#include <stdio.h>

int debug_depth;

void dpvs_implementation(
    const char* expression,
    char quote,
    const unsigned char* string_value,
    size_t len)
{
    printf("%*s", debug_depth, "");
    
    printf("%s = %c", expression, quote);
    
    for (const unsigned char* m = string_value; len && *m; m++, len--)
    {
        switch (*m)
        {
            case ' ':
            case '~':
            case '@':
            case '$':
            case ',':
            case '%':
            case '^':
            case '&':
            case '\'':
            case '*':
            case '#':
            case '`':
            case ';':
            case '.':
            case '=':
            case '/':
            case '+':
            case '-':
            case '_':
            case '!':
            case ':':
            case '<': case '>':
            case '(': case ')':
            case '[': case ']':
            case '{': case '}':
            case '0' ... '9':
            case 'a' ... 'z':
            case 'A' ... 'Z':
                putchar(*m);
                break;
            
            case '\\':
                printf("\\\\");
                break;
               
            case '\"':
                printf("\\\"");
                break;
                
            case '\e':
                printf("\\e");
                break;
                
            case '\n':
                printf("\\n");
                break;
                
            default:
                printf("\\x%02X", *m);
                break;
        }
    }
    
    
    printf("%c\n", quote);
}