000

/*
**********************************************************************
*   Copyright (C) 2001-2011 IBM and others. All rights reserved.
**********************************************************************
*   Date        Name        Description
*  03/22/2000   helena      Creation.
**********************************************************************
*/

#ifndef SEARCH_H
#define SEARCH_H

#include "unicode/utypes.h"

/**
 * \file 
 * \brief C++ API: SearchIterator object.
 */
 
#if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION

#include "unicode/uobject.h"
#include "unicode/unistr.h"
#include "unicode/chariter.h"
#include "unicode/brkiter.h"
#include "unicode/usearch.h"

/**
* @stable ICU 2.0
*/
struct USearch;
/**
* @stable ICU 2.0
*/
typedef struct USearch USearch;

U_NAMESPACE_BEGIN

/**
 *
 * <tt>SearchIterator</tt> is an abstract base class that provides 
 * methods to search for a pattern within a text string. Instances of
 * <tt>SearchIterator</tt> maintain a current position and scans over the 
 * target text, returning the indices the pattern is matched and the length 
 * of each match.
 * 
 * <tt>SearchIterator</tt> defines a protocol for text searching. 
 * Subclasses provide concrete implementations of various search algorithms. 
 * For example, <tt>StringSearch</tt> implements language-sensitive pattern 
 * matching based on the comparison rules defined in a 
 * <tt>RuleBasedCollator</tt> object. 
 * 
 * Other options for searching includes using a BreakIterator to restrict 
 * the points at which matches are detected.
 * 
 * <tt>SearchIterator</tt> provides an API that is similar to that of
 * other text iteration classes such as <tt>BreakIterator</tt>. Using 
 * this class, it is easy to scan through text looking for all occurances of 
 * a given pattern. The following example uses a <tt>StringSearch</tt> 
 * object to find all instances of "fox" in the target string. Any other 
 * subclass of <tt>SearchIterator</tt> can be used in an identical 
 * manner.
 * <pre><code>
 * 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.getMatchLength());
 * }
 * </code></pre>
 *
 * @see StringSearch
 * @see RuleBasedCollator
 */
class U_I18N_API SearchIterator : public UObject {

public:

// public constructors and destructors -------------------------------

/** 
    * Copy constructor that creates a SearchIterator instance with the same 
    * behavior, and iterating over the same text. 
    * @param other the SearchIterator instance to be copied.
    * @stable ICU 2.0
    */
    SearchIterator(const SearchIterator &other);

/**
     * Destructor. Cleans up the search iterator data struct.
     * @stable ICU 2.0
     */
    virtual ~SearchIterator();

// public get and set methods ----------------------------------------

/**
 * 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. 
 * @param 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
 * @param status for errors if it occurs
 * @stable ICU 2.0
 */
 virtual void setOffset(int32_t position, UErrorCode &status) = 0;

/**
     * 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.
     * @return current index in the text being searched.
     * @stable ICU 2.0
     */
    virtual int32_t getOffset(void) const = 0;

/**
    * 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.
    * @param attribute text attribute (enum USearchAttribute) to be set
    * @param value text attribute value
    * @param status for errors if it occurs
    * @stable ICU 2.0
    */
    void setAttribute(USearchAttribute       attribute,
                      USearchAttributeValue  value,
                      UErrorCode            &status);

/** 
 * Gets the text searching attributes
 * @param attribute text attribute (enum USearchAttribute) to be retrieve
 * @return text attribute value
 * @stable ICU 2.0
 */
 USearchAttributeValue getAttribute(USearchAttribute attribute) 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 
 * <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 * Just after construction, or after a searching method returns 
 * <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
 * 
 * Use getMatchedLength to get the matched string length.
 * @return index of a substring within the text string that is being 
 * searched.
 * @see #first
 * @see #next
 * @see #previous
 * @see #last
 * @stable ICU 2.0
 */
 int32_t getMatchedStart(void) 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 <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 * Just after construction, or after a searching method returns 
 * <tt>USEARCH_DONE</tt>, this method will return 0.
 * @return The length of the match in the target text, or 0 if there
 * is no match currently.
 * @see #first
 * @see #next
 * @see #previous
 * @see #last
 * @stable ICU 2.0
 */
 int32_t getMatchedLength(void) const;
 
 /**
 * Returns the text that was matched by the most recent call to 
 * <tt>first</tt>, <tt>next</tt>, <tt>previous</tt>, or <tt>last</tt>.
 * If the iterator is not pointing at a valid match (e.g. just after 
 * construction or after <tt>USEARCH_DONE</tt> has been returned, 
 * returns an empty string. 
 * @param result stores the matched string or an empty string if a match
 * is not found.
 * @see #first
 * @see #next
 * @see #previous
 * @see #last
 * @stable ICU 2.0
 */
 void getMatchedText(UnicodeString &result) const;
 
 /**
 * Set the BreakIterator that will be used to restrict the points
 * at which matches are detected. The user is responsible for deleting 
 * the breakiterator.
 * @param 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 <tt>BreakIterator</tt>, 
 * the match will be rejected and another will be searched 
 * for. If this parameter is <tt>NULL</tt>, no break
 * detection is attempted.
 * @param status for errors if it occurs
 * @see BreakIterator
 * @stable ICU 2.0
 */
 void setBreakIterator(BreakIterator *breakiter, UErrorCode &status);
 
 /**
 * 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 <tt>setBreakIterator</tt>.
 * Note that <tt>NULL</tt> is a legal value; it means that break
 * detection should not be attempted.
 * @return BreakIterator used to restrict matchings.
 * @see #setBreakIterator
 * @stable ICU 2.0
 */
 const BreakIterator * getBreakIterator(void) const;

/**
     * 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.
     * @param text string to be searched.
     * @param status for errors. If the text length is 0, 
     *        an U_ILLEGAL_ARGUMENT_ERROR is returned.
     * @stable ICU 2.0
     */
    virtual void setText(const UnicodeString &text, UErrorCode &status);

/**
 * 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 <tt>CharacterIterator</tt> 
 * will be done during searching for this version. The block of text 
 * in <tt>CharacterIterator</tt> will be used as it is.
 * The user is responsible for deleting the text.
 * @param text string iterator to be searched.
 * @param status for errors if any. If the text length is 0 then an 
 * U_ILLEGAL_ARGUMENT_ERROR is returned.
 * @stable ICU 2.0
 */
 virtual void setText(CharacterIterator &text, UErrorCode &status);
 
 /**
 * Return the string text to be searched.
 * @return text string to be searched.
 * @stable ICU 2.0
 */
 const UnicodeString & getText(void) const;

// operator overloading ----------------------------------------------

/**
     * Equality operator. 
     * @param that SearchIterator instance to be compared.
     * @return 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
     */
    virtual UBool operator==(const SearchIterator &that) const;

/**
     * Not-equal operator. 
     * @param that SearchIterator instance to be compared.
     * @return FALSE if operator== returns TRUE, and vice versa.
     * @stable ICU 2.0
     */
    UBool operator!=(const SearchIterator &that) const;

// public methods ----------------------------------------------------

/**
     * 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.
     * @return cloned object
     * @stable ICU 2.0
     */
    virtual SearchIterator* safeClone(void) const = 0;

/**
 * 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 <tt>getOffset</tt>) is the match position if one 
 * was found.
 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 * the iterator will be adjusted to the index USEARCH_DONE
 * @param status for errors if it occurs
 * @return The character index of the first match, or 
 * <tt>USEARCH_DONE</tt> if there are no matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t first(UErrorCode &status);

/**
 * Returns the first index equal or greater than <tt>position</tt> at which the 
 * string text matches the search pattern. The iterator is adjusted so 
 * that its current index (as returned by <tt>getOffset</tt>) is the 
 * match position if one was found.
 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and the
 * iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
 * @param 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
 * @param status for errors if it occurs
 * @return The character index of the first match following 
 * <tt>position</tt>, or <tt>USEARCH_DONE</tt> if there are no 
 * matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t following(int32_t position, 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 <tt>getOffset</tt>) is the match position if one was 
 * found.
 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 * the iterator will be adjusted to the index USEARCH_DONE.
 * @param status for errors if it occurs
 * @return The index of the first match, or <tt>USEARCH_DONE</tt> if 
 * there are no matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t last(UErrorCode &status);

/**
 * Returns the first index less than <tt>position</tt> at which the string 
 * text matches the search pattern. The iterator is adjusted so that its 
 * current index (as returned by <tt>getOffset</tt>) is the match 
 * position if one was found. If a match is not found, 
 * <tt>USEARCH_DONE</tt> will be returned and the iterator will be 
 * adjusted to the index USEARCH_DONE
 * 
 * When <tt>USEARCH_OVERLAP</tt> option is off, the last index of the
 * result match is always less than <tt>position</tt>.
 * When <tt>USERARCH_OVERLAP</tt> is on, the result match may span across
 * <tt>position</tt>.
 *
 * @param 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
 * @param status for errors if it occurs
 * @return The character index of the first match preceding 
 * <tt>position</tt>, or <tt>USEARCH_DONE</tt> if there are 
 * no matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t preceding(int32_t position, 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 
 * <tt>getOffset</tt>) is the match position if one was found.
 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 * the iterator will be adjusted to a position after the end of the text 
 * string.
 * @param status for errors if it occurs
 * @return The index of the next match after the current position,
 * or <tt>USEARCH_DONE</tt> if there are no more matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t next(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 
 * <tt>getOffset</tt>) is the match position if one was found.
 * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
 * the iterator will be adjusted to the index USEARCH_DONE
 * @param status for errors if it occurs
 * @return The index of the previous match before the current position,
 * or <tt>USEARCH_DONE</tt> if there are no more matches.
 * @see #getOffset
 * @stable ICU 2.0
 */
 int32_t previous(UErrorCode &status);

/** 
    * 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
    */
    virtual void reset();

protected:
    // protected data members ---------------------------------------------

/**
    * C search data struct
    * @stable ICU 2.0
    */
    USearch *m_search_;

/**
    * 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
    */
    BreakIterator *m_breakiterator_;
    
    /**
    * Unicode string version of the search text
    * @stable ICU 2.0
    */
    UnicodeString  m_text_;

// protected constructors and destructors -----------------------------

/**
    * Default constructor.
    * Initializes data to the default values.
    * @stable ICU 2.0
    */
    SearchIterator();

/**
 * Constructor for use by subclasses.
 * @param text The target text to be searched.
 * @param breakiter A {@link BreakIterator} that is used to restrict the 
 * points at which matches are detected. If 
 * <tt>handleNext</tt> or <tt>handlePrev</tt> finds a 
 * match, but the match's start or end index is not a 
 * boundary as determined by the <tt>BreakIterator</tt>, 
 * the match is rejected and <tt>handleNext</tt> or 
 * <tt>handlePrev</tt> is called again. If this parameter 
 * is <tt>NULL</tt>, no break detection is attempted. 
 * @see #handleNext
 * @see #handlePrev
 * @stable ICU 2.0
 */
 SearchIterator(const UnicodeString &text, 
 BreakIterator *breakiter = NULL);

/**
 * Constructor for use by subclasses.
 * 
 * Note: No parsing of the text within the <tt>CharacterIterator</tt> 
 * will be done during searching for this version. The block of text 
 * in <tt>CharacterIterator</tt> will be used as it is.
 * @param text The target text to be searched.
 * @param breakiter A {@link BreakIterator} that is used to restrict the 
 * points at which matches are detected. If 
 * <tt>handleNext</tt> or <tt>handlePrev</tt> finds a 
 * match, but the match's start or end index is not a 
 * boundary as determined by the <tt>BreakIterator</tt>, 
 * the match is rejected and <tt>handleNext</tt> or 
 * <tt>handlePrev</tt> is called again. If this parameter 
 * is <tt>NULL</tt>, no break detection is attempted.
 * @see #handleNext
 * @see #handlePrev
 * @stable ICU 2.0
 */
 SearchIterator(CharacterIterator &text, BreakIterator *breakiter = NULL);

// protected methods --------------------------------------------------

/**
     * Assignment operator. Sets this iterator to have the same behavior,
     * and iterate over the same text, as the one passed in.
     * @param that instance to be copied.
     * @stable ICU 2.0
     */
    SearchIterator & operator=(const SearchIterator &that);

/**
 * 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 
 * <tt>setMatchLength</tt> 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.
 * 
 * @param position The index in the target text at which the search 
 * should start.
 * @param status for error codes if it occurs.
 * @return index at which the match starts, else if match is not found 
 * USEARCH_DONE is returned
 * @see #setMatchLength
 * @stable ICU 2.0
 */
 virtual int32_t handleNext(int32_t position, UErrorCode &status) 
 = 0;

/**
 * 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 
 * <tt>setMatchLength</tt> 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.
 * 
 * @param position The index in the target text at which the search 
 * should start.
 * @param status for error codes if it occurs.
 * @return index at which the match starts, else if match is not found 
 * USEARCH_DONE is returned
 * @see #setMatchLength
 * @stable ICU 2.0
 */
 virtual int32_t handlePrev(int32_t position, UErrorCode &status) 
 = 0;

/**
 * Sets the length of the currently matched string in the text string to
 * be searched.
 * Subclasses' <tt>handleNext</tt> and <tt>handlePrev</tt>
 * methods should call this when they find a match in the target text.
 * @param length length of the matched text.
 * @see #handleNext
 * @see #handlePrev
 * @stable ICU 2.0
 */
 virtual void setMatchLength(int32_t length);

/**
 * Sets the offset of the currently matched string in the text string to
 * be searched.
 * Subclasses' <tt>handleNext</tt> and <tt>handlePrev</tt>
 * methods should call this when they find a match in the target text.
 * @param position start offset of the matched text.
 * @see #handleNext
 * @see #handlePrev
 * @stable ICU 2.0
 */
 virtual void setMatchStart(int32_t position);

/**
    * sets match not found 
    * @stable ICU 2.0
    */
    void setMatchNotFound();
};

inline UBool SearchIterator::operator!=(const SearchIterator &that) const
{
   return !operator==(that); 
}
U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_COLLATION */

#endif