icu::SearchIterator Class Referenceabstract

`SearchIterator` is an abstract base class that provides methods to search for a pattern within a text string. More...

`#include <search.h>`

Inheritance diagram for icu::SearchIterator:

## Public Member Functions

| SearchIterator (const SearchIterator &other)
| Copy constructor that creates a SearchIterator instance with the same behavior, and iterating over the same text. More...
virtual | ~SearchIterator ()
| Destructor. More...
virtual void | setOffset (int32_t position, UErrorCode &status)=0
| Sets the index to point to the given position, and clears any state that's affected. More...
virtual int32_t | getOffset () const =0
| Return the current index in the text being searched. More...
void | setAttribute (USearchAttribute attribute, USearchAttributeValue value, UErrorCode &status)
| Sets the text searching attributes located in the enum USearchAttribute with values from the enum USearchAttributeValue. More...
USearchAttributeValue | getAttribute (USearchAttribute attribute) const
| Gets the text searching attributes. More...
int32_t | getMatchedStart () const
| Returns the index to the match in the text string that was searched. More...
int32_t | getMatchedLength () const
| Returns the length of text in the string which matches the search pattern. More...
void | getMatchedText (UnicodeString &result) const
| Returns the text that was matched by the most recent call to `first`, `next`, `previous`, or `last`. More...
void | setBreakIterator (BreakIterator *breakiter, UErrorCode &status)
| Set the BreakIterator that will be used to restrict the points at which matches are detected. More...
const BreakIterator * | getBreakIterator () const
| Returns the BreakIterator that is used to restrict the points at which matches are detected. More...
virtual void | setText (const UnicodeString &text, UErrorCode &status)
| Set the string text to be searched. More...
virtual void | setText (CharacterIterator &text, UErrorCode &status)
| Set the string text to be searched. More...
const UnicodeString & | getText () const
| Return the string text to be searched. More...
virtual bool | operator== (const SearchIterator &that) const
| Equality operator. More...
bool | operator!= (const SearchIterator &that) const
| Not-equal operator. More...
virtual SearchIterator * | safeClone () const =0
| Returns a copy of SearchIterator with the same behavior, and iterating over the same text, as this one. More...
int32_t | first (UErrorCode &status)
| Returns the first index at which the string text matches the search pattern. More...
int32_t | following (int32_t position, UErrorCode &status)
| Returns the first index equal or greater than `position` at which the string text matches the search pattern. More...
int32_t | last (UErrorCode &status)
| Returns the last index in the target text at which it matches the search pattern. More...
int32_t | preceding (int32_t position, UErrorCode &status)
| Returns the first index less than `position` at which the string text matches the search pattern. More...
int32_t | next (UErrorCode &status)
| Returns the index of the next point at which the text matches the search pattern, starting from the current position The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. More...
int32_t | previous (UErrorCode &status)
| Returns the index of the previous point at which the string text matches the search pattern, starting at the current position. More...
virtual void | reset ()
| Resets the iteration. More...
Public Member Functions inherited from icu::UObject
virtual | ~UObject ()
| Destructor. More...
virtual UClassID | getDynamicClassID () const
| ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class. More...

## Protected Member Functions

| SearchIterator ()
| Default constructor. More...
| SearchIterator (const UnicodeString &text, BreakIterator *breakiter=nullptr)
| Constructor for use by subclasses. More...
| SearchIterator (CharacterIterator &text, BreakIterator *breakiter=nullptr)
| Constructor for use by subclasses. More...
SearchIterator & | operator= (const SearchIterator &that)
| Assignment operator. More...
virtual int32_t | handleNext (int32_t position, UErrorCode &status)=0
| Abstract method which subclasses override to provide the mechanism for finding the next match in the target text. More...
virtual int32_t | handlePrev (int32_t position, UErrorCode &status)=0
| Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text. More...
virtual void | setMatchLength (int32_t length)
| Sets the length of the currently matched string in the text string to be searched. More...
virtual void | setMatchStart (int32_t position)
| Sets the offset of the currently matched string in the text string to be searched. More...
void | setMatchNotFound ()
| sets match not found More...

## Protected Attributes

USearch * | m_search_
| C search data struct. More...
BreakIterator * | m_breakiterator_
| Break iterator. More...
UnicodeString | m_text_
| Unicode string version of the search text. More...

## Detailed Description

`SearchIterator` is an abstract base class that provides methods to search for a pattern within a text string.

Instances of `SearchIterator` maintain a current position and scans over the target text, returning the indices the pattern is matched and the length of each match.

`SearchIterator` defines a protocol for text searching. Subclasses provide concrete implementations of various search algorithms. For example, `StringSearch` implements language-sensitive pattern matching based on the comparison rules defined in a `RuleBasedCollator` object.

Other options for searching includes using a BreakIterator to restrict the points at which matches are detected.

`SearchIterator` provides an API that is similar to that of other text iteration classes such as `BreakIterator`. Using this class, it is easy to scan through text looking for all occurrences of a given pattern. The following example uses a `StringSearch` object to find all instances of "fox" in the target string. Any other subclass of `SearchIterator` can be used in an identical manner.

    UnicodeString target("The quick brown fox jumped over the lazy fox");
    UnicodeString pattern("fox");

    SearchIterator *iter  = new StringSearch(pattern, target);
    UErrorCode      error = U_ZERO_ERROR;
    for (int pos = iter->first(error); pos != USEARCH_DONE;
                                  pos = iter->next(error)) {
        printf("Found match at %d pos, length is %d\n", pos, iter.getMatchedLength());
    }

See also
  StringSearch
  RuleBasedCollator

Definition at line 82 of file search.h.

## Constructor & Destructor Documentation

## SearchIterator() [1/4]

icu::SearchIterator::SearchIterator | ( | const SearchIterator & | other | ) |

Copy constructor that creates a SearchIterator instance with the same behavior, and iterating over the same text.

Parameters

  other | the SearchIterator instance to be copied.

Stable:
  ICU 2.0

## ~SearchIterator()

virtual icu::SearchIterator::~SearchIterator | ( |  | ) |

virtual

Destructor.

Cleans up the search iterator data struct.

Stable:
  ICU 2.0

## SearchIterator() [2/4]

icu::SearchIterator::SearchIterator | ( |  | ) |

protected

Default constructor.

Initializes data to the default values.

Stable:
  ICU 2.0

## SearchIterator() [3/4]

icu::SearchIterator::SearchIterator | ( | const UnicodeString & | text,
|  | BreakIterator * | breakiter = `nullptr`
| ) |  |

protected

Constructor for use by subclasses.

Parameters

  text | The target text to be searched.
  breakiter | A BreakIterator that is used to restrict the points at which matches are detected. If `handleNext` or `handlePrev` finds a match, but the match's start or end index is not a boundary as determined by the `BreakIterator`, the match is rejected and `handleNext` or `handlePrev` is called again. If this parameter is `nullptr`, no break detection is attempted.

See also
  handleNext
  handlePrev

Stable:
  ICU 2.0

## SearchIterator() [4/4]

icu::SearchIterator::SearchIterator | ( | CharacterIterator & | text,
|  | BreakIterator * | breakiter = `nullptr`
| ) |  |

protected

Constructor for use by subclasses.

Note: No parsing of the text within the `CharacterIterator` will be done during searching for this version. The block of text in `CharacterIterator` will be used as it is.

Parameters

  text | The target text to be searched.
  breakiter | A BreakIterator that is used to restrict the points at which matches are detected. If `handleNext` or `handlePrev` finds a match, but the match's start or end index is not a boundary as determined by the `BreakIterator`, the match is rejected and `handleNext` or `handlePrev` is called again. If this parameter is `nullptr`, no break detection is attempted.

See also
  handleNext
  handlePrev

Stable:
  ICU 2.0

## Member Function Documentation

## first()

int32_t icu::SearchIterator::first | ( | UErrorCode & | status | ) |

Returns the first index at which the string text matches the search pattern.

The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to the index USEARCH_DONE

Parameters

  status | for errors if it occurs

Returns
  The character index of the first match, or `USEARCH_DONE` if there are no matches.

See also
  getOffset

Stable:
  ICU 2.0

## following()

int32_t icu::SearchIterator::following | ( | int32_t | position,
|  | UErrorCode & | status
| ) |  |

Returns the first index equal or greater than `position` at which the string text matches the search pattern.

The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to the index `USEARCH_DONE`.

Parameters

  position | where search if to start from. If position is less than or greater than the text range for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
  status | for errors if it occurs

Returns
  The character index of the first match following `position`, or `USEARCH_DONE` if there are no matches.

See also
  getOffset

Stable:
  ICU 2.0

## getAttribute()

USearchAttributeValue icu::SearchIterator::getAttribute | ( | USearchAttribute | attribute | ) | const

Gets the text searching attributes.

Parameters

  attribute | text attribute (enum USearchAttribute) to be retrieve

Returns
  text attribute value

Stable:
  ICU 2.0

## getBreakIterator()

const BreakIterator* icu::SearchIterator::getBreakIterator | ( |  | ) | const

Returns the BreakIterator that is used to restrict the points at which matches are detected.

This will be the same object that was passed to the constructor or to `setBreakIterator`. Note that `nullptr` is a legal value; it means that break detection should not be attempted.

Returns
  BreakIterator used to restrict matchings.

See also
  setBreakIterator

Stable:
  ICU 2.0

## getMatchedLength()

int32_t icu::SearchIterator::getMatchedLength | ( |  | ) | const

Returns the length of text in the string which matches the search pattern.

This call returns a valid result only after a successful call to `first`, `next`, `previous`, or `last`. Just after construction, or after a searching method returns `USEARCH_DONE`, this method will return 0.

Returns
  The length of the match in the target text, or 0 if there is no match currently.

See also
  first
  next
  previous
  last

Stable:
  ICU 2.0

## getMatchedStart()

int32_t icu::SearchIterator::getMatchedStart | ( |  | ) | const

Returns the index to the match in the text string that was searched.

This call returns a valid result only after a successful call to `first`, `next`, `previous`, or `last`. Just after construction, or after a searching method returns `USEARCH_DONE`, this method will return `USEARCH_DONE`.

Use getMatchedLength to get the matched string length.

Returns
  index of a substring within the text string that is being searched.

See also
  first
  next
  previous
  last

Stable:
  ICU 2.0

## getMatchedText()

void icu::SearchIterator::getMatchedText | ( | UnicodeString & | result | ) | const

Returns the text that was matched by the most recent call to `first`, `next`, `previous`, or `last`.

If the iterator is not pointing at a valid match (e.g. just after construction or after `USEARCH_DONE` has been returned, returns an empty string.

Parameters

  result | stores the matched string or an empty string if a match is not found.

See also
  first
  next
  previous
  last

Stable:
  ICU 2.0

## getOffset()

virtual int32_t icu::SearchIterator::getOffset | ( |  | ) | const

pure virtual

Return the current index in the text being searched.

If the iteration has gone past the end of the text (or past the beginning for a backwards search), USEARCH_DONE is returned.

Returns
  current index in the text being searched.

Stable:
  ICU 2.0

Implemented in icu::StringSearch.

## getText()

const UnicodeString& icu::SearchIterator::getText | ( |  | ) | const

Return the string text to be searched.

Returns
  text string to be searched.

Stable:
  ICU 2.0

## handleNext()

virtual int32_t icu::SearchIterator::handleNext | ( | int32_t | position,
|  | UErrorCode & | status
| ) |  |

protectedpure virtual

Abstract method which subclasses override to provide the mechanism for finding the next match in the target text.

This allows different subclasses to provide different search algorithms.

If a match is found, the implementation should return the index at which the match starts and should call `setMatchLength` with the number of characters in the target text that make up the match. If no match is found, the method should return USEARCH_DONE.

Parameters

  position | The index in the target text at which the search should start.
  status | for error codes if it occurs.

Returns
  index at which the match starts, else if match is not found USEARCH_DONE is returned

See also
  setMatchLength

Stable:
  ICU 2.0

Implemented in icu::StringSearch.

## handlePrev()

virtual int32_t icu::SearchIterator::handlePrev | ( | int32_t | position,
|  | UErrorCode & | status
| ) |  |

protectedpure virtual

Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text.

This allows different subclasses to provide different search algorithms.

If a match is found, the implementation should return the index at which the match starts and should call `setMatchLength` with the number of characters in the target text that make up the match. If no match is found, the method should return USEARCH_DONE.

Parameters

  position | The index in the target text at which the search should start.
  status | for error codes if it occurs.

Returns
  index at which the match starts, else if match is not found USEARCH_DONE is returned

See also
  setMatchLength

Stable:
  ICU 2.0

Implemented in icu::StringSearch.

## last()

int32_t icu::SearchIterator::last | ( | UErrorCode & | status | ) |

Returns the last index in the target text at which it matches the search pattern.

The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to the index USEARCH_DONE.

Parameters

  status | for errors if it occurs

Returns
  The index of the first match, or `USEARCH_DONE` if there are no matches.

See also
  getOffset

Stable:
  ICU 2.0

## next()

int32_t icu::SearchIterator::next | ( | UErrorCode & | status | ) |

Returns the index of the next point at which the text matches the search pattern, starting from the current position The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found.

If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to a position after the end of the text string.

Parameters

  status | for errors if it occurs

Returns
  The index of the next match after the current position, or `USEARCH_DONE` if there are no more matches.

See also
  getOffset

Stable:
  ICU 2.0

## operator!=()

bool icu::SearchIterator::operator!= | ( | const SearchIterator & | that | ) | const

inline

Not-equal operator.

Parameters

  that | SearchIterator instance to be compared.

Returns
  false if operator== returns true, and vice versa.

Stable:
  ICU 2.0

Definition at line 569 of file search.h.

References icu::operator==().

## operator=()

SearchIterator& icu::SearchIterator::operator= | ( | const SearchIterator & | that | ) |

protected

Assignment operator.

Sets this iterator to have the same behavior, and iterate over the same text, as the one passed in.

Parameters

  that | instance to be copied.

Stable:
  ICU 2.0

## operator==()

virtual bool icu::SearchIterator::operator== | ( | const SearchIterator & | that | ) | const

virtual

Equality operator.

Parameters

  that | SearchIterator instance to be compared.

Returns
  true if both BreakIterators are of the same class, have the same behavior, terates over the same text and have the same attributes. false otherwise.

Stable:
  ICU 2.0

Reimplemented in icu::StringSearch.

## preceding()

int32_t icu::SearchIterator::preceding | ( | int32_t | position,
|  | UErrorCode & | status
| ) |  |

Returns the first index less than `position` at which the string text matches the search pattern.

The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to the index USEARCH_DONE

When `USEARCH_OVERLAP` option is off, the last index of the result match is always less than `position`. When `USERARCH_OVERLAP` is on, the result match may span across `position`.

Parameters

  position | where search is to start from. If position is less than or greater than the text range for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
  status | for errors if it occurs

Returns
  The character index of the first match preceding `position`, or `USEARCH_DONE` if there are no matches.

See also
  getOffset

Stable:
  ICU 2.0

## previous()

int32_t icu::SearchIterator::previous | ( | UErrorCode & | status | ) |

Returns the index of the previous point at which the string text matches the search pattern, starting at the current position.

The iterator is adjusted so that its current index (as returned by `getOffset`) is the match position if one was found. If a match is not found, `USEARCH_DONE` will be returned and the iterator will be adjusted to the index USEARCH_DONE

Parameters

  status | for errors if it occurs

Returns
  The index of the previous match before the current position, or `USEARCH_DONE` if there are no more matches.

See also
  getOffset

Stable:
  ICU 2.0

## reset()

virtual void icu::SearchIterator::reset | ( |  | ) |

virtual

Resets the iteration.

Search will begin at the start of the text string if a forward iteration is initiated before a backwards iteration. Otherwise if a backwards iteration is initiated before a forwards iteration, the search will begin at the end of the text string.

Stable:
  ICU 2.0

Reimplemented in icu::StringSearch.

## safeClone()

virtual SearchIterator* icu::SearchIterator::safeClone | ( |  | ) | const

pure virtual

Returns a copy of SearchIterator with the same behavior, and iterating over the same text, as this one.

Note that all data will be replicated, except for the text string to be searched.

Returns
  cloned object

Stable:
  ICU 2.0

Implemented in icu::StringSearch.

## setAttribute()

void icu::SearchIterator::setAttribute | ( | USearchAttribute | attribute,
|  | USearchAttributeValue | value,
|  | UErrorCode & | status
| ) |  |

Sets the text searching attributes located in the enum USearchAttribute with values from the enum USearchAttributeValue.

USEARCH_DEFAULT can be used for all attributes for resetting.

Parameters

  attribute | text attribute (enum USearchAttribute) to be set
  value | text attribute value
  status | for errors if it occurs

Stable:
  ICU 2.0

## setBreakIterator()

void icu::SearchIterator::setBreakIterator | ( | BreakIterator * | breakiter,
|  | UErrorCode & | status
| ) |  |

Set the BreakIterator that will be used to restrict the points at which matches are detected.

The user is responsible for deleting the breakiterator.

Parameters

  breakiter | A BreakIterator that will be used to restrict the points at which matches are detected. If a match is found, but the match's start or end index is not a boundary as determined by the `BreakIterator`, the match will be rejected and another will be searched for. If this parameter is `nullptr`, no break detection is attempted.
  status | for errors if it occurs

See also
  BreakIterator

Stable:
  ICU 2.0

## setMatchLength()

virtual void icu::SearchIterator::setMatchLength | ( | int32_t | length | ) |

protectedvirtual

Sets the length of the currently matched string in the text string to be searched.

Subclasses' `handleNext` and `handlePrev` methods should call this when they find a match in the target text.

Parameters

  length | length of the matched text.

See also
  handleNext
  handlePrev

Stable:
  ICU 2.0

## setMatchNotFound()

void icu::SearchIterator::setMatchNotFound | ( |  | ) |

protected

sets match not found

Stable:
  ICU 2.0

## setMatchStart()

virtual void icu::SearchIterator::setMatchStart | ( | int32_t | position | ) |

protectedvirtual

Sets the offset of the currently matched string in the text string to be searched.

Subclasses' `handleNext` and `handlePrev` methods should call this when they find a match in the target text.

Parameters

  position | start offset of the matched text.

See also
  handleNext
  handlePrev

Stable:
  ICU 2.0

## setOffset()

virtual void icu::SearchIterator::setOffset | ( | int32_t | position,
|  | UErrorCode & | status
| ) |  |

pure virtual

Sets the index to point to the given position, and clears any state that's affected.

This method takes the argument index and sets the position in the text string accordingly without checking if the index is pointing to a valid starting point to begin searching.

Parameters

  position | within the text to be set. If position is less than or greater than the text range for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
  status | for errors if it occurs

Stable:
  ICU 2.0

Implemented in icu::StringSearch.

## setText() [1/2]

virtual void icu::SearchIterator::setText | ( | CharacterIterator & | text,
|  | UErrorCode & | status
| ) |  |

virtual

Set the string text to be searched.

Text iteration will hence begin at the start of the text string. This method is useful if you want to re-use an iterator to search for the same pattern within a different body of text.

Note: No parsing of the text within the `CharacterIterator` will be done during searching for this version. The block of text in `CharacterIterator` will be used as it is. The user is responsible for deleting the text.

Parameters

  text | string iterator to be searched.
  status | for errors if any. If the text length is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.

Stable:
  ICU 2.0

Reimplemented in icu::StringSearch.

## setText() [2/2]

virtual void icu::SearchIterator::setText | ( | const UnicodeString & | text,
|  | UErrorCode & | status
| ) |  |

virtual

Set the string text to be searched.

Text iteration will hence begin at the start of the text string. This method is useful if you want to re-use an iterator to search for the same pattern within a different body of text. The user is responsible for deleting the text.

Parameters

  text | string to be searched.
  status | for errors. If the text length is 0, an U_ILLEGAL_ARGUMENT_ERROR is returned.

Stable:
  ICU 2.0

Reimplemented in icu::StringSearch.

## Field Documentation

## m_breakiterator_

BreakIterator* icu::SearchIterator::m_breakiterator_

protected

Break iterator.

Currently the C++ breakiterator does not have getRules etc to reproduce another in C. Hence we keep the original around and do the verification at the end of the match. The user is responsible for deleting this break iterator.

Stable:
  ICU 2.0

Definition at line 428 of file search.h.

## m_search_

USearch* icu::SearchIterator::m_search_

protected

C search data struct.

Stable:
  ICU 2.0

Definition at line 418 of file search.h.

## m_text_

UnicodeString icu::SearchIterator::m_text_

protected

Unicode string version of the search text.

Stable:
  ICU 2.0

Definition at line 434 of file search.h.

The documentation for this class was generated from the following file:

- i18n/unicode/search.h