From 1ee6c58a97470ac71f0aed21a0b9696ad0c7a378 Mon Sep 17 00:00:00 2001
From: Felix Raimundo <felix.raimundo@numworks.com>
Date: Fri, 18 Mar 2016 15:46:08 +0100
Subject: [PATCH] Add associativity rules to the lexer

Change-Id: I684264a4bec04567a2edc9fcb1b418d517a552a2
---
 poincare/src/expression_parser.y | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/poincare/src/expression_parser.y b/poincare/src/expression_parser.y
index 78470dc45..6727e860d 100644
--- a/poincare/src/expression_parser.y
+++ b/poincare/src/expression_parser.y
@@ -49,15 +49,22 @@ void poincare_expression_yyerror(yyscan_t scanner, Expression ** expressionOutpu
 %token <string> INTEGER
 %token <string> SYMBOL
 
+/* Operator tokens */
 %token PLUS
 %token MINUS
 %token MULTIPLY
 %token DIVIDE
 %token POW
-
 %token LEFT_PARENTHESIS
 %token RIGHT_PARENTHESIS
 
+/* Make the operators left associative.
+ * This makes 1 - 2 - 5’  be ‘(1 - 2) - 5’ instead of ‘1 - (2 - 5)’.
+ * This makes 1 / 2 / 5’  be ‘(1 / 2) / 5’ instead of ‘1 / (2 / 5)’.
+ */
+%left '-' '+'
+%left '*' '/'
+
 /* The "exp" symbol uses the "expression" part of the union. */
 %type <expression> exp;