532 lines
21 KiB
C++
532 lines
21 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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// edits.h
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// created: 2016dec30 Markus W. Scherer
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#ifndef __EDITS_H__
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#define __EDITS_H__
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#include "unicode/utypes.h"
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#if U_SHOW_CPLUSPLUS_API
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#include "unicode/uobject.h"
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/**
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* \file
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* \brief C++ API: C++ class Edits for low-level string transformations on styled text.
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*/
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U_NAMESPACE_BEGIN
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class UnicodeString;
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/**
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* Records lengths of string edits but not replacement text. Supports replacements, insertions, deletions
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* in linear progression. Does not support moving/reordering of text.
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*
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* There are two types of edits: <em>change edits</em> and <em>no-change edits</em>. Add edits to
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* instances of this class using {@link #addReplace(int32_t, int32_t)} (for change edits) and
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* {@link #addUnchanged(int32_t)} (for no-change edits). Change edits are retained with full granularity,
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* whereas adjacent no-change edits are always merged together. In no-change edits, there is a one-to-one
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* mapping between code points in the source and destination strings.
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*
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* After all edits have been added, instances of this class should be considered immutable, and an
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* {@link Edits::Iterator} can be used for queries.
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*
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* There are four flavors of Edits::Iterator:
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*
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* <ul>
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* <li>{@link #getFineIterator()} retains full granularity of change edits.
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* <li>{@link #getFineChangesIterator()} retains full granularity of change edits, and when calling
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* next() on the iterator, skips over no-change edits (unchanged regions).
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* <li>{@link #getCoarseIterator()} treats adjacent change edits as a single edit. (Adjacent no-change
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* edits are automatically merged during the construction phase.)
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* <li>{@link #getCoarseChangesIterator()} treats adjacent change edits as a single edit, and when
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* calling next() on the iterator, skips over no-change edits (unchanged regions).
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* </ul>
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*
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* For example, consider the string "abcßDeF", which case-folds to "abcssdef". This string has the
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* following fine edits:
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* <ul>
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* <li>abc ⇨ abc (no-change)
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* <li>ß ⇨ ss (change)
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* <li>D ⇨ d (change)
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* <li>e ⇨ e (no-change)
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* <li>F ⇨ f (change)
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* </ul>
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* and the following coarse edits (note how adjacent change edits get merged together):
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* <ul>
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* <li>abc ⇨ abc (no-change)
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* <li>ßD ⇨ ssd (change)
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* <li>e ⇨ e (no-change)
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* <li>F ⇨ f (change)
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* </ul>
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*
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* The "fine changes" and "coarse changes" iterators will step through only the change edits when their
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* `Edits::Iterator::next()` methods are called. They are identical to the non-change iterators when
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* their `Edits::Iterator::findSourceIndex()` or `Edits::Iterator::findDestinationIndex()`
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* methods are used to walk through the string.
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*
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* For examples of how to use this class, see the test `TestCaseMapEditsIteratorDocs` in
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* UCharacterCaseTest.java.
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*
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* An Edits object tracks a separate UErrorCode, but ICU string transformation functions
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* (e.g., case mapping functions) merge any such errors into their API's UErrorCode.
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*
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* @stable ICU 59
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*/
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class U_COMMON_API Edits final : public UMemory {
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public:
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/**
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* Constructs an empty object.
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* @stable ICU 59
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*/
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Edits() :
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array(stackArray), capacity(STACK_CAPACITY), length(0), delta(0), numChanges(0),
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errorCode_(U_ZERO_ERROR) {}
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/**
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* Copy constructor.
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* @param other source edits
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* @stable ICU 60
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*/
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Edits(const Edits &other) :
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array(stackArray), capacity(STACK_CAPACITY), length(other.length),
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delta(other.delta), numChanges(other.numChanges),
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errorCode_(other.errorCode_) {
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copyArray(other);
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}
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/**
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* Move constructor, might leave src empty.
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* This object will have the same contents that the source object had.
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* @param src source edits
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* @stable ICU 60
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*/
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Edits(Edits &&src) noexcept :
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array(stackArray), capacity(STACK_CAPACITY), length(src.length),
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delta(src.delta), numChanges(src.numChanges),
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errorCode_(src.errorCode_) {
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moveArray(src);
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}
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/**
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* Destructor.
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* @stable ICU 59
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*/
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~Edits();
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/**
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* Assignment operator.
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* @param other source edits
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* @return *this
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* @stable ICU 60
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*/
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Edits &operator=(const Edits &other);
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/**
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* Move assignment operator, might leave src empty.
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* This object will have the same contents that the source object had.
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* The behavior is undefined if *this and src are the same object.
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* @param src source edits
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* @return *this
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* @stable ICU 60
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*/
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Edits &operator=(Edits &&src) noexcept;
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/**
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* Resets the data but may not release memory.
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* @stable ICU 59
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*/
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void reset() noexcept;
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/**
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* Adds a no-change edit: a record for an unchanged segment of text.
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* Normally called from inside ICU string transformation functions, not user code.
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* @stable ICU 59
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*/
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void addUnchanged(int32_t unchangedLength);
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/**
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* Adds a change edit: a record for a text replacement/insertion/deletion.
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* Normally called from inside ICU string transformation functions, not user code.
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* @stable ICU 59
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*/
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void addReplace(int32_t oldLength, int32_t newLength);
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/**
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* Sets the UErrorCode if an error occurred while recording edits.
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* Preserves older error codes in the outErrorCode.
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* Normally called from inside ICU string transformation functions, not user code.
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* @param outErrorCode Set to an error code if it does not contain one already
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* and an error occurred while recording edits.
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* Otherwise unchanged.
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* @return true if U_FAILURE(outErrorCode)
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* @stable ICU 59
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*/
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UBool copyErrorTo(UErrorCode &outErrorCode) const;
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/**
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* How much longer is the new text compared with the old text?
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* @return new length minus old length
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* @stable ICU 59
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*/
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int32_t lengthDelta() const { return delta; }
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/**
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* @return true if there are any change edits
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* @stable ICU 59
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*/
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UBool hasChanges() const { return numChanges != 0; }
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/**
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* @return the number of change edits
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* @stable ICU 60
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*/
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int32_t numberOfChanges() const { return numChanges; }
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/**
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* Access to the list of edits.
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*
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* At any moment in time, an instance of this class points to a single edit: a "window" into a span
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* of the source string and the corresponding span of the destination string. The source string span
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* starts at {@link #sourceIndex()} and runs for {@link #oldLength()} chars; the destination string
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* span starts at {@link #destinationIndex()} and runs for {@link #newLength()} chars.
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*
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* The iterator can be moved between edits using the `next()`, `findSourceIndex(int32_t, UErrorCode &)`,
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* and `findDestinationIndex(int32_t, UErrorCode &)` methods.
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* Calling any of these methods mutates the iterator to make it point to the corresponding edit.
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*
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* For more information, see the documentation for {@link Edits}.
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*
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* @see getCoarseIterator
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* @see getFineIterator
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* @stable ICU 59
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*/
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struct U_COMMON_API Iterator final : public UMemory {
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/**
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* Default constructor, empty iterator.
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* @stable ICU 60
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*/
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Iterator() :
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array(nullptr), index(0), length(0),
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remaining(0), onlyChanges_(false), coarse(false),
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dir(0), changed(false), oldLength_(0), newLength_(0),
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srcIndex(0), replIndex(0), destIndex(0) {}
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/**
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* Copy constructor.
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* @stable ICU 59
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*/
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Iterator(const Iterator &other) = default;
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/**
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* Assignment operator.
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* @stable ICU 59
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*/
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Iterator &operator=(const Iterator &other) = default;
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/**
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* Advances the iterator to the next edit.
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* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
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* or else the function returns immediately. Check for U_FAILURE()
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* on output or use with function chaining. (See User Guide for details.)
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* @return true if there is another edit
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* @stable ICU 59
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*/
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UBool next(UErrorCode &errorCode) { return next(onlyChanges_, errorCode); }
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/**
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* Moves the iterator to the edit that contains the source index.
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* The source index may be found in a no-change edit
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* even if normal iteration would skip no-change edits.
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* Normal iteration can continue from a found edit.
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*
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* The iterator state before this search logically does not matter.
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* (It may affect the performance of the search.)
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*
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* The iterator state after this search is undefined
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* if the source index is out of bounds for the source string.
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*
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* @param i source index
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* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
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* or else the function returns immediately. Check for U_FAILURE()
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* on output or use with function chaining. (See User Guide for details.)
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* @return true if the edit for the source index was found
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* @stable ICU 59
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*/
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UBool findSourceIndex(int32_t i, UErrorCode &errorCode) {
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return findIndex(i, true, errorCode) == 0;
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}
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/**
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* Moves the iterator to the edit that contains the destination index.
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* The destination index may be found in a no-change edit
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* even if normal iteration would skip no-change edits.
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* Normal iteration can continue from a found edit.
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*
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* The iterator state before this search logically does not matter.
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* (It may affect the performance of the search.)
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*
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* The iterator state after this search is undefined
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* if the source index is out of bounds for the source string.
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*
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* @param i destination index
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* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
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* or else the function returns immediately. Check for U_FAILURE()
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* on output or use with function chaining. (See User Guide for details.)
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* @return true if the edit for the destination index was found
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* @stable ICU 60
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*/
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UBool findDestinationIndex(int32_t i, UErrorCode &errorCode) {
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return findIndex(i, false, errorCode) == 0;
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}
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/**
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* Computes the destination index corresponding to the given source index.
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* If the source index is inside a change edit (not at its start),
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* then the destination index at the end of that edit is returned,
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* since there is no information about index mapping inside a change edit.
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*
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* (This means that indexes to the start and middle of an edit,
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* for example around a grapheme cluster, are mapped to indexes
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* encompassing the entire edit.
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* The alternative, mapping an interior index to the start,
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* would map such an interval to an empty one.)
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*
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* This operation will usually but not always modify this object.
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* The iterator state after this search is undefined.
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*
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* @param i source index
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* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
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* or else the function returns immediately. Check for U_FAILURE()
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* on output or use with function chaining. (See User Guide for details.)
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* @return destination index; undefined if i is not 0..string length
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* @stable ICU 60
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*/
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int32_t destinationIndexFromSourceIndex(int32_t i, UErrorCode &errorCode);
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/**
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* Computes the source index corresponding to the given destination index.
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* If the destination index is inside a change edit (not at its start),
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* then the source index at the end of that edit is returned,
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* since there is no information about index mapping inside a change edit.
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*
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* (This means that indexes to the start and middle of an edit,
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* for example around a grapheme cluster, are mapped to indexes
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* encompassing the entire edit.
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* The alternative, mapping an interior index to the start,
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* would map such an interval to an empty one.)
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*
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* This operation will usually but not always modify this object.
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* The iterator state after this search is undefined.
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*
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* @param i destination index
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* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
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* or else the function returns immediately. Check for U_FAILURE()
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* on output or use with function chaining. (See User Guide for details.)
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* @return source index; undefined if i is not 0..string length
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* @stable ICU 60
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*/
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int32_t sourceIndexFromDestinationIndex(int32_t i, UErrorCode &errorCode);
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/**
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* Returns whether the edit currently represented by the iterator is a change edit.
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*
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* @return true if this edit replaces oldLength() units with newLength() different ones.
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* false if oldLength units remain unchanged.
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* @stable ICU 59
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*/
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UBool hasChange() const { return changed; }
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/**
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* The length of the current span in the source string, which starts at {@link #sourceIndex}.
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*
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* @return the number of units in the original string which are replaced or remain unchanged.
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* @stable ICU 59
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*/
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int32_t oldLength() const { return oldLength_; }
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/**
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* The length of the current span in the destination string, which starts at
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* {@link #destinationIndex}, or in the replacement string, which starts at
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* {@link #replacementIndex}.
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*
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* @return the number of units in the modified string, if hasChange() is true.
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* Same as oldLength if hasChange() is false.
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* @stable ICU 59
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*/
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int32_t newLength() const { return newLength_; }
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/**
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* The start index of the current span in the source string; the span has length
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* {@link #oldLength}.
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*
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* @return the current index into the source string
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* @stable ICU 59
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*/
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int32_t sourceIndex() const { return srcIndex; }
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/**
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* The start index of the current span in the replacement string; the span has length
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* {@link #newLength}. Well-defined only if the current edit is a change edit.
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*
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* The *replacement string* is the concatenation of all substrings of the destination
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* string corresponding to change edits.
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*
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* This method is intended to be used together with operations that write only replacement
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* characters (e.g. operations specifying the \ref U_OMIT_UNCHANGED_TEXT option).
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* The source string can then be modified in-place.
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*
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* @return the current index into the replacement-characters-only string,
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* not counting unchanged spans
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* @stable ICU 59
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*/
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int32_t replacementIndex() const {
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// TODO: Throw an exception if we aren't in a change edit?
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return replIndex;
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}
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/**
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* The start index of the current span in the destination string; the span has length
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* {@link #newLength}.
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*
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* @return the current index into the full destination string
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* @stable ICU 59
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*/
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int32_t destinationIndex() const { return destIndex; }
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#ifndef U_HIDE_INTERNAL_API
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/**
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* A string representation of the current edit represented by the iterator for debugging. You
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* should not depend on the contents of the return string.
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* @internal
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*/
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UnicodeString& toString(UnicodeString& appendTo) const;
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#endif // U_HIDE_INTERNAL_API
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private:
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friend class Edits;
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Iterator(const uint16_t *a, int32_t len, UBool oc, UBool crs);
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int32_t readLength(int32_t head);
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void updateNextIndexes();
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void updatePreviousIndexes();
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UBool noNext();
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UBool next(UBool onlyChanges, UErrorCode &errorCode);
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UBool previous(UErrorCode &errorCode);
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/** @return -1: error or i<0; 0: found; 1: i>=string length */
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int32_t findIndex(int32_t i, UBool findSource, UErrorCode &errorCode);
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const uint16_t *array;
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int32_t index, length;
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// 0 if we are not within compressed equal-length changes.
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// Otherwise the number of remaining changes, including the current one.
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int32_t remaining;
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UBool onlyChanges_, coarse;
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int8_t dir; // iteration direction: back(<0), initial(0), forward(>0)
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UBool changed;
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int32_t oldLength_, newLength_;
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int32_t srcIndex, replIndex, destIndex;
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};
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/**
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* Returns an Iterator for coarse-grained change edits
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* (adjacent change edits are treated as one).
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* Can be used to perform simple string updates.
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* Skips no-change edits.
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* @return an Iterator that merges adjacent changes.
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* @stable ICU 59
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*/
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Iterator getCoarseChangesIterator() const {
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return Iterator(array, length, true, true);
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}
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/**
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* Returns an Iterator for coarse-grained change and no-change edits
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* (adjacent change edits are treated as one).
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* Can be used to perform simple string updates.
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* Adjacent change edits are treated as one edit.
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* @return an Iterator that merges adjacent changes.
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* @stable ICU 59
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*/
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Iterator getCoarseIterator() const {
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return Iterator(array, length, false, true);
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}
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/**
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* Returns an Iterator for fine-grained change edits
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* (full granularity of change edits is retained).
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* Can be used for modifying styled text.
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* Skips no-change edits.
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* @return an Iterator that separates adjacent changes.
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* @stable ICU 59
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*/
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Iterator getFineChangesIterator() const {
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return Iterator(array, length, true, false);
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}
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/**
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* Returns an Iterator for fine-grained change and no-change edits
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* (full granularity of change edits is retained).
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* Can be used for modifying styled text.
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* @return an Iterator that separates adjacent changes.
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* @stable ICU 59
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*/
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Iterator getFineIterator() const {
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return Iterator(array, length, false, false);
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}
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/**
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* Merges the two input Edits and appends the result to this object.
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*
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* Consider two string transformations (for example, normalization and case mapping)
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* where each records Edits in addition to writing an output string.<br>
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* Edits ab reflect how substrings of input string a
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* map to substrings of intermediate string b.<br>
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* Edits bc reflect how substrings of intermediate string b
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* map to substrings of output string c.<br>
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* This function merges ab and bc such that the additional edits
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* recorded in this object reflect how substrings of input string a
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* map to substrings of output string c.
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*
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* If unrelated Edits are passed in where the output string of the first
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* has a different length than the input string of the second,
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* then a U_ILLEGAL_ARGUMENT_ERROR is reported.
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*
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* @param ab reflects how substrings of input string a
|
|
* map to substrings of intermediate string b.
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|
* @param bc reflects how substrings of intermediate string b
|
|
* map to substrings of output string c.
|
|
* @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test,
|
|
* or else the function returns immediately. Check for U_FAILURE()
|
|
* on output or use with function chaining. (See User Guide for details.)
|
|
* @return *this, with the merged edits appended
|
|
* @stable ICU 60
|
|
*/
|
|
Edits &mergeAndAppend(const Edits &ab, const Edits &bc, UErrorCode &errorCode);
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|
|
|
private:
|
|
void releaseArray() noexcept;
|
|
Edits ©Array(const Edits &other);
|
|
Edits &moveArray(Edits &src) 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 /* U_SHOW_CPLUSPLUS_API */
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|
|
|
#endif // __EDITS_H__
|