grammar.txt

expression: number
          | expression '*' expression
          | expression '/' expression
          | expression '+' expression
          | expression '-' expression
          ;

expression: additive_expression
          ;

additive_expression:
            multiplicative_expression
          | additive_expression '+' multiplicative_expression
          | additive_expression '-' multiplicative_expression
          ;

multiplicative_expression: prefix_expression 
          | multiplicative_expression '*' prefix_expression 
          | multiplicative_expression '/' prefix_expression
          | multiplicative_expression '%' prefix_expression
          ;

number: INTLIT_T
        ;

compound_statement: '{' '}' // empty, i.e. no statement
    | '{' statement '}'
    | '{' statement statements '}'
    ;

statement: print_statement
    |      declaration
    |      assignment_statement
    |      if_statement
    |      while_statement
    ;

print_statement: 'print' '(' expression ')' ';' 
    ;

declaration: 'int' identifier ';' 
    ;

identifier: IDENT_T
    ;

assignment_statement: identifier '=' expression ';' 
    ;

if_statement: if_head
    |         if_head 'else' compound_statement
    ;

if_head: 'if' '(' true_false_expression ')' compound_statement 
    ;


while_statement: 'while' '(' true_false_expression ')' compound_statement
    ;

for_statement: 'for' preop_statement ';'
                     true_false_expression ';'
                     postop_statement ')' compound_statement 
    ;

preop_statement:  statement (for now)
postop_statement: statement (for now)


global_declarations: global_declarations
    | global_declaration global_declarations
    ;

global_declaration: function_declaration | var_declaration
    ;

function_declaration: type identifier '(' ')' compound_statement
    ;

variable_declaration: type identifier_List ';'
    | type identifier '[' P_INTLIT ']' ';'
    ;

type: type_keyword opt_pointer
    ;

type_keyword: 'void' | 'char' | 'int' | 'long'
    ;

opt_pointer: <empty> | '*' opt_pointer
    ;

identifier_list: identifier | identifier ',' identifier_list
    ;

function_call : identifier '(' expression ')' 
    ;

return_statement: 'return' '(' expression ')' 
    ;

prefix_expression: postfix_expression
    | '++' prefix_expression
    | '--' prefix_expression
    | prefix_operator prefix_expression
    ;

primary_expression: T_IDENT
    | T_INTLIT
    | T_STRLIT
    | '(' expression ')'
    ;

postfix_expression : primary_expression
    | postfix_expression '[' expression ']'
    | postfix_expression '(' expression ')'
    | postfix_expression '++'
    | postfix_expression '--'
    ;

prefix_operator: '&'
    | '*'
    | '-'
    | '~'
    | '!'
    ;