Check in the pristine copy of ICU 51.2

icu51/source/common/unicode/ucharstrie.h

Index: icu51/source/common/unicode/ucharstrie.h
===================================================================
--- icu51/source/common/unicode/ucharstrie.h	(revision 0)
+++ icu51/source/common/unicode/ucharstrie.h	(revision 0)
@@ -0,0 +1,576 @@
+/*
+*******************************************************************************
+*   Copyright (C) 2010-2012, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*******************************************************************************
+*   file name:  ucharstrie.h
+*   encoding:   US-ASCII
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2010nov14
+*   created by: Markus W. Scherer
+*/
+
+#ifndef __UCHARSTRIE_H__
+#define __UCHARSTRIE_H__
+
+/**
+ * \file
+ * \brief C++ API: Trie for mapping Unicode strings (or 16-bit-unit sequences)
+ *                 to integer values.
+ */
+
+#include "unicode/utypes.h"
+#include "unicode/unistr.h"
+#include "unicode/uobject.h"
+#include "unicode/ustringtrie.h"
+
+U_NAMESPACE_BEGIN
+
+class Appendable;
+class UCharsTrieBuilder;
+class UVector32;
+
+/**
+ * Light-weight, non-const reader class for a UCharsTrie.
+ * Traverses a UChar-serialized data structure with minimal state,
+ * for mapping strings (16-bit-unit sequences) to non-negative integer values.
+ *
+ * This class owns the serialized trie data only if it was constructed by
+ * the builder's build() method.
+ * The public constructor and the copy constructor only alias the data (only copy the pointer).
+ * There is no assignment operator.
+ *
+ * This class is not intended for public subclassing.
+ * @stable ICU 4.8
+ */
+class U_COMMON_API UCharsTrie : public UMemory {
+public:
+    /**
+     * Constructs a UCharsTrie reader instance.
+     *
+     * The trieUChars must contain a copy of a UChar sequence from the UCharsTrieBuilder,
+     * starting with the first UChar of that sequence.
+     * The UCharsTrie object will not read more UChars than
+     * the UCharsTrieBuilder generated in the corresponding build() call.
+     *
+     * The array is not copied/cloned and must not be modified while
+     * the UCharsTrie object is in use.
+     *
+     * @param trieUChars The UChar array that contains the serialized trie.
+     * @stable ICU 4.8
+     */
+    UCharsTrie(const UChar *trieUChars)
+            : ownedArray_(NULL), uchars_(trieUChars),
+              pos_(uchars_), remainingMatchLength_(-1) {}
+
+    /**
+     * Destructor.
+     * @stable ICU 4.8
+     */
+    ~UCharsTrie();
+
+    /**
+     * Copy constructor, copies the other trie reader object and its state,
+     * but not the UChar array which will be shared. (Shallow copy.)
+     * @param other Another UCharsTrie object.
+     * @stable ICU 4.8
+     */
+    UCharsTrie(const UCharsTrie &other)
+            : ownedArray_(NULL), uchars_(other.uchars_),
+              pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
+
+    /**
+     * Resets this trie to its initial state.
+     * @return *this
+     * @stable ICU 4.8
+     */
+    UCharsTrie &reset() {
+        pos_=uchars_;
+        remainingMatchLength_=-1;
+        return *this;
+    }
+
+    /**
+     * UCharsTrie state object, for saving a trie's current state
+     * and resetting the trie back to this state later.
+     * @stable ICU 4.8
+     */
+    class State : public UMemory {
+    public:
+        /**
+         * Constructs an empty State.
+         * @stable ICU 4.8
+         */
+        State() { uchars=NULL; }
+    private:
+        friend class UCharsTrie;
+
+        const UChar *uchars;
+        const UChar *pos;
+        int32_t remainingMatchLength;
+    };
+
+    /**
+     * Saves the state of this trie.
+     * @param state The State object to hold the trie's state.
+     * @return *this
+     * @see resetToState
+     * @stable ICU 4.8
+     */
+    const UCharsTrie &saveState(State &state) const {
+        state.uchars=uchars_;
+        state.pos=pos_;
+        state.remainingMatchLength=remainingMatchLength_;
+        return *this;
+    }
+
+    /**
+     * Resets this trie to the saved state.
+     * If the state object contains no state, or the state of a different trie,
+     * then this trie remains unchanged.
+     * @param state The State object which holds a saved trie state.
+     * @return *this
+     * @see saveState
+     * @see reset
+     * @stable ICU 4.8
+     */
+    UCharsTrie &resetToState(const State &state) {
+        if(uchars_==state.uchars && uchars_!=NULL) {
+            pos_=state.pos;
+            remainingMatchLength_=state.remainingMatchLength;
+        }
+        return *this;
+    }
+
+    /**
+     * Determines whether the string so far matches, whether it has a value,
+     * and whether another input UChar can continue a matching string.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    UStringTrieResult current() const;
+
+    /**
+     * Traverses the trie from the initial state for this input UChar.
+     * Equivalent to reset().next(uchar).
+     * @param uchar Input char value. Values below 0 and above 0xffff will never match.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    inline UStringTrieResult first(int32_t uchar) {
+        remainingMatchLength_=-1;
+        return nextImpl(uchars_, uchar);
+    }
+
+    /**
+     * Traverses the trie from the initial state for the
+     * one or two UTF-16 code units for this input code point.
+     * Equivalent to reset().nextForCodePoint(cp).
+     * @param cp A Unicode code point 0..0x10ffff.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    UStringTrieResult firstForCodePoint(UChar32 cp);
+
+    /**
+     * Traverses the trie from the current state for this input UChar.
+     * @param uchar Input char value. Values below 0 and above 0xffff will never match.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    UStringTrieResult next(int32_t uchar);
+
+    /**
+     * Traverses the trie from the current state for the
+     * one or two UTF-16 code units for this input code point.
+     * @param cp A Unicode code point 0..0x10ffff.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    UStringTrieResult nextForCodePoint(UChar32 cp);
+
+    /**
+     * Traverses the trie from the current state for this string.
+     * Equivalent to
+     * \code
+     * Result result=current();
+     * for(each c in s)
+     *   if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH;
+     *   result=next(c);
+     * return result;
+     * \endcode
+     * @param s A string. Can be NULL if length is 0.
+     * @param length The length of the string. Can be -1 if NUL-terminated.
+     * @return The match/value Result.
+     * @stable ICU 4.8
+     */
+    UStringTrieResult next(const UChar *s, int32_t length);
+
+    /**
+     * Returns a matching string's value if called immediately after
+     * current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE.
+     * getValue() can be called multiple times.
+     *
+     * Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE!
+     * @return The value for the string so far.
+     * @stable ICU 4.8
+     */
+    inline int32_t getValue() const {
+        const UChar *pos=pos_;
+        int32_t leadUnit=*pos++;
+        // U_ASSERT(leadUnit>=kMinValueLead);
+        return leadUnit&kValueIsFinal ?
+            readValue(pos, leadUnit&0x7fff) : readNodeValue(pos, leadUnit);
+    }
+
+    /**
+     * Determines whether all strings reachable from the current state
+     * map to the same value.
+     * @param uniqueValue Receives the unique value, if this function returns TRUE.
+     *                    (output-only)
+     * @return TRUE if all strings reachable from the current state
+     *         map to the same value.
+     * @stable ICU 4.8
+     */
+    inline UBool hasUniqueValue(int32_t &uniqueValue) const {
+        const UChar *pos=pos_;
+        // Skip the rest of a pending linear-match node.
+        return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, FALSE, uniqueValue);
+    }
+
+    /**
+     * Finds each UChar which continues the string from the current state.
+     * That is, each UChar c for which it would be next(c)!=USTRINGTRIE_NO_MATCH now.
+     * @param out Each next UChar is appended to this object.
+     * @return the number of UChars which continue the string from here
+     * @stable ICU 4.8
+     */
+    int32_t getNextUChars(Appendable &out) const;
+
+    /**
+     * Iterator for all of the (string, value) pairs in a UCharsTrie.
+     * @stable ICU 4.8
+     */
+    class U_COMMON_API Iterator : public UMemory {
+    public:
+        /**
+         * Iterates from the root of a UChar-serialized UCharsTrie.
+         * @param trieUChars The trie UChars.
+         * @param maxStringLength If 0, the iterator returns full strings.
+         *                        Otherwise, the iterator returns strings with this maximum length.
+         * @param errorCode Standard ICU error code. Its input value must
+         *                  pass the U_SUCCESS() test, or else the function returns
+         *                  immediately. Check for U_FAILURE() on output or use with
+         *                  function chaining. (See User Guide for details.)
+         * @stable ICU 4.8
+         */
+        Iterator(const UChar *trieUChars, int32_t maxStringLength, UErrorCode &errorCode);
+
+        /**
+         * Iterates from the current state of the specified UCharsTrie.
+         * @param trie The trie whose state will be copied for iteration.
+         * @param maxStringLength If 0, the iterator returns full strings.
+         *                        Otherwise, the iterator returns strings with this maximum length.
+         * @param errorCode Standard ICU error code. Its input value must
+         *                  pass the U_SUCCESS() test, or else the function returns
+         *                  immediately. Check for U_FAILURE() on output or use with
+         *                  function chaining. (See User Guide for details.)
+         * @stable ICU 4.8
+         */
+        Iterator(const UCharsTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
+
+        /**
+         * Destructor.
+         * @stable ICU 4.8
+         */
+        ~Iterator();
+
+        /**
+         * Resets this iterator to its initial state.
+         * @return *this
+         * @stable ICU 4.8
+         */
+        Iterator &reset();
+
+        /**
+         * @return TRUE if there are more elements.
+         * @stable ICU 4.8
+         */
+        UBool hasNext() const;
+
+        /**
+         * Finds the next (string, value) pair if there is one.
+         *
+         * If the string is truncated to the maximum length and does not
+         * have a real value, then the value is set to -1.
+         * In this case, this "not a real value" is indistinguishable from
+         * a real value of -1.
+         * @param errorCode Standard ICU error code. Its input value must
+         *                  pass the U_SUCCESS() test, or else the function returns
+         *                  immediately. Check for U_FAILURE() on output or use with
+         *                  function chaining. (See User Guide for details.)
+         * @return TRUE if there is another element.
+         * @stable ICU 4.8
+         */
+        UBool next(UErrorCode &errorCode);
+
+        /**
+         * @return The string for the last successful next().
+         * @stable ICU 4.8
+         */
+        const UnicodeString &getString() const { return str_; }
+        /**
+         * @return The value for the last successful next().
+         * @stable ICU 4.8
+         */
+        int32_t getValue() const { return value_; }
+
+    private:
+        UBool truncateAndStop() {
+            pos_=NULL;
+            value_=-1;  // no real value for str
+            return TRUE;
+        }
+
+        const UChar *branchNext(const UChar *pos, int32_t length, UErrorCode &errorCode);
+
+        const UChar *uchars_;
+        const UChar *pos_;
+        const UChar *initialPos_;
+        int32_t remainingMatchLength_;
+        int32_t initialRemainingMatchLength_;
+        UBool skipValue_;  // Skip intermediate value which was already delivered.
+
+        UnicodeString str_;
+        int32_t maxLength_;
+        int32_t value_;
+
+        // The stack stores pairs of integers for backtracking to another
+        // outbound edge of a branch node.
+        // The first integer is an offset from uchars_.
+        // The second integer has the str_.length() from before the node in bits 15..0,
+        // and the remaining branch length in bits 31..16.
+        // (We could store the remaining branch length minus 1 in bits 30..16 and not use the sign bit,
+        // but the code looks more confusing that way.)
+        UVector32 *stack_;
+    };
+
+private:
+    friend class UCharsTrieBuilder;
+
+    /**
+     * Constructs a UCharsTrie reader instance.
+     * Unlike the public constructor which just aliases an array,
+     * this constructor adopts the builder's array.
+     * This constructor is only called by the builder.
+     */
+    UCharsTrie(UChar *adoptUChars, const UChar *trieUChars)
+            : ownedArray_(adoptUChars), uchars_(trieUChars),
+              pos_(uchars_), remainingMatchLength_(-1) {}
+
+    // No assignment operator.
+    UCharsTrie &operator=(const UCharsTrie &other);
+
+    inline void stop() {
+        pos_=NULL;
+    }
+
+    // Reads a compact 32-bit integer.
+    // pos is already after the leadUnit, and the lead unit has bit 15 reset.
+    static inline int32_t readValue(const UChar *pos, int32_t leadUnit) {
+        int32_t value;
+        if(leadUnit<kMinTwoUnitValueLead) {
+            value=leadUnit;
+        } else if(leadUnit<kThreeUnitValueLead) {
+            value=((leadUnit-kMinTwoUnitValueLead)<<16)|*pos;
+        } else {
+            value=(pos[0]<<16)|pos[1];
+        }
+        return value;
+    }
+    static inline const UChar *skipValue(const UChar *pos, int32_t leadUnit) {
+        if(leadUnit>=kMinTwoUnitValueLead) {
+            if(leadUnit<kThreeUnitValueLead) {
+                ++pos;
+            } else {
+                pos+=2;
+            }
+        }
+        return pos;
+    }
+    static inline const UChar *skipValue(const UChar *pos) {
+        int32_t leadUnit=*pos++;
+        return skipValue(pos, leadUnit&0x7fff);
+    }
+
+    static inline int32_t readNodeValue(const UChar *pos, int32_t leadUnit) {
+        // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
+        int32_t value;
+        if(leadUnit<kMinTwoUnitNodeValueLead) {
+            value=(leadUnit>>6)-1;
+        } else if(leadUnit<kThreeUnitNodeValueLead) {
+            value=(((leadUnit&0x7fc0)-kMinTwoUnitNodeValueLead)<<10)|*pos;
+        } else {
+            value=(pos[0]<<16)|pos[1];
+        }
+        return value;
+    }
+    static inline const UChar *skipNodeValue(const UChar *pos, int32_t leadUnit) {
+        // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
+        if(leadUnit>=kMinTwoUnitNodeValueLead) {
+            if(leadUnit<kThreeUnitNodeValueLead) {
+                ++pos;
+            } else {
+                pos+=2;
+            }
+        }
+        return pos;
+    }
+
+    static inline const UChar *jumpByDelta(const UChar *pos) {
+        int32_t delta=*pos++;
+        if(delta>=kMinTwoUnitDeltaLead) {
+            if(delta==kThreeUnitDeltaLead) {
+                delta=(pos[0]<<16)|pos[1];
+                pos+=2;
+            } else {
+                delta=((delta-kMinTwoUnitDeltaLead)<<16)|*pos++;
+            }
+        }
+        return pos+delta;
+    }
+
+    static const UChar *skipDelta(const UChar *pos) {
+        int32_t delta=*pos++;
+        if(delta>=kMinTwoUnitDeltaLead) {
+            if(delta==kThreeUnitDeltaLead) {
+                pos+=2;
+            } else {
+                ++pos;
+            }
+        }
+        return pos;
+    }
+
+    static inline UStringTrieResult valueResult(int32_t node) {
+        return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node>>15));
+    }
+
+    // Handles a branch node for both next(uchar) and next(string).
+    UStringTrieResult branchNext(const UChar *pos, int32_t length, int32_t uchar);
+
+    // Requires remainingLength_<0.
+    UStringTrieResult nextImpl(const UChar *pos, int32_t uchar);
+
+    // Helper functions for hasUniqueValue().
+    // Recursively finds a unique value (or whether there is not a unique one)
+    // from a branch.
+    static const UChar *findUniqueValueFromBranch(const UChar *pos, int32_t length,
+                                                  UBool haveUniqueValue, int32_t &uniqueValue);
+    // Recursively finds a unique value (or whether there is not a unique one)
+    // starting from a position on a node lead unit.
+    static UBool findUniqueValue(const UChar *pos, UBool haveUniqueValue, int32_t &uniqueValue);
+
+    // Helper functions for getNextUChars().
+    // getNextUChars() when pos is on a branch node.
+    static void getNextBranchUChars(const UChar *pos, int32_t length, Appendable &out);
+
+    // UCharsTrie data structure
+    //
+    // The trie consists of a series of UChar-serialized nodes for incremental
+    // Unicode string/UChar sequence matching. (UChar=16-bit unsigned integer)
+    // The root node is at the beginning of the trie data.
+    //
+    // Types of nodes are distinguished by their node lead unit ranges.
+    // After each node, except a final-value node, another node follows to
+    // encode match values or continue matching further units.
+    //
+    // Node types:
+    //  - Final-value node: Stores a 32-bit integer in a compact, variable-length format.
+    //    The value is for the string/UChar sequence so far.
+    //  - Match node, optionally with an intermediate value in a different compact format.
+    //    The value, if present, is for the string/UChar sequence so far.
+    //
+    //  Aside from the value, which uses the node lead unit's high bits:
+    //
+    //  - Linear-match node: Matches a number of units.
+    //  - Branch node: Branches to other nodes according to the current input unit.
+    //    The node unit is the length of the branch (number of units to select from)
+    //    minus 1. It is followed by a sub-node:
+    //    - If the length is at most kMaxBranchLinearSubNodeLength, then
+    //      there are length-1 (key, value) pairs and then one more comparison unit.
+    //      If one of the key units matches, then the value is either a final value for
+    //      the string so far, or a "jump" delta to the next node.
+    //      If the last unit matches, then matching continues with the next node.
+    //      (Values have the same encoding as final-value nodes.)
+    //    - If the length is greater than kMaxBranchLinearSubNodeLength, then
+    //      there is one unit and one "jump" delta.
+    //      If the input unit is less than the sub-node unit, then "jump" by delta to
+    //      the next sub-node which will have a length of length/2.
+    //      (The delta has its own compact encoding.)
+    //      Otherwise, skip the "jump" delta to the next sub-node
+    //      which will have a length of length-length/2.
+
+    // Match-node lead unit values, after masking off intermediate-value bits:
+
+    // 0000..002f: Branch node. If node!=0 then the length is node+1, otherwise
+    // the length is one more than the next unit.
+
+    // For a branch sub-node with at most this many entries, we drop down
+    // to a linear search.
+    static const int32_t kMaxBranchLinearSubNodeLength=5;
+
+    // 0030..003f: Linear-match node, match 1..16 units and continue reading the next node.
+    static const int32_t kMinLinearMatch=0x30;
+    static const int32_t kMaxLinearMatchLength=0x10;
+
+    // Match-node lead unit bits 14..6 for the optional intermediate value.
+    // If these bits are 0, then there is no intermediate value.
+    // Otherwise, see the *NodeValue* constants below.
+    static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength;  // 0x0040
+    static const int32_t kNodeTypeMask=kMinValueLead-1;  // 0x003f
+
+    // A final-value node has bit 15 set.
+    static const int32_t kValueIsFinal=0x8000;
+
+    // Compact value: After testing and masking off bit 15, use the following thresholds.
+    static const int32_t kMaxOneUnitValue=0x3fff;
+
+    static const int32_t kMinTwoUnitValueLead=kMaxOneUnitValue+1;  // 0x4000
+    static const int32_t kThreeUnitValueLead=0x7fff;
+
+    static const int32_t kMaxTwoUnitValue=((kThreeUnitValueLead-kMinTwoUnitValueLead)<<16)-1;  // 0x3ffeffff
+
+    // Compact intermediate-value integer, lead unit shared with a branch or linear-match node.
+    static const int32_t kMaxOneUnitNodeValue=0xff;
+    static const int32_t kMinTwoUnitNodeValueLead=kMinValueLead+((kMaxOneUnitNodeValue+1)<<6);  // 0x4040
+    static const int32_t kThreeUnitNodeValueLead=0x7fc0;
+
+    static const int32_t kMaxTwoUnitNodeValue=
+        ((kThreeUnitNodeValueLead-kMinTwoUnitNodeValueLead)<<10)-1;  // 0xfdffff
+
+    // Compact delta integers.
+    static const int32_t kMaxOneUnitDelta=0xfbff;
+    static const int32_t kMinTwoUnitDeltaLead=kMaxOneUnitDelta+1;  // 0xfc00
+    static const int32_t kThreeUnitDeltaLead=0xffff;
+
+    static const int32_t kMaxTwoUnitDelta=((kThreeUnitDeltaLead-kMinTwoUnitDeltaLead)<<16)-1;  // 0x03feffff
+
+    UChar *ownedArray_;
+
+    // Fixed value referencing the UCharsTrie words.
+    const UChar *uchars_;
+
+    // Iterator variables.
+
+    // Pointer to next trie unit to read. NULL if no more matches.
+    const UChar *pos_;
+    // Remaining length of a linear-match node, minus 1. Negative if not in such a node.
+    int32_t remainingMatchLength_;
+};
+
+U_NAMESPACE_END
+
+#endif  // __UCHARSTRIE_H__
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