main.c

一个编译器修改的例子

#include "declaration.h"
#include "error.h"
#include "expression.h"
#include "list.h"
#include "io.h"
#include "scope.h"

#include <stdlib.h>


static const char *input_file = 0;


static void read_command_line(int argc, char **argv)
{
    int i;
    
    for (i = 1; i < argc; i++)
    {
	if (argv [i][0] == '-')
	{
	    switch (argv [i][1])
	    {
		case 'I' :
		     list_append(search_path, argv [i] + 2);
		     break;

		default :
		     error(0, "unknown option -%c", argv [i][1]);
		     exit(1);
	    }
	}
	else if (input_file != 0)
	{
	    error(0, "multiple input files specified");
	    exit(1);
	}
	else
	    input_file = argv [i];
    }
}


static void init(int argc, char **argv)
{
    search_path = new_list();
    string_list = new_list();
    read_command_line(argc, argv);
    open_input_file(input_file);
    open_output_files();
}


static void semantic_analyses(void)
{
    type_check_declaration_list(global_declarations);
}


static void code_generation(void)
{
    generate_declaration_list(global_declarations);
    generate_string_list();
}


static void terminate(void)
{
    delete_declaration_list(global_declarations);
    delete_scope(global_scope);
    close_files();
    delete_list(string_list);
    delete_list(search_path);
}

/* -------------- PROCESSING STARTS HERE! -------------- */
int main(int argc, char **argv)
{
    int yyparse(void);

    /* Open in- and output files */
    init(argc, argv);

    /* Parse the source file
     * Build the AST using yacc (which in turn uses flex).
     * This also sets up the scopes. The global scope is created in the
     * yacc rule 'program', the scopes for subprogrammes are created in
     * name_and_argument_list, and those for compound statement in
     * compound_statement.
     */
    yyparse();

    /* Now we have an AST, stored in the global variable global_declarations.
     * Next, we invoke the type checking phase on that list.
     */
    semantic_analyses();

    /* If type checking didn't produce any errors (error_seen is set by
     * the error() function (see error.h), start the code generation phase,
     * again using the global_declarations list.
     */
    if (!error_seen)
	code_generation();

    /* Finally, clean up by deleting the global variables (AST, scopes,
     * string list, etc.) and close all open files.
     */
    terminate();

    /* If a error occurred, return 1 so a programme calling the compiler
     * knows about it (make for instance).
     */
    return error_seen ? 1 : 0;
}