diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
commit | 18657a960e125336f704ea058e25c27bd3900dcb (patch) | |
tree | 17b438b680ed45a996d7b59951e6aa34023783f2 /ext/misc/closure.c | |
parent | Initial commit. (diff) | |
download | sqlite3-upstream.tar.xz sqlite3-upstream.zip |
Adding upstream version 3.40.1.upstream/3.40.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'ext/misc/closure.c')
-rw-r--r-- | ext/misc/closure.c | 965 |
1 files changed, 965 insertions, 0 deletions
diff --git a/ext/misc/closure.c b/ext/misc/closure.c new file mode 100644 index 0000000..db9b2b7 --- /dev/null +++ b/ext/misc/closure.c @@ -0,0 +1,965 @@ +/* +** 2013-04-16 +** +** 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 virtual table that finds the transitive +** closure of a parent/child relationship in a real table. The virtual +** table is called "transitive_closure". +** +** A transitive_closure virtual table is created like this: +** +** CREATE VIRTUAL TABLE x USING transitive_closure( +** tablename=<tablename>, -- T +** idcolumn=<columnname>, -- X +** parentcolumn=<columnname> -- P +** ); +** +** When it is created, the new transitive_closure table may be supplied +** with default values for the name of a table T and columns T.X and T.P. +** The T.X and T.P columns must contain integers. The ideal case is for +** T.X to be the INTEGER PRIMARY KEY. The T.P column should reference +** the T.X column. The row referenced by T.P is the parent of the current row. +** +** The tablename, idcolumn, and parentcolumn supplied by the CREATE VIRTUAL +** TABLE statement may be overridden in individual queries by including +** terms like tablename='newtable', idcolumn='id2', or +** parentcolumn='parent3' in the WHERE clause of the query. +** +** For efficiency, it is essential that there be an index on the P column: +** +** CREATE Tidx1 ON T(P) +** +** Suppose a specific instance of the closure table is as follows: +** +** CREATE VIRTUAL TABLE ct1 USING transitive_closure( +** tablename='group', +** idcolumn='groupId', +** parentcolumn='parentId' +** ); +** +** Such an instance of the transitive_closure virtual table would be +** appropriate for walking a tree defined using a table like this, for example: +** +** CREATE TABLE group( +** groupId INTEGER PRIMARY KEY, +** parentId INTEGER REFERENCES group +** ); +** CREATE INDEX group_idx1 ON group(parentId); +** +** The group table above would presumably have other application-specific +** fields. The key point here is that rows of the group table form a +** tree. The purpose of the ct1 virtual table is to easily extract +** branches of that tree. +** +** Once it has been created, the ct1 virtual table can be queried +** as follows: +** +** SELECT * FROM element +** WHERE element.groupId IN (SELECT id FROM ct1 WHERE root=?1); +** +** The above query will return all elements that are part of group ?1 +** or children of group ?1 or grand-children of ?1 and so forth for all +** descendents of group ?1. The same query can be formulated as a join: +** +** SELECT element.* FROM element, ct1 +** WHERE element.groupid=ct1.id +** AND ct1.root=?1; +** +** The depth of the transitive_closure (the number of generations of +** parent/child relations to follow) can be limited by setting "depth" +** column in the WHERE clause. So, for example, the following query +** finds only children and grandchildren but no further descendents: +** +** SELECT element.* FROM element, ct1 +** WHERE element.groupid=ct1.id +** AND ct1.root=?1 +** AND ct1.depth<=2; +** +** The "ct1.depth<=2" term could be a strict equality "ct1.depth=2" in +** order to find only the grandchildren of ?1, not ?1 itself or the +** children of ?1. +** +** The root=?1 term must be supplied in WHERE clause or else the query +** of the ct1 virtual table will return an empty set. The tablename, +** idcolumn, and parentcolumn attributes can be overridden in the WHERE +** clause if desired. So, for example, the ct1 table could be repurposed +** to find ancestors rather than descendents by inverting the roles of +** the idcolumn and parentcolumn: +** +** SELECT element.* FROM element, ct1 +** WHERE element.groupid=ct1.id +** AND ct1.root=?1 +** AND ct1.idcolumn='parentId' +** AND ct1.parentcolumn='groupId'; +** +** Multiple calls to ct1 could be combined. For example, the following +** query finds all elements that "cousins" of groupId ?1. That is to say +** elements where the groupId is a grandchild of the grandparent of ?1. +** (This definition of "cousins" also includes siblings and self.) +** +** SELECT element.* FROM element, ct1 +** WHERE element.groupId=ct1.id +** AND ct1.depth=2 +** AND ct1.root IN (SELECT id FROM ct1 +** WHERE root=?1 +** AND depth=2 +** AND idcolumn='parentId' +** AND parentcolumn='groupId'); +** +** In our example, the group.groupId column is unique and thus the +** subquery will return exactly one row. For that reason, the IN +** operator could be replaced by "=" to get the same result. But +** in the general case where the idcolumn is not unique, an IN operator +** would be required for this kind of query. +** +** Note that because the tablename, idcolumn, and parentcolumn can +** all be specified in the query, it is possible for an application +** to define a single transitive_closure virtual table for use on lots +** of different hierarchy tables. One might say: +** +** CREATE VIRTUAL TABLE temp.closure USING transitive_closure; +** +** As each database connection is being opened. Then the application +** would always have a "closure" virtual table handy to use for querying. +** +** SELECT element.* FROM element, closure +** WHERE element.groupid=ct1.id +** AND closure.root=?1 +** AND closure.tablename='group' +** AND closure.idname='groupId' +** AND closure.parentname='parentId'; +** +** See the documentation at http://www.sqlite.org/loadext.html for information +** on how to compile and use loadable extensions such as this one. +*/ +#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 closure_vtab closure_vtab; +typedef struct closure_cursor closure_cursor; +typedef struct closure_queue closure_queue; +typedef struct closure_avl closure_avl; + +/***************************************************************************** +** AVL Tree implementation +*/ +/* +** Objects that want to be members of the AVL tree should embedded an +** instance of this structure. +*/ +struct closure_avl { + sqlite3_int64 id; /* Id of this entry in the table */ + int iGeneration; /* Which generation is this entry part of */ + closure_avl *pList; /* A linked list of nodes */ + closure_avl *pBefore; /* Other elements less than id */ + closure_avl *pAfter; /* Other elements greater than id */ + closure_avl *pUp; /* Parent element */ + short int height; /* Height of this node. Leaf==1 */ + short int imbalance; /* Height difference between pBefore and pAfter */ +}; + +/* Recompute the closure_avl.height and closure_avl.imbalance fields for p. +** Assume that the children of p have correct heights. +*/ +static void closureAvlRecomputeHeight(closure_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 closure_avl *closureAvlRotateBefore(closure_avl *pP){ + closure_avl *pB = pP->pBefore; + closure_avl *pY = pB->pAfter; + pB->pUp = pP->pUp; + pB->pAfter = pP; + pP->pUp = pB; + pP->pBefore = pY; + if( pY ) pY->pUp = pP; + closureAvlRecomputeHeight(pP); + closureAvlRecomputeHeight(pB); + return pB; +} + +/* +** P A +** / \ / \ +** X A ==> P Z +** / \ / \ +** Y Z X Y +** +*/ +static closure_avl *closureAvlRotateAfter(closure_avl *pP){ + closure_avl *pA = pP->pAfter; + closure_avl *pY = pA->pBefore; + pA->pUp = pP->pUp; + pA->pBefore = pP; + pP->pUp = pA; + pP->pAfter = pY; + if( pY ) pY->pUp = pP; + closureAvlRecomputeHeight(pP); + closureAvlRecomputeHeight(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 closure_avl **closureAvlFromPtr(closure_avl *p, closure_avl **pp){ + closure_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 closure_avl *closureAvlBalance(closure_avl *p){ + closure_avl *pTop = p; + closure_avl **pp; + while( p ){ + closureAvlRecomputeHeight(p); + if( p->imbalance>=2 ){ + closure_avl *pB = p->pBefore; + if( pB->imbalance<0 ) p->pBefore = closureAvlRotateAfter(pB); + pp = closureAvlFromPtr(p,&p); + p = *pp = closureAvlRotateBefore(p); + }else if( p->imbalance<=(-2) ){ + closure_avl *pA = p->pAfter; + if( pA->imbalance>0 ) p->pAfter = closureAvlRotateBefore(pA); + pp = closureAvlFromPtr(p,&p); + p = *pp = closureAvlRotateAfter(p); + } + pTop = p; + p = p->pUp; + } + return pTop; +} + +/* Search the tree rooted at p for an entry with id. Return a pointer +** to the entry or return NULL. +*/ +static closure_avl *closureAvlSearch(closure_avl *p, sqlite3_int64 id){ + while( p && id!=p->id ){ + p = (id<p->id) ? p->pBefore : p->pAfter; + } + return p; +} + +/* Find the first node (the one with the smallest key). +*/ +static closure_avl *closureAvlFirst(closure_avl *p){ + if( p ) while( p->pBefore ) p = p->pBefore; + return p; +} + +/* Return the node with the next larger key after p. +*/ +closure_avl *closureAvlNext(closure_avl *p){ + closure_avl *pPrev = 0; + while( p && p->pAfter==pPrev ){ + pPrev = p; + p = p->pUp; + } + if( p && pPrev==0 ){ + p = closureAvlFirst(p->pAfter); + } + return p; +} + +/* 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 closure_avl *closureAvlInsert( + closure_avl **ppHead, /* Head of the tree */ + closure_avl *pNew /* New node to be inserted */ +){ + closure_avl *p = *ppHead; + if( p==0 ){ + p = pNew; + pNew->pUp = 0; + }else{ + while( p ){ + if( pNew->id<p->id ){ + if( p->pBefore ){ + p = p->pBefore; + }else{ + p->pBefore = pNew; + pNew->pUp = p; + break; + } + }else if( pNew->id>p->id ){ + 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 = closureAvlBalance(p); + return 0; +} + +/* Walk the tree can call xDestroy on each node +*/ +static void closureAvlDestroy(closure_avl *p, void (*xDestroy)(closure_avl*)){ + if( p ){ + closureAvlDestroy(p->pBefore, xDestroy); + closureAvlDestroy(p->pAfter, xDestroy); + xDestroy(p); + } +} +/* +** End of the AVL Tree implementation +******************************************************************************/ + +/* +** A closure virtual-table object +*/ +struct closure_vtab { + sqlite3_vtab base; /* Base class - must be first */ + char *zDb; /* Name of database. (ex: "main") */ + char *zSelf; /* Name of this virtual table */ + char *zTableName; /* Name of table holding parent/child relation */ + char *zIdColumn; /* Name of ID column of zTableName */ + char *zParentColumn; /* Name of PARENT column in zTableName */ + sqlite3 *db; /* The database connection */ + int nCursor; /* Number of pending cursors */ +}; + +/* A closure cursor object */ +struct closure_cursor { + sqlite3_vtab_cursor base; /* Base class - must be first */ + closure_vtab *pVtab; /* The virtual table this cursor belongs to */ + char *zTableName; /* Name of table holding parent/child relation */ + char *zIdColumn; /* Name of ID column of zTableName */ + char *zParentColumn; /* Name of PARENT column in zTableName */ + closure_avl *pCurrent; /* Current element of output */ + closure_avl *pClosure; /* The complete closure tree */ +}; + +/* A queue of AVL nodes */ +struct closure_queue { + closure_avl *pFirst; /* Oldest node on the queue */ + closure_avl *pLast; /* Youngest node on the queue */ +}; + +/* +** Add a node to the end of the queue +*/ +static void queuePush(closure_queue *pQueue, closure_avl *pNode){ + pNode->pList = 0; + if( pQueue->pLast ){ + pQueue->pLast->pList = pNode; + }else{ + pQueue->pFirst = pNode; + } + pQueue->pLast = pNode; +} + +/* +** Extract the oldest element (the front element) from the queue. +*/ +static closure_avl *queuePull(closure_queue *pQueue){ + closure_avl *p = pQueue->pFirst; + if( p ){ + pQueue->pFirst = p->pList; + if( pQueue->pFirst==0 ) pQueue->pLast = 0; + } + return p; +} + +/* +** 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 *closureDequote(const char *zIn){ + sqlite3_int64 nIn; /* Size of input string, in bytes */ + char *zOut; /* Output (dequoted) string */ + + nIn = strlen(zIn); + zOut = sqlite3_malloc64(nIn+1); + if( zOut ){ + char q = zIn[0]; /* Quote character (if any ) */ + + if( q!='[' && q!= '\'' && q!='"' && q!='`' ){ + memcpy(zOut, zIn, (size_t)(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 an closure_vtab object +*/ +static void closureFree(closure_vtab *p){ + if( p ){ + sqlite3_free(p->zDb); + sqlite3_free(p->zSelf); + sqlite3_free(p->zTableName); + sqlite3_free(p->zIdColumn); + sqlite3_free(p->zParentColumn); + memset(p, 0, sizeof(*p)); + sqlite3_free(p); + } +} + +/* +** xDisconnect/xDestroy method for the closure module. +*/ +static int closureDisconnect(sqlite3_vtab *pVtab){ + closure_vtab *p = (closure_vtab*)pVtab; + assert( p->nCursor==0 ); + closureFree(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 *closureValueOfKey(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 closure module. Arguments are: +** +** argv[0] -> module name ("transitive_closure") +** argv[1] -> database name +** argv[2] -> table name +** argv[3...] -> arguments +*/ +static int closureConnect( + sqlite3 *db, + void *pAux, + int argc, const char *const*argv, + sqlite3_vtab **ppVtab, + char **pzErr +){ + int rc = SQLITE_OK; /* Return code */ + closure_vtab *pNew = 0; /* New virtual table */ + 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->zDb = sqlite3_mprintf("%s", zDb); + if( pNew->zDb==0 ) goto closureConnectError; + pNew->zSelf = sqlite3_mprintf("%s", argv[2]); + if( pNew->zSelf==0 ) goto closureConnectError; + for(i=3; i<argc; i++){ + zVal = closureValueOfKey("tablename", argv[i]); + if( zVal ){ + sqlite3_free(pNew->zTableName); + pNew->zTableName = closureDequote(zVal); + if( pNew->zTableName==0 ) goto closureConnectError; + continue; + } + zVal = closureValueOfKey("idcolumn", argv[i]); + if( zVal ){ + sqlite3_free(pNew->zIdColumn); + pNew->zIdColumn = closureDequote(zVal); + if( pNew->zIdColumn==0 ) goto closureConnectError; + continue; + } + zVal = closureValueOfKey("parentcolumn", argv[i]); + if( zVal ){ + sqlite3_free(pNew->zParentColumn); + pNew->zParentColumn = closureDequote(zVal); + if( pNew->zParentColumn==0 ) goto closureConnectError; + continue; + } + *pzErr = sqlite3_mprintf("unrecognized argument: [%s]\n", argv[i]); + closureFree(pNew); + *ppVtab = 0; + return SQLITE_ERROR; + } + rc = sqlite3_declare_vtab(db, + "CREATE TABLE x(id,depth,root HIDDEN,tablename HIDDEN," + "idcolumn HIDDEN,parentcolumn HIDDEN)" + ); +#define CLOSURE_COL_ID 0 +#define CLOSURE_COL_DEPTH 1 +#define CLOSURE_COL_ROOT 2 +#define CLOSURE_COL_TABLENAME 3 +#define CLOSURE_COL_IDCOLUMN 4 +#define CLOSURE_COL_PARENTCOLUMN 5 + if( rc!=SQLITE_OK ){ + closureFree(pNew); + } + *ppVtab = &pNew->base; + return rc; + +closureConnectError: + closureFree(pNew); + return rc; +} + +/* +** Open a new closure cursor. +*/ +static int closureOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){ + closure_vtab *p = (closure_vtab*)pVTab; + closure_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 closureClearCursor(closure_cursor *pCur){ + closureAvlDestroy(pCur->pClosure, (void(*)(closure_avl*))sqlite3_free); + sqlite3_free(pCur->zTableName); + sqlite3_free(pCur->zIdColumn); + sqlite3_free(pCur->zParentColumn); + pCur->zTableName = 0; + pCur->zIdColumn = 0; + pCur->zParentColumn = 0; + pCur->pCurrent = 0; + pCur->pClosure = 0; +} + +/* +** Close a closure cursor. +*/ +static int closureClose(sqlite3_vtab_cursor *cur){ + closure_cursor *pCur = (closure_cursor *)cur; + closureClearCursor(pCur); + pCur->pVtab->nCursor--; + sqlite3_free(pCur); + return SQLITE_OK; +} + +/* +** Advance a cursor to its next row of output +*/ +static int closureNext(sqlite3_vtab_cursor *cur){ + closure_cursor *pCur = (closure_cursor*)cur; + pCur->pCurrent = closureAvlNext(pCur->pCurrent); + return SQLITE_OK; +} + +/* +** Allocate and insert a node +*/ +static int closureInsertNode( + closure_queue *pQueue, /* Add new node to this queue */ + closure_cursor *pCur, /* The cursor into which to add the node */ + sqlite3_int64 id, /* The node ID */ + int iGeneration /* The generation number for this node */ +){ + closure_avl *pNew = sqlite3_malloc( sizeof(*pNew) ); + if( pNew==0 ) return SQLITE_NOMEM; + memset(pNew, 0, sizeof(*pNew)); + pNew->id = id; + pNew->iGeneration = iGeneration; + closureAvlInsert(&pCur->pClosure, pNew); + queuePush(pQueue, pNew); + 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 closureColumn, closureRowid, or closureEof call. +** +** This routine actually computes the closure. +** +** See the comment at the beginning of closureBestIndex() for a +** description of the meaning of idxNum. The idxStr parameter is +** not used. +*/ +static int closureFilter( + sqlite3_vtab_cursor *pVtabCursor, + int idxNum, const char *idxStr, + int argc, sqlite3_value **argv +){ + closure_cursor *pCur = (closure_cursor *)pVtabCursor; + closure_vtab *pVtab = pCur->pVtab; + sqlite3_int64 iRoot; + int mxGen = 999999999; + char *zSql; + sqlite3_stmt *pStmt; + closure_avl *pAvl; + int rc = SQLITE_OK; + const char *zTableName = pVtab->zTableName; + const char *zIdColumn = pVtab->zIdColumn; + const char *zParentColumn = pVtab->zParentColumn; + closure_queue sQueue; + + (void)idxStr; /* Unused parameter */ + (void)argc; /* Unused parameter */ + closureClearCursor(pCur); + memset(&sQueue, 0, sizeof(sQueue)); + if( (idxNum & 1)==0 ){ + /* No root=$root in the WHERE clause. Return an empty set */ + return SQLITE_OK; + } + iRoot = sqlite3_value_int64(argv[0]); + if( (idxNum & 0x000f0)!=0 ){ + mxGen = sqlite3_value_int(argv[(idxNum>>4)&0x0f]); + if( (idxNum & 0x00002)!=0 ) mxGen--; + } + if( (idxNum & 0x00f00)!=0 ){ + zTableName = (const char*)sqlite3_value_text(argv[(idxNum>>8)&0x0f]); + pCur->zTableName = sqlite3_mprintf("%s", zTableName); + } + if( (idxNum & 0x0f000)!=0 ){ + zIdColumn = (const char*)sqlite3_value_text(argv[(idxNum>>12)&0x0f]); + pCur->zIdColumn = sqlite3_mprintf("%s", zIdColumn); + } + if( (idxNum & 0x0f0000)!=0 ){ + zParentColumn = (const char*)sqlite3_value_text(argv[(idxNum>>16)&0x0f]); + pCur->zParentColumn = sqlite3_mprintf("%s", zParentColumn); + } + + zSql = sqlite3_mprintf( + "SELECT \"%w\".\"%w\" FROM \"%w\" WHERE \"%w\".\"%w\"=?1", + zTableName, zIdColumn, zTableName, zTableName, zParentColumn); + if( zSql==0 ){ + return SQLITE_NOMEM; + }else{ + rc = sqlite3_prepare_v2(pVtab->db, zSql, -1, &pStmt, 0); + sqlite3_free(zSql); + if( rc ){ + sqlite3_free(pVtab->base.zErrMsg); + pVtab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pVtab->db)); + return rc; + } + } + if( rc==SQLITE_OK ){ + rc = closureInsertNode(&sQueue, pCur, iRoot, 0); + } + while( (pAvl = queuePull(&sQueue))!=0 ){ + if( pAvl->iGeneration>=mxGen ) continue; + sqlite3_bind_int64(pStmt, 1, pAvl->id); + while( rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){ + if( sqlite3_column_type(pStmt,0)==SQLITE_INTEGER ){ + sqlite3_int64 iNew = sqlite3_column_int64(pStmt, 0); + if( closureAvlSearch(pCur->pClosure, iNew)==0 ){ + rc = closureInsertNode(&sQueue, pCur, iNew, pAvl->iGeneration+1); + } + } + } + sqlite3_reset(pStmt); + } + sqlite3_finalize(pStmt); + if( rc==SQLITE_OK ){ + pCur->pCurrent = closureAvlFirst(pCur->pClosure); + } + + return rc; +} + +/* +** Only the word and distance columns have values. All other columns +** return NULL +*/ +static int closureColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){ + closure_cursor *pCur = (closure_cursor*)cur; + switch( i ){ + case CLOSURE_COL_ID: { + sqlite3_result_int64(ctx, pCur->pCurrent->id); + break; + } + case CLOSURE_COL_DEPTH: { + sqlite3_result_int(ctx, pCur->pCurrent->iGeneration); + break; + } + case CLOSURE_COL_ROOT: { + sqlite3_result_null(ctx); + break; + } + case CLOSURE_COL_TABLENAME: { + sqlite3_result_text(ctx, + pCur->zTableName ? pCur->zTableName : pCur->pVtab->zTableName, + -1, SQLITE_TRANSIENT); + break; + } + case CLOSURE_COL_IDCOLUMN: { + sqlite3_result_text(ctx, + pCur->zIdColumn ? pCur->zIdColumn : pCur->pVtab->zIdColumn, + -1, SQLITE_TRANSIENT); + break; + } + case CLOSURE_COL_PARENTCOLUMN: { + sqlite3_result_text(ctx, + pCur->zParentColumn ? pCur->zParentColumn : pCur->pVtab->zParentColumn, + -1, SQLITE_TRANSIENT); + break; + } + } + return SQLITE_OK; +} + +/* +** The rowid. For the closure table, this is the same as the "id" column. +*/ +static int closureRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){ + closure_cursor *pCur = (closure_cursor*)cur; + *pRowid = pCur->pCurrent->id; + return SQLITE_OK; +} + +/* +** EOF indicator +*/ +static int closureEof(sqlite3_vtab_cursor *cur){ + closure_cursor *pCur = (closure_cursor*)cur; + return pCur->pCurrent==0; +} + +/* +** Search for terms of these forms: +** +** (A) root = $root +** (B1) depth < $depth +** (B2) depth <= $depth +** (B3) depth = $depth +** (C) tablename = $tablename +** (D) idcolumn = $idcolumn +** (E) parentcolumn = $parentcolumn +** +** +** +** idxNum meaning +** ---------- ------------------------------------------------------ +** 0x00000001 Term of the form (A) found +** 0x00000002 The term of bit-2 is like (B1) +** 0x000000f0 Index in filter.argv[] of $depth. 0 if not used. +** 0x00000f00 Index in filter.argv[] of $tablename. 0 if not used. +** 0x0000f000 Index in filter.argv[] of $idcolumn. 0 if not used +** 0x000f0000 Index in filter.argv[] of $parentcolumn. 0 if not used. +** +** There must be a term of type (A). If there is not, then the index type +** is 0 and the query will return an empty set. +*/ +static int closureBestIndex( + sqlite3_vtab *pTab, /* The virtual table */ + sqlite3_index_info *pIdxInfo /* Information about the query */ +){ + int iPlan = 0; + int i; + int idx = 1; + const struct sqlite3_index_constraint *pConstraint; + closure_vtab *pVtab = (closure_vtab*)pTab; + double rCost = 10000000.0; + + pConstraint = pIdxInfo->aConstraint; + for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){ + if( pConstraint->usable==0 ) continue; + if( (iPlan & 1)==0 + && pConstraint->iColumn==CLOSURE_COL_ROOT + && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ + ){ + iPlan |= 1; + pIdxInfo->aConstraintUsage[i].argvIndex = 1; + pIdxInfo->aConstraintUsage[i].omit = 1; + rCost /= 100.0; + } + if( (iPlan & 0x0000f0)==0 + && pConstraint->iColumn==CLOSURE_COL_DEPTH + && (pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT + || pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE + || pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ) + ){ + iPlan |= idx<<4; + pIdxInfo->aConstraintUsage[i].argvIndex = ++idx; + if( pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT ) iPlan |= 0x000002; + rCost /= 5.0; + } + if( (iPlan & 0x000f00)==0 + && pConstraint->iColumn==CLOSURE_COL_TABLENAME + && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ + ){ + iPlan |= idx<<8; + pIdxInfo->aConstraintUsage[i].argvIndex = ++idx; + pIdxInfo->aConstraintUsage[i].omit = 1; + rCost /= 5.0; + } + if( (iPlan & 0x00f000)==0 + && pConstraint->iColumn==CLOSURE_COL_IDCOLUMN + && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ + ){ + iPlan |= idx<<12; + pIdxInfo->aConstraintUsage[i].argvIndex = ++idx; + pIdxInfo->aConstraintUsage[i].omit = 1; + } + if( (iPlan & 0x0f0000)==0 + && pConstraint->iColumn==CLOSURE_COL_PARENTCOLUMN + && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ + ){ + iPlan |= idx<<16; + pIdxInfo->aConstraintUsage[i].argvIndex = ++idx; + pIdxInfo->aConstraintUsage[i].omit = 1; + } + } + if( (pVtab->zTableName==0 && (iPlan & 0x000f00)==0) + || (pVtab->zIdColumn==0 && (iPlan & 0x00f000)==0) + || (pVtab->zParentColumn==0 && (iPlan & 0x0f0000)==0) + ){ + /* All of tablename, idcolumn, and parentcolumn must be specified + ** in either the CREATE VIRTUAL TABLE or in the WHERE clause constraints + ** or else the result is an empty set. */ + iPlan = 0; + } + if( (iPlan&1)==0 ){ + /* If there is no usable "root=?" term, then set the index-type to 0. + ** Also clear any argvIndex variables already set. This is necessary + ** to prevent the core from throwing an "xBestIndex malfunction error" + ** error (because the argvIndex values are not contiguously assigned + ** starting from 1). */ + rCost *= 1e30; + for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){ + pIdxInfo->aConstraintUsage[i].argvIndex = 0; + } + iPlan = 0; + } + pIdxInfo->idxNum = iPlan; + if( pIdxInfo->nOrderBy==1 + && pIdxInfo->aOrderBy[0].iColumn==CLOSURE_COL_ID + && pIdxInfo->aOrderBy[0].desc==0 + ){ + pIdxInfo->orderByConsumed = 1; + } + pIdxInfo->estimatedCost = rCost; + + return SQLITE_OK; +} + +/* +** A virtual table module that implements the "transitive_closure". +*/ +static sqlite3_module closureModule = { + 0, /* iVersion */ + closureConnect, /* xCreate */ + closureConnect, /* xConnect */ + closureBestIndex, /* xBestIndex */ + closureDisconnect, /* xDisconnect */ + closureDisconnect, /* xDestroy */ + closureOpen, /* xOpen - open a cursor */ + closureClose, /* xClose - close a cursor */ + closureFilter, /* xFilter - configure scan constraints */ + closureNext, /* xNext - advance a cursor */ + closureEof, /* xEof - check for end of scan */ + closureColumn, /* xColumn - read data */ + closureRowid, /* xRowid - read data */ + 0, /* xUpdate */ + 0, /* xBegin */ + 0, /* xSync */ + 0, /* xCommit */ + 0, /* xRollback */ + 0, /* xFindMethod */ + 0, /* xRename */ + 0, /* xSavepoint */ + 0, /* xRelease */ + 0, /* xRollbackTo */ + 0 /* xShadowName */ +}; + +#endif /* SQLITE_OMIT_VIRTUALTABLE */ + +/* +** Register the closure virtual table +*/ +#ifdef _WIN32 +__declspec(dllexport) +#endif +int sqlite3_closure_init( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc = SQLITE_OK; + SQLITE_EXTENSION_INIT2(pApi); + (void)pzErrMsg; +#ifndef SQLITE_OMIT_VIRTUALTABLE + rc = sqlite3_create_module(db, "transitive_closure", &closureModule, 0); +#endif /* SQLITE_OMIT_VIRTUALTABLE */ + return rc; +} |