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stringtriebuilder.h
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/* ******************************************************************************* * Copyright (C) 2010-2011, International Business Machines * Corporation and others. All Rights Reserved. ******************************************************************************* * file name: stringtriebuilder.h * encoding: US-ASCII * tab size: 8 (not used) * indentation:4 * * created on: 2010dec24 * created by: Markus W. Scherer */ #ifndef __STRINGTRIEBUILDER_H__ #define __STRINGTRIEBUILDER_H__ #include "unicode/utypes.h" #include "unicode/uobject.h" // Forward declaration. struct UHashtable; typedef struct UHashtable UHashtable; /** * Build options for BytesTrieBuilder and CharsTrieBuilder. * @draft ICU 4.8 */ enum UStringTrieBuildOption { /** * Builds a trie quickly. * @draft ICU 4.8 */ USTRINGTRIE_BUILD_FAST, /** * Builds a trie more slowly, attempting to generate * a shorter but equivalent serialization. * This build option also uses more memory. * * This option can be effective when many integer values are the same * and string/byte sequence suffixes can be shared. * Runtime speed is not expected to improve. * @draft ICU 4.8 */ USTRINGTRIE_BUILD_SMALL }; U_NAMESPACE_BEGIN /** * Base class for string trie builder classes. * * This class is not intended for public subclassing. * @draft ICU 4.8 */ class U_COMMON_API StringTrieBuilder : public UObject { public: /** @internal */ static UBool hashNode(const void *node); /** @internal */ static UBool equalNodes(const void *left, const void *right); protected: /** @internal */ StringTrieBuilder(); /** @internal */ virtual ~StringTrieBuilder(); /** @internal */ void createCompactBuilder(int32_t sizeGuess, UErrorCode &errorCode); /** @internal */ void deleteCompactBuilder(); /** @internal */ void build(UStringTrieBuildOption buildOption, int32_t elementsLength, UErrorCode &errorCode); /** @internal */ int32_t writeNode(int32_t start, int32_t limit, int32_t unitIndex); /** @internal */ int32_t writeBranchSubNode(int32_t start, int32_t limit, int32_t unitIndex, int32_t length); class Node; /** @internal */ Node *makeNode(int32_t start, int32_t limit, int32_t unitIndex, UErrorCode &errorCode); /** @internal */ Node *makeBranchSubNode(int32_t start, int32_t limit, int32_t unitIndex, int32_t length, UErrorCode &errorCode); /** @internal */ virtual int32_t getElementStringLength(int32_t i) const = 0; /** @internal */ virtual UChar getElementUnit(int32_t i, int32_t unitIndex) const = 0; /** @internal */ virtual int32_t getElementValue(int32_t i) const = 0; // Finds the first unit index after this one where // the first and last element have different units again. /** @internal */ virtual int32_t getLimitOfLinearMatch(int32_t first, int32_t last, int32_t unitIndex) const = 0; // Number of different units at unitIndex. /** @internal */ virtual int32_t countElementUnits(int32_t start, int32_t limit, int32_t unitIndex) const = 0; /** @internal */ virtual int32_t skipElementsBySomeUnits(int32_t i, int32_t unitIndex, int32_t count) const = 0; /** @internal */ virtual int32_t indexOfElementWithNextUnit(int32_t i, int32_t unitIndex, UChar unit) const = 0; /** @internal */ virtual UBool matchNodesCanHaveValues() const = 0; /** @internal */ virtual int32_t getMaxBranchLinearSubNodeLength() const = 0; /** @internal */ virtual int32_t getMinLinearMatch() const = 0; /** @internal */ virtual int32_t getMaxLinearMatchLength() const = 0; // max(BytesTrie::kMaxBranchLinearSubNodeLength, UCharsTrie::kMaxBranchLinearSubNodeLength). /** @internal */ static const int32_t kMaxBranchLinearSubNodeLength=5; // Maximum number of nested split-branch levels for a branch on all 2^16 possible UChar units. // log2(2^16/kMaxBranchLinearSubNodeLength) rounded up. /** @internal */ static const int32_t kMaxSplitBranchLevels=14; /** * Makes sure that there is only one unique node registered that is * equivalent to newNode. * @param newNode Input node. The builder takes ownership. * @param errorCode ICU in/out UErrorCode. Set to U_MEMORY_ALLOCATION_ERROR if it was success but newNode==NULL. * @return newNode if it is the first of its kind, or * an equivalent node if newNode is a duplicate. * @internal */ Node *registerNode(Node *newNode, UErrorCode &errorCode); /** * Makes sure that there is only one unique FinalValueNode registered * with this value. * Avoids creating a node if the value is a duplicate. * @param value A final value. * @param errorCode ICU in/out UErrorCode. Set to U_MEMORY_ALLOCATION_ERROR if it was success but newNode==NULL. * @return A FinalValueNode with the given value. * @internal */ Node *registerFinalValue(int32_t value, UErrorCode &errorCode); /* * C++ note: * registerNode() and registerFinalValue() take ownership of their input nodes, * and only return owned nodes. * If they see a failure UErrorCode, they will delete the input node. * If they get a NULL pointer, they will record a U_MEMORY_ALLOCATION_ERROR. * If there is a failure, they return NULL. * * NULL Node pointers can be safely passed into other Nodes because * they call the static Node::hashCode() which checks for a NULL pointer first. * * Therefore, as long as builder functions register a new node, * they need to check for failures only before explicitly dereferencing * a Node pointer, or before setting a new UErrorCode. */ // Hash set of nodes, maps from nodes to integer 1. /** @internal */ UHashtable *nodes; /** @internal */ class Node : public UObject { public: Node(int32_t initialHash) : hash(initialHash), offset(0) {} inline int32_t hashCode() const { return hash; } // Handles node==NULL. static inline int32_t hashCode(const Node *node) { return node==NULL ? 0 : node->hashCode(); } // Base class operator==() compares the actual class types. virtual UBool operator==(const Node &other) const; inline UBool operator!=(const Node &other) const { return !operator==(other); } /** * Traverses the Node graph and numbers branch edges, with rightmost edges first. * This is to avoid writing a duplicate node twice. * * Branch nodes in this trie data structure are not symmetric. * Most branch edges "jump" to other nodes but the rightmost branch edges * just continue without a jump. * Therefore, write() must write the rightmost branch edge last * (trie units are written backwards), and must write it at that point even if * it is a duplicate of a node previously written elsewhere. * * This function visits and marks right branch edges first. * Edges are numbered with increasingly negative values because we share the * offset field which gets positive values when nodes are written. * A branch edge also remembers the first number for any of its edges. * * When a further-left branch edge has a number in the range of the rightmost * edge's numbers, then it will be written as part of the required right edge * and we can avoid writing it first. * * After root.markRightEdgesFirst(-1) the offsets of all nodes are negative * edge numbers. * * @param edgeNumber The first edge number for this node and its sub-nodes. * @return An edge number that is at least the maximum-negative * of the input edge number and the numbers of this node and all of its sub-nodes. */ virtual int32_t markRightEdgesFirst(int32_t edgeNumber); // write() must set the offset to a positive value. virtual void write(StringTrieBuilder &builder) = 0; // See markRightEdgesFirst. inline void writeUnlessInsideRightEdge(int32_t firstRight, int32_t lastRight, StringTrieBuilder &builder) { // Note: Edge numbers are negative, lastRight<=firstRight. // If offset>0 then this node and its sub-nodes have been written already // and we need not write them again. // If this node is part of the unwritten right branch edge, // then we wait until that is written. if(offset<0 && (offset<lastRight || firstRight<offset)) { write(builder); } } inline int32_t getOffset() const { return offset; } protected: int32_t hash; int32_t offset; private: // No ICU "poor man's RTTI" for this class nor its subclasses. virtual UClassID getDynamicClassID() const; }; // This class should not be overridden because // registerFinalValue() compares a stack-allocated FinalValueNode // (stack-allocated so that we don't unnecessarily create lots of duplicate nodes) // with the input node, and the // !Node::operator==(other) used inside FinalValueNode::operator==(other) // will be false if the typeid's are different. /** @internal */ class FinalValueNode : public Node { public: FinalValueNode(int32_t v) : Node(0x111111*37+v), value(v) {} virtual UBool operator==(const Node &other) const; virtual void write(StringTrieBuilder &builder); protected: int32_t value; }; /** @internal */ class ValueNode : public Node { public: ValueNode(int32_t initialHash) : Node(initialHash), hasValue(FALSE), value(0) {} virtual UBool operator==(const Node &other) const; void setValue(int32_t v) { hasValue=TRUE; value=v; hash=hash*37+v; } protected: UBool hasValue; int32_t value; }; /** @internal */ class IntermediateValueNode : public ValueNode { public: IntermediateValueNode(int32_t v, Node *nextNode) : ValueNode(0x222222*37+hashCode(nextNode)), next(nextNode) { setValue(v); } virtual UBool operator==(const Node &other) const; virtual int32_t markRightEdgesFirst(int32_t edgeNumber); virtual void write(StringTrieBuilder &builder); protected: Node *next; }; /** @internal */ class LinearMatchNode : public ValueNode { public: LinearMatchNode(int32_t len, Node *nextNode) : ValueNode((0x333333*37+len)*37+hashCode(nextNode)), length(len), next(nextNode) {} virtual UBool operator==(const Node &other) const; virtual int32_t markRightEdgesFirst(int32_t edgeNumber); protected: int32_t length; Node *next; }; /** @internal */ class BranchNode : public Node { public: BranchNode(int32_t initialHash) : Node(initialHash) {} protected: int32_t firstEdgeNumber; }; /** @internal */ class ListBranchNode : public BranchNode { public: ListBranchNode() : BranchNode(0x444444), length(0) {} virtual UBool operator==(const Node &other) const; virtual int32_t markRightEdgesFirst(int32_t edgeNumber); virtual void write(StringTrieBuilder &builder); // Adds a unit with a final value. void add(int32_t c, int32_t value) { units[length]=(UChar)c; equal[length]=NULL; values[length]=value; ++length; hash=(hash*37+c)*37+value; } // Adds a unit which leads to another match node. void add(int32_t c, Node *node) { units[length]=(UChar)c; equal[length]=node; values[length]=0; ++length; hash=(hash*37+c)*37+hashCode(node); } protected: Node *equal[kMaxBranchLinearSubNodeLength]; // NULL means "has final value". int32_t length; int32_t values[kMaxBranchLinearSubNodeLength]; UChar units[kMaxBranchLinearSubNodeLength]; }; /** @internal */ class SplitBranchNode : public BranchNode { public: SplitBranchNode(UChar middleUnit, Node *lessThanNode, Node *greaterOrEqualNode) : BranchNode(((0x555555*37+middleUnit)*37+ hashCode(lessThanNode))*37+hashCode(greaterOrEqualNode)), unit(middleUnit), lessThan(lessThanNode), greaterOrEqual(greaterOrEqualNode) {} virtual UBool operator==(const Node &other) const; virtual int32_t markRightEdgesFirst(int32_t edgeNumber); virtual void write(StringTrieBuilder &builder); protected: UChar unit; Node *lessThan; Node *greaterOrEqual; }; // Branch head node, for writing the actual node lead unit. /** @internal */ class BranchHeadNode : public ValueNode { public: BranchHeadNode(int32_t len, Node *subNode) : ValueNode((0x666666*37+len)*37+hashCode(subNode)), length(len), next(subNode) {} virtual UBool operator==(const Node &other) const; virtual int32_t markRightEdgesFirst(int32_t edgeNumber); virtual void write(StringTrieBuilder &builder); protected: int32_t length; Node *next; // A branch sub-node. }; /** @internal */ virtual Node *createLinearMatchNode(int32_t i, int32_t unitIndex, int32_t length, Node *nextNode) const = 0; /** @internal */ virtual int32_t write(int32_t unit) = 0; /** @internal */ virtual int32_t writeElementUnits(int32_t i, int32_t unitIndex, int32_t length) = 0; /** @internal */ virtual int32_t writeValueAndFinal(int32_t i, UBool isFinal) = 0; /** @internal */ virtual int32_t writeValueAndType(UBool hasValue, int32_t value, int32_t node) = 0; /** @internal */ virtual int32_t writeDeltaTo(int32_t jumpTarget) = 0; private: // No ICU "poor man's RTTI" for this class nor its subclasses. virtual UClassID getDynamicClassID() const; }; U_NAMESPACE_END #endif // __STRINGTRIEBUILDER_H__