grammar.txt

#---------------------------------------
# Statements
#---------------------------------------

stmt      : block
          | breakStmt
          | contStmt
          | declStmt
          | exprStmt
          | ifStmt
          | readStmt
          | repeatStmt
          | whileStmt
          | writeStmt
          | caseStmt
		  ;

ifStmt	  : stmt
		  | checkStmt
	      ;

stmts     : stmts ';' stmt
          | stmt
		  ;

ifStmts   : ifStmts ';' ifStmt
          | ifStmt
		  ;


#---------------------------------------

block     	: '{' stmts ';' '}'
			;

ifBlock		: '{' ifStmts ';' '}'
			;

function	: 'fn' '(' varList ')' '->' varType block
			;

#---------------------------------------

breakStmt   : 'break'
			;

contStmt    : 'continue'
			;


declStmt    : 'var' ID varType ':=' expr 
			| 'var' ID varType
			;


exprStmt    : expr
			;


ifStmt      : 'if' '(' expr ')' ifBlock elifChain 'else' block
			| 'if' '(' expr ')' ifBlock 'else' block
			| 'if' '(' expr ')' ifBlock elifChain
			| 'if' '(' expr ')' ifBlock
			;


multiIfStmt : 'if' '[' integer ']' exprList ifBlock elifChain 'else' block
			| 'if' '[' integer ']' exprList ifBlock 'else' block
			| 'if' '[' integer ']' exprList ifBlock elifChain
			| 'if' '[' integer ']' exprList ifBlock 
			;


elifChain	: multiElif 
			| elif
			;


multiElif	: 'elif '[' integer ']' exprList ifBlock elifChain
			| 'elif '[' integer ']' exprList ifBlock
			;


elif		: 'elif '(' expr ')' ifBlock elifChain
			| 'elif '(' expr ')' ifBlock 
			;


readStmt    : 'read' exprList
			;


repeatStmt  : 'repeat' block 'until' expr
			;


whileStmt   : 'while' expr block
			;


writeStmt   : 'write' exprList
			;


caseStmt    : 'case' integer block
			;


checkStmt	: 'check' '(' integer ')'
			;



#---------------------------------------
# Expressions
#---------------------------------------

expr        : prefixOpr expr
            | expr binaryOpr expr
            | number
            | stringLiteral
            | '(' expr ')'
            | ID
			;


number		: integer
			| real
			;


varList		: varList ',' ID ':' varType
			| %empty
			;


varType		: 'integer'
			| 'real'
			| 'string'
			;


exprList    : exprList ',' '(' expr ')'
            | '(' expr ')'
			;


# Prefix (unary) operators :
#   Math      : '+' '-'
#   Logical   : 'not'

# Binary operators :
#   Assignment    : '<-'
#   Math          : '+' '-' '*' '/' '%' '^' '?'
#   Relational    : '<' '<=' '>=' '>' '<>' '=='
#   Logical       : 'and' 'or'

#---------------------------------------
# Operator precedence, lowest to highest
#---------------------------------------
Logical OR
Logical AND
Relational EQ and NE
Relational LT, LE, GE, GT
Math random number (?)
Math add, subtract
Math multiply, divide, modulus
Math exponent
Math prefix -, Math prefix +, Logical prefix NOT

#---------------------------------------