/Compiler-FrontEnd

The front end of a simple compiler

Primary LanguageC++

Compiler-FrontEnd

The front end of a simple compiler

Lexical Analyzer

  • Input 
    int main()
{
printf("HelloWorld");
return 0;
}
  • Output 
    1: <int,17>
2: <main,81>
3: <(,44>
4: <),45>
5: <{,59>
6: <printf,81>
7: <(,44>
8: <",78>
9: <HelloWorld,81>
10: <",78>
11: <),45>
12: <;,53>
13: <return,20>
14: <0,80>
15: <;,53>
16: <},63>

LL Parser

  • input 
    {
ID = NUM ;
}
  • output 
    program
    compoundstmt
        {
        stmts
            stmt
                assgstmt
                    ID
                    =
                    arithexpr
                        multexpr
                            simpleexpr
                                NUM
                            multexprprime
                                E
                        arithexprprime
                            E
                    ;
            stmts
                E
        }

LR Parser

  • input 
    {
ID = NUM ;
}
  • output 
    program =>
compoundstmt =>
{ stmts } =>
{ stmt stmts } =>
{ stmt } =>
{ assgstmt } =>
{ ID = arithexpr ; } =>
{ ID = multexpr arithexprprime ; } =>
{ ID = multexpr ; } =>
{ ID = simpleexpr multexprprime ; } =>
{ ID = simpleexpr ; } =>
{ ID = NUM ; }

Translation Scheme

  • input 
    int a = 1 ; int b = 2 ; real c = 3.0 ;
{
a = a + 1 ;
b = b * a ;
if ( a < b ) then c = c / 2 ; else c = c / 4 ;
}
  • output 
    a: 2
b: 4
c: 1.5

Note

  • implement with C++