From 17304c82fd99374246fbc78fc166ac80f9b777c4 Mon Sep 17 00:00:00 2001
From: mathias <mathias.rieder@gmail.com>
Date: Sat, 14 Dec 2019 22:17:34 +0100
Subject: [PATCH] #17 parsing support for comparison expressions

---
 src/ast.rs    |  2 ++
 src/lexer.rs  |  6 ++++++
 src/parser.rs | 20 ++++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/src/ast.rs b/src/ast.rs
index 1af7875a86..07c9093dc1 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -42,4 +42,6 @@ pub enum Operator {
     Minus,
     Multiplication,
     Division,
+    OperatorEqual,
+    OperatorNotEqual,
 }
diff --git a/src/lexer.rs b/src/lexer.rs
index 35d9519f17..3c37eefcfe 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -51,6 +51,12 @@ pub enum Token {
     #[token = "/"]
     OperatorDivision,
 
+    #[token = "="]
+    OperatorEqual,
+
+    #[token = "<>"]
+    OperatorNotEqual,
+
     #[regex = r"[0-9]+(\.(0-9)+)?"]
     LiteralNumber,
 }
diff --git a/src/parser.rs b/src/parser.rs
index 59174dd9ea..9efb4ca124 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -117,6 +117,26 @@ fn parse_primary_expression(lexer: &mut RustyLexer) -> Result<Statement, String>
     parse_additive_expression(lexer)
 }
 
+fn parse_equality_expression(lexer: &mut RustyLexer) -> Result<Statement, String> {
+    let left = parse_compare_expression(lexer);
+    let operator = match lexer.token {
+        OperatorEqual => Operator::Equal,
+        OperatorNotEqual => Operator::NotEqual,
+        _ => return Ok(left),
+    };
+    lexer.advance();
+    let right = parse_primary_expression(lexer)?;
+    Ok(Statement::BinaryExpression {
+        operator,
+        left: Box::new(left),
+        right: Box::new(right),
+    })
+}
+
+fn parse_compare_expression(lexer: &mut RustyLexer) -> Result<Statement, String> {
+
+}
+
 fn parse_additive_expression(lexer: &mut RustyLexer) -> Result<Statement, String> {
     let left = parse_multiplication_expression(lexer)?;
     let operator = match lexer.token {