262 lines
12 KiB
C
262 lines
12 KiB
C
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#ifndef TRIE_H
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#define TRIE_H
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#include <windows.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Abstract trie node structure. wch is a character to transition on; flags describe various things
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about the compressed trie; lpbNode points to the first byte of the next node in this state, and
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lpbDown points to the first byte referenced by the down pointer, if any */
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typedef struct tagTAGDATA
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{
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DWORD cTag; // Count of tagged nodes below this node in the subtree
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DWORD dwData; // Stored tagged data for this node
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} TAGDATA;
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#define MAXTAGS 8
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#if MAXTAGS > 8
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#error No more than 8 tags are allowed
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#endif
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typedef struct tagTRIESCAN
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{
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WCHAR wch; // Unicode character
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WORD wFlags; // see below
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WORD wMask; // which tags are valid
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WORD __pad0; //
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DWORD cWords; // Words in subtree (only valid if TRIE_NODE_COUNT is set)
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DWORD cSkipWords; // Words in subtrees ignored when following a skip pointer
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LPBYTE lpbNode; // Address of next byte within the compressed trie
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LPBYTE lpbDown; // Address referenced by down pointer, if any
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LPBYTE lpbRight; // Address referenced by right pointer, if any
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LPBYTE lpbSRDown; // Last single-ref address referenced
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TAGDATA aTags[MAXTAGS]; // The list of tag counts/data
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} TRIESCAN, *PTRIESCAN, *LPTRIESCAN;
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// Trie node flags, only the lower 16 bits of the flags are saved in the trie
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#define TRIE_NODE_VALID 0x00000001 // wch is the last letter of a valid word
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#define TRIE_NODE_END 0x00000002 // Last node in the state (no more alternatives to wch)
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#define TRIE_NODE_COUNT 0x00000004 // The count of words in the subtree is stored in the node
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#define TRIE_NODE_TAGGED 0x00000008 // The node has tagged data
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#define TRIE_NODE_DOWN 0x00000010 // iDown is valid (word so far is a valid prefix)
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#define TRIE_NODE_RIGHT 0x00000020 // iRight is valid (word connects to a substate)
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#define TRIE_DOWN_INLINE 0x00000040 // iDown omitted, since it points to next node in memory
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#define TRIE_DOWN_MULTI 0x00000080 // iDown is a second reference or worse
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#define TRIE_DOWN_ABS 0x00000100 // iDown is an absolute immediate offset into the trie
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#define TRIE_NODE_SKIP 0x00000200 // Either iRight is a skip pointer or EOS is a 'soft' EOS
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#define TRIE_NODE_SKIP_COUNT 0x00000400 // cSkipWords is valid
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/* Macro to access the data in the node, works for dawgs and tries */
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#define DAWGDATA(pdawg) ((pdawg)->wch)
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#define DAWGDOWNFLAG(pdawg) ((pdawg)->wFlags & TRIE_NODE_DOWN)
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#define DAWGENDFLAG(pdawg) ((pdawg)->wFlags & TRIE_NODE_END)
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#define DAWGWORDFLAG(pdawg) ((pdawg)->wFlags & TRIE_NODE_VALID)
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/* Fixed-length part of the compressed trie header */
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typedef struct tagTRIESTATS
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{
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WORD version; // Version of this particular compressed trie
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WORD __pad0; //
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BYTE wTagsMask; // Which tags are in use
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BYTE wEnumMask; // Which tags have enumeration
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BYTE wDataMask; // Which tags have stored data
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BYTE cTagFields; // Total tags in use
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WORD cMaxWord; // Number of characters in longest word
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WORD cMaxState; // Number of nodes in longest state (max alternatives)
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WORD cCharFlagsCodesMax; // Bytes in longest char/flags code
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WORD cTagsCodesMax; // Bytes in longest tagged data code
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WORD cMRPointersCodesMax; // Bytes in longest MR pointer code
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WORD cSROffsetsCodesMax; // Bytes in longest Single-ref code
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DWORD cWords; // Number of words in dictionary
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DWORD cUniqueSROffsets; // Unique offsets in Single-ref segment
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DWORD cUniqueCharFlags; // Unique char/flags pairs
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DWORD cUniqueTags; // Unique tagged data values
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DWORD cUniqueMRPointers; // Unique multi-ref pointers
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DWORD cbHeader; // Bytes in header & tables
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DWORD cbTrie; // Bytes in trie
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} TRIESTATS, *PTRIESTATS, *LPTRIESTATS;
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/* Primary unit of a node. Nodes usually contain a pointer too */
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typedef struct tagCHARFLAGS {
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wchar_t wch;
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short wFlags;
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} CHARFLAGS, *PCHARFLAGS, *LPCHARFLAGS;
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/* Control structure used to decompress the trie */
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typedef struct tagTRIECTRL
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{
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TRIESTATS *lpTrieStats; // Pointer to base of header segment
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WORD *lpwCharFlagsCodes; // decoding table for Char/flags
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WORD *lpwTagsCodes; // decoding table for tagged data
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WORD *lpwMRPointersCodes; // decoding table for multiref pointers
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WORD *lpwSROffsetsCodes; // decoding table for singleref offsets
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CHARFLAGS *lpCharFlags; // table to convert codes to char/flags
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DWORD *lpwTags; // table to convert codes to tagged data
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DWORD *lpwMRPointers; // table to convert codes to multiref pointers
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DWORD *lpwSROffsets; // table to convert codes to Singleref offsets
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BYTE *lpbTrie; // Pointer to the trie.
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} TRIECTRL, *PTRIECTRL, *LPTRIECTRL;
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/* Useful Constants */
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#define TRIE_MAX_DEPTH 128 // We'll fail on any words longer than this
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// The prototypes below are plain C (this is required for use with C++)
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/* Given a pointer to a mapped file or resource containing a compressed trie,
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read the trie into memory, making all the allocations required */
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TRIECTRL * WINAPI TrieInit(LPBYTE lpByte);
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/* Free all the allocations associated with a trie */
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void WINAPI TrieFree(LPTRIECTRL lpTrieCtrl);
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void WINAPI TrieDecompressNode(LPTRIECTRL lpTrieCtrl, LPTRIESCAN lpTrieScan);
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/* Given a compressed trie and a pointer to a decompresed node from it, find and decompress
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the next node in the same state. lpTrieScan is a user-allocated structure that holds the
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decompressed node and into which the new node is copied.
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This is equivalent to traversing a right pointer or finding the next alternative
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letter at the same position. If there is no next node (i.e.this is the end of the state)
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then TrieGetNextNode returns FALSE. To scan from the beginning of the trie, set the lpTrieScan
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structure to zero */
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BOOL WINAPI
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TrieGetNextNode(LPTRIECTRL lpTrieCtrl, LPTRIESCAN lpTrieScan);
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BOOL WINAPI
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TrieSkipNextNode(LPTRIECTRL lpTrieCtrl, LPTRIESCAN lpTrieScan, WCHAR wch);
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/* Follow the down pointer to the next state. This is equivalent to accepting the character
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in this node and advancing to the next character position. Returns FALSE if there is no
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down pointer. This also decompresses the first node in the state, so all the values in
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lpTrieScan will be good. */
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BOOL WINAPI
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TrieGetNextState(LPTRIECTRL lpTrieCtrl, LPTRIESCAN lpTrieScan);
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/* Check the validity of a word or prefix. Starts from the root of pTrie looking for
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pwszWord. If it finds it, it returns TRUE and the user-provided lpTrieScan structure
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contains the final node in the word. If there is no path, TrieCheckWord returns FALSE
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To distinguisha valid word from a valid prefix, caller must test
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wFlags for fTrieNodeValid. */
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BOOL WINAPI
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TrieCheckWord(LPTRIECTRL lpTrieCtrl, LPTRIESCAN lpTrieScan, wchar_t * lpwszWord);
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int WINAPI
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TrieWordToIndex(
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TRIECTRL *ptc, // Trie in which to find word index
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wchar_t *pwszWord // Word for which we're looking
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);
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BOOL WINAPI
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TrieIndexToWord(
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TRIECTRL *ptc, // Trie in which to find indexed word
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DWORD nIndex, // Index for which we're looking
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wchar_t *pwszWord, // Returned word
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int cwc // Max characters in buffer (including NULL)
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);
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int WINAPI
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TrieWordToTagIndex(
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TRIECTRL *ptc, // Trie in which to find word index
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wchar_t *pwszWord, // Word for which we're looking
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int tag // Which tag to enumerate
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);
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BOOL WINAPI
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TrieTagIndexToWord(
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TRIECTRL *ptc, // Trie in which to find indexed word
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DWORD nIndex, // Index for which we're looking
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wchar_t *pwszWord, // Returned word
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int cwc, // Max characters in buffer (including NULL)
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int tag // Which tag to enumerate
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);
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BOOL WINAPI
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TrieGetTagsFromWord(
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TRIECTRL *ptc, // Trie in which to find word
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wchar_t *pwszWord, // Word for which we're looking
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DWORD *pdw, // Returned values
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BYTE *pbValid // Mask for valid return values
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);
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int WINAPI
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TriePrefixToRange(
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TRIECTRL *ptc, // Trie in which to find prefix range
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wchar_t *pwszWord, // Prefix for which we're looking
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int *piStart // Start of range with this prefix
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);
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/**** Subroutines for traversing Directed Acyclic Word Graphs ****/
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/* Abstract trie node structure. wch is a character to transition on; flags describe various things
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about the compressed trie; iDown indexes the first node in the state wch transitions to. DAWG is a special
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kind of trie: a "Directed Acyclic Word Graph," essentially an ending-compressed trie. */
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typedef struct tagDAWGNODE
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{
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DWORD wch; // Unicode character
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DWORD wFlags; // see below
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DWORD cWords; // Words below this node in the subtree
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DWORD cSkipWords; // Words below skipped nodes
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DWORD iDown; // Offset of first node in next state
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DWORD iRight; // Offset to first node in next substate
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DWORD cTags[8]; // Count of tagged nodes below this node in the subtree
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DWORD dwData[8]; // Stored tagged data for this node
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} DAWGNODE, *PDAWGNODE, *LPDAWGNODE;
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/* Given a trie and a pointer to a node in it, find the next node in that state.
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This is equivalent to traversing a right pointer or finding the next alternative
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letter at the same position. Returns a pointer to the new node, NULL if there is
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no next node (i.e. if this is the end of a state).*/
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DAWGNODE * WINAPI DawgGetNextNode(void *pTrie, DAWGNODE *pTrieNode);
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/* From this node, find the first node in the state it points to. This is equivalent
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to traversing a down pointer or extending the word one letter and finding the first
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alternative. Returns a pointer to the first node in the new state, NULL if there is
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no down pointer. To find the first state in the trie, use pTrieNode == NULL */
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DAWGNODE * WINAPI DawgGetNextState(void *pTrie, DAWGNODE *pTrieNode);
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/* Check the validity of a word or prefix. Starts from the root of pTrie looking for
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pwszWord. If it finds it, it returns a pointer to the terminal node in pTrie Returns
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NULL if there is no path through the trie that corresponds to pwszWord. To distinguish
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a valid word from a valid prefix, caller must test wFlags for fTrieNodeValid. */
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DAWGNODE * WINAPI DawgCheckWord(void *pTrie, wchar_t *pwszWord);
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/* Walk the trie from pTrieNode, calling pfnTrieWord on every valid word. pvParam is passed through
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to pfnTrieWord. If pfnTrieWord returns non-zero, the enumeration stops. pwszWord must point to a
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space of cwchTrieWordMax+1 wchar_t's. To walk the entire trie, pass NULL for pTrieNode. Returns
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the number of words traversed. pfnTrieWord may be null if all you want is the count of words. */
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int WINAPI
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DawgEnumerate(
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void *pTrie, // Trie to enumerate
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DAWGNODE *pTrieNodeStart, // point to enumerate from, NULL if all
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wchar_t *pwszWord, // buffer to hold words being enumerated
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void *pvParam, // parameter to pass to pfnTrieWord
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int (*pfnTrieWord)(wchar_t *pwszWord, void *pvParam)
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);
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// end plain C Prototypes
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#ifdef __cplusplus
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}
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#endif
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#endif // TRIE_H
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