mylang.grammar

program
	-> statements {% id %}

statements
	-> _ statement _ 	  {%
		data => [data[1]]
		%}
	| _ statement _ "\n" statements {%
		data => [data[1], ...data[4]]
	%}

statement
	-> var_assignment {% id %}
	| print_statement {% id %}
	| while_loop      {% id %}

while_loop
	-> "while" __ binary_expression __ "{" _ "\n" statements "\n" "}" {%
		data => {
			return {
				type: "while_loop",
				condition: data[2],
				body: data[7]
			}
		}
	%}

print_statement
	-> "print" __ expression {%
		data => {
			return {
				type: "print_statement",
				expression: data[2]
			}
		}
	%}

expression
	-> unary_expression  {% id %}
	|  binary_expression {% id %}

unary_expression
	-> number 			 {% id %}
	| identifier 		 {% id %}

operator
	-> "+" {% id %}
	|  "-" {% id %}
	|  "*" {% id %}
	|  "/" {% id %}

	|  ">=" {% id %}
	|  "<=" {% id %}
	|  ">" {% id %}
	|  "<" {% id %}
	|  "=" {% id %}

binary_expression
	-> unary_expression _ operator _ expression {%
		data => {
			return {
				type: "binary_expression",
				left: data[0],
				operator: data[2],
				right: data[4],
			}
		}
	%}

var_assignment
	-> identifier _ ":=" _ expression {%
		data => {
			return {
				type: "var_assignment",
				varname: data[0],
				value: data[4]
			}
		}
	%}

identifier
	-> [a-z]:+ {%
		data => data[0].join("")
	%}

number
	-> digits "." digits {%
		data => Number(data[0] + "." + data[2])
	%}
	| digits {%
		data => Number(data[0])
	%}

digits ->[0-9]:+ {%
		data => data[0].join("")

	%}

_ -> [ \t]:*

__ -> [ \t]:+