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#include <memory>
#include <mbgl/text/bidi.hpp>
#include <unicode/ubidi.h>
#include <unicode/ushape.h>
namespace mbgl {
BiDi::BiDi() {
UErrorCode errorCode = U_ZERO_ERROR;
transform = ubiditransform_open(&errorCode); // Only error is failure to allocate memory, in
// that case ubidi_transform would fall back to
// creating transform object on the fly
}
BiDi::~BiDi() {
if (transform)
ubiditransform_close(transform);
}
std::u16string BiDi::bidiTransform(const std::u16string& input) {
UErrorCode errorCode = U_ZERO_ERROR;
std::unique_ptr<UChar[]> outputText =
std::make_unique<UChar[]>(input.size() * 2); // Maximum output of ubidi_transform is twice
// the size of input according to
// ubidi_transform.h
uint32_t outputLength = ubiditransform_transform(
transform, input.c_str(), static_cast<int32_t>(input.size()), outputText.get(),
static_cast<int32_t>(input.size()) * 2,
UBIDI_DEFAULT_LTR, // Assume input is LTR unless strong RTL characters are found
UBIDI_LOGICAL, // Input is in logical order
UBIDI_LTR, // Output is in "visual LTR" order
UBIDI_VISUAL, // ''
UBIDI_MIRRORING_ON, // Use mirroring lookups for things like parentheses that need mirroring
// in RTL text
U_SHAPE_LETTERS_SHAPE, // Add options here for handling numbers in bidirectional text
&errorCode);
// If the algorithm fails for any reason, fall back to non-transformed text
if (U_FAILURE(errorCode))
return input;
return std::u16string(outputText.get(), outputLength);
}
bool BiDi::baseDirectionRightToLeft(const std::u16string& input) {
// This just looks for the first character with a strong direction property, it does not perform
// the BiDi algorithm
return ubidi_getBaseDirection(input.c_str(), static_cast<int32_t>(input.size())) == UBIDI_RTL;
}
} // end namespace mbgl
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