Add initial parser

Makefile

@@ -6,5 +6,8 @@ scan: main.cpp scanner.cpp
 scanner.cpp: scanner.l
 	flex -o scanner.cpp scanner.l
 
+parser.tab.cpp: parser.y
+	bison -d parser.y
+
 clean:
 	rm -f scan scanner.cpp

parser.y

@@ -0,0 +1,58 @@
+%{
+
+#include <string>
+
+%}
+
+%token INDENT
+%token DEDENT
+%token NEWLINE
+%token AND
+%token BREAK
+%token DEF
+%token ELIF
+%token ELSE
+%token FOR
+%token IF
+%token NOT
+%token OR
+%token RETURN
+%token WHILE
+%token BOOLEAN
+%token IDENTIFIER
+%token ASSIGN
+%token PLUS
+%token MINUS
+%token TIMES
+%token DIVIDEDBY
+%token EQ
+%token NEQ
+%token GT
+%token GTE
+%token LT
+%token LTE
+%token LPAREN
+%token RPAREN
+%token COMMA
+%token COLON
+
+%define api.value.type { std::string }
+%define api.pure full
+%define api.push-pull push
+
+%%
+
+program
+    : statements {}
+    ;
+
+statements
+    : statement statements {}
+    | statement {}
+    ;
+
+statement
+    : PLUS {}
+    ;
+
+%%