
         fun: fn(&mut Machine, usize) -> Result<BuiltinExit>,
@@ -392,7 +346,7 @@ impl MachineBuilder {
         );
     }
 
-    fn register_global(&mut self, name: &str, value: Value) {
+    pub(super) fn register_global(&mut self, name: &str, value: Value) {
         let word = self.scope_stack.insert_local(name);
         self.globals.insert(word, value);
     }

src/vm/mod.rs

@@ -1,3 +1,4 @@
+mod builtins;
 pub mod error;
 pub mod inst;
 pub mod machine;