Implement assign,ent and a symbol table. The project is described in this pdf: Add the following rule to the recursive descent parser:  →  = ` The new start symbol is Define a new function...

Implement assign,ent and a symbol table. The project is described in this pdf:

Add the following rule to the recursive descent parser:

 →  = `

The new start symbol is Define a new function named statement() to parse this rule. On a successful parse, statement() should call a function

assign(id, value)

The assign function is part of the parser back end, value is what the call to exp() returns. You could do assign(id, exp()). The parser will now keep a symbol table. This will be a Python dictionary named symbol_table where the key values are the identifiers, and the values are the expression values. The assign function should make an entry in the symbol table. We will also modify the atomic() function. At present it assumes the only atomic value (a leaf node in the parse tree) is a numeric literal. Now we will add the possibility it could be a variable. In psuedo-code:

atomic(token)   try to convert token to a float.   On success, return the float   on ValueError exception:     look for token in the symbol table.     if found       return the value     else       error: “float literal or variable expected”