Method: String#undump

Defined in:

string.c

#undump ⇒ String

Returns an unescaped version of the string. This does the inverse of String#dump.

"\"hello \\n ''\"".undump #=> "hello \n ''"

Returns:

• (String)

# File 'string.c', line 6558

static VALUE
str_undump(VALUE str)
{
    const char *s = RSTRING_PTR(str);
    const char *s_end = RSTRING_END(str);
    rb_encoding *enc = rb_enc_get(str);
    VALUE undumped = rb_enc_str_new(s, 0L, enc);
    bool utf8 = false;
    bool binary = false;
    int w;

    rb_must_asciicompat(str);
    if (rb_str_is_ascii_only_p(str) == Qfalse) {
	rb_raise(rb_eRuntimeError, "non-ASCII character detected");
    }
    if (!str_null_check(str, &w)) {
	rb_raise(rb_eRuntimeError, "string contains null byte");
    }
    if (RSTRING_LEN(str) < 2) goto invalid_format;
    if (*s != '"') goto invalid_format;

    /* strip '"' at the start */
    s++;

    for (;;) {
	if (s >= s_end) {
	    rb_raise(rb_eRuntimeError, "unterminated dumped string");
	}

	if (*s == '"') {
	    /* epilogue */
	    s++;
	    if (s == s_end) {
		/* ascii compatible dumped string */
		break;
	    }
	    else {
		static const char force_encoding_suffix[] = ".force_encoding(\""; /* "\")" */
		static const char dup_suffix[] = ".dup";
		const char *encname;
		int encidx;
		ptrdiff_t size;

		/* check separately for strings dumped by older versions */
		size = sizeof(dup_suffix) - 1;
		if (s_end - s > size && memcmp(s, dup_suffix, size) == 0) s += size;

		size = sizeof(force_encoding_suffix) - 1;
		if (s_end - s <= size) goto invalid_format;
		if (memcmp(s, force_encoding_suffix, size) != 0) goto invalid_format;
		s += size;

		if (utf8) {
		    rb_raise(rb_eRuntimeError, "dumped string contained Unicode escape but used force_encoding");
		}

		encname = s;
		s = memchr(s, '"', s_end-s);
		size = s - encname;
		if (!s) goto invalid_format;
		if (s_end - s != 2) goto invalid_format;
		if (s[0] != '"' || s[1] != ')') goto invalid_format;

		encidx = rb_enc_find_index2(encname, (long)size);
		if (encidx < 0) {
		    rb_raise(rb_eRuntimeError, "dumped string has unknown encoding name");
		}
		rb_enc_associate_index(undumped, encidx);
	    }
	    break;
	}

	if (*s == '\\') {
	    s++;
	    if (s >= s_end) {
		rb_raise(rb_eRuntimeError, "invalid escape");
	    }
	    undump_after_backslash(undumped, &s, s_end, &enc, &utf8, &binary);
	}
	else {
	    rb_str_cat(undumped, s++, 1);
	}
    }

    return undumped;
invalid_format:
    rb_raise(rb_eRuntimeError, "invalid dumped string; not wrapped with '\"' nor '\"...\".force_encoding(\"...\")' form");
}