decl.c

#include "defs.h"
#include "data.h"
#include "decl.h"

// Parsing of declarations
// Copyright (c) 2019 Warren Toomey, GPL3


// Parse the current token and
// return a primitive type enum value
int parse_type(int t) {
  if (t == T_CHAR)
    return (P_CHAR);
  if (t == T_INT)
    return (P_INT);
  if (t == T_VOID)
    return (P_VOID);
  fatald("Illegal type, token", t);
}

// variable_declaration: 'int' identifier ';'  ;
//
// Parse the declaration of a variable
void var_declaration(void) {
  int id, type;

  // Get the type of the variable, then the identifier
  type = parse_type(Token.token);
  scan(&Token);
  ident();
  // Text now has the identifier's name.
  // Add it as a known identifier
  // and generate its space in assembly
  id = addglob(Text, type, S_VARIABLE);
  genglobsym(id);
  // Get the trailing semicolon
  semi();
}

// For now we have a very simplistic function definition grammar
//
// function_declaration: 'void' identifier '(' ')' compound_statement   ;
//
// Parse the declaration of a simplistic function
struct ASTnode *function_declaration(void) {
  struct ASTnode *tree;
  int nameslot;

  // Find the 'void', the identifier, and the '(' ')'.
  // For now, do nothing with them
  match(T_VOID, "void");
  ident();
  nameslot = addglob(Text, P_VOID, S_FUNCTION);
  lparen();
  rparen();

  // Get the AST tree for the compound statement
  tree = compound_statement();

  // Return an A_FUNCTION node which has the function's nameslot
  // and the compound statement sub-tree
  return (mkastunary(A_FUNCTION, P_VOID, tree, nameslot));
}