Add infix expressions

src/grammar.pest

@@ -1,5 +1,15 @@
 file = { "hello world" }
 
+expr = { infix_expr | term }
+
+term = _{ literal | "(" ~ expr ~ ")" }
+
+infix_expr = {
+    #lhs = term ~ operator ~ #rhs = expr
+}
+
+operator = { "+" | "-" | "*" | "/" | "&&" | "||" }
+
 literal = { string | number | boolean }
 
 string = { "\"" ~ (!"\"" ~ ANY)* ~ "\"" }

src/test/infix_expressions.rs

@@ -0,0 +1,68 @@
+use pest::{consumes_to, parses_to};
+
+use crate::{Rule, SnekParser};
+
+#[test]
+fn it_parses_addition() {
+    parses_to!(parser: SnekParser, input: "1 + 1", rule: Rule::expr, tokens: [
+        expr(0, 5, [
+            infix_expr(0, 5, [
+                literal(0, 1, [
+                    integer(0, 1)
+                ]),
+                operator(2, 3),
+                expr(4, 5, [
+                    literal(4, 5, [
+                        integer(4, 5)
+                    ])
+                ])
+            ])
+        ])
+    ]);
+}
+
+#[test]
+fn it_parses_subtraction() {
+    parses_to!(parser: SnekParser, input: "1.0 - 1.1", rule: Rule::expr, tokens: [
+        expr(0, 9, [
+            infix_expr(0, 9, [
+                literal(0, 3, [
+                    float(0, 3)
+                ]),
+                operator(4, 5),
+                expr(6, 9, [
+                    literal(6, 9, [
+                        float(6, 9)
+                    ])
+                ])
+            ])
+        ])
+    ]);
+}
+
+#[test]
+fn it_parses_multiple_operations() {
+    parses_to!(parser: SnekParser, input: "1 + 2 + 3", rule: Rule::expr, tokens: [
+        expr(0, 9, [
+            infix_expr(0, 9, [
+                literal(0, 1, [
+                    integer(0, 1)
+                ]),
+                operator(2, 3),
+                expr(4, 9, [
+                    infix_expr(4, 9, [
+                        literal(4, 5, [
+                            integer(4, 5)
+                        ]),
+                        operator(6, 7),
+                        expr(8, 9, [
+                            literal(8, 9, [
+                                integer(8, 9)
+                            ])
+                        ])
+                    ])
+                ])
+            ])
+        ])
+    ]);
+}

src/test/mod.rs

@@ -1,4 +1,5 @@
 use pest::iterators::Pair;
+mod infix_expressions;
 mod literals;
 
 use crate::{parse, parse_rule, Rule};