Machine-generated code

• Bison is a parser generator
• It converts .y files to .c files
  • Example of a .y file:
    

      %type  word_list pattern
      %type  pattern_list case_clause_sequence case_clause
     
     %start inputunit
     
     %%
     
     inputunit:	simple_list simple_list_terminator
      			{
      			  global_command = $1;
      			  eof_encountered = 0;
      			  YYACCEPT;
      			}
      ...
      

  • Example of output:
    

      case 1:
      {
      			  global_command = yyvsp[-1].command;
      			  eof_encountered = 0;
      			  YYACCEPT;
      			;
          break;}
     
     

    
    
• For Bison parsers, the .y file is the source code
  • It's what programmers who have Bison prefer to edit
• The generated .c file is too
  • Some programmers won't have access to Bison
  • They will prefer C code
    

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