Break out obj module into individual files by type

object.rs was getting a little big and the implementations are only
going to get bigger.

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

src/obj/quote.rs

@@ -0,0 +1,84 @@
+use crate::obj::{Obj, VTable};
+use crate::syn::ast::SpStmt;
+use crate::vm::{error::*, machine::Machine};
+use crate::{scope::Scope, syn::span::Span, vm::inst::SpInst};
+use gc::{unsafe_empty_trace, Finalize, Trace};
+use std::fmt::Debug;
+use std::rc::Rc;
+
+/// A handle to a quote pointing to an element in a `QuoteTable`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Finalize)]
+pub struct Quote(usize);
+
+impl Quote {
+    pub fn index(&self) -> usize {
+        self.0
+    }
+}
+
+unsafe impl Trace for Quote {
+    unsafe_empty_trace!();
+}
+
+#[derive(Debug, Trace, Finalize)]
+pub struct QuoteObj {
+    value: Quote,
+    vtable: VTable,
+}
+
+impl QuoteObj {
+    pub fn new(value: Quote) -> Self {
+        QuoteObj {
+            value,
+            vtable: vtable! {},
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn value(&self) -> Quote {
+        self.value
+    }
+}
+
+impl Obj for QuoteObj {
+    fn vtable(&self) -> &VTable {
+        &self.vtable
+    }
+
+    fn vtable_mut(&mut self) -> &mut VTable {
+        &mut self.vtable
+    }
+
+    fn call(&self, _call_site: Option<Span>, machine: &mut Machine) -> Result<()> {
+        machine.call_quote(self.value);
+        Ok(())
+    }
+
+    fn as_any(&self) -> &(dyn std::any::Any + 'static) {
+        self
+    }
+}
+
+/// A table of compiled quotes, their expression trees, and their spans.
+#[derive(Debug, Clone, Default)]
+pub struct QuoteTable {
+    table: Vec<(Span, Scope, Vec<SpStmt>, Rc<Vec<SpInst>>)>,
+}
+
+impl QuoteTable {
+    pub fn insert(
+        &mut self,
+        span: Span,
+        scope: Scope,
+        quote: Vec<SpStmt>,
+        compiled: Rc<Vec<SpInst>>,
+    ) -> Quote {
+        let next = Quote(self.table.len());
+        self.table.push((span, scope, quote, compiled));
+        next
+    }
+
+    pub fn get(&self, quote: Quote) -> &(Span, Scope, Vec<SpStmt>, Rc<Vec<SpInst>>) {
+        &self.table[quote.index()]
+    }
+}