From 9891204b026c7660676f456128c94b01ae7f39cf Mon Sep 17 00:00:00 2001
From: David Li <li.davidm96@gmail.com>
Date: Sat, 4 Nov 2017 19:33:45 -0400
Subject: Parse comparison operators

---
 src/ast.rs        |  6 ++++++
 src/taiga.lalrpop | 30 ++++++++++++++++++++++++++++--
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/src/ast.rs b/src/ast.rs
index 97ed91d..ab9493e 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -47,6 +47,12 @@ pub enum BinOp {
     Mul,
     Div,
     FloorDiv,
+    Eq,
+    Neq,
+    Gt,
+    Lt,
+    Ge,
+    Le,
 }
 
 #[derive(Debug)]
diff --git a/src/taiga.lalrpop b/src/taiga.lalrpop
index 6bf750d..6aedf42 100644
--- a/src/taiga.lalrpop
+++ b/src/taiga.lalrpop
@@ -8,10 +8,36 @@ pub Program: ast::Program = {
 };
 
 Expression: Box<ast::WithLocation<ast::Expression>> = {
-    <e1:Expression> "+" <e2:ExpressionMul> => Box::new(e1.join_map(*e2, |v1, v2| {
+    <e1:Expression> "=" <e2:ExpressionCmp> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Eq, Box::new(v1), Box::new(v2))
+    })),
+    <e1:Expression> "!=" <e2:ExpressionCmp> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Neq, Box::new(v1), Box::new(v2))
+    })),
+    <ExpressionCmp> => <>,
+};
+
+ExpressionCmp: Box<ast::WithLocation<ast::Expression>> = {
+    <e1:ExpressionCmp> ">" <e2:ExpressionAdd> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Gt, Box::new(v1), Box::new(v2))
+    })),
+    <e1:ExpressionCmp> "<" <e2:ExpressionAdd> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Lt, Box::new(v1), Box::new(v2))
+    })),
+    <e1:ExpressionCmp> ">=" <e2:ExpressionAdd> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Ge, Box::new(v1), Box::new(v2))
+    })),
+    <e1:ExpressionCmp> "<=" <e2:ExpressionAdd> => Box::new(e1.join_map(*e2, |v1, v2| {
+        ast::Expression::BinOp(ast::BinOp::Le, Box::new(v1), Box::new(v2))
+    })),
+    <ExpressionAdd> => <>,
+};
+
+ExpressionAdd: Box<ast::WithLocation<ast::Expression>> = {
+    <e1:ExpressionAdd> "+" <e2:ExpressionMul> => Box::new(e1.join_map(*e2, |v1, v2| {
         ast::Expression::BinOp(ast::BinOp::Add, Box::new(v1), Box::new(v2))
     })),
-    <e1:Expression> "-" <e2:ExpressionMul> => Box::new(e1.join_map(*e2, |v1, v2| {
+    <e1:ExpressionAdd> "-" <e2:ExpressionMul> => Box::new(e1.join_map(*e2, |v1, v2| {
         ast::Expression::BinOp(ast::BinOp::Sub, Box::new(v1), Box::new(v2))
     })),
     <ExpressionMul> => <>,
-- 
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