From 927ad5e955911cc75cc01557322246d9f7daad95 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Mon, 7 Jun 2021 09:17:18 +0200
Subject: [PATCH] Binary operator boilerplate reduction

---
 src/ast.rs    | 21 ++++++++++++++++++++
 src/parser.rs | 55 +++++++++++++++------------------------------------
 2 files changed, 37 insertions(+), 39 deletions(-)

diff --git a/src/ast.rs b/src/ast.rs
index bbf6d691..a5fbae01 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -112,3 +112,24 @@ pub enum BinOpKind {
     And,
     Or,
 }
+
+impl BinOpKind {
+    pub fn from_token(t: crate::lexer::Token) -> Result<Self, crate::error::ErrorKind> {
+        use crate::lexer::Token;
+        use crate::error::*;
+
+        match t {
+            Token::Plus => Ok(Self::Add),
+            Token::Minus => Ok(Self::Subtract),
+            Token::Star => Ok(Self::Multiply),
+            Token::FwdSlash => Ok(Self::Divide),
+            Token::GreaterThan => Ok(Self::Greater),
+            Token::LessThan => Ok(Self::Less),
+            Token::EqualEqual => Ok(Self::Equal),
+            Token::NotEqual => Ok(Self::NotEqual),
+            Token::And => Ok(Self::And),
+            Token::Or => Ok(Self::Or),
+            t=> Err(ErrorKind::UnexpectedToken(t)),
+        }
+    }
+}
diff --git a/src/parser.rs b/src/parser.rs
index 0a51fc79..7f66de1f 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -111,44 +111,21 @@ impl<'source> Parser<'source> {
             )),
 
             // Operations
-            Token::Plus => Ok(Expr::new(
-                self.op_flow(BinOpKind::Add, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::Minus => Ok(Expr::new(
-                self.op_flow(BinOpKind::Subtract, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::Star => Ok(Expr::new(
-                self.op_flow(BinOpKind::Multiply, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::FwdSlash => Ok(Expr::new(
-                self.op_flow(BinOpKind::Divide, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::EqualEqual => Ok(Expr::new(
-                self.op_flow(BinOpKind::Equal, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::NotEqual => Ok(Expr::new(
-                self.op_flow(BinOpKind::NotEqual, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::And => Ok(Expr::new(
-                self.op_flow(BinOpKind::And, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::Or => Ok(Expr::new(
-                self.op_flow(BinOpKind::Or, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::LessThan => Ok(Expr::new(
-                self.op_flow(BinOpKind::Less, buf)?,
-                start..self.lexer.span().end,
-            )),
-            Token::GreaterThan => Ok(Expr::new(
-                self.op_flow(BinOpKind::Greater, buf)?,
+            Token::Plus
+            | Token::Minus
+            | Token::Star
+            | Token::FwdSlash
+            | Token::EqualEqual
+            | Token::NotEqual
+            | Token::LessThan
+            | Token::GreaterThan => Ok(Expr::new(
+                self.op_flow(
+                    match BinOpKind::from_token(token) {
+                        Ok(op) => op,
+                        Err(e) => return Err(Error::new(e, self.lexer.span())),
+                    },
+                    buf,
+                )?,
                 start..self.lexer.span().end,
             )),
 
@@ -218,7 +195,7 @@ impl<'source> Parser<'source> {
         self.require(Token::LeftParen)?;
 
         let cond = self.expr_flow(Token::RightParen)?;
-        
+
         let body = self.parse_block()?;
 
         Ok(StmtKind::If { cond, body })