edits.h

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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html

// edits.h
// created: 2016dec30 Markus W. Scherer

#ifndef __EDITS_H__
#define __EDITS_H__

#include "unicode/utypes.h"
#include "unicode/uobject.h"

U_NAMESPACE_BEGIN

class UnicodeString;

class U_COMMON_API Edits U_FINAL : public UMemory {
public:
    Edits() :
            array(stackArray), capacity(STACK_CAPACITY), length(0), delta(0), numChanges(0),
            errorCode_(U_ZERO_ERROR) {}
    Edits(const Edits &other) :
            array(stackArray), capacity(STACK_CAPACITY), length(other.length),
            delta(other.delta), numChanges(other.numChanges),
            errorCode_(other.errorCode_) {
        copyArray(other);
    }
    Edits(Edits &&src) U_NOEXCEPT :
            array(stackArray), capacity(STACK_CAPACITY), length(src.length),
            delta(src.delta), numChanges(src.numChanges),
            errorCode_(src.errorCode_) {
        moveArray(src);
    }

    ~Edits();

    Edits &operator=(const Edits &other);

    Edits &operator=(Edits &&src) U_NOEXCEPT;

    void reset() U_NOEXCEPT;

    void addUnchanged(int32_t unchangedLength);
    void addReplace(int32_t oldLength, int32_t newLength);
    UBool copyErrorTo(UErrorCode &outErrorCode);

    int32_t lengthDelta() const { return delta; }
    UBool hasChanges() const { return numChanges != 0; }

    int32_t numberOfChanges() const { return numChanges; }

    struct U_COMMON_API Iterator U_FINAL : public UMemory {
        Iterator() :
                array(nullptr), index(0), length(0),
                remaining(0), onlyChanges_(FALSE), coarse(FALSE),
                dir(0), changed(FALSE), oldLength_(0), newLength_(0),
                srcIndex(0), replIndex(0), destIndex(0) {}
        Iterator(const Iterator &other) = default;
        Iterator &operator=(const Iterator &other) = default;

        UBool next(UErrorCode &errorCode) { return next(onlyChanges_, errorCode); }

        UBool findSourceIndex(int32_t i, UErrorCode &errorCode) {
            return findIndex(i, TRUE, errorCode) == 0;
        }

        UBool findDestinationIndex(int32_t i, UErrorCode &errorCode) {
            return findIndex(i, FALSE, errorCode) == 0;
        }

        int32_t destinationIndexFromSourceIndex(int32_t i, UErrorCode &errorCode);

        int32_t sourceIndexFromDestinationIndex(int32_t i, UErrorCode &errorCode);

        UBool hasChange() const { return changed; }

        int32_t oldLength() const { return oldLength_; }

        int32_t newLength() const { return newLength_; }

        int32_t sourceIndex() const { return srcIndex; }

        int32_t replacementIndex() const {
            // TODO: Throw an exception if we aren't in a change edit?
            return replIndex;
        }

        int32_t destinationIndex() const { return destIndex; }

#ifndef U_HIDE_INTERNAL_API

        UnicodeString& toString(UnicodeString& appendTo) const;
#endif  // U_HIDE_INTERNAL_API

    private:
        friend class Edits;

        Iterator(const uint16_t *a, int32_t len, UBool oc, UBool crs);

        int32_t readLength(int32_t head);
        void updateNextIndexes();
        void updatePreviousIndexes();
        UBool noNext();
        UBool next(UBool onlyChanges, UErrorCode &errorCode);
        UBool previous(UErrorCode &errorCode);
        int32_t findIndex(int32_t i, UBool findSource, UErrorCode &errorCode);

        const uint16_t *array;
        int32_t index, length;
        // 0 if we are not within compressed equal-length changes.
        // Otherwise the number of remaining changes, including the current one.
        int32_t remaining;
        UBool onlyChanges_, coarse;

        int8_t dir;  // iteration direction: back(<0), initial(0), forward(>0)
        UBool changed;
        int32_t oldLength_, newLength_;
        int32_t srcIndex, replIndex, destIndex;
    };

    Iterator getCoarseChangesIterator() const {
        return Iterator(array, length, TRUE, TRUE);
    }

    Iterator getCoarseIterator() const {
        return Iterator(array, length, FALSE, TRUE);
    }

    Iterator getFineChangesIterator() const {
        return Iterator(array, length, TRUE, FALSE);
    }

    Iterator getFineIterator() const {
        return Iterator(array, length, FALSE, FALSE);
    }

    Edits &mergeAndAppend(const Edits &ab, const Edits &bc, UErrorCode &errorCode);

private:
    void releaseArray() U_NOEXCEPT;
    Edits &copyArray(const Edits &other);
    Edits &moveArray(Edits &src) U_NOEXCEPT;

    void setLastUnit(int32_t last) { array[length - 1] = (uint16_t)last; }
    int32_t lastUnit() const { return length > 0 ? array[length - 1] : 0xffff; }

    void append(int32_t r);
    UBool growArray();

    static const int32_t STACK_CAPACITY = 100;
    uint16_t *array;
    int32_t capacity;
    int32_t length;
    int32_t delta;
    int32_t numChanges;
    UErrorCode errorCode_;
    uint16_t stackArray[STACK_CAPACITY];
};

U_NAMESPACE_END

#endif  // __EDITS_H__