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Diffstat (limited to 'chromium/third_party/sqlite/sqlite-src-3240000/ext/misc/amatch.c')
| -rw-r--r-- | chromium/third_party/sqlite/sqlite-src-3240000/ext/misc/amatch.c | 1499 |
1 files changed, 0 insertions, 1499 deletions
diff --git a/chromium/third_party/sqlite/sqlite-src-3240000/ext/misc/amatch.c b/chromium/third_party/sqlite/sqlite-src-3240000/ext/misc/amatch.c deleted file mode 100644 index 914e2633d4b..00000000000 --- a/chromium/third_party/sqlite/sqlite-src-3240000/ext/misc/amatch.c +++ /dev/null @@ -1,1499 +0,0 @@ -/* -** 2013-03-14 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** -** This file contains code for a demonstration virtual table that finds -** "approximate matches" - strings from a finite set that are nearly the -** same as a single input string. The virtual table is called "amatch". -** -** A amatch virtual table is created like this: -** -** CREATE VIRTUAL TABLE f USING approximate_match( -** vocabulary_table=<tablename>, -- V -** vocabulary_word=<columnname>, -- W -** vocabulary_language=<columnname>, -- L -** edit_distances=<edit-cost-table> -** ); -** -** When it is created, the new amatch table must be supplied with the -** the name of a table V and columns V.W and V.L such that -** -** SELECT W FROM V WHERE L=$language -** -** returns the allowed vocabulary for the match. If the "vocabulary_language" -** or L columnname is left unspecified or is an empty string, then no -** filtering of the vocabulary by language is performed. -** -** For efficiency, it is essential that the vocabulary table be indexed: -** -** CREATE vocab_index ON V(W) -** -** A separate edit-cost-table provides scoring information that defines -** what it means for one string to be "close" to another. -** -** The edit-cost-table must contain exactly four columns (more precisely, -** the statement "SELECT * FROM <edit-cost-table>" must return records -** that consist of four columns). It does not matter what the columns are -** named. -** -** Each row in the edit-cost-table represents a single character -** transformation going from user input to the vocabulary. The leftmost -** column of the row (column 0) contains an integer identifier of the -** language to which the transformation rule belongs (see "MULTIPLE LANGUAGES" -** below). The second column of the row (column 1) contains the input -** character or characters - the characters of user input. The third -** column contains characters as they appear in the vocabulary table. -** And the fourth column contains the integer cost of making the -** transformation. For example: -** -** CREATE TABLE f_data(iLang, cFrom, cTo, Cost); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '', 'a', 100); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'b', '', 87); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'o', 'oe', 38); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, 'oe', 'o', 40); -** -** The first row inserted into the edit-cost-table by the SQL script -** above indicates that the cost of having an extra 'a' in the vocabulary -** table that is missing in the user input 100. (All costs are integers. -** Overall cost must not exceed 16777216.) The second INSERT statement -** creates a rule saying that the cost of having a single letter 'b' in -** user input which is missing in the vocabulary table is 87. The third -** INSERT statement mean that the cost of matching an 'o' in user input -** against an 'oe' in the vocabulary table is 38. And so forth. -** -** The following rules are special: -** -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '?', '', 97); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '', '?', 98); -** INSERT INTO f_data(iLang, cFrom, cTo, Cost) VALUES(0, '?', '?', 99); -** -** The '?' to '' rule is the cost of having any single character in the input -** that is not found in the vocabular. The '' to '?' rule is the cost of -** having a character in the vocabulary table that is missing from input. -** And the '?' to '?' rule is the cost of doing an arbitrary character -** substitution. These three generic rules apply across all languages. -** In other words, the iLang field is ignored for the generic substitution -** rules. If more than one cost is given for a generic substitution rule, -** then the lowest cost is used. -** -** Once it has been created, the amatch virtual table can be queried -** as follows: -** -** SELECT word, distance FROM f -** WHERE word MATCH 'abcdefg' -** AND distance<200; -** -** This query outputs the strings contained in the T(F) field that -** are close to "abcdefg" and in order of increasing distance. No string -** is output more than once. If there are multiple ways to transform the -** target string ("abcdefg") into a string in the vocabulary table then -** the lowest cost transform is the one that is returned. In this example, -** the search is limited to strings with a total distance of less than 200. -** -** For efficiency, it is important to put tight bounds on the distance. -** The time and memory space needed to perform this query is exponential -** in the maximum distance. A good rule of thumb is to limit the distance -** to no more than 1.5 or 2 times the maximum cost of any rule in the -** edit-cost-table. -** -** The amatch is a read-only table. Any attempt to DELETE, INSERT, or -** UPDATE on a amatch table will throw an error. -** -** It is important to put some kind of a limit on the amatch output. This -** can be either in the form of a LIMIT clause at the end of the query, -** or better, a "distance<NNN" constraint where NNN is some number. The -** running time and memory requirement is exponential in the value of NNN -** so you want to make sure that NNN is not too big. A value of NNN that -** is about twice the average transformation cost seems to give good results. -** -** The amatch table can be useful for tasks such as spelling correction. -** Suppose all allowed words are in table vocabulary(w). Then one would create -** an amatch virtual table like this: -** -** CREATE VIRTUAL TABLE ex1 USING amatch( -** vocabtable=vocabulary, -** vocabcolumn=w, -** edit_distances=ec1 -** ); -** -** Then given an input word $word, look up close spellings this way: -** -** SELECT word, distance FROM ex1 -** WHERE word MATCH $word AND distance<200; -** -** MULTIPLE LANGUAGES -** -** Normally, the "iLang" value associated with all character transformations -** in the edit-cost-table is zero. However, if required, the amatch -** virtual table allows multiple languages to be defined. Each query uses -** only a single iLang value. This allows, for example, a single -** amatch table to support multiple languages. -** -** By default, only the rules with iLang=0 are used. To specify an -** alternative language, a "language = ?" expression must be added to the -** WHERE clause of a SELECT, where ? is the integer identifier of the desired -** language. For example: -** -** SELECT word, distance FROM ex1 -** WHERE word MATCH $word -** AND distance<=200 -** AND language=1 -- Specify use language 1 instead of 0 -** -** If no "language = ?" constraint is specified in the WHERE clause, language -** 0 is used. -** -** LIMITS -** -** The maximum language number is 2147483647. The maximum length of either -** of the strings in the second or third column of the amatch data table -** is 50 bytes. The maximum cost on a rule is 1000. -*/ -#include "sqlite3ext.h" -SQLITE_EXTENSION_INIT1 -#include <stdlib.h> -#include <string.h> -#include <assert.h> -#include <stdio.h> -#include <ctype.h> - -#ifndef SQLITE_OMIT_VIRTUALTABLE - -/* -** Forward declaration of objects used by this implementation -*/ -typedef struct amatch_vtab amatch_vtab; -typedef struct amatch_cursor amatch_cursor; -typedef struct amatch_rule amatch_rule; -typedef struct amatch_word amatch_word; -typedef struct amatch_avl amatch_avl; - - -/***************************************************************************** -** AVL Tree implementation -*/ -/* -** Objects that want to be members of the AVL tree should embedded an -** instance of this structure. -*/ -struct amatch_avl { - amatch_word *pWord; /* Points to the object being stored in the tree */ - char *zKey; /* Key. zero-terminated string. Must be unique */ - amatch_avl *pBefore; /* Other elements less than zKey */ - amatch_avl *pAfter; /* Other elements greater than zKey */ - amatch_avl *pUp; /* Parent element */ - short int height; /* Height of this node. Leaf==1 */ - short int imbalance; /* Height difference between pBefore and pAfter */ -}; - -/* Recompute the amatch_avl.height and amatch_avl.imbalance fields for p. -** Assume that the children of p have correct heights. -*/ -static void amatchAvlRecomputeHeight(amatch_avl *p){ - short int hBefore = p->pBefore ? p->pBefore->height : 0; - short int hAfter = p->pAfter ? p->pAfter->height : 0; - p->imbalance = hBefore - hAfter; /* -: pAfter higher. +: pBefore higher */ - p->height = (hBefore>hAfter ? hBefore : hAfter)+1; -} - -/* -** P B -** / \ / \ -** B Z ==> X P -** / \ / \ -** X Y Y Z -** -*/ -static amatch_avl *amatchAvlRotateBefore(amatch_avl *pP){ - amatch_avl *pB = pP->pBefore; - amatch_avl *pY = pB->pAfter; - pB->pUp = pP->pUp; - pB->pAfter = pP; - pP->pUp = pB; - pP->pBefore = pY; - if( pY ) pY->pUp = pP; - amatchAvlRecomputeHeight(pP); - amatchAvlRecomputeHeight(pB); - return pB; -} - -/* -** P A -** / \ / \ -** X A ==> P Z -** / \ / \ -** Y Z X Y -** -*/ -static amatch_avl *amatchAvlRotateAfter(amatch_avl *pP){ - amatch_avl *pA = pP->pAfter; - amatch_avl *pY = pA->pBefore; - pA->pUp = pP->pUp; - pA->pBefore = pP; - pP->pUp = pA; - pP->pAfter = pY; - if( pY ) pY->pUp = pP; - amatchAvlRecomputeHeight(pP); - amatchAvlRecomputeHeight(pA); - return pA; -} - -/* -** Return a pointer to the pBefore or pAfter pointer in the parent -** of p that points to p. Or if p is the root node, return pp. -*/ -static amatch_avl **amatchAvlFromPtr(amatch_avl *p, amatch_avl **pp){ - amatch_avl *pUp = p->pUp; - if( pUp==0 ) return pp; - if( pUp->pAfter==p ) return &pUp->pAfter; - return &pUp->pBefore; -} - -/* -** Rebalance all nodes starting with p and working up to the root. -** Return the new root. -*/ -static amatch_avl *amatchAvlBalance(amatch_avl *p){ - amatch_avl *pTop = p; - amatch_avl **pp; - while( p ){ - amatchAvlRecomputeHeight(p); - if( p->imbalance>=2 ){ - amatch_avl *pB = p->pBefore; - if( pB->imbalance<0 ) p->pBefore = amatchAvlRotateAfter(pB); - pp = amatchAvlFromPtr(p,&p); - p = *pp = amatchAvlRotateBefore(p); - }else if( p->imbalance<=(-2) ){ - amatch_avl *pA = p->pAfter; - if( pA->imbalance>0 ) p->pAfter = amatchAvlRotateBefore(pA); - pp = amatchAvlFromPtr(p,&p); - p = *pp = amatchAvlRotateAfter(p); - } - pTop = p; - p = p->pUp; - } - return pTop; -} - -/* Search the tree rooted at p for an entry with zKey. Return a pointer -** to the entry or return NULL. -*/ -static amatch_avl *amatchAvlSearch(amatch_avl *p, const char *zKey){ - int c; - while( p && (c = strcmp(zKey, p->zKey))!=0 ){ - p = (c<0) ? p->pBefore : p->pAfter; - } - return p; -} - -/* Find the first node (the one with the smallest key). -*/ -static amatch_avl *amatchAvlFirst(amatch_avl *p){ - if( p ) while( p->pBefore ) p = p->pBefore; - return p; -} - -#if 0 /* NOT USED */ -/* Return the node with the next larger key after p. -*/ -static amatch_avl *amatchAvlNext(amatch_avl *p){ - amatch_avl *pPrev = 0; - while( p && p->pAfter==pPrev ){ - pPrev = p; - p = p->pUp; - } - if( p && pPrev==0 ){ - p = amatchAvlFirst(p->pAfter); - } - return p; -} -#endif - -#if 0 /* NOT USED */ -/* Verify AVL tree integrity -*/ -static int amatchAvlIntegrity(amatch_avl *pHead){ - amatch_avl *p; - if( pHead==0 ) return 1; - if( (p = pHead->pBefore)!=0 ){ - assert( p->pUp==pHead ); - assert( amatchAvlIntegrity(p) ); - assert( strcmp(p->zKey, pHead->zKey)<0 ); - while( p->pAfter ) p = p->pAfter; - assert( strcmp(p->zKey, pHead->zKey)<0 ); - } - if( (p = pHead->pAfter)!=0 ){ - assert( p->pUp==pHead ); - assert( amatchAvlIntegrity(p) ); - assert( strcmp(p->zKey, pHead->zKey)>0 ); - p = amatchAvlFirst(p); - assert( strcmp(p->zKey, pHead->zKey)>0 ); - } - return 1; -} -static int amatchAvlIntegrity2(amatch_avl *pHead){ - amatch_avl *p, *pNext; - for(p=amatchAvlFirst(pHead); p; p=pNext){ - pNext = amatchAvlNext(p); - if( pNext==0 ) break; - assert( strcmp(p->zKey, pNext->zKey)<0 ); - } - return 1; -} -#endif - -/* Insert a new node pNew. Return NULL on success. If the key is not -** unique, then do not perform the insert but instead leave pNew unchanged -** and return a pointer to an existing node with the same key. -*/ -static amatch_avl *amatchAvlInsert(amatch_avl **ppHead, amatch_avl *pNew){ - int c; - amatch_avl *p = *ppHead; - if( p==0 ){ - p = pNew; - pNew->pUp = 0; - }else{ - while( p ){ - c = strcmp(pNew->zKey, p->zKey); - if( c<0 ){ - if( p->pBefore ){ - p = p->pBefore; - }else{ - p->pBefore = pNew; - pNew->pUp = p; - break; - } - }else if( c>0 ){ - if( p->pAfter ){ - p = p->pAfter; - }else{ - p->pAfter = pNew; - pNew->pUp = p; - break; - } - }else{ - return p; - } - } - } - pNew->pBefore = 0; - pNew->pAfter = 0; - pNew->height = 1; - pNew->imbalance = 0; - *ppHead = amatchAvlBalance(p); - /* assert( amatchAvlIntegrity(*ppHead) ); */ - /* assert( amatchAvlIntegrity2(*ppHead) ); */ - return 0; -} - -/* Remove node pOld from the tree. pOld must be an element of the tree or -** the AVL tree will become corrupt. -*/ -static void amatchAvlRemove(amatch_avl **ppHead, amatch_avl *pOld){ - amatch_avl **ppParent; - amatch_avl *pBalance = 0; - /* assert( amatchAvlSearch(*ppHead, pOld->zKey)==pOld ); */ - ppParent = amatchAvlFromPtr(pOld, ppHead); - if( pOld->pBefore==0 && pOld->pAfter==0 ){ - *ppParent = 0; - pBalance = pOld->pUp; - }else if( pOld->pBefore && pOld->pAfter ){ - amatch_avl *pX, *pY; - pX = amatchAvlFirst(pOld->pAfter); - *amatchAvlFromPtr(pX, 0) = pX->pAfter; - if( pX->pAfter ) pX->pAfter->pUp = pX->pUp; - pBalance = pX->pUp; - pX->pAfter = pOld->pAfter; - if( pX->pAfter ){ - pX->pAfter->pUp = pX; - }else{ - assert( pBalance==pOld ); - pBalance = pX; - } - pX->pBefore = pY = pOld->pBefore; - if( pY ) pY->pUp = pX; - pX->pUp = pOld->pUp; - *ppParent = pX; - }else if( pOld->pBefore==0 ){ - *ppParent = pBalance = pOld->pAfter; - pBalance->pUp = pOld->pUp; - }else if( pOld->pAfter==0 ){ - *ppParent = pBalance = pOld->pBefore; - pBalance->pUp = pOld->pUp; - } - *ppHead = amatchAvlBalance(pBalance); - pOld->pUp = 0; - pOld->pBefore = 0; - pOld->pAfter = 0; - /* assert( amatchAvlIntegrity(*ppHead) ); */ - /* assert( amatchAvlIntegrity2(*ppHead) ); */ -} -/* -** End of the AVL Tree implementation -******************************************************************************/ - - -/* -** Various types. -** -** amatch_cost is the "cost" of an edit operation. -** -** amatch_len is the length of a matching string. -** -** amatch_langid is an ruleset identifier. -*/ -typedef int amatch_cost; -typedef signed char amatch_len; -typedef int amatch_langid; - -/* -** Limits -*/ -#define AMATCH_MX_LENGTH 50 /* Maximum length of a rule string */ -#define AMATCH_MX_LANGID 2147483647 /* Maximum rule ID */ -#define AMATCH_MX_COST 1000 /* Maximum single-rule cost */ - -/* -** A match or partial match -*/ -struct amatch_word { - amatch_word *pNext; /* Next on a list of all amatch_words */ - amatch_avl sCost; /* Linkage of this node into the cost tree */ - amatch_avl sWord; /* Linkage of this node into the word tree */ - amatch_cost rCost; /* Cost of the match so far */ - int iSeq; /* Sequence number */ - char zCost[10]; /* Cost key (text rendering of rCost) */ - short int nMatch; /* Input characters matched */ - char zWord[4]; /* Text of the word. Extra space appended as needed */ -}; - -/* -** Each transformation rule is stored as an instance of this object. -** All rules are kept on a linked list sorted by rCost. -*/ -struct amatch_rule { - amatch_rule *pNext; /* Next rule in order of increasing rCost */ - char *zFrom; /* Transform from (a string from user input) */ - amatch_cost rCost; /* Cost of this transformation */ - amatch_langid iLang; /* The langauge to which this rule belongs */ - amatch_len nFrom, nTo; /* Length of the zFrom and zTo strings */ - char zTo[4]; /* Tranform to V.W value (extra space appended) */ -}; - -/* -** A amatch virtual-table object -*/ -struct amatch_vtab { - sqlite3_vtab base; /* Base class - must be first */ - char *zClassName; /* Name of this class. Default: "amatch" */ - char *zDb; /* Name of database. (ex: "main") */ - char *zSelf; /* Name of this virtual table */ - char *zCostTab; /* Name of edit-cost-table */ - char *zVocabTab; /* Name of vocabulary table */ - char *zVocabWord; /* Name of vocabulary table word column */ - char *zVocabLang; /* Name of vocabulary table language column */ - amatch_rule *pRule; /* All active rules in this amatch */ - amatch_cost rIns; /* Generic insertion cost '' -> ? */ - amatch_cost rDel; /* Generic deletion cost ? -> '' */ - amatch_cost rSub; /* Generic substitution cost ? -> ? */ - sqlite3 *db; /* The database connection */ - sqlite3_stmt *pVCheck; /* Query to check zVocabTab */ - int nCursor; /* Number of active cursors */ -}; - -/* A amatch cursor object */ -struct amatch_cursor { - sqlite3_vtab_cursor base; /* Base class - must be first */ - sqlite3_int64 iRowid; /* The rowid of the current word */ - amatch_langid iLang; /* Use this language ID */ - amatch_cost rLimit; /* Maximum cost of any term */ - int nBuf; /* Space allocated for zBuf */ - int oomErr; /* True following an OOM error */ - int nWord; /* Number of amatch_word objects */ - char *zBuf; /* Temp-use buffer space */ - char *zInput; /* Input word to match against */ - amatch_vtab *pVtab; /* The virtual table this cursor belongs to */ - amatch_word *pAllWords; /* List of all amatch_word objects */ - amatch_word *pCurrent; /* Most recent solution */ - amatch_avl *pCost; /* amatch_word objects keyed by iCost */ - amatch_avl *pWord; /* amatch_word objects keyed by zWord */ -}; - -/* -** The two input rule lists are both sorted in order of increasing -** cost. Merge them together into a single list, sorted by cost, and -** return a pointer to the head of that list. -*/ -static amatch_rule *amatchMergeRules(amatch_rule *pA, amatch_rule *pB){ - amatch_rule head; - amatch_rule *pTail; - - pTail = &head; - while( pA && pB ){ - if( pA->rCost<=pB->rCost ){ - pTail->pNext = pA; - pTail = pA; - pA = pA->pNext; - }else{ - pTail->pNext = pB; - pTail = pB; - pB = pB->pNext; - } - } - if( pA==0 ){ - pTail->pNext = pB; - }else{ - pTail->pNext = pA; - } - return head.pNext; -} - -/* -** Statement pStmt currently points to a row in the amatch data table. This -** function allocates and populates a amatch_rule structure according to -** the content of the row. -** -** If successful, *ppRule is set to point to the new object and SQLITE_OK -** is returned. Otherwise, *ppRule is zeroed, *pzErr may be set to point -** to an error message and an SQLite error code returned. -*/ -static int amatchLoadOneRule( - amatch_vtab *p, /* Fuzzer virtual table handle */ - sqlite3_stmt *pStmt, /* Base rule on statements current row */ - amatch_rule **ppRule, /* OUT: New rule object */ - char **pzErr /* OUT: Error message */ -){ - sqlite3_int64 iLang = sqlite3_column_int64(pStmt, 0); - const char *zFrom = (const char *)sqlite3_column_text(pStmt, 1); - const char *zTo = (const char *)sqlite3_column_text(pStmt, 2); - amatch_cost rCost = sqlite3_column_int(pStmt, 3); - - int rc = SQLITE_OK; /* Return code */ - int nFrom; /* Size of string zFrom, in bytes */ - int nTo; /* Size of string zTo, in bytes */ - amatch_rule *pRule = 0; /* New rule object to return */ - - if( zFrom==0 ) zFrom = ""; - if( zTo==0 ) zTo = ""; - nFrom = (int)strlen(zFrom); - nTo = (int)strlen(zTo); - - /* Silently ignore null transformations */ - if( strcmp(zFrom, zTo)==0 ){ - if( zFrom[0]=='?' && zFrom[1]==0 ){ - if( p->rSub==0 || p->rSub>rCost ) p->rSub = rCost; - } - *ppRule = 0; - return SQLITE_OK; - } - - if( rCost<=0 || rCost>AMATCH_MX_COST ){ - *pzErr = sqlite3_mprintf("%s: cost must be between 1 and %d", - p->zClassName, AMATCH_MX_COST - ); - rc = SQLITE_ERROR; - }else - if( nFrom>AMATCH_MX_LENGTH || nTo>AMATCH_MX_LENGTH ){ - *pzErr = sqlite3_mprintf("%s: maximum string length is %d", - p->zClassName, AMATCH_MX_LENGTH - ); - rc = SQLITE_ERROR; - }else - if( iLang<0 || iLang>AMATCH_MX_LANGID ){ - *pzErr = sqlite3_mprintf("%s: iLang must be between 0 and %d", - p->zClassName, AMATCH_MX_LANGID - ); - rc = SQLITE_ERROR; - }else - if( strcmp(zFrom,"")==0 && strcmp(zTo,"?")==0 ){ - if( p->rIns==0 || p->rIns>rCost ) p->rIns = rCost; - }else - if( strcmp(zFrom,"?")==0 && strcmp(zTo,"")==0 ){ - if( p->rDel==0 || p->rDel>rCost ) p->rDel = rCost; - }else - { - pRule = sqlite3_malloc( sizeof(*pRule) + nFrom + nTo ); - if( pRule==0 ){ - rc = SQLITE_NOMEM; - }else{ - memset(pRule, 0, sizeof(*pRule)); - pRule->zFrom = &pRule->zTo[nTo+1]; - pRule->nFrom = (amatch_len)nFrom; - memcpy(pRule->zFrom, zFrom, nFrom+1); - memcpy(pRule->zTo, zTo, nTo+1); - pRule->nTo = (amatch_len)nTo; - pRule->rCost = rCost; - pRule->iLang = (int)iLang; - } - } - - *ppRule = pRule; - return rc; -} - -/* -** Free all the content in the edit-cost-table -*/ -static void amatchFreeRules(amatch_vtab *p){ - while( p->pRule ){ - amatch_rule *pRule = p->pRule; - p->pRule = pRule->pNext; - sqlite3_free(pRule); - } - p->pRule = 0; -} - -/* -** Load the content of the amatch data table into memory. -*/ -static int amatchLoadRules( - sqlite3 *db, /* Database handle */ - amatch_vtab *p, /* Virtual amatch table to configure */ - char **pzErr /* OUT: Error message */ -){ - int rc = SQLITE_OK; /* Return code */ - char *zSql; /* SELECT used to read from rules table */ - amatch_rule *pHead = 0; - - zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", p->zDb, p->zCostTab); - if( zSql==0 ){ - rc = SQLITE_NOMEM; - }else{ - int rc2; /* finalize() return code */ - sqlite3_stmt *pStmt = 0; - rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0); - if( rc!=SQLITE_OK ){ - *pzErr = sqlite3_mprintf("%s: %s", p->zClassName, sqlite3_errmsg(db)); - }else if( sqlite3_column_count(pStmt)!=4 ){ - *pzErr = sqlite3_mprintf("%s: %s has %d columns, expected 4", - p->zClassName, p->zCostTab, sqlite3_column_count(pStmt) - ); - rc = SQLITE_ERROR; - }else{ - while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){ - amatch_rule *pRule = 0; - rc = amatchLoadOneRule(p, pStmt, &pRule, pzErr); - if( pRule ){ - pRule->pNext = pHead; - pHead = pRule; - } - } - } - rc2 = sqlite3_finalize(pStmt); - if( rc==SQLITE_OK ) rc = rc2; - } - sqlite3_free(zSql); - - /* All rules are now in a singly linked list starting at pHead. This - ** block sorts them by cost and then sets amatch_vtab.pRule to point to - ** point to the head of the sorted list. - */ - if( rc==SQLITE_OK ){ - unsigned int i; - amatch_rule *pX; - amatch_rule *a[15]; - for(i=0; i<sizeof(a)/sizeof(a[0]); i++) a[i] = 0; - while( (pX = pHead)!=0 ){ - pHead = pX->pNext; - pX->pNext = 0; - for(i=0; a[i] && i<sizeof(a)/sizeof(a[0])-1; i++){ - pX = amatchMergeRules(a[i], pX); - a[i] = 0; - } - a[i] = amatchMergeRules(a[i], pX); - } - for(pX=a[0], i=1; i<sizeof(a)/sizeof(a[0]); i++){ - pX = amatchMergeRules(a[i], pX); - } - p->pRule = amatchMergeRules(p->pRule, pX); - }else{ - /* An error has occurred. Setting p->pRule to point to the head of the - ** allocated list ensures that the list will be cleaned up in this case. - */ - assert( p->pRule==0 ); - p->pRule = pHead; - } - - return rc; -} - -/* -** This function converts an SQL quoted string into an unquoted string -** and returns a pointer to a buffer allocated using sqlite3_malloc() -** containing the result. The caller should eventually free this buffer -** using sqlite3_free. -** -** Examples: -** -** "abc" becomes abc -** 'xyz' becomes xyz -** [pqr] becomes pqr -** `mno` becomes mno -*/ -static char *amatchDequote(const char *zIn){ - int nIn; /* Size of input string, in bytes */ - char *zOut; /* Output (dequoted) string */ - - nIn = (int)strlen(zIn); - zOut = sqlite3_malloc(nIn+1); - if( zOut ){ - char q = zIn[0]; /* Quote character (if any ) */ - - if( q!='[' && q!= '\'' && q!='"' && q!='`' ){ - memcpy(zOut, zIn, nIn+1); - }else{ - int iOut = 0; /* Index of next byte to write to output */ - int iIn; /* Index of next byte to read from input */ - - if( q=='[' ) q = ']'; - for(iIn=1; iIn<nIn; iIn++){ - if( zIn[iIn]==q ) iIn++; - zOut[iOut++] = zIn[iIn]; - } - } - assert( (int)strlen(zOut)<=nIn ); - } - return zOut; -} - -/* -** Deallocate the pVCheck prepared statement. -*/ -static void amatchVCheckClear(amatch_vtab *p){ - if( p->pVCheck ){ - sqlite3_finalize(p->pVCheck); - p->pVCheck = 0; - } -} - -/* -** Deallocate an amatch_vtab object -*/ -static void amatchFree(amatch_vtab *p){ - if( p ){ - amatchFreeRules(p); - amatchVCheckClear(p); - sqlite3_free(p->zClassName); - sqlite3_free(p->zDb); - sqlite3_free(p->zCostTab); - sqlite3_free(p->zVocabTab); - sqlite3_free(p->zVocabWord); - sqlite3_free(p->zVocabLang); - sqlite3_free(p->zSelf); - memset(p, 0, sizeof(*p)); - sqlite3_free(p); - } -} - -/* -** xDisconnect/xDestroy method for the amatch module. -*/ -static int amatchDisconnect(sqlite3_vtab *pVtab){ - amatch_vtab *p = (amatch_vtab*)pVtab; - assert( p->nCursor==0 ); - amatchFree(p); - return SQLITE_OK; -} - -/* -** Check to see if the argument is of the form: -** -** KEY = VALUE -** -** If it is, return a pointer to the first character of VALUE. -** If not, return NULL. Spaces around the = are ignored. -*/ -static const char *amatchValueOfKey(const char *zKey, const char *zStr){ - int nKey = (int)strlen(zKey); - int nStr = (int)strlen(zStr); - int i; - if( nStr<nKey+1 ) return 0; - if( memcmp(zStr, zKey, nKey)!=0 ) return 0; - for(i=nKey; isspace((unsigned char)zStr[i]); i++){} - if( zStr[i]!='=' ) return 0; - i++; - while( isspace((unsigned char)zStr[i]) ){ i++; } - return zStr+i; -} - -/* -** xConnect/xCreate method for the amatch module. Arguments are: -** -** argv[0] -> module name ("approximate_match") -** argv[1] -> database name -** argv[2] -> table name -** argv[3...] -> arguments -*/ -static int amatchConnect( - sqlite3 *db, - void *pAux, - int argc, const char *const*argv, - sqlite3_vtab **ppVtab, - char **pzErr -){ - int rc = SQLITE_OK; /* Return code */ - amatch_vtab *pNew = 0; /* New virtual table */ - const char *zModule = argv[0]; - const char *zDb = argv[1]; - const char *zVal; - int i; - - (void)pAux; - *ppVtab = 0; - pNew = sqlite3_malloc( sizeof(*pNew) ); - if( pNew==0 ) return SQLITE_NOMEM; - rc = SQLITE_NOMEM; - memset(pNew, 0, sizeof(*pNew)); - pNew->db = db; - pNew->zClassName = sqlite3_mprintf("%s", zModule); - if( pNew->zClassName==0 ) goto amatchConnectError; - pNew->zDb = sqlite3_mprintf("%s", zDb); - if( pNew->zDb==0 ) goto amatchConnectError; - pNew->zSelf = sqlite3_mprintf("%s", argv[2]); - if( pNew->zSelf==0 ) goto amatchConnectError; - for(i=3; i<argc; i++){ - zVal = amatchValueOfKey("vocabulary_table", argv[i]); - if( zVal ){ - sqlite3_free(pNew->zVocabTab); - pNew->zVocabTab = amatchDequote(zVal); - if( pNew->zVocabTab==0 ) goto amatchConnectError; - continue; - } - zVal = amatchValueOfKey("vocabulary_word", argv[i]); - if( zVal ){ - sqlite3_free(pNew->zVocabWord); - pNew->zVocabWord = amatchDequote(zVal); - if( pNew->zVocabWord==0 ) goto amatchConnectError; - continue; - } - zVal = amatchValueOfKey("vocabulary_language", argv[i]); - if( zVal ){ - sqlite3_free(pNew->zVocabLang); - pNew->zVocabLang = amatchDequote(zVal); - if( pNew->zVocabLang==0 ) goto amatchConnectError; - continue; - } - zVal = amatchValueOfKey("edit_distances", argv[i]); - if( zVal ){ - sqlite3_free(pNew->zCostTab); - pNew->zCostTab = amatchDequote(zVal); - if( pNew->zCostTab==0 ) goto amatchConnectError; - continue; - } - *pzErr = sqlite3_mprintf("unrecognized argument: [%s]\n", argv[i]); - amatchFree(pNew); - *ppVtab = 0; - return SQLITE_ERROR; - } - rc = SQLITE_OK; - if( pNew->zCostTab==0 ){ - *pzErr = sqlite3_mprintf("no edit_distances table specified"); - rc = SQLITE_ERROR; - }else{ - rc = amatchLoadRules(db, pNew, pzErr); - } - if( rc==SQLITE_OK ){ - rc = sqlite3_declare_vtab(db, - "CREATE TABLE x(word,distance,language," - "command HIDDEN,nword HIDDEN)" - ); -#define AMATCH_COL_WORD 0 -#define AMATCH_COL_DISTANCE 1 -#define AMATCH_COL_LANGUAGE 2 -#define AMATCH_COL_COMMAND 3 -#define AMATCH_COL_NWORD 4 - } - if( rc!=SQLITE_OK ){ - amatchFree(pNew); - } - *ppVtab = &pNew->base; - return rc; - -amatchConnectError: - amatchFree(pNew); - return rc; -} - -/* -** Open a new amatch cursor. -*/ -static int amatchOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){ - amatch_vtab *p = (amatch_vtab*)pVTab; - amatch_cursor *pCur; - pCur = sqlite3_malloc( sizeof(*pCur) ); - if( pCur==0 ) return SQLITE_NOMEM; - memset(pCur, 0, sizeof(*pCur)); - pCur->pVtab = p; - *ppCursor = &pCur->base; - p->nCursor++; - return SQLITE_OK; -} - -/* -** Free up all the memory allocated by a cursor. Set it rLimit to 0 -** to indicate that it is at EOF. -*/ -static void amatchClearCursor(amatch_cursor *pCur){ - amatch_word *pWord, *pNextWord; - for(pWord=pCur->pAllWords; pWord; pWord=pNextWord){ - pNextWord = pWord->pNext; - sqlite3_free(pWord); - } - pCur->pAllWords = 0; - sqlite3_free(pCur->zInput); - pCur->zInput = 0; - sqlite3_free(pCur->zBuf); - pCur->zBuf = 0; - pCur->nBuf = 0; - pCur->pCost = 0; - pCur->pWord = 0; - pCur->pCurrent = 0; - pCur->rLimit = 1000000; - pCur->iLang = 0; - pCur->nWord = 0; -} - -/* -** Close a amatch cursor. -*/ -static int amatchClose(sqlite3_vtab_cursor *cur){ - amatch_cursor *pCur = (amatch_cursor *)cur; - amatchClearCursor(pCur); - pCur->pVtab->nCursor--; - sqlite3_free(pCur); - return SQLITE_OK; -} - -/* -** Render a 24-bit unsigned integer as a 4-byte base-64 number. -*/ -static void amatchEncodeInt(int x, char *z){ - static const char a[] = - "0123456789" - "ABCDEFGHIJ" - "KLMNOPQRST" - "UVWXYZ^abc" - "defghijklm" - "nopqrstuvw" - "xyz~"; - z[0] = a[(x>>18)&0x3f]; - z[1] = a[(x>>12)&0x3f]; - z[2] = a[(x>>6)&0x3f]; - z[3] = a[x&0x3f]; -} - -/* -** Write the zCost[] field for a amatch_word object -*/ -static void amatchWriteCost(amatch_word *pWord){ - amatchEncodeInt(pWord->rCost, pWord->zCost); - amatchEncodeInt(pWord->iSeq, pWord->zCost+4); - pWord->zCost[8] = 0; -} - -/* Circumvent compiler warnings about the use of strcpy() by supplying -** our own implementation. -*/ -static void amatchStrcpy(char *dest, const char *src){ - while( (*(dest++) = *(src++))!=0 ){} -} -static void amatchStrcat(char *dest, const char *src){ - while( *dest ) dest++; - amatchStrcpy(dest, src); -} - -/* -** Add a new amatch_word object to the queue. -** -** If a prior amatch_word object with the same zWord, and nMatch -** already exists, update its rCost (if the new rCost is less) but -** otherwise leave it unchanged. Do not add a duplicate. -** -** Do nothing if the cost exceeds threshold. -*/ -static void amatchAddWord( - amatch_cursor *pCur, - amatch_cost rCost, - int nMatch, - const char *zWordBase, - const char *zWordTail -){ - amatch_word *pWord; - amatch_avl *pNode; - amatch_avl *pOther; - int nBase, nTail; - char zBuf[4]; - - if( rCost>pCur->rLimit ){ - return; - } - nBase = (int)strlen(zWordBase); - nTail = (int)strlen(zWordTail); - if( nBase+nTail+3>pCur->nBuf ){ - pCur->nBuf = nBase+nTail+100; - pCur->zBuf = sqlite3_realloc(pCur->zBuf, pCur->nBuf); - if( pCur->zBuf==0 ){ - pCur->nBuf = 0; - return; - } - } - amatchEncodeInt(nMatch, zBuf); - memcpy(pCur->zBuf, zBuf+2, 2); - memcpy(pCur->zBuf+2, zWordBase, nBase); - memcpy(pCur->zBuf+2+nBase, zWordTail, nTail+1); - pNode = amatchAvlSearch(pCur->pWord, pCur->zBuf); - if( pNode ){ - pWord = pNode->pWord; - if( pWord->rCost>rCost ){ -#ifdef AMATCH_TRACE_1 - printf("UPDATE [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", - pWord->zWord+2, pWord->nMatch, pCur->zInput, pCur->zInput, - pWord->rCost, pWord->zWord, pWord->zCost); -#endif - amatchAvlRemove(&pCur->pCost, &pWord->sCost); - pWord->rCost = rCost; - amatchWriteCost(pWord); -#ifdef AMATCH_TRACE_1 - printf(" ---> %d (\"%s\" \"%s\")\n", - pWord->rCost, pWord->zWord, pWord->zCost); -#endif - pOther = amatchAvlInsert(&pCur->pCost, &pWord->sCost); - assert( pOther==0 ); (void)pOther; - } - return; - } - pWord = sqlite3_malloc( sizeof(*pWord) + nBase + nTail - 1 ); - if( pWord==0 ) return; - memset(pWord, 0, sizeof(*pWord)); - pWord->rCost = rCost; - pWord->iSeq = pCur->nWord++; - amatchWriteCost(pWord); - pWord->nMatch = (short)nMatch; - pWord->pNext = pCur->pAllWords; - pCur->pAllWords = pWord; - pWord->sCost.zKey = pWord->zCost; - pWord->sCost.pWord = pWord; - pOther = amatchAvlInsert(&pCur->pCost, &pWord->sCost); - assert( pOther==0 ); (void)pOther; - pWord->sWord.zKey = pWord->zWord; - pWord->sWord.pWord = pWord; - amatchStrcpy(pWord->zWord, pCur->zBuf); - pOther = amatchAvlInsert(&pCur->pWord, &pWord->sWord); - assert( pOther==0 ); (void)pOther; -#ifdef AMATCH_TRACE_1 - printf("INSERT [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", pWord->zWord+2, - pWord->nMatch, pCur->zInput, pCur->zInput+pWord->nMatch, rCost, - pWord->zWord, pWord->zCost); -#endif -} - - -/* -** Advance a cursor to its next row of output -*/ -static int amatchNext(sqlite3_vtab_cursor *cur){ - amatch_cursor *pCur = (amatch_cursor*)cur; - amatch_word *pWord = 0; - amatch_avl *pNode; - int isMatch = 0; - amatch_vtab *p = pCur->pVtab; - int nWord; - int rc; - int i; - const char *zW; - amatch_rule *pRule; - char *zBuf = 0; - char nBuf = 0; - char zNext[8]; - char zNextIn[8]; - int nNextIn; - - if( p->pVCheck==0 ){ - char *zSql; - if( p->zVocabLang && p->zVocabLang[0] ){ - zSql = sqlite3_mprintf( - "SELECT \"%w\" FROM \"%w\"", - " WHERE \"%w\">=?1 AND \"%w\"=?2" - " ORDER BY 1", - p->zVocabWord, p->zVocabTab, - p->zVocabWord, p->zVocabLang - ); - }else{ - zSql = sqlite3_mprintf( - "SELECT \"%w\" FROM \"%w\"" - " WHERE \"%w\">=?1" - " ORDER BY 1", - p->zVocabWord, p->zVocabTab, - p->zVocabWord - ); - } - rc = sqlite3_prepare_v2(p->db, zSql, -1, &p->pVCheck, 0); - sqlite3_free(zSql); - if( rc ) return rc; - } - sqlite3_bind_int(p->pVCheck, 2, pCur->iLang); - - do{ - pNode = amatchAvlFirst(pCur->pCost); - if( pNode==0 ){ - pWord = 0; - break; - } - pWord = pNode->pWord; - amatchAvlRemove(&pCur->pCost, &pWord->sCost); - -#ifdef AMATCH_TRACE_1 - printf("PROCESS [%s][%.*s^%s] %d (\"%s\" \"%s\")\n", - pWord->zWord+2, pWord->nMatch, pCur->zInput, pCur->zInput+pWord->nMatch, - pWord->rCost, pWord->zWord, pWord->zCost); -#endif - nWord = (int)strlen(pWord->zWord+2); - if( nWord+20>nBuf ){ - nBuf = (char)(nWord+100); - zBuf = sqlite3_realloc(zBuf, nBuf); - if( zBuf==0 ) return SQLITE_NOMEM; - } - amatchStrcpy(zBuf, pWord->zWord+2); - zNext[0] = 0; - zNextIn[0] = pCur->zInput[pWord->nMatch]; - if( zNextIn[0] ){ - for(i=1; i<=4 && (pCur->zInput[pWord->nMatch+i]&0xc0)==0x80; i++){ - zNextIn[i] = pCur->zInput[pWord->nMatch+i]; - } - zNextIn[i] = 0; - nNextIn = i; - }else{ - nNextIn = 0; - } - - if( zNextIn[0] && zNextIn[0]!='*' ){ - sqlite3_reset(p->pVCheck); - amatchStrcat(zBuf, zNextIn); - sqlite3_bind_text(p->pVCheck, 1, zBuf, nWord+nNextIn, SQLITE_STATIC); - rc = sqlite3_step(p->pVCheck); - if( rc==SQLITE_ROW ){ - zW = (const char*)sqlite3_column_text(p->pVCheck, 0); - if( strncmp(zBuf, zW, nWord+nNextIn)==0 ){ - amatchAddWord(pCur, pWord->rCost, pWord->nMatch+nNextIn, zBuf, ""); - } - } - zBuf[nWord] = 0; - } - - while( 1 ){ - amatchStrcpy(zBuf+nWord, zNext); - sqlite3_reset(p->pVCheck); - sqlite3_bind_text(p->pVCheck, 1, zBuf, -1, SQLITE_TRANSIENT); - rc = sqlite3_step(p->pVCheck); - if( rc!=SQLITE_ROW ) break; - zW = (const char*)sqlite3_column_text(p->pVCheck, 0); - amatchStrcpy(zBuf+nWord, zNext); - if( strncmp(zW, zBuf, nWord)!=0 ) break; - if( (zNextIn[0]=='*' && zNextIn[1]==0) - || (zNextIn[0]==0 && zW[nWord]==0) - ){ - isMatch = 1; - zNextIn[0] = 0; - nNextIn = 0; - break; - } - zNext[0] = zW[nWord]; - for(i=1; i<=4 && (zW[nWord+i]&0xc0)==0x80; i++){ - zNext[i] = zW[nWord+i]; - } - zNext[i] = 0; - zBuf[nWord] = 0; - if( p->rIns>0 ){ - amatchAddWord(pCur, pWord->rCost+p->rIns, pWord->nMatch, - zBuf, zNext); - } - if( p->rSub>0 ){ - amatchAddWord(pCur, pWord->rCost+p->rSub, pWord->nMatch+nNextIn, - zBuf, zNext); - } - if( p->rIns<0 && p->rSub<0 ) break; - zNext[i-1]++; /* FIX ME */ - } - sqlite3_reset(p->pVCheck); - - if( p->rDel>0 ){ - zBuf[nWord] = 0; - amatchAddWord(pCur, pWord->rCost+p->rDel, pWord->nMatch+nNextIn, - zBuf, ""); - } - - for(pRule=p->pRule; pRule; pRule=pRule->pNext){ - if( pRule->iLang!=pCur->iLang ) continue; - if( strncmp(pRule->zFrom, pCur->zInput+pWord->nMatch, pRule->nFrom)==0 ){ - amatchAddWord(pCur, pWord->rCost+pRule->rCost, - pWord->nMatch+pRule->nFrom, pWord->zWord+2, pRule->zTo); - } - } - }while( !isMatch ); - pCur->pCurrent = pWord; - sqlite3_free(zBuf); - return SQLITE_OK; -} - -/* -** Called to "rewind" a cursor back to the beginning so that -** it starts its output over again. Always called at least once -** prior to any amatchColumn, amatchRowid, or amatchEof call. -*/ -static int amatchFilter( - sqlite3_vtab_cursor *pVtabCursor, - int idxNum, const char *idxStr, - int argc, sqlite3_value **argv -){ - amatch_cursor *pCur = (amatch_cursor *)pVtabCursor; - const char *zWord = "*"; - int idx; - - amatchClearCursor(pCur); - idx = 0; - if( idxNum & 1 ){ - zWord = (const char*)sqlite3_value_text(argv[0]); - idx++; - } - if( idxNum & 2 ){ - pCur->rLimit = (amatch_cost)sqlite3_value_int(argv[idx]); - idx++; - } - if( idxNum & 4 ){ - pCur->iLang = (amatch_cost)sqlite3_value_int(argv[idx]); - idx++; - } - pCur->zInput = sqlite3_mprintf("%s", zWord); - if( pCur->zInput==0 ) return SQLITE_NOMEM; - amatchAddWord(pCur, 0, 0, "", ""); - amatchNext(pVtabCursor); - - return SQLITE_OK; -} - -/* -** Only the word and distance columns have values. All other columns -** return NULL -*/ -static int amatchColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){ - amatch_cursor *pCur = (amatch_cursor*)cur; - switch( i ){ - case AMATCH_COL_WORD: { - sqlite3_result_text(ctx, pCur->pCurrent->zWord+2, -1, SQLITE_STATIC); - break; - } - case AMATCH_COL_DISTANCE: { - sqlite3_result_int(ctx, pCur->pCurrent->rCost); - break; - } - case AMATCH_COL_LANGUAGE: { - sqlite3_result_int(ctx, pCur->iLang); - break; - } - case AMATCH_COL_NWORD: { - sqlite3_result_int(ctx, pCur->nWord); - break; - } - default: { - sqlite3_result_null(ctx); - break; - } - } - return SQLITE_OK; -} - -/* -** The rowid. -*/ -static int amatchRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ - amatch_cursor *pCur = (amatch_cursor*)cur; - *pRowid = pCur->iRowid; - return SQLITE_OK; -} - -/* -** EOF indicator -*/ -static int amatchEof(sqlite3_vtab_cursor *cur){ - amatch_cursor *pCur = (amatch_cursor*)cur; - return pCur->pCurrent==0; -} - -/* -** Search for terms of these forms: -** -** (A) word MATCH $str -** (B1) distance < $value -** (B2) distance <= $value -** (C) language == $language -** -** The distance< and distance<= are both treated as distance<=. -** The query plan number is a bit vector: -** -** bit 1: Term of the form (A) found -** bit 2: Term like (B1) or (B2) found -** bit 3: Term like (C) found -** -** If bit-1 is set, $str is always in filter.argv[0]. If bit-2 is set -** then $value is in filter.argv[0] if bit-1 is clear and is in -** filter.argv[1] if bit-1 is set. If bit-3 is set, then $ruleid is -** in filter.argv[0] if bit-1 and bit-2 are both zero, is in -** filter.argv[1] if exactly one of bit-1 and bit-2 are set, and is in -** filter.argv[2] if both bit-1 and bit-2 are set. -*/ -static int amatchBestIndex( - sqlite3_vtab *tab, - sqlite3_index_info *pIdxInfo -){ - int iPlan = 0; - int iDistTerm = -1; - int iLangTerm = -1; - int i; - const struct sqlite3_index_constraint *pConstraint; - - (void)tab; - pConstraint = pIdxInfo->aConstraint; - for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){ - if( pConstraint->usable==0 ) continue; - if( (iPlan & 1)==0 - && pConstraint->iColumn==0 - && pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH - ){ - iPlan |= 1; - pIdxInfo->aConstraintUsage[i].argvIndex = 1; - pIdxInfo->aConstraintUsage[i].omit = 1; - } - if( (iPlan & 2)==0 - && pConstraint->iColumn==1 - && (pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT - || pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE) - ){ - iPlan |= 2; - iDistTerm = i; - } - if( (iPlan & 4)==0 - && pConstraint->iColumn==2 - && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ - ){ - iPlan |= 4; - pIdxInfo->aConstraintUsage[i].omit = 1; - iLangTerm = i; - } - } - if( iPlan & 2 ){ - pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = 1+((iPlan&1)!=0); - } - if( iPlan & 4 ){ - int idx = 1; - if( iPlan & 1 ) idx++; - if( iPlan & 2 ) idx++; - pIdxInfo->aConstraintUsage[iLangTerm].argvIndex = idx; - } - pIdxInfo->idxNum = iPlan; - if( pIdxInfo->nOrderBy==1 - && pIdxInfo->aOrderBy[0].iColumn==1 - && pIdxInfo->aOrderBy[0].desc==0 - ){ - pIdxInfo->orderByConsumed = 1; - } - pIdxInfo->estimatedCost = (double)10000; - - return SQLITE_OK; -} - -/* -** The xUpdate() method. -** -** This implementation disallows DELETE and UPDATE. The only thing -** allowed is INSERT into the "command" column. -*/ -static int amatchUpdate( - sqlite3_vtab *pVTab, - int argc, - sqlite3_value **argv, - sqlite_int64 *pRowid -){ - amatch_vtab *p = (amatch_vtab*)pVTab; - const unsigned char *zCmd; - (void)pRowid; - if( argc==1 ){ - pVTab->zErrMsg = sqlite3_mprintf("DELETE from %s is not allowed", - p->zSelf); - return SQLITE_ERROR; - } - if( sqlite3_value_type(argv[0])!=SQLITE_NULL ){ - pVTab->zErrMsg = sqlite3_mprintf("UPDATE of %s is not allowed", - p->zSelf); - return SQLITE_ERROR; - } - if( sqlite3_value_type(argv[2+AMATCH_COL_WORD])!=SQLITE_NULL - || sqlite3_value_type(argv[2+AMATCH_COL_DISTANCE])!=SQLITE_NULL - || sqlite3_value_type(argv[2+AMATCH_COL_LANGUAGE])!=SQLITE_NULL - ){ - pVTab->zErrMsg = sqlite3_mprintf( - "INSERT INTO %s allowed for column [command] only", p->zSelf); - return SQLITE_ERROR; - } - zCmd = sqlite3_value_text(argv[2+AMATCH_COL_COMMAND]); - if( zCmd==0 ) return SQLITE_OK; - - return SQLITE_OK; -} - -/* -** A virtual table module that implements the "approximate_match". -*/ -static sqlite3_module amatchModule = { - 0, /* iVersion */ - amatchConnect, /* xCreate */ - amatchConnect, /* xConnect */ - amatchBestIndex, /* xBestIndex */ - amatchDisconnect, /* xDisconnect */ - amatchDisconnect, /* xDestroy */ - amatchOpen, /* xOpen - open a cursor */ - amatchClose, /* xClose - close a cursor */ - amatchFilter, /* xFilter - configure scan constraints */ - amatchNext, /* xNext - advance a cursor */ - amatchEof, /* xEof - check for end of scan */ - amatchColumn, /* xColumn - read data */ - amatchRowid, /* xRowid - read data */ - amatchUpdate, /* xUpdate */ - 0, /* xBegin */ - 0, /* xSync */ - 0, /* xCommit */ - 0, /* xRollback */ - 0, /* xFindMethod */ - 0, /* xRename */ - 0, /* xSavepoint */ - 0, /* xRelease */ - 0 /* xRollbackTo */ -}; - -#endif /* SQLITE_OMIT_VIRTUALTABLE */ - -/* -** Register the amatch virtual table -*/ -#ifdef _WIN32 -__declspec(dllexport) -#endif -int sqlite3_amatch_init( - sqlite3 *db, - char **pzErrMsg, - const sqlite3_api_routines *pApi -){ - int rc = SQLITE_OK; - SQLITE_EXTENSION_INIT2(pApi); - (void)pzErrMsg; /* Not used */ -#ifndef SQLITE_OMIT_VIRTUALTABLE - rc = sqlite3_create_module(db, "approximate_match", &amatchModule, 0); -#endif /* SQLITE_OMIT_VIRTUALTABLE */ - return rc; -} |