path.grammar

%class "Parser";

%terminals            SEMI, COMMA, DOT;
%terminals            CLASS, PUBLIC, STATIC, VOID, MAIN, NEW, EXTENDS;
%terminals            PRINT, LENGTH;
%terminals            PLUS, MINUS, TIMES;
%terminals            LPAREN, RPAREN, LBRACK, RBRACK, LBRACE, RBRACE;
%terminals            IF, ELSE, WHILE;
%terminals            TRUE, FALSE, NOT, AND;
%terminals            RETURN, THIS;
%terminals            STRING, INT, BOOLEAN;
%terminals            EQUALS, LESS;
%terminals            INT_LIT;        // our scanner provides numbers as integers
%terminals            ID;

%left DOT;
%left LBRACK;
%left AND;
%left PLUS, MINUS;
%left TIMES;
%left LESS;
%left ID;

%goal Program;

Program = MainClass ClassDecl*;

MainClass = CLASS ID LBRACE PUBLIC STATIC VOID MAIN LPAREN STRING LBRACK RBRACK ID RPAREN LBRACE Statement RBRACE RBRACE;

ClassDecl = CLASS ID LBRACE VarDecl* MethodDecl* RBRACE
| CLASS ID EXTENDS ID LBRACE VarDecl* MethodDecl* RBRACE;

VarDecl = Type ID;

MethodDecl = PUBLIC Type ID LPAREN FormalList RPAREN LBRACE VarDecl* Statement* RETURN Exp SEMI RBRACE;

FormalList = Type ID FormalRest*
|;

FormalRest = COMMA Type ID;

Type = INT LBRACK RBRACK
| BOOLEAN
| INT
| ID;

Statement = LBRACE Statement* RBRACE
| IF LPAREN Exp RPAREN Statement ELSE Statement
| WHILE LPAREN Exp RPAREN Statement
| PRINT LPAREN Exp RPAREN SEMI
| ID EQUALS Exp SEMI
| ID LBRACK Exp RBRACK EQUALS Exp SEMI;

Exp = Exp Op Exp
| Exp LBRACK Exp RBRACK
| Exp DOT LENGTH
| Exp DOT ID LPAREN ExpList RPAREN
| INT_LIT
| TRUE
| FALSE
| ID
| THIS
| NEW INT LBRACK Exp RBRACK
| NEW ID LPAREN RPAREN
| NOT Exp
| LPAREN Exp RPAREN;

ExpList = Exp ExpRest*
|;

ExpRest = COMMA Exp;

Op = TIMES
| PLUS
| MINUS
| LESS
| AND;