From abbbb34901a20035af07c28576fc3e8fbf6dff26 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Mon, 2 Oct 2017 20:11:27 -0700
Subject: [PATCH] Some very basic evaluation stuff

---
 src/schala_lang/eval.rs    | 33 ++++++++++++++++++++++++++++++++-
 src/schala_lang/parsing.rs |  2 +-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/schala_lang/eval.rs b/src/schala_lang/eval.rs
index bb13fd0..f9fc283 100644
--- a/src/schala_lang/eval.rs
+++ b/src/schala_lang/eval.rs
@@ -1,4 +1,4 @@
-use schala_lang::parsing::{AST, Statement, Declaration, Expression, ExpressionType, TypeAnno};
+use schala_lang::parsing::{AST, Statement, Declaration, Expression, ExpressionType, Operation, TypeAnno};
 
 pub struct ReplState {
 }
@@ -72,9 +72,40 @@ impl ReplState {
       FloatLiteral(f) => Ok(Float(f)),
       StringLiteral(s) => Ok(Str(s.to_string())),
       BoolLiteral(b) => Ok(Bool(b)),
+      PrefixExp(op, expr) => self.eval_prefix_exp(op, expr),
+      BinExp(op, lhs, rhs) => self.eval_binexp(op, lhs, rhs),
       _ => Err(format!("Unimplemented")),
     }
   }
+
+  fn eval_binexp(&mut self, op: Operation, lhs: Box<Expression>, rhs: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::FullyEvaluatedExpr::*;
+    let evaled_lhs = self.eval_expr(*lhs)?;
+    let evaled_rhs = self.eval_expr(*rhs)?;
+    let opstr: &str = &op.0;
+    Ok(match (opstr, evaled_lhs, evaled_rhs) {
+      ("+", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l + r),
+      ("-", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l - r),
+      ("*", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l * r),
+      ("/", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l / r),
+      ("%", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l % r),
+      _ => return Err(format!("Runtime error: not yet implemented")),
+    })
+  }
+
+  fn eval_prefix_exp(&mut self, op: Operation, expr: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::FullyEvaluatedExpr::*;
+    let evaled_expr = self.eval_expr(*expr)?;
+    let opstr: &str = &op.0;
+
+    Ok(match (opstr, evaled_expr) {
+      ("!", Bool(true)) => Bool(false),
+      ("!", Bool(false)) => Bool(true),
+      ("-", UnsignedInt(n)) => SignedInt(-1*(n as i64)),
+      ("-", SignedInt(n)) => SignedInt(-1*(n as i64)),
+      _ => return Err(format!("Runtime error: not yet implemented")),
+    })
+  }
 }
 
 pub enum TypeCheck {
diff --git a/src/schala_lang/parsing.rs b/src/schala_lang/parsing.rs
index 092d6b2..3197786 100644
--- a/src/schala_lang/parsing.rs
+++ b/src/schala_lang/parsing.rs
@@ -463,7 +463,7 @@ pub struct MatchArm {
 pub struct Pattern(Rc<String>);
 
 #[derive(Debug, PartialEq)]
-pub struct Operation(Rc<String>);
+pub struct Operation(pub Rc<String>);
 
 impl Operation {
   fn min_precedence() -> i32 {