Turtle.grammar

%header%
GRAMMARTYPE = "LL"

%tokens%
WHITESPACE = <<[ \t\n\r]+>> %ignore%  //ignore tag to discard such tokens

STRING = <<\'.*?\'>>
INTEGER = <<([-|+]?[0-9]+)>>  //includes shorts and bytes

//value literals
TRUE = "true"
FALSE = "false"
NULL = "null"

//control flow keywords
WHILE = "while"
IF = "if"

//built-in type names
INT = "int"
STR = "string"
BOOL = "bool"
VOID = "void"


//other keywords
LET = "let"
DEF = "def"
SET = "set"
DATA = "data"
MUTATE = "mut"
GET = "get"

NAME = <<[a-zA-Z][a-zA-Z0-9_]*>>  //reduce spaces between "<<" and ">>"

//operators
NOT_EQ = "!="
GR_EQ = ">=" 
LS_EQ = "<="
PLUS = "+"
MINUS = "-"
MULT = "*"
LESS = "<"
GREAT = ">"
EQUAL = "="


COLON = ":"
EXPONENT = "^"

OP_PAREN = "("
CL_PAREN = ")"


%productions%


program = (expr+);

expr = (atom
       | (OP_PAREN funcDef CL_PAREN)
       | (OP_PAREN letDec CL_PAREN)
	   | (OP_PAREN ifExpr CL_PAREN)
	   | (OP_PAREN binOp CL_PAREN)
	   | (OP_PAREN setVar CL_PAREN)
	   | (OP_PAREN funcCall CL_PAREN)
	   | (OP_PAREN whileLoop CL_PAREN))
	   | (OP_PAREN dataDec CL_PAREN)
	   | (OP_PAREN mute CL_PAREN)
	   | (OP_PAREN retrieve CL_PAREN);
	   
dataDec = DATA NAME OP_PAREN (NAME COLON type)+ CL_PAREN;
mute = MUTATE expr NAME expr;  //first expr is target, second one is the new value, name argument is the member to mutate
retrieve = GET expr NAME; //expr is the target, and name is the member to retrieve
	   
funcDef = DEF NAME (OP_PAREN (NAME COLON type) CL_PAREN)* COLON (type | VOID) (expr)* ;
letDec = LET OP_PAREN (OP_PAREN (NAME COLON type)  expr CL_PAREN)+ CL_PAREN (expr)* ;
ifExpr = IF expr expr expr;
binOp = (PLUS | MINUS | MULT | EXPONENT | LESS | GREAT | EQUAL | NOT_EQ | GR_EQ | LS_EQ) expr expr;
setVar = SET NAME expr;
funcCall = NAME (expr)*;
whileLoop = WHILE expr (expr)*;

nullExpr = OP_PAREN NULL type CL_PAREN;
	   
type = (INT | BOOL | STR | NAME);

atom = ( ( [MINUS] INTEGER) | FALSE | TRUE | STRING | NAME | nullExpr);