ucnv.c

/* 
 * MacRuby implementation of Ruby 1.9 String.
 *
 * This file is covered by the Ruby license. See COPYING for more details.
 * 
 * Copyright (C) 2007-2011, Apple Inc. All rights reserved.
 * Copyright (C) 1993-2007 Yukihiro Matsumoto
 * Copyright (C) 2000 Network Applied Communication Laboratory, Inc.
 * Copyright (C) 2000 Information-technology Promotion Agency, Japan
 */

#include "macruby_internal.h"
#include "encoding_ucnv.h"
#include "unicode/ucnv.h"

// do not forget to close the converter
// before leaving the function
#define USE_CONVERTER(cnv, encoding) \
    assert(encoding->private_data != NULL); \
    char cnv##_buffer[U_CNV_SAFECLONE_BUFFERSIZE]; \
    UErrorCode cnv##_err = U_ZERO_ERROR; \
    int32_t cnv##_buffer_size = U_CNV_SAFECLONE_BUFFERSIZE; \
    UConverter *cnv = ucnv_safeClone( \
	    (UConverter *)encoding->private_data, \
	    cnv##_buffer, \
	    &cnv##_buffer_size, \
	    &cnv##_err \
	); \
    ucnv_reset(cnv);

void
str_ucnv_update_flags(rb_str_t *self)
{
    USE_CONVERTER(cnv, self->encoding);

    bool ascii_only = true;
    bool valid_encoding = true;

    const char *pos = self->bytes;
    const char *end = pos + self->length_in_bytes;
    for (;;) {
	// iterate through the string one Unicode code point at a time
	UErrorCode err = U_ZERO_ERROR;
	UChar32 c = ucnv_getNextUChar(cnv, &pos, end, &err);
	if (U_FAILURE(err)) {
	    if (err == U_INDEX_OUTOFBOUNDS_ERROR) {
		// end of the string
		break;
	    }
	    else {
		// conversion error
		valid_encoding = false;
		ascii_only = false;
		break;
	    }
	}
	else {
	    if (c > 127) {
		ascii_only = false;
	    }
	}
    }

    ucnv_close(cnv);

    str_set_valid_encoding(self, valid_encoding);
    str_set_ascii_only(self, ascii_only);
}

static long
utf16_bytesize_approximation(rb_encoding_t *enc, int bytesize)
{
    long approximation;
    if (IS_UTF16_ENC(enc)) {
	approximation = bytesize; // the bytesize in UTF-16 is the same
				  // whatever the endianness
    }
    else if (IS_UTF32_ENC(enc)) {
	// the bytesize in UTF-16 is nearly half of the bytesize in UTF-32
	// (if there characters not in the BMP it's a bit more though)
	approximation = bytesize / 2;
    }
    else {
	// take a quite large size to not have to reallocate
	approximation = bytesize * 2;
    }

    if (ODD_NUMBER(approximation)) {
	// the size must be an even number
	++approximation;
    }

    return approximation;
}

long
str_ucnv_length(rb_str_t *self, bool ucs2_mode)
{
    USE_CONVERTER(cnv, self->encoding);

    const char *pos = self->bytes;
    const char *end = pos + self->length_in_bytes;
    long len = 0;
    bool valid_encoding = true;
    for (;;) {
	const char *character_start_pos = pos;
	// iterate through the string one Unicode code point at a time
	UErrorCode err = U_ZERO_ERROR;
	UChar32 c = ucnv_getNextUChar(cnv, &pos, end, &err);
	if (err == U_INDEX_OUTOFBOUNDS_ERROR) {
	    // end of the string
	    break;
	}
	else if (U_FAILURE(err)) {
	    valid_encoding = false;
	    long min_char_size = self->encoding->min_char_size;
	    long converted_width = pos - character_start_pos;
	    len += div_round_up(converted_width, min_char_size);
	}
	else {
	    if (ucs2_mode && !U_IS_BMP(c)) {
		len += 2;
	    }
	    else {
		++len;
	    }
	}
    }

    ucnv_close(cnv);

    str_set_valid_encoding(self, valid_encoding);

    return len;
}


void rb_ensure_b(void (^b_block)(void), void (^e_block)(void));

void
str_ucnv_each_uchar32_starting_from(rb_str_t *self,
	long start_offset_in_bytes,
	each_uchar32_callback_t callback)
{
    USE_CONVERTER(cnv, self->encoding);

    rb_ensure_b(^{
	const char *pos = self->bytes + start_offset_in_bytes;
	const char *end = pos + self->length_in_bytes;
	bool stop = false;
	for (;;) {
	    const char *char_start_pos = pos;
	    // iterate through the string one Unicode code point at a time
	    UErrorCode err = U_ZERO_ERROR;
	    UChar32 c = ucnv_getNextUChar(cnv, &pos, end, &err);
	    if (err == U_INDEX_OUTOFBOUNDS_ERROR) {
		// end of the string
		break;
	    }
	    else if (U_FAILURE(err)) {
		long min_char_size = self->encoding->min_char_size;
		while (char_start_pos < pos) {
		    long char_len = pos - char_start_pos;
		    if (char_len > min_char_size) {
			char_len = min_char_size;
		    }
		    callback(U_SENTINEL, char_start_pos-self->bytes, char_len, &stop);
		    if (stop) {
			return;
		    }
		    char_start_pos += char_len;
		}
	    }
	    else {
		long char_len = pos - char_start_pos;
		callback(c, char_start_pos-self->bytes, char_len, &stop);
		if (stop) {
		    return;
		}
	    }
	}
    }, ^{
	ucnv_close(cnv);
    });
}

character_boundaries_t
str_ucnv_get_character_boundaries(rb_str_t *self, long index, bool ucs2_mode)
{
    character_boundaries_t boundaries = {-1, -1};
    assert(index >= 0);

    // the code has many similarities with str_length
    USE_CONVERTER(cnv, self->encoding);

    const char *pos = self->bytes;
    const char *end = pos + self->length_in_bytes;
    long current_index = 0;
    for (;;) {
	const char *character_start_pos = pos;
	// iterate through the string one Unicode code point at a time
	// (we dont care what the character is or if it's valid or not)
	UErrorCode err = U_ZERO_ERROR;
	UChar32 c = ucnv_getNextUChar(cnv, &pos, end, &err);
	if (err == U_INDEX_OUTOFBOUNDS_ERROR) {
	    // end of the string
	    break;
	}
	long offset_in_bytes = character_start_pos - self->bytes;
	long converted_width = pos - character_start_pos;
	if (U_FAILURE(err)) {
	    long min_char_size = self->encoding->min_char_size;
	    // division of converted_width by min_char_size rounded up
	    long diff = div_round_up(converted_width, min_char_size);
	    long length_in_bytes;
	    if (current_index == index) {
		if (min_char_size > converted_width) {
		    length_in_bytes = converted_width;
		}
		else {
		    length_in_bytes = min_char_size;
		}
		boundaries.start_offset_in_bytes = offset_in_bytes;
		boundaries.end_offset_in_bytes =
		    boundaries.start_offset_in_bytes + length_in_bytes;
		break;
	    }
	    else if (current_index + diff > index) {
		long adjusted_offset = offset_in_bytes + (index
			- current_index) * min_char_size;
		if (adjusted_offset + min_char_size > offset_in_bytes
			+ converted_width) {
		    length_in_bytes = offset_in_bytes + converted_width
			- adjusted_offset;
		}
		else {
		    length_in_bytes = min_char_size;
		}
		boundaries.start_offset_in_bytes = adjusted_offset;
		boundaries.end_offset_in_bytes =
		    boundaries.start_offset_in_bytes + length_in_bytes;
		break;
	    }
	    current_index += diff;
	}
	else {
	    if (ucs2_mode && !U_IS_BMP(c)) {
		// you cannot cut a surrogate in an encoding that is not UTF-16
		if (current_index == index) {
		    boundaries.start_offset_in_bytes = offset_in_bytes;
		    break;
		}
		else if (current_index+1 == index) {
		    boundaries.end_offset_in_bytes = offset_in_bytes
			+ converted_width;
		    break;
		}
		++current_index;
	    }

	    if (current_index == index) {
		boundaries.start_offset_in_bytes = offset_in_bytes;
		boundaries.end_offset_in_bytes =
		    boundaries.start_offset_in_bytes + converted_width;
		break;
	    }

	    ++current_index;
	}
    }

    ucnv_close(cnv);

    return boundaries;
}

long
str_ucnv_offset_in_bytes_to_index(rb_str_t *self, long offset_in_bytes,
	bool ucs2_mode)
{
    // the code has many similarities with str_length
    USE_CONVERTER(cnv, self->encoding);

    const char *current_position = self->bytes;
    const char *searched_position = current_position + offset_in_bytes;
    const char *end = current_position + self->length_in_bytes;
    long index = 0;
    for (;;) {
	const char *character_start_position = current_position;
	// iterate through the string one Unicode code point at a time
	UErrorCode err = U_ZERO_ERROR;
	UChar32 c = ucnv_getNextUChar(cnv, &current_position, end, &err);
	if (err == U_INDEX_OUTOFBOUNDS_ERROR) {
	    // end of the string
	    // should not happen because str_offset_in_bytes_to_index
	    // checks before that offset_in_bytes is inferior to the length
	    // in bytes
	    abort();
	}
	else if (U_FAILURE(err)) {
	    long min_char_size = self->encoding->min_char_size;
	    long converted_width = current_position - character_start_position;
	    long to_add = div_round_up(converted_width, min_char_size);
	    if (searched_position < character_start_position + to_add) {
		long difference = searched_position - character_start_position;
		index += (difference / min_char_size);
		break;
	    }
	    index += to_add;
	}
	else {
	    if (searched_position < current_position) {
		// if we are in the middle of a character
		// there is no valid index
		index = -1;
		break;
	    }
	    if (ucs2_mode && !U_IS_BMP(c)) {
		index += 2;
	    }
	    else {
		++index;
	    }
	}
	if (searched_position == current_position) {
	    break;
	}
    }

    ucnv_close(cnv);

    return index;
}

void
str_ucnv_transcode_to_utf16(struct rb_encoding *src_enc,
	rb_str_t *self, long *pos,
	UChar **utf16, long *utf16_length)
{
    USE_CONVERTER(cnv, src_enc);

    long capa = utf16_bytesize_approximation(src_enc,
	    self->length_in_bytes);
    const char *source_pos = self->bytes + *pos;
    const char *source_end = self->bytes + self->length_in_bytes;
    UChar *buffer = xmalloc(capa);
    UChar *target_pos = buffer;
    UErrorCode err = U_ZERO_ERROR;
    for (;;) {
	UChar *target_end = buffer + BYTES_TO_UCHARS(capa);
	err = U_ZERO_ERROR;
	ucnv_toUnicode(cnv, &target_pos, target_end, &source_pos, source_end,
		NULL, true, &err);
	if (err == U_BUFFER_OVERFLOW_ERROR) {
	    long index = target_pos - buffer;
	    capa *= 2; // double the buffer's size
	    buffer = xrealloc(buffer, capa);
	    target_pos = buffer + index;
	}
	else {
	    break;
	}
    }

    ucnv_close(cnv);

    *utf16 = buffer;
    *utf16_length = target_pos - buffer;
    *pos = source_pos - self->bytes;

    if (U_FAILURE(err)) {
	// the invalid character will be skipped by str_transcode
	*pos -= src_enc->min_char_size;
    }
}

void
str_ucnv_transcode_from_utf16(struct rb_encoding *dst_enc,
	UChar *utf16, long utf16_length, long *utf16_pos,
	char **bytes, long *bytes_length)
{
    USE_CONVERTER(cnv, dst_enc);

    UErrorCode err = U_ZERO_ERROR;
    long capa = UCNV_GET_MAX_BYTES_FOR_STRING(
	    utf16_length - *utf16_pos, ucnv_getMaxCharSize(cnv));
    char *buffer = xmalloc(capa);
    const UChar *source_pos = &utf16[*utf16_pos];
    const UChar *source_end = &utf16[utf16_length];
    char *target_pos = buffer;
    char *target_end = buffer + capa;
    ucnv_fromUnicode(cnv, &target_pos, target_end, &source_pos, source_end,
	    NULL, true, &err);
    assert((err != U_ILLEGAL_ARGUMENT_ERROR) && (err != U_BUFFER_OVERFLOW_ERROR));

    ucnv_close(cnv);

    *bytes = buffer;
    *bytes_length = target_pos - buffer;
    *utf16_pos = source_pos - utf16;

    if (U_FAILURE(err)) {
	// the undefined character will be skipped by str_transcode
	U16_BACK_1(utf16, 0, *utf16_pos);
    }
}

void
enc_init_ucnv_encoding(rb_encoding_t *encoding)
{
    // create the ICU converter
    UErrorCode err = U_ZERO_ERROR;
    UConverter *converter = ucnv_open(encoding->public_name, &err);
    if (!U_SUCCESS(err) || (converter == NULL)) {
	fprintf(stderr, "Couldn't create the encoder for %s\n",
		encoding->public_name);
	abort();
    }
    // stop the conversion when the conversion failed
    err = U_ZERO_ERROR;
    ucnv_setToUCallBack(converter, UCNV_TO_U_CALLBACK_STOP, NULL, NULL, NULL,
	    &err);
    err = U_ZERO_ERROR;
    ucnv_setFromUCallBack(converter, UCNV_FROM_U_CALLBACK_STOP, NULL, NULL,
	    NULL, &err);

    // fill the fields not filled yet
    encoding->private_data = converter;
}