eval

/*
 *  call-seq:
 *     eval(string [, binding [, filename [,lineno]]])  => obj
 *  
 *  Evaluates the Ruby expression(s) in <em>string</em>. If
 *  <em>binding</em> is given, the evaluation is performed in its
 *  context. The binding may be a <code>Binding</code> object or a
 *  <code>Proc</code> object. If the optional <em>filename</em> and
 *  <em>lineno</em> parameters are present, they will be used when
 *  reporting syntax errors.
 *     
 *     def getBinding(str)
 *       return binding
 *     end
 *     str = "hello"
 *     eval "str + ' Fred'"                      #=> "hello Fred"
 *     eval "str + ' Fred'", getBinding("bye")   #=> "bye Fred"
 */

static VALUE
rb_f_eval(argc, argv, self)
    int argc;
    VALUE *argv;
    VALUE self;
{
    VALUE src, scope, vfile, vline;
    const char *file = "(eval)";
    int line = 1;

    rb_scan_args(argc, argv, "13", &src, &scope, &vfile, &vline);
    if (ruby_safe_level >= 4) {
        StringValue(src);
        if (!NIL_P(scope) && !OBJ_TAINTED(scope)) {
            rb_raise(rb_eSecurityError, "Insecure: can't modify trusted binding");
        }
    }
    else {
        SafeStringValue(src);
    }
    if (argc >= 3) {
        StringValue(vfile);
    }
    if (argc >= 4) {
        line = NUM2INT(vline);
    }

    if (!NIL_P(vfile)) file = RSTRING(vfile)->ptr;
    if (NIL_P(scope) && ruby_frame->prev) {
        struct FRAME *prev;
        VALUE val;

        prev = ruby_frame;
        PUSH_FRAME();
        *ruby_frame = *prev->prev;
        ruby_frame->prev = prev;
        val = eval(self, src, scope, file, line);
        POP_FRAME();

        return val;
    }
    return eval(self, src, scope, file, line);
}