Class: StringIO

Inherits:
Data
  • Object
show all
Includes:
Enumerable, IO::generic_readable, IO::generic_writable
Defined in:
stringio.c

Class Method Summary collapse

Instance Method Summary collapse

Methods included from IO::generic_readable

#read_nonblock, #readbyte, #readchar, #readline, #readpartial, #sysread

Methods included from IO::generic_writable

#<<, #print, #printf, #puts, #syswrite, #write_nonblock

Constructor Details

#new(string = ""[, mode]) ⇒ Object

Creates new StringIO instance from with string and mode.


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# File 'stringio.c', line 166

static VALUE
strio_initialize(int argc, VALUE *argv, VALUE self)
{
    struct StringIO *ptr = check_strio(self);

    if (!ptr) {
	DATA_PTR(self) = ptr = strio_alloc();
    }
    rb_call_super(0, 0);
    strio_init(argc, argv, ptr, self);
    return self;
}

Class Method Details

.open(string = ""[, mode]) {|strio| ... } ⇒ Object

Equivalent to StringIO.new except that when it is called with a block, it yields with the new instance and closes it, and returns the result which returned from the block.

Yields:

  • (strio)

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# File 'stringio.c', line 237

static VALUE
strio_s_open(int argc, VALUE *argv, VALUE klass)
{
    VALUE obj = rb_class_new_instance(argc, argv, klass);
    if (!rb_block_given_p()) return obj;
    return rb_ensure(rb_yield, obj, strio_finalize, obj);
}

Instance Method Details

#binmodetrue

#bytesObject

This is a deprecated alias for #each_byte.


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# File 'stringio.c', line 653

static VALUE
strio_bytes(VALUE self)
{
    rb_warn("StringIO#bytes is deprecated; use #each_byte instead");
    if (!rb_block_given_p())
	return rb_enumeratorize(self, ID2SYM(rb_intern("each_byte")), 0, 0);
    return strio_each_byte(self);
}

#charsObject

This is a deprecated alias for each_char.


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# File 'stringio.c', line 873

static VALUE
strio_chars(VALUE self)
{
    rb_warn("StringIO#chars is deprecated; use #each_char instead");
    if (!rb_block_given_p())
	return rb_enumeratorize(self, ID2SYM(rb_intern("each_char")), 0, 0);
    return strio_each_char(self);
}

#closenil

Closes strio. The strio is unavailable for any further data operations; an IOError is raised if such an attempt is made.


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# File 'stringio.c', line 345

static VALUE
strio_close(VALUE self)
{
    StringIO(self);
    if (CLOSED(self)) {
	rb_raise(rb_eIOError, "closed stream");
    }
    RBASIC(self)->flags &= ~STRIO_READWRITE;
    return Qnil;
}

#close_readnil

Closes the read end of a StringIO. Will raise an IOError if the strio is not readable.


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# File 'stringio.c', line 363

static VALUE
strio_close_read(VALUE self)
{
    StringIO(self);
    if (!READABLE(self)) {
	rb_raise(rb_eIOError, "closing non-duplex IO for reading");
    }
    RBASIC(self)->flags &= ~STRIO_READABLE;
    return Qnil;
}

#close_writenil

Closes the write end of a StringIO. Will raise an IOError if the strio is not writeable.


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# File 'stringio.c', line 381

static VALUE
strio_close_write(VALUE self)
{
    StringIO(self);
    if (!WRITABLE(self)) {
	rb_raise(rb_eIOError, "closing non-duplex IO for writing");
    }
    RBASIC(self)->flags &= ~STRIO_WRITABLE;
    return Qnil;
}

#closed?Boolean

Returns true if strio is completely closed, false otherwise.


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# File 'stringio.c', line 398

static VALUE
strio_closed(VALUE self)
{
    StringIO(self);
    if (!CLOSED(self)) return Qfalse;
    return Qtrue;
}

#closed_read?Boolean

Returns true if strio is not readable, false otherwise.


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# File 'stringio.c', line 412

static VALUE
strio_closed_read(VALUE self)
{
    StringIO(self);
    if (READABLE(self)) return Qfalse;
    return Qtrue;
}

#closed_write?Boolean

Returns true if strio is not writable, false otherwise.


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# File 'stringio.c', line 426

static VALUE
strio_closed_write(VALUE self)
{
    StringIO(self);
    if (WRITABLE(self)) return Qfalse;
    return Qtrue;
}

#codepointsObject

This is a deprecated alias for each_codepoint.


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# File 'stringio.c', line 917

static VALUE
strio_codepoints(VALUE self)
{
    rb_warn("StringIO#codepoints is deprecated; use #each_codepoint instead");
    if (!rb_block_given_p())
	return rb_enumeratorize(self, ID2SYM(rb_intern("each_codepoint")), 0, 0);
    return strio_each_codepoint(self);
}

#each(sep = $/) {|line| ... } ⇒ Object #each(limit) {|line| ... } ⇒ Object #each(sep, limit) {|line| ... } ⇒ Object #each(...) ⇒ Enumerator

strio.each_line(sep=$/) {|line| block } -> strio

strio.each_line(limit) {|line| block }     -> strio
strio.each_line(sep,limit) {|line| block } -> strio
strio.each_line(...)                       -> anEnumerator

See IO#each.

Overloads:

  • #each(sep = $/) {|line| ... } ⇒ Object

    Yields:

    • (line)
  • #each(limit) {|line| ... } ⇒ Object

    Yields:

    • (line)
  • #each(sep, limit) {|line| ... } ⇒ Object

    Yields:

    • (line)

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# File 'stringio.c', line 1099

static VALUE
strio_each(int argc, VALUE *argv, VALUE self)
{
    VALUE line;

    StringIO(self);
    RETURN_ENUMERATOR(self, argc, argv);

    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
	NUM2LONG(argv[argc-1]) == 0) {
	rb_raise(rb_eArgError, "invalid limit: 0 for each_line");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
	rb_yield(line);
    }
    return self;
}

#each_byte {|byte| ... } ⇒ Object #each_byteEnumerator

See IO#each_byte.

Overloads:

  • #each_byte {|byte| ... } ⇒ Object

    Yields:

    • (byte)

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# File 'stringio.c', line 636

static VALUE
strio_each_byte(VALUE self)
{
    struct StringIO *ptr = readable(self);

    RETURN_ENUMERATOR(self, 0, 0);

    while (ptr->pos < RSTRING_LEN(ptr->string)) {
	char c = RSTRING_PTR(ptr->string)[ptr->pos++];
	rb_yield(CHR2FIX(c));
    }
    return self;
}

#each_char {|char| ... } ⇒ Object #each_charEnumerator

See IO#each_char.

Overloads:

  • #each_char {|char| ... } ⇒ Object

    Yields:

    • (char)

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# File 'stringio.c', line 857

static VALUE
strio_each_char(VALUE self)
{
    VALUE c;

    RETURN_ENUMERATOR(self, 0, 0);

    while (!NIL_P(c = strio_getc(self))) {
	rb_yield(c);
    }
    return self;
}

#each_codepoint {|c| ... } ⇒ Object #each_codepointEnumerator

See IO#each_codepoint.

Overloads:

  • #each_codepoint {|c| ... } ⇒ Object

    Yields:

    • (c)

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# File 'stringio.c', line 889

static VALUE
strio_each_codepoint(VALUE self)
{
    struct StringIO *ptr;
    rb_encoding *enc;
    unsigned int c;
    int n;

    RETURN_ENUMERATOR(self, 0, 0);

    ptr = readable(self);
    enc = rb_enc_get(ptr->string);
    for (;;) {
	if (ptr->pos >= RSTRING_LEN(ptr->string)) {
	    return self;
	}

	c = rb_enc_codepoint_len(RSTRING_PTR(ptr->string)+ptr->pos,
				 RSTRING_END(ptr->string), &n, enc);
	rb_yield(UINT2NUM(c));
	ptr->pos += n;
    }
    return self;
}

#each(sep = $/) {|line| ... } ⇒ Object #each(limit) {|line| ... } ⇒ Object #each(sep, limit) {|line| ... } ⇒ Object #each(...) ⇒ Enumerator

strio.each_line(sep=$/) {|line| block } -> strio

strio.each_line(limit) {|line| block }     -> strio
strio.each_line(sep,limit) {|line| block } -> strio
strio.each_line(...)                       -> anEnumerator

See IO#each.

Overloads:

  • #each(sep = $/) {|line| ... } ⇒ Object

    Yields:

    • (line)
  • #each(limit) {|line| ... } ⇒ Object

    Yields:

    • (line)
  • #each(sep, limit) {|line| ... } ⇒ Object

    Yields:

    • (line)

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# File 'stringio.c', line 1099

static VALUE
strio_each(int argc, VALUE *argv, VALUE self)
{
    VALUE line;

    StringIO(self);
    RETURN_ENUMERATOR(self, argc, argv);

    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
	NUM2LONG(argv[argc-1]) == 0) {
	rb_raise(rb_eArgError, "invalid limit: 0 for each_line");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
	rb_yield(line);
    }
    return self;
}

#eofBoolean #eof?Boolean

Returns true if strio is at end of file. The stringio must be opened for reading or an IOError will be raised.


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# File 'stringio.c', line 442

static VALUE
strio_eof(VALUE self)
{
    struct StringIO *ptr = readable(self);
    if (ptr->pos < RSTRING_LEN(ptr->string)) return Qfalse;
    return Qtrue;
}

#eofBoolean #eof?Boolean

Returns true if strio is at end of file. The stringio must be opened for reading or an IOError will be raised.


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# File 'stringio.c', line 442

static VALUE
strio_eof(VALUE self)
{
    struct StringIO *ptr = readable(self);
    if (ptr->pos < RSTRING_LEN(ptr->string)) return Qfalse;
    return Qtrue;
}

#external_encodingEncoding

Returns the Encoding object that represents the encoding of the file. If strio is write mode and no encoding is specified, returns nil.


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# File 'stringio.c', line 1452

static VALUE
strio_external_encoding(VALUE self)
{
    return rb_enc_from_encoding(rb_enc_get(StringIO(self)->string));
}

#fcntlObject

#filenonil

#flushObject

#fsync0

#getbyteFixnum?

See IO#getbyte.


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# File 'stringio.c', line 691

static VALUE
strio_getbyte(VALUE self)
{
    struct StringIO *ptr = readable(self);
    int c;
    if (ptr->pos >= RSTRING_LEN(ptr->string)) {
	return Qnil;
    }
    c = RSTRING_PTR(ptr->string)[ptr->pos++];
    return CHR2FIX(c);
}

#getcString?

See IO#getc.


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# File 'stringio.c', line 668

static VALUE
strio_getc(VALUE self)
{
    struct StringIO *ptr = readable(self);
    rb_encoding *enc = rb_enc_get(ptr->string);
    int len;
    char *p;

    if (ptr->pos >= RSTRING_LEN(ptr->string)) {
	return Qnil;
    }
    p = RSTRING_PTR(ptr->string)+ptr->pos;
    len = rb_enc_mbclen(p, RSTRING_END(ptr->string), enc);
    ptr->pos += len;
    return rb_enc_str_new(p, len, rb_enc_get(ptr->string));
}

#gets(sep = $/) ⇒ String? #gets(limit) ⇒ String? #gets(sep, limit) ⇒ String?

See IO#gets.


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# File 'stringio.c', line 1060

static VALUE
strio_gets(int argc, VALUE *argv, VALUE self)
{
    VALUE str = strio_getline(argc, argv, readable(self));

    rb_lastline_set(str);
    return str;
}

#initialize_copyObject

:nodoc:


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# File 'stringio.c', line 451

static VALUE
strio_copy(VALUE copy, VALUE orig)
{
    struct StringIO *ptr;

    orig = rb_convert_type(orig, T_DATA, "StringIO", "to_strio");
    if (copy == orig) return copy;
    ptr = StringIO(orig);
    if (check_strio(copy)) {
	strio_free(DATA_PTR(copy));
    }
    DATA_PTR(copy) = ptr;
    OBJ_INFECT(copy, orig);
    RBASIC(copy)->flags &= ~STRIO_READWRITE;
    RBASIC(copy)->flags |= RBASIC(orig)->flags & STRIO_READWRITE;
    ++ptr->count;
    return copy;
}

#internal_encodingEncoding

Returns the Encoding of the internal string if conversion is specified. Otherwise returns nil.


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# File 'stringio.c', line 1466

static VALUE
strio_internal_encoding(VALUE self)
{
     return Qnil;
}

#isattynil #tty?nil

#lengthInteger #sizeInteger

Returns the size of the buffer string.


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# File 'stringio.c', line 1411

static VALUE
strio_size(VALUE self)
{
    VALUE string = StringIO(self)->string;
    if (NIL_P(string)) {
	rb_raise(rb_eIOError, "not opened");
    }
    return ULONG2NUM(RSTRING_LEN(string));
}

#linenoInteger

Returns the current line number in strio. The stringio must be opened for reading. lineno counts the number of times gets is called, rather than the number of newlines encountered. The two values will differ if gets is called with a separator other than newline. See also the $. variable.


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# File 'stringio.c', line 480

static VALUE
strio_get_lineno(VALUE self)
{
    return LONG2NUM(StringIO(self)->lineno);
}

#lineno=(integer) ⇒ Integer

Manually sets the current line number to the given value. $. is updated only on the next read.


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# File 'stringio.c', line 493

static VALUE
strio_set_lineno(VALUE self, VALUE lineno)
{
    StringIO(self)->lineno = NUM2LONG(lineno);
    return lineno;
}

#linesObject

This is a deprecated alias for each_line.


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# File 'stringio.c', line 1121

static VALUE
strio_lines(int argc, VALUE *argv, VALUE self)
{
    rb_warn("StringIO#lines is deprecated; use #each_line instead");
    if (!rb_block_given_p())
	return rb_enumeratorize(self, ID2SYM(rb_intern("each_line")), argc, argv);
    return strio_each(argc, argv, self);
}

#pidnil

#posInteger #tellInteger

Returns the current offset (in bytes) of strio.


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# File 'stringio.c', line 534

static VALUE
strio_get_pos(VALUE self)
{
    return LONG2NUM(StringIO(self)->pos);
}

#pos=(integer) ⇒ Integer

Seeks to the given position (in bytes) in strio.


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# File 'stringio.c', line 546

static VALUE
strio_set_pos(VALUE self, VALUE pos)
{
    struct StringIO *ptr = StringIO(self);
    long p = NUM2LONG(pos);
    if (p < 0) {
	error_inval(0);
    }
    ptr->pos = p;
    return pos;
}

#putc(obj) ⇒ Object

See IO#putc.


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# File 'stringio.c', line 1239

static VALUE
strio_putc(VALUE self, VALUE ch)
{
    struct StringIO *ptr = writable(self);
    VALUE str;

    check_modifiable(ptr);
    if (RB_TYPE_P(ch, T_STRING)) {
	str = rb_str_substr(ch, 0, 1);
    }
    else {
	char c = NUM2CHR(ch);
	str = rb_str_new(&c, 1);
    }
    strio_write(self, str);
    return ch;
}

#read([length [, outbuf]]) ⇒ String?

See IO#read.


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# File 'stringio.c', line 1271

static VALUE
strio_read(int argc, VALUE *argv, VALUE self)
{
    struct StringIO *ptr = readable(self);
    VALUE str = Qnil;
    long len;
    int binary = 0;

    switch (argc) {
      case 2:
	str = argv[1];
	if (!NIL_P(str)) {
	    StringValue(str);
	    rb_str_modify(str);
	}
      case 1:
	if (!NIL_P(argv[0])) {
	    len = NUM2LONG(argv[0]);
	    if (len < 0) {
		rb_raise(rb_eArgError, "negative length %ld given", len);
	    }
	    if (len > 0 && ptr->pos >= RSTRING_LEN(ptr->string)) {
		if (!NIL_P(str)) rb_str_resize(str, 0);
		return Qnil;
	    }
	    binary = 1;
	    break;
	}
	/* fall through */
      case 0:
	len = RSTRING_LEN(ptr->string);
	if (len <= ptr->pos) {
	    if (NIL_P(str)) {
		str = rb_str_new(0, 0);
	    }
	    else {
		rb_str_resize(str, 0);
	    }
	    return str;
	}
	else {
	    len -= ptr->pos;
	}
	break;
      default:
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
    }
    if (NIL_P(str)) {
	str = strio_substr(ptr, ptr->pos, len);
	if (binary) rb_enc_associate(str, rb_ascii8bit_encoding());
    }
    else {
	long rest = RSTRING_LEN(ptr->string) - ptr->pos;
	if (len > rest) len = rest;
	rb_str_resize(str, len);
	MEMCPY(RSTRING_PTR(str), RSTRING_PTR(ptr->string) + ptr->pos, char, len);
	if (binary)
	    rb_enc_associate(str, rb_ascii8bit_encoding());
	else
	    rb_enc_copy(str, ptr->string);
    }
    ptr->pos += RSTRING_LEN(str);
    return str;
}

#readlines(sep = $/) ⇒ Array #readlines(limit) ⇒ Array #readlines(sep, limit) ⇒ Array

See IO#readlines.


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# File 'stringio.c', line 1138

static VALUE
strio_readlines(int argc, VALUE *argv, VALUE self)
{
    VALUE ary, line;

    StringIO(self);
    ary = rb_ary_new();
    if (argc > 0 && !NIL_P(argv[argc-1]) && NIL_P(rb_check_string_type(argv[argc-1])) &&
	NUM2LONG(argv[argc-1]) == 0) {
	rb_raise(rb_eArgError, "invalid limit: 0 for readlines");
    }

    while (!NIL_P(line = strio_getline(argc, argv, readable(self)))) {
	rb_ary_push(ary, line);
    }
    return ary;
}

#reopen(other_StrIO) ⇒ Object #reopen(string, mode) ⇒ Object

Reinitializes strio with the given other_StrIO or string and mode (see StringIO#new).


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# File 'stringio.c', line 516

static VALUE
strio_reopen(int argc, VALUE *argv, VALUE self)
{
    rb_io_taint_check(self);
    if (argc == 1 && !RB_TYPE_P(*argv, T_STRING)) {
	return strio_copy(self, *argv);
    }
    strio_init(argc, argv, StringIO(self), self);
    return self;
}

#rewind0

Positions strio to the beginning of input, resetting lineno to zero.


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# File 'stringio.c', line 565

static VALUE
strio_rewind(VALUE self)
{
    struct StringIO *ptr = StringIO(self);
    ptr->pos = 0;
    ptr->lineno = 0;
    return INT2FIX(0);
}

#seek(amount, whence = SEEK_SET) ⇒ 0

Seeks to a given offset amount in the stream according to the value of whence (see IO#seek).


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# File 'stringio.c', line 581

static VALUE
strio_seek(int argc, VALUE *argv, VALUE self)
{
    VALUE whence;
    struct StringIO *ptr = StringIO(self);
    long offset;

    rb_scan_args(argc, argv, "11", NULL, &whence);
    offset = NUM2LONG(argv[0]);
    if (CLOSED(self)) {
	rb_raise(rb_eIOError, "closed stream");
    }
    switch (NIL_P(whence) ? 0 : NUM2LONG(whence)) {
      case 0:
	break;
      case 1:
	offset += ptr->pos;
	break;
      case 2:
	offset += RSTRING_LEN(ptr->string);
	break;
      default:
	error_inval("invalid whence");
    }
    if (offset < 0) {
	error_inval(0);
    }
    ptr->pos = offset;
    return INT2FIX(0);
}

#set_encoding(ext_enc, [int_enc[, opt]]) ⇒ Object

Specify the encoding of the StringIO as ext_enc. Use the default external encoding if ext_enc is nil. 2nd argument int_enc and optional hash opt argument are ignored; they are for API compatibility to IO.


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# File 'stringio.c', line 1482

static VALUE
strio_set_encoding(int argc, VALUE *argv, VALUE self)
{
    rb_encoding* enc;
    VALUE str = StringIO(self)->string;
    VALUE ext_enc, int_enc, opt;

    argc = rb_scan_args(argc, argv, "11:", &ext_enc, &int_enc, &opt);

    if (NIL_P(ext_enc)) {
	enc = rb_default_external_encoding();
    }
    else {
	enc = rb_to_encoding(ext_enc);
    }
    rb_enc_associate(str, enc);
    return self;
}

#lengthInteger #sizeInteger

Returns the size of the buffer string.


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# File 'stringio.c', line 1411

static VALUE
strio_size(VALUE self)
{
    VALUE string = StringIO(self)->string;
    if (NIL_P(string)) {
	rb_raise(rb_eIOError, "not opened");
    }
    return ULONG2NUM(RSTRING_LEN(string));
}

#stringString

Returns underlying String object, the subject of IO.


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# File 'stringio.c', line 312

static VALUE
strio_get_string(VALUE self)
{
    return StringIO(self)->string;
}

#string=(string) ⇒ String

Changes underlying String object, the subject of IO.


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# File 'stringio.c', line 324

static VALUE
strio_set_string(VALUE self, VALUE string)
{
    struct StringIO *ptr = StringIO(self);

    rb_io_taint_check(self);
    ptr->flags &= ~FMODE_READWRITE;
    StringValue(string);
    ptr->flags = OBJ_FROZEN(string) ? FMODE_READABLE : FMODE_READWRITE;
    ptr->pos = 0;
    ptr->lineno = 0;
    return ptr->string = string;
}

#synctrue

Returns true always.


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# File 'stringio.c', line 618

static VALUE
strio_get_sync(VALUE self)
{
    StringIO(self);
    return Qtrue;
}

#sync=(boolean) ⇒ Boolean

#tellObject

#truncate(integer) ⇒ 0

Truncates the buffer string to at most integer bytes. The strio must be opened for writing.


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# File 'stringio.c', line 1428

static VALUE
strio_truncate(VALUE self, VALUE len)
{
    VALUE string = writable(self)->string;
    long l = NUM2LONG(len);
    long plen = RSTRING_LEN(string);
    if (l < 0) {
	error_inval("negative length");
    }
    rb_str_resize(string, l);
    if (plen < l) {
	MEMZERO(RSTRING_PTR(string) + plen, char, l - plen);
    }
    return len;
}

#tty?Boolean

#ungetbyte(fixnum) ⇒ nil

See IO#ungetbyte


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# File 'stringio.c', line 785

static VALUE
strio_ungetbyte(VALUE self, VALUE c)
{
    struct StringIO *ptr = readable(self);
    char buf[1], *cp = buf;
    long pos = ptr->pos, cl = 1;
    VALUE str = ptr->string;

    if (NIL_P(c)) return Qnil;
    if (FIXNUM_P(c)) {
	buf[0] = (char)FIX2INT(c);
    }
    else {
	SafeStringValue(c);
	cp = RSTRING_PTR(c);
	cl = RSTRING_LEN(c);
	if (cl == 0) return Qnil;
    }
    check_modifiable(ptr);
    rb_str_modify(str);
    if (cl > pos) {
	char *s;
	long rest = RSTRING_LEN(str) - pos;
	rb_str_resize(str, rest + cl);
	s = RSTRING_PTR(str);
	memmove(s + cl, s + pos, rest);
	pos = 0;
    }
    else {
	pos -= cl;
    }
    memcpy(RSTRING_PTR(str) + pos, cp, cl);
    ptr->pos = pos;
    RB_GC_GUARD(c);
    return Qnil;
}

#ungetc(string) ⇒ nil

Pushes back one character (passed as a parameter) onto strio such that a subsequent buffered read will return it. There is no limitation for multiple pushbacks including pushing back behind the beginning of the buffer string.


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# File 'stringio.c', line 729

static VALUE
strio_ungetc(VALUE self, VALUE c)
{
    struct StringIO *ptr = readable(self);
    long lpos, clen;
    char *p, *pend;
    rb_encoding *enc, *enc2;

    if (NIL_P(c)) return Qnil;
    check_modifiable(ptr);
    if (FIXNUM_P(c)) {
	int cc = FIX2INT(c);
	char buf[16];

	enc = rb_enc_get(ptr->string);
	rb_enc_mbcput(cc, buf, enc);
	c = rb_enc_str_new(buf, rb_enc_codelen(cc, enc), enc);
    }
    else {
	SafeStringValue(c);
	enc = rb_enc_get(ptr->string);
	enc2 = rb_enc_get(c);
	if (enc != enc2 && enc != rb_ascii8bit_encoding()) {
	    c = rb_str_conv_enc(c, enc2, enc);
	}
    }
    if (RSTRING_LEN(ptr->string) < ptr->pos) {
	long len = RSTRING_LEN(ptr->string);
	rb_str_resize(ptr->string, ptr->pos - 1);
	memset(RSTRING_PTR(ptr->string) + len, 0, ptr->pos - len - 1);
	rb_str_concat(ptr->string, c);
	ptr->pos--;
    }
    else {
	/* get logical position */
	lpos = 0; p = RSTRING_PTR(ptr->string); pend = p + ptr->pos;
	for (;;) {
	    clen = rb_enc_mbclen(p, pend, enc);
	    if (p+clen >= pend) break;
	    p += clen;
	    lpos++;
	}
	clen = p - RSTRING_PTR(ptr->string);
	rb_str_update(ptr->string, lpos, ptr->pos ? 1 : 0, c);
	ptr->pos = clen;
    }

    return Qnil;
}

#write(string) ⇒ Integer #syswrite(string) ⇒ Integer

Appends the given string to the underlying buffer string of strio. The stream must be opened for writing. If the argument is not a string, it will be converted to a string using to_s. Returns the number of bytes written. See IO#write.


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# File 'stringio.c', line 1166

static VALUE
strio_write(VALUE self, VALUE str)
{
    struct StringIO *ptr = writable(self);
    long len, olen;
    rb_encoding *enc, *enc2;
    rb_encoding *const ascii8bit = rb_ascii8bit_encoding();

    if (!RB_TYPE_P(str, T_STRING))
	str = rb_obj_as_string(str);
    enc = rb_enc_get(ptr->string);
    enc2 = rb_enc_get(str);
    if (enc != enc2 && enc != ascii8bit) {
	str = rb_str_conv_enc(str, enc2, enc);
    }
    len = RSTRING_LEN(str);
    if (len == 0) return INT2FIX(0);
    check_modifiable(ptr);
    olen = RSTRING_LEN(ptr->string);
    if (ptr->flags & FMODE_APPEND) {
	ptr->pos = olen;
    }
    if (ptr->pos == olen) {
	if (enc == ascii8bit || enc2 == ascii8bit) {
	    rb_enc_str_buf_cat(ptr->string, RSTRING_PTR(str), len, enc);
	    OBJ_INFECT(ptr->string, str);
	}
	else {
	    rb_str_buf_append(ptr->string, str);
	}
    }
    else {
	strio_extend(ptr, ptr->pos, len);
	memmove(RSTRING_PTR(ptr->string)+ptr->pos, RSTRING_PTR(str), len);
	OBJ_INFECT(ptr->string, str);
    }
    OBJ_INFECT(ptr->string, self);
    RB_GC_GUARD(str);
    ptr->pos += len;
    return LONG2NUM(len);
}