tor-browser

alphaindex.h (27067B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*
*   Copyright (C) 2011-2014 International Business Machines
*   Corporation and others.  All Rights Reserved.
*
*******************************************************************************
*/

#ifndef INDEXCHARS_H
#define INDEXCHARS_H

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#include "unicode/uobject.h"
#include "unicode/locid.h"
#include "unicode/unistr.h"

#if !UCONFIG_NO_COLLATION

/**
* \file
* \brief C++ API: Index Characters
*/

U_CDECL_BEGIN

/**
* Constants for Alphabetic Index Label Types.
* The form of these enum constants anticipates having a plain C API
* for Alphabetic Indexes that will also use them.
* @stable ICU 4.8
*/
typedef enum UAlphabeticIndexLabelType {
   /**
    *  Normal Label, typically the starting letter of the names
    *  in the bucket with this label.
    * @stable ICU 4.8
    */
   U_ALPHAINDEX_NORMAL    = 0,

   /**
    * Underflow Label.  The bucket with this label contains names
    * in scripts that sort before any of the bucket labels in this index.
    * @stable ICU 4.8
    */
   U_ALPHAINDEX_UNDERFLOW = 1,

   /**
    * Inflow Label.  The bucket with this label contains names
    * in scripts that sort between two of the bucket labels in this index.
    * Inflow labels are created when an index contains normal labels for
    * multiple scripts, and skips other scripts that sort between some of the
    * included scripts.
    * @stable ICU 4.8
    */
   U_ALPHAINDEX_INFLOW    = 2,

   /**
    * Overflow Label. The bucket with this label contains names in scripts
    * that sort after all of the bucket labels in this index.
    * @stable ICU 4.8
    */
   U_ALPHAINDEX_OVERFLOW  = 3
} UAlphabeticIndexLabelType;


struct UHashtable;
U_CDECL_END

U_NAMESPACE_BEGIN

// Forward Declarations

class BucketList;
class Collator;
class RuleBasedCollator;
class StringEnumeration;
class UnicodeSet;
class UVector;

/**
* AlphabeticIndex supports the creation of a UI index appropriate for a given language.
* It can support either direct use, or use with a client that doesn't support localized collation.
* The following is an example of what an index might look like in a UI:
* 
* <pre>
*  <b>... A B C D E F G H I J K L M N O P Q R S T U V W X Y Z  ...</b>
*
*  <b>A</b>
*     Addison
*     Albertson
*     Azensky
*  <b>B</b>
*     Baker
*  ...
* </pre>
*
* The class can generate a list of labels for use as a UI "index", that is, a list of
* clickable characters (or character sequences) that allow the user to see a segment
* (bucket) of a larger "target" list. That is, each label corresponds to a bucket in
* the target list, where everything in the bucket is greater than or equal to the character
* (according to the locale's collation). Strings can be added to the index;
* they will be in sorted order in the right bucket.
* <p>
* The class also supports having buckets for strings before the first (underflow),
* after the last (overflow), and between scripts (inflow). For example, if the index
* is constructed with labels for Russian and English, Greek characters would fall
* into an inflow bucket between the other two scripts.
* <p>
* The AlphabeticIndex class is not intended for public subclassing.
*
* <p><em>Note:</em> If you expect to have a lot of ASCII or Latin characters
* as well as characters from the user's language,
* then it is a good idea to call addLabels(Locale::getEnglish(), status).</p>
*
* <h2>Direct Use</h2>
* <p>The following shows an example of building an index directly.
*  The "show..." methods below are just to illustrate usage.
*
* <pre>
* // Create a simple index.  "Item" is assumed to be an application
* // defined type that the application's UI and other processing knows about,
* //  and that has a name.
*
* UErrorCode status = U_ZERO_ERROR;
* AlphabeticIndex index = new AlphabeticIndex(desiredLocale, status);
* index->addLabels(additionalLocale, status);
* for (Item *item in some source of Items ) {
*     index->addRecord(item->name(), item, status);
* }
* ...
* // Show index at top. We could skip or gray out empty buckets
*
* while (index->nextBucket(status)) {
*     if (showAll || index->getBucketRecordCount() != 0) {
*         showLabelAtTop(UI, index->getBucketLabel());
*     }
* }
*  ...
* // Show the buckets with their contents, skipping empty buckets
*
* index->resetBucketIterator(status);
* while (index->nextBucket(status)) {
*    if (index->getBucketRecordCount() != 0) {
*        showLabelInList(UI, index->getBucketLabel());
*        while (index->nextRecord(status)) {
*            showIndexedItem(UI, static_cast<Item *>(index->getRecordData()))
* </pre>
*
* The caller can build different UIs using this class.
* For example, an index character could be omitted or grayed-out
* if its bucket is empty. Small buckets could also be combined based on size, such as:
*
* <pre>
* <b>... A-F G-N O-Z ...</b>
* </pre>
*
* <h2>Client Support</h2>
* <p>Callers can also use the AlphabeticIndex::ImmutableIndex, or the AlphabeticIndex itself,
* to support sorting on a client that doesn't support AlphabeticIndex functionality.
*
* <p>The ImmutableIndex is both immutable and thread-safe.
* The corresponding AlphabeticIndex methods are not thread-safe because
* they "lazily" build the index buckets.
* <ul>
* <li>ImmutableIndex.getBucket(index) provides random access to all
*     buckets and their labels and label types.
* <li>The AlphabeticIndex bucket iterator or ImmutableIndex.getBucket(0..getBucketCount-1)
*     can be used to get a list of the labels,
*     such as "...", "A", "B",..., and send that list to the client.
* <li>When the client has a new name, it sends that name to the server.
* The server needs to call the following methods,
* and communicate the bucketIndex and collationKey back to the client.
*
* <pre>
* int32_t bucketIndex = index.getBucketIndex(name, status);
* const UnicodeString &label = immutableIndex.getBucket(bucketIndex)->getLabel();  // optional
* int32_t skLength = collator.getSortKey(name, sk, skCapacity);
* </pre>
*
* <li>The client would put the name (and associated information) into its bucket for bucketIndex. The sort key sk is a
* sequence of bytes that can be compared with a binary compare, and produce the right localized result.</li>
* </ul>
*
* @stable ICU 4.8
*/
class U_I18N_API AlphabeticIndex: public UObject {
public:
    /**
     * An index "bucket" with a label string and type.
     * It is referenced by getBucketIndex(),
     * and returned by ImmutableIndex.getBucket().
     *
     * The Bucket class is not intended for public subclassing.
     * @stable ICU 51
     */
    class U_I18N_API Bucket : public UObject {
    public:
       /**
        * Destructor.
        * @stable ICU 51
        */
       virtual ~Bucket();

       /**
        * Returns the label string.
        *
        * @return the label string for the bucket
        * @stable ICU 51
        */
       const UnicodeString &getLabel() const { return label_; }
       /**
        * Returns whether this bucket is a normal, underflow, overflow, or inflow bucket.
        *
        * @return the bucket label type
        * @stable ICU 51
        */
       UAlphabeticIndexLabelType getLabelType() const { return labelType_; }

    private:
       friend class AlphabeticIndex;
       friend class BucketList;

       UnicodeString label_;
       UnicodeString lowerBoundary_;
       UAlphabeticIndexLabelType labelType_;
       Bucket *displayBucket_;
       int32_t displayIndex_;
       UVector *records_;  // Records are owned by the inputList_ vector.

       Bucket(const UnicodeString &label,   // Parameter strings are copied.
              const UnicodeString &lowerBoundary,
              UAlphabeticIndexLabelType type);
    };

   /**
    * Immutable, thread-safe version of AlphabeticIndex.
    * This class provides thread-safe methods for bucketing,
    * and random access to buckets and their properties,
    * but does not offer adding records to the index.
    *
    * The ImmutableIndex class is not intended for public subclassing.
    *
    * @stable ICU 51
    */
   class U_I18N_API ImmutableIndex : public UObject {
   public:
       /**
        * Destructor.
        * @stable ICU 51
        */
       virtual ~ImmutableIndex();

       /**
        * Returns the number of index buckets and labels, including underflow/inflow/overflow.
        *
        * @return the number of index buckets
        * @stable ICU 51
        */
       int32_t getBucketCount() const;

       /**
        * Finds the index bucket for the given name and returns the number of that bucket.
        * Use getBucket() to get the bucket's properties.
        *
        * @param name the string to be sorted into an index bucket
        * @param errorCode Error code, will be set with the reason if the
        *                  operation fails.
        * @return the bucket number for the name
        * @stable ICU 51
        */
       int32_t getBucketIndex(const UnicodeString &name, UErrorCode &errorCode) const;

       /**
        * Returns the index-th bucket. Returns nullptr if the index is out of range.
        *
        * @param index bucket number
        * @return the index-th bucket
        * @stable ICU 51
        */
       const Bucket *getBucket(int32_t index) const;

   private:
       friend class AlphabeticIndex;

       ImmutableIndex(BucketList *bucketList, Collator *collatorPrimaryOnly)
               : buckets_(bucketList), collatorPrimaryOnly_(collatorPrimaryOnly) {}

       BucketList *buckets_;
       Collator *collatorPrimaryOnly_;
   };

   /**
    * Construct an AlphabeticIndex object for the specified locale.  If the locale's
    * data does not include index characters, a set of them will be
    * synthesized based on the locale's exemplar characters.  The locale
    * determines the sorting order for both the index characters and the
    * user item names appearing under each Index character.
    *
    * @param locale the desired locale.
    * @param status Error code, will be set with the reason if the construction
    *               of the AlphabeticIndex object fails.
    * @stable ICU 4.8
    */
    AlphabeticIndex(const Locale &locale, UErrorCode &status);

  /** 
    * Construct an AlphabeticIndex that uses a specific collator.
    * 
    * The index will be created with no labels; the addLabels() function must be called
    * after creation to add the desired labels to the index.
    * 
    * The index adopts the collator, and is responsible for deleting it. 
    * The caller should make no further use of the collator after creating the index.
    * 
    * @param collator The collator to use to order the contents of this index.
    * @param status Error code, will be set with the reason if the 
    *               operation fails.
    * @stable ICU 51
    */
   AlphabeticIndex(RuleBasedCollator *collator, UErrorCode &status);

   /**
    * Add Labels to this Index.  The labels are additions to those
    * that are already in the index; they do not replace the existing
    * ones.
    * @param additions The additional characters to add to the index, such as A-Z.
    * @param status Error code, will be set with the reason if the 
    *               operation fails.
    * @return this, for chaining
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &addLabels(const UnicodeSet &additions, UErrorCode &status);

   /**
    * Add the index characters from a Locale to the index.  The labels
    * are added to those that are already in the index; they do not replace the
    * existing index characters.  The collation order for this index is not
    * changed; it remains that of the locale that was originally specified
    * when creating this Index.
    *
    * @param locale The locale whose index characters are to be added.
    * @param status Error code, will be set with the reason if the 
    *               operation fails.
    * @return this, for chaining
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &addLabels(const Locale &locale, UErrorCode &status);

    /**
     * Destructor
     * @stable ICU 4.8
     */
   virtual ~AlphabeticIndex();

   /**
    * Builds an immutable, thread-safe version of this instance, without data records.
    *
    * @return an immutable index instance
    * @stable ICU 51
    */
   ImmutableIndex *buildImmutableIndex(UErrorCode &errorCode);

   /**
    * Get the Collator that establishes the ordering of the items in this index.
    * Ownership of the collator remains with the AlphabeticIndex instance.
    *
    * The returned collator is a reference to the internal collator used by this
    * index.  It may be safely used to compare the names of items or to get
    * sort keys for names.  However if any settings need to be changed,
    * or other non-const methods called, a cloned copy must be made first.
    *
    * @return The collator
    * @stable ICU 4.8
    */
   virtual const RuleBasedCollator &getCollator() const;


  /**
    * Get the default label used for abbreviated buckets *between* other index characters.
    * For example, consider the labels when Latin (X Y Z) and Greek (Α Β Γ) are used:
    *
    *     X Y Z ... Α Β Γ.
    *
    * @return inflow label
    * @stable ICU 4.8
    */
   virtual const UnicodeString &getInflowLabel() const;

  /**
    * Set the default label used for abbreviated buckets <i>between</i> other index characters.
    * An inflow label will be automatically inserted if two otherwise-adjacent label characters
    * are from different scripts, e.g. Latin and Cyrillic, and a third script, e.g. Greek,
    * sorts between the two.  The default inflow character is an ellipsis (...)
    *
    * @param inflowLabel the new Inflow label.
    * @param status Error code, will be set with the reason if the operation fails.
    * @return this
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &setInflowLabel(const UnicodeString &inflowLabel, UErrorCode &status);


  /**
    * Get the special label used for items that sort after the last normal label,
    * and that would not otherwise have an appropriate label.
    *
    * @return the overflow label
    * @stable ICU 4.8
    */
   virtual const UnicodeString &getOverflowLabel() const;


  /**
    * Set the label used for items that sort after the last normal label,
    * and that would not otherwise have an appropriate label.
    *
    * @param overflowLabel the new overflow label.
    * @param status Error code, will be set with the reason if the operation fails.
    * @return this
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &setOverflowLabel(const UnicodeString &overflowLabel, UErrorCode &status);

  /**
    * Get the special label used for items that sort before the first normal label,
    * and that would not otherwise have an appropriate label.
    *
    * @return underflow label
    * @stable ICU 4.8
    */
   virtual const UnicodeString &getUnderflowLabel() const;

  /**
    * Set the label used for items that sort before the first normal label,
    * and that would not otherwise have an appropriate label.
    *
    * @param underflowLabel the new underflow label.
    * @param status Error code, will be set with the reason if the operation fails.
    * @return this
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &setUnderflowLabel(const UnicodeString &underflowLabel, UErrorCode &status);


   /**
    * Get the limit on the number of labels permitted in the index.
    * The number does not include over, under and inflow labels.
    *
    * @return maxLabelCount maximum number of labels.
    * @stable ICU 4.8
    */
   virtual int32_t getMaxLabelCount() const;

   /**
    * Set a limit on the number of labels permitted in the index.
    * The number does not include over, under and inflow labels.
    * Currently, if the number is exceeded, then every
    * nth item is removed to bring the count down.
    * A more sophisticated mechanism may be available in the future.
    *
    * @param maxLabelCount the maximum number of labels.
    * @param status error code
    * @return This, for chaining
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &setMaxLabelCount(int32_t maxLabelCount, UErrorCode &status);


   /**
    * Add a record to the index.  Each record will be associated with an index Bucket
    *  based on the record's name.  The list of records for each bucket will be sorted
    *  based on the collation ordering of the names in the index's locale.
    *  Records with duplicate names are permitted; they will be kept in the order
    *  that they were added.
    *
    * @param name The display name for the Record.  The Record will be placed in
    *             a bucket based on this name.
    * @param data An optional pointer to user data associated with this
    *             item.  When iterating the contents of a bucket, both the
    *             data pointer the name will be available for each Record.
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return        This, for chaining.
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &addRecord(const UnicodeString &name, const void *data, UErrorCode &status);

   /**
    * Remove all Records from the Index.  The set of Buckets, which define the headings under
    * which records are classified, is not altered.
    *
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return        This, for chaining.
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &clearRecords(UErrorCode &status);


   /**  Get the number of labels in this index.
    *      Note: may trigger lazy index construction.
    *
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return        The number of labels in this index, including any under, over or
    *                in-flow labels.
    * @stable ICU 4.8
    */
   virtual int32_t  getBucketCount(UErrorCode &status);


   /**  Get the total number of Records in this index, that is, the number
    *   of <name, data> pairs added.
    *
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return        The number of records in this index, that is, the total number
    *                of (name, data) items added with addRecord().
    * @stable ICU 4.8
    */
   virtual int32_t  getRecordCount(UErrorCode &status);



   /**
    *   Given the name of a record, return the zero-based index of the Bucket
    *   in which the item should appear.  The name need not be in the index.
    *   A Record will not be added to the index by this function.
    *   Bucket numbers are zero-based, in Bucket iteration order.
    *
    * @param itemName  The name whose bucket position in the index is to be determined.
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return The bucket number for this name.
    * @stable ICU 4.8
    *
    */
   virtual int32_t  getBucketIndex(const UnicodeString &itemName, UErrorCode &status);


   /**
    *   Get the zero based index of the current Bucket from an iteration
    *   over the Buckets of this index.  Return -1 if no iteration is in process.
    *   @return  the index of the current Bucket
    *   @stable ICU 4.8
    */
   virtual int32_t  getBucketIndex() const;


   /**
    *   Advance the iteration over the Buckets of this index.  Return false if
    *   there are no more Buckets.
    *
    *   @param status  Error code, will be set with the reason if the operation fails.
    *   U_ENUM_OUT_OF_SYNC_ERROR will be reported if the index is modified while
    *   an enumeration of its contents are in process.
    *
    *   @return true if success, false if at end of iteration
    *   @stable ICU 4.8
    */
   virtual UBool nextBucket(UErrorCode &status);

   /**
    *   Return the name of the Label of the current bucket from an iteration over the buckets.
    *   If the iteration is before the first Bucket (nextBucket() has not been called),
    *   or after the last, return an empty string.
    *
    *   @return the bucket label.
    *   @stable ICU 4.8
    */
   virtual const UnicodeString &getBucketLabel() const;

   /**
    *  Return the type of the label for the current Bucket (selected by the
    *  iteration over Buckets.)
    *
    * @return the label type.
    * @stable ICU 4.8
    */
   virtual UAlphabeticIndexLabelType getBucketLabelType() const;

   /**
     * Get the number of <name, data> Records in the current Bucket.
     * If the current bucket iteration position is before the first label or after the
     * last, return 0.
     *
     *  @return the number of Records.
     *  @stable ICU 4.8
     */
   virtual int32_t getBucketRecordCount() const;


   /**
    *  Reset the Bucket iteration for this index.  The next call to nextBucket()
    *  will restart the iteration at the first label.
    *
    * @param status  Error code, will be set with the reason if the operation fails.
    * @return        this, for chaining.
    * @stable ICU 4.8
    */
   virtual AlphabeticIndex &resetBucketIterator(UErrorCode &status);

   /**
    * Advance to the next record in the current Bucket.
    * When nextBucket() is called, Record iteration is reset to just before the
    * first Record in the new Bucket.
    *
    *   @param status  Error code, will be set with the reason if the operation fails.
    *   U_ENUM_OUT_OF_SYNC_ERROR will be reported if the index is modified while
    *   an enumeration of its contents are in process.
    *   @return true if successful, false when the iteration advances past the last item.
    *   @stable ICU 4.8
    */
   virtual UBool nextRecord(UErrorCode &status);

   /**
    * Get the name of the current Record.
    * Return an empty string if the Record iteration position is before first
    * or after the last.
    *
    *  @return The name of the current index item.
    *  @stable ICU 4.8
    */
   virtual const UnicodeString &getRecordName() const;


   /**
    * Return the data pointer of the Record currently being iterated over.
    * Return nullptr if the current iteration position before the first item in this Bucket,
    * or after the last.
    *
    *  @return The current Record's data pointer.
    *  @stable ICU 4.8
    */
   virtual const void *getRecordData() const;


   /**
    * Reset the Record iterator position to before the first Record in the current Bucket.
    *
    *  @return This, for chaining.
    *  @stable ICU 4.8
    */
   virtual AlphabeticIndex &resetRecordIterator();

private:
    /**
     * No Copy constructor.
     */
    AlphabeticIndex(const AlphabeticIndex &other) = delete;

    /**
     *   No assignment.
     */
    AlphabeticIndex &operator =(const AlphabeticIndex & /*other*/) { return *this;}

   /**
    * No Equality operators.
    */
    virtual bool operator==(const AlphabeticIndex& other) const;

   /**
    * Inequality operator.
    */
    virtual bool operator!=(const AlphabeticIndex& other) const;

    // Common initialization, for use from all constructors.
    void init(const Locale *locale, UErrorCode &status);

   /**
    * This method is called to get the index exemplars. Normally these come from the locale directly,
    * but if they aren't available, we have to synthesize them.
    */
   void addIndexExemplars(const Locale &locale, UErrorCode &status);
   /**
    * Add Chinese index characters from the tailoring.
    */
   UBool addChineseIndexCharacters(UErrorCode &errorCode);

   UVector *firstStringsInScript(UErrorCode &status);

   static UnicodeString separated(const UnicodeString &item);

   /**
    * Determine the best labels to use.
    * This is based on the exemplars, but we also process to make sure that they are unique,
    * and sort differently, and that the overall list is small enough.
    */
   void initLabels(UVector &indexCharacters, UErrorCode &errorCode) const;
   BucketList *createBucketList(UErrorCode &errorCode) const;
   void initBuckets(UErrorCode &errorCode);
   void clearBuckets();
   void internalResetBucketIterator();

public:

   //  The Record is declared public only to allow access from
   //  implementation code written in plain C.
   //  It is not intended for public use.

#ifndef U_HIDE_INTERNAL_API
   /**
    * A (name, data) pair, to be sorted by name into one of the index buckets.
    * The user data is not used by the index implementation.
    * \cond
    * @internal
    */
   struct Record: public UMemory {
       const UnicodeString  name_;
       const void           *data_;
       Record(const UnicodeString &name, const void *data);
       ~Record();
   };
   /** \endcond */
#endif  /* U_HIDE_INTERNAL_API */

private:

   /**
    * Holds all user records before they are distributed into buckets.
    * Type of contents is (Record *)
    */
   UVector  *inputList_;

   int32_t  labelsIterIndex_;        // Index of next item to return.
   int32_t  itemsIterIndex_;
   Bucket   *currentBucket_;         // While an iteration of the index in underway,
                                     //   point to the bucket for the current label.
                                     // nullptr when no iteration underway.

   int32_t    maxLabelCount_;        // Limit on # of labels permitted in the index.

   UnicodeSet *initialLabels_;       // Initial (unprocessed) set of Labels.  Union
                                     //   of those explicitly set by the user plus
                                     //   those from locales.  Raw values, before
                                     //   crunching into bucket labels.

   UVector *firstCharsInScripts_;    // The first character from each script,
                                     //   in collation order.

   RuleBasedCollator *collator_;
   RuleBasedCollator *collatorPrimaryOnly_;

   // Lazy evaluated: null means that we have not built yet.
   BucketList *buckets_;

   UnicodeString  inflowLabel_;
   UnicodeString  overflowLabel_;
   UnicodeString  underflowLabel_;
   UnicodeString  overflowComparisonString_;

   UnicodeString emptyString_;
};

U_NAMESPACE_END

#endif  // !UCONFIG_NO_COLLATION

#endif /* U_SHOW_CPLUSPLUS_API */

#endif