icuSources/common/unicode/stringtriebuilder.h

   1 /*
   2 *******************************************************************************
   3 *   Copyright (C) 2010-2012, International Business Machines
   4 *   Corporation and others.  All Rights Reserved.
   5 *******************************************************************************
   6 *   file name:  stringtriebuilder.h
   7 *   encoding:   US-ASCII
   8 *   tab size:   8 (not used)
   9 *   indentation:4
  10 *
  11 *   created on: 2010dec24
  12 *   created by: Markus W. Scherer
  13 */
  14
  15 #ifndef __STRINGTRIEBUILDER_H__
  16 #define __STRINGTRIEBUILDER_H__
  17
  18 #include "unicode/utypes.h"
  19 #include "unicode/uobject.h"
  20
  21 /**
  22  * \file
  23  * \brief C++ API: Builder API for trie builders
  24  */
  25
  26 // Forward declaration.
  27 struct UHashtable;
  28 typedef struct UHashtable UHashtable;
  29
  30 /**
  31  * Build options for BytesTrieBuilder and CharsTrieBuilder.
  32  * @stable ICU 4.8
  33  */
  34 enum UStringTrieBuildOption {
  35     /**
  36      * Builds a trie quickly.
  37      * @stable ICU 4.8
  38      */
  39     USTRINGTRIE_BUILD_FAST,
  40     /**
  41      * Builds a trie more slowly, attempting to generate
  42      * a shorter but equivalent serialization.
  43      * This build option also uses more memory.
  44      *
  45      * This option can be effective when many integer values are the same
  46      * and string/byte sequence suffixes can be shared.
  47      * Runtime speed is not expected to improve.
  48      * @stable ICU 4.8
  49      */
  50     USTRINGTRIE_BUILD_SMALL
  51 };
  52
  53 U_NAMESPACE_BEGIN
  54
  55 /**
  56  * Base class for string trie builder classes.
  57  *
  58  * This class is not intended for public subclassing.
  59  * @stable ICU 4.8
  60  */
  61 class U_COMMON_API StringTrieBuilder : public UObject {
  62 public:
  63 #ifndef U_HIDE_INTERNAL_API
  64     /** @internal */
  65     static UBool hashNode(const void *node);
  66     /** @internal */
  67     static UBool equalNodes(const void *left, const void *right);
  68 #endif  /* U_HIDE_INTERNAL_API */
  69
  70 protected:
  71     // Do not enclose the protected default constructor with #ifndef U_HIDE_INTERNAL_API
  72     // or else the compiler will create a public default constructor.
  73     /** @internal */
  74     StringTrieBuilder();
  75     /** @internal */
  76     virtual ~StringTrieBuilder();
  77
  78 #ifndef U_HIDE_INTERNAL_API
  79     /** @internal */
  80     void createCompactBuilder(int32_t sizeGuess, UErrorCode &errorCode);
  81     /** @internal */
  82     void deleteCompactBuilder();
  83
  84     /** @internal */
  85     void build(UStringTrieBuildOption buildOption, int32_t elementsLength, UErrorCode &errorCode);
  86
  87     /** @internal */
  88     int32_t writeNode(int32_t start, int32_t limit, int32_t unitIndex);
  89     /** @internal */
  90     int32_t writeBranchSubNode(int32_t start, int32_t limit, int32_t unitIndex, int32_t length);
  91 #endif  /* U_HIDE_INTERNAL_API */
  92
  93     class Node;
  94
  95 #ifndef U_HIDE_INTERNAL_API
  96     /** @internal */
  97     Node *makeNode(int32_t start, int32_t limit, int32_t unitIndex, UErrorCode &errorCode);
  98     /** @internal */
  99     Node *makeBranchSubNode(int32_t start, int32_t limit, int32_t unitIndex,
 100                             int32_t length, UErrorCode &errorCode);
 101 #endif  /* U_HIDE_INTERNAL_API */
 102
 103     /** @internal */
 104     virtual int32_t getElementStringLength(int32_t i) const = 0;
 105     /** @internal */
 106     virtual UChar getElementUnit(int32_t i, int32_t unitIndex) const = 0;
 107     /** @internal */
 108     virtual int32_t getElementValue(int32_t i) const = 0;
 109
 110     // Finds the first unit index after this one where
 111     // the first and last element have different units again.
 112     /** @internal */
 113     virtual int32_t getLimitOfLinearMatch(int32_t first, int32_t last, int32_t unitIndex) const = 0;
 114
 115     // Number of different units at unitIndex.
 116     /** @internal */
 117     virtual int32_t countElementUnits(int32_t start, int32_t limit, int32_t unitIndex) const = 0;
 118     /** @internal */
 119     virtual int32_t skipElementsBySomeUnits(int32_t i, int32_t unitIndex, int32_t count) const = 0;
 120     /** @internal */
 121     virtual int32_t indexOfElementWithNextUnit(int32_t i, int32_t unitIndex, UChar unit) const = 0;
 122
 123     /** @internal */
 124     virtual UBool matchNodesCanHaveValues() const = 0;
 125
 126     /** @internal */
 127     virtual int32_t getMaxBranchLinearSubNodeLength() const = 0;
 128     /** @internal */
 129     virtual int32_t getMinLinearMatch() const = 0;
 130     /** @internal */
 131     virtual int32_t getMaxLinearMatchLength() const = 0;
 132
 133 #ifndef U_HIDE_INTERNAL_API
 134     // max(BytesTrie::kMaxBranchLinearSubNodeLength, UCharsTrie::kMaxBranchLinearSubNodeLength).
 135     /** @internal */
 136     static const int32_t kMaxBranchLinearSubNodeLength=5;
 137
 138     // Maximum number of nested split-branch levels for a branch on all 2^16 possible UChar units.
 139     // log2(2^16/kMaxBranchLinearSubNodeLength) rounded up.
 140     /** @internal */
 141     static const int32_t kMaxSplitBranchLevels=14;
 142
 143     /**
 144      * Makes sure that there is only one unique node registered that is
 145      * equivalent to newNode.
 146      * @param newNode Input node. The builder takes ownership.
 147      * @param errorCode ICU in/out UErrorCode.
 148                         Set to U_MEMORY_ALLOCATION_ERROR if it was success but newNode==NULL.
 149      * @return newNode if it is the first of its kind, or
 150      *         an equivalent node if newNode is a duplicate.
 151      * @internal
 152      */
 153     Node *registerNode(Node *newNode, UErrorCode &errorCode);
 154     /**
 155      * Makes sure that there is only one unique FinalValueNode registered
 156      * with this value.
 157      * Avoids creating a node if the value is a duplicate.
 158      * @param value A final value.
 159      * @param errorCode ICU in/out UErrorCode.
 160                         Set to U_MEMORY_ALLOCATION_ERROR if it was success but newNode==NULL.
 161      * @return A FinalValueNode with the given value.
 162      * @internal
 163      */
 164     Node *registerFinalValue(int32_t value, UErrorCode &errorCode);
 165
 166     /*
 167      * C++ note:
 168      * registerNode() and registerFinalValue() take ownership of their input nodes,
 169      * and only return owned nodes.
 170      * If they see a failure UErrorCode, they will delete the input node.
 171      * If they get a NULL pointer, they will record a U_MEMORY_ALLOCATION_ERROR.
 172      * If there is a failure, they return NULL.
 173      *
 174      * NULL Node pointers can be safely passed into other Nodes because
 175      * they call the static Node::hashCode() which checks for a NULL pointer first.
 176      *
 177      * Therefore, as long as builder functions register a new node,
 178      * they need to check for failures only before explicitly dereferencing
 179      * a Node pointer, or before setting a new UErrorCode.
 180      */
 181
 182     // Hash set of nodes, maps from nodes to integer 1.
 183     /** @internal */
 184     UHashtable *nodes;
 185
 186     /** @internal */
 187     class Node : public UObject {
 188     public:
 189         Node(int32_t initialHash) : hash(initialHash), offset(0) {}
 190         inline int32_t hashCode() const { return hash; }
 191         // Handles node==NULL.
 192         static inline int32_t hashCode(const Node *node) { return node==NULL ? 0 : node->hashCode(); }
 193         // Base class operator==() compares the actual class types.
 194         virtual UBool operator==(const Node &other) const;
 195         inline UBool operator!=(const Node &other) const { return !operator==(other); }
 196         /**
 197          * Traverses the Node graph and numbers branch edges, with rightmost edges first.
 198          * This is to avoid writing a duplicate node twice.
 199          *
 200          * Branch nodes in this trie data structure are not symmetric.
 201          * Most branch edges "jump" to other nodes but the rightmost branch edges
 202          * just continue without a jump.
 203          * Therefore, write() must write the rightmost branch edge last
 204          * (trie units are written backwards), and must write it at that point even if
 205          * it is a duplicate of a node previously written elsewhere.
 206          *
 207          * This function visits and marks right branch edges first.
 208          * Edges are numbered with increasingly negative values because we share the
 209          * offset field which gets positive values when nodes are written.
 210          * A branch edge also remembers the first number for any of its edges.
 211          *
 212          * When a further-left branch edge has a number in the range of the rightmost
 213          * edge's numbers, then it will be written as part of the required right edge
 214          * and we can avoid writing it first.
 215          *
 216          * After root.markRightEdgesFirst(-1) the offsets of all nodes are negative
 217          * edge numbers.
 218          *
 219          * @param edgeNumber The first edge number for this node and its sub-nodes.
 220          * @return An edge number that is at least the maximum-negative
 221          *         of the input edge number and the numbers of this node and all of its sub-nodes.
 222          */
 223         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 224         // write() must set the offset to a positive value.
 225         virtual void write(StringTrieBuilder &builder) = 0;
 226         // See markRightEdgesFirst.
 227         inline void writeUnlessInsideRightEdge(int32_t firstRight, int32_t lastRight,
 228                                                StringTrieBuilder &builder) {
 229             // Note: Edge numbers are negative, lastRight<=firstRight.
 230             // If offset>0 then this node and its sub-nodes have been written already
 231             // and we need not write them again.
 232             // If this node is part of the unwritten right branch edge,
 233             // then we wait until that is written.
 234             if(offset<0 && (offset<lastRight || firstRight<offset)) {
 235                 write(builder);
 236             }
 237         }
 238         inline int32_t getOffset() const { return offset; }
 239     protected:
 240         int32_t hash;
 241         int32_t offset;
 242     };
 243
 244     // This class should not be overridden because
 245     // registerFinalValue() compares a stack-allocated FinalValueNode
 246     // (stack-allocated so that we don't unnecessarily create lots of duplicate nodes)
 247     // with the input node, and the
 248     // !Node::operator==(other) used inside FinalValueNode::operator==(other)
 249     // will be false if the typeid's are different.
 250     /** @internal */
 251     class FinalValueNode : public Node {
 252     public:
 253         FinalValueNode(int32_t v) : Node(0x111111*37+v), value(v) {}
 254         virtual UBool operator==(const Node &other) const;
 255         virtual void write(StringTrieBuilder &builder);
 256     protected:
 257         int32_t value;
 258     };
 259
 260     /**
 261      * @internal
 262      */
 263     class ValueNode : public Node {
 264     public:
 265         ValueNode(int32_t initialHash) : Node(initialHash), hasValue(FALSE), value(0) {}
 266         virtual UBool operator==(const Node &other) const;
 267         void setValue(int32_t v) {
 268             hasValue=TRUE;
 269             value=v;
 270             hash=hash*37+v;
 271         }
 272     protected:
 273         UBool hasValue;
 274         int32_t value;
 275     };
 276
 277     /**
 278      * @internal
 279      */
 280     class IntermediateValueNode : public ValueNode {
 281     public:
 282         IntermediateValueNode(int32_t v, Node *nextNode)
 283                 : ValueNode(0x222222*37+hashCode(nextNode)), next(nextNode) { setValue(v); }
 284         virtual UBool operator==(const Node &other) const;
 285         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 286         virtual void write(StringTrieBuilder &builder);
 287     protected:
 288         Node *next;
 289     };
 290
 291     /**
 292      * @internal
 293      */
 294     class LinearMatchNode : public ValueNode {
 295     public:
 296         LinearMatchNode(int32_t len, Node *nextNode)
 297                 : ValueNode((0x333333*37+len)*37+hashCode(nextNode)),
 298                   length(len), next(nextNode) {}
 299         virtual UBool operator==(const Node &other) const;
 300         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 301     protected:
 302         int32_t length;
 303         Node *next;
 304     };
 305
 306     /**
 307      * @internal
 308      */
 309     class BranchNode : public Node {
 310     public:
 311         BranchNode(int32_t initialHash) : Node(initialHash) {}
 312     protected:
 313         int32_t firstEdgeNumber;
 314     };
 315
 316     /**
 317      * @internal
 318      */
 319     class ListBranchNode : public BranchNode {
 320     public:
 321         ListBranchNode() : BranchNode(0x444444), length(0) {}
 322         virtual UBool operator==(const Node &other) const;
 323         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 324         virtual void write(StringTrieBuilder &builder);
 325         // Adds a unit with a final value.
 326         void add(int32_t c, int32_t value) {
 327             units[length]=(UChar)c;
 328             equal[length]=NULL;
 329             values[length]=value;
 330             ++length;
 331             hash=(hash*37+c)*37+value;
 332         }
 333         // Adds a unit which leads to another match node.
 334         void add(int32_t c, Node *node) {
 335             units[length]=(UChar)c;
 336             equal[length]=node;
 337             values[length]=0;
 338             ++length;
 339             hash=(hash*37+c)*37+hashCode(node);
 340         }
 341     protected:
 342         Node *equal[kMaxBranchLinearSubNodeLength];  // NULL means "has final value".
 343         int32_t length;
 344         int32_t values[kMaxBranchLinearSubNodeLength];
 345         UChar units[kMaxBranchLinearSubNodeLength];
 346     };
 347
 348     /**
 349      * @internal
 350      */
 351     class SplitBranchNode : public BranchNode {
 352     public:
 353         SplitBranchNode(UChar middleUnit, Node *lessThanNode, Node *greaterOrEqualNode)
 354                 : BranchNode(((0x555555*37+middleUnit)*37+
 355                               hashCode(lessThanNode))*37+hashCode(greaterOrEqualNode)),
 356                   unit(middleUnit), lessThan(lessThanNode), greaterOrEqual(greaterOrEqualNode) {}
 357         virtual UBool operator==(const Node &other) const;
 358         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 359         virtual void write(StringTrieBuilder &builder);
 360     protected:
 361         UChar unit;
 362         Node *lessThan;
 363         Node *greaterOrEqual;
 364     };
 365
 366     // Branch head node, for writing the actual node lead unit.
 367     /** @internal */
 368     class BranchHeadNode : public ValueNode {
 369     public:
 370         BranchHeadNode(int32_t len, Node *subNode)
 371                 : ValueNode((0x666666*37+len)*37+hashCode(subNode)),
 372                   length(len), next(subNode) {}
 373         virtual UBool operator==(const Node &other) const;
 374         virtual int32_t markRightEdgesFirst(int32_t edgeNumber);
 375         virtual void write(StringTrieBuilder &builder);
 376     protected:
 377         int32_t length;
 378         Node *next;  // A branch sub-node.
 379     };
 380 #endif  /* U_HIDE_INTERNAL_API */
 381
 382     /** @internal */
 383     virtual Node *createLinearMatchNode(int32_t i, int32_t unitIndex, int32_t length,
 384                                         Node *nextNode) const = 0;
 385
 386     /** @internal */
 387     virtual int32_t write(int32_t unit) = 0;
 388     /** @internal */
 389     virtual int32_t writeElementUnits(int32_t i, int32_t unitIndex, int32_t length) = 0;
 390     /** @internal */
 391     virtual int32_t writeValueAndFinal(int32_t i, UBool isFinal) = 0;
 392     /** @internal */
 393     virtual int32_t writeValueAndType(UBool hasValue, int32_t value, int32_t node) = 0;
 394     /** @internal */
 395     virtual int32_t writeDeltaTo(int32_t jumpTarget) = 0;
 396 };
 397
 398 U_NAMESPACE_END
 399
 400 #endif  // __STRINGTRIEBUILDER_H__