Diseño de Lenguajes (Reto)

Modifica la gramática corrigiendo los errores que veas, de manera que genere frases como estas:

1. a[4][b+c][5] = c[2][3]
2. a.b.c = a[x]
3. a.b[x*y].d = c.d[3][1].e(temp)

• Procura que exprese bien la precedencia de operadores (vigila la asignación)

• La variable <value> no se describe (y debería describirse)

Grammar

<program> ::= <block>

<block> ::= '{' <statement>* '}'  // Modified Casiano

<statement> ::=
               <declaration> ';'? |
              "if" <parenthesis> <block> ("else" "if" <block>)* ('else' <block>)? |
              "for" '(' <declaration> ';' <comp>? ';' <expr>? ')' <block> |
              "while" <parenthesis> <block> |
              'function' WORD? '(' WORD (',' WORD)* ')' <block> |
              '@' WORD WORD <apply> ';'? |
              <expr> ";"?
              
<declaration> ::= 'var' WORD ('=' <expr>)?

<expr> ::= ( <leftVal> '=' )*  <comp>

<leftVal> ::= WORD ( '.' WORD | '[' <expr> ']' )*

<comp> ::= <term> (('==', '!=', '>', '>=', '<', '<=') <term>)*

<term> ::= <sum> (('+', '-') <sum>)*

<sum> ::= <fact> (('*', '/') <fact>)*

<fact> ::= 
              <value> |
              WORD <apply> |
              <parenthesis> |
              <array> | // Added by: Casiano
              '{' ( VALUE ';' <expr> )* '}' // Implementacion de objeto

<apply> ::= '(' <expr>? (',' <expr> )* ')' <apply> | '.'WORD <apply> | '[' <expr> ']' | empty

<array> ::= '[' ']' | '[' <expr> (',' <expr> )*] // Added by Casiano

<parenthesis> ::= '(' <expr> ')'

<value> ::= ( WORD | VALUE ) <apply>*

Tokens

WORD = [a-zA-Z_]\w*
VALUE = STRING | NUMBER
STRING = "( [^"\\]   #any character except " and escape
           | \\.     #any character before an escape
           )*"
NUMBER = ([-+]?\d+     #entero
          (\.\d+)?    #flotante
          ([eE][-+]?\d+)?  #con exponente
          )