SQLite

  $(TOP)/src/test_wsd.c       \
  $(TOP)/ext/fts3/fts3_term.c \
  $(TOP)/ext/fts3/fts3_test.c 

# Statically linked extensions
#
TESTSRC += \
  $(TOP)/ext/misc/amatch.c \
  $(TOP)/ext/misc/closure.c \
  $(TOP)/ext/misc/fuzzer.c \
  $(TOP)/ext/misc/ieee754.c \
  $(TOP)/ext/misc/regexp.c \
  $(TOP)/ext/misc/spellfix.c \
  $(TOP)/ext/misc/wholenumber.c

# Source code to the library files needed by the test fixture
#
TESTSRC2 = \

  $(TOP)\src\test_wsd.c \
  $(TOP)\ext\fts3\fts3_term.c \
  $(TOP)\ext\fts3\fts3_test.c

# Statically linked extensions
#
TESTEXT = \
  $(TOP)\ext\misc\amatch.c \
  $(TOP)\ext\misc\closure.c \
  $(TOP)\ext\misc\fuzzer.c \
  $(TOP)\ext\misc\ieee754.c \
  $(TOP)\ext\misc\regexp.c \
  $(TOP)\ext\misc\spellfix.c \
  $(TOP)\ext\misc\wholenumber.c


# Source code to the library files needed by the test fixture
#

/*
** 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>

/*
** 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;
  /* 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 = nFrom;
      memcpy(pRule->zFrom, zFrom, nFrom+1);
      memcpy(pRule->zTo, zTo, nTo+1);
      pRule->nTo = 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);
    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(zStr[i]); i++){}
  if( zStr[i]!='=' ) return 0;
  i++;
  while( isspace(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;
  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;
}

/*
** 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 = 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;
  strcpy(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 \"%s\" FROM \"%s\"",
          " WHERE \"%w\">=?1 AND \"%w\"=?2"
          " ORDER BY 1",
          p->zVocabWord, p->zVocabTab,
          p->zVocabWord, p->zVocabLang
      );
    }else{
      zSql = sqlite3_mprintf(
          "SELECT \"%s\" FROM \"%s\""
          " 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 = nWord+100;
      zBuf = sqlite3_realloc(zBuf, nBuf);
      if( zBuf==0 ) return SQLITE_NOMEM;
    }
    strcpy(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);
      strcat(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 ){
      strcpy(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);
      strcpy(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 */
};

/*
** 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 */
  rc = sqlite3_create_module(db, "approximate_match", &amatchModule, 0);
  return rc;
}

/*
** 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>

/*
** 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){
  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 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(zStr[i]); i++){}
  if( zStr[i]!='=' ) return 0;
  i++;
  while( isspace(zStr[i]) ){ i++; }
  return zStr+i;
}

/*
** xConnect/xCreate method for the closure module. Arguments are:
**
**   argv[0]    -> module name  ("approximate_match")
**   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;

  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;
    }
    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;
    }
    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;
    }
    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;
  }
  pIdxInfo->idxNum = iPlan;
  if( pIdxInfo->nOrderBy==1
   && pIdxInfo->aOrderBy[0].iColumn==CLOSURE_COL_ID
   && pIdxInfo->aOrderBy[0].desc==0
  ){
    pIdxInfo->orderByConsumed = 1;
  }
  pIdxInfo->estimatedCost = (double)10000;
   
  return SQLITE_OK;
}

/*
** A virtual table module that implements the "approximate_match".
*/
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 */
};

/*
** 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;
  rc = sqlite3_create_module(db, "transitive_closure", &closureModule, 0);
  return rc;
}

/*
** 2013-04-17
**
** 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 SQLite extension implements functions for the exact display
** and input of IEEE754 Binary64 floating-point numbers.
**
**   ieee754(X)
**   ieee754(Y,Z)
**
** In the first form, the value X should be a floating-point number.
** The function will return a string of the form 'ieee754(Y,Z)' where
** Y and Z are integers such that X==Y*pow(w.0,Z).
**
** In the second form, Y and Z are integers which are the mantissa and
** base-2 exponent of a new floating point number.  The function returns
** a floating-point value equal to Y*pow(2.0,Z).
**
** Examples:
**
**     ieee754(2.0)       ->     'ieee754(2,0)'
**     ieee754(45.25)     ->     'ieee754(181,-2)'
**     ieee754(2, 0)      ->     2.0
**     ieee754(181, -2)   ->     45.25
*/
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <assert.h>
#include <string.h>

/*
** Implementation of the ieee754() function
*/
static void ieee754func(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  if( argc==1 ){
    sqlite3_int64 m, a;
    double r;
    int e;
    int isNeg;
    char zResult[100];
    assert( sizeof(m)==sizeof(r) );
    if( sqlite3_value_type(argv[0])!=SQLITE_FLOAT ) return;
    r = sqlite3_value_double(argv[0]);
    if( r<0.0 ){
      isNeg = 1;
      r = -r;
    }else{
      isNeg = 0;
    }
    memcpy(&a,&r,sizeof(a));
    if( a==0 ){
      e = 0;
      m = 0;
    }else{
      e = a>>52;
      m = a & ((((sqlite3_int64)1)<<52)-1);
      m |= ((sqlite3_int64)1)<<52;
      while( e<1075 && m>0 && (m&1)==0 ){
        m >>= 1;
        e++;
      }
      if( isNeg ) m = -m;
    }
    sqlite3_snprintf(sizeof(zResult), zResult, "ieee754(%lld,%d)",
                     m, e-1075);
    sqlite3_result_text(context, zResult, -1, SQLITE_TRANSIENT);
  }else if( argc==2 ){
    sqlite3_int64 m, e, a;
    double r;
    int isNeg = 0;
    m = sqlite3_value_int64(argv[0]);
    e = sqlite3_value_int64(argv[1]);
    if( m<0 ){
      isNeg = 1;
      m = -m;
      if( m<0 ) return;
    }else if( m==0 && e>1000 && e<1000 ){
      sqlite3_result_double(context, 0.0);
      return;
    }
    while( (m>>32)&0xffe00000 ){
      m >>= 1;
      e++;
    }
    while( ((m>>32)&0xfff00000)==0 ){
      m <<= 1;
      e--;
    }
    e += 1075;
    if( e<0 ) e = m = 0;
    if( e>0x7ff ) m = 0;
    a = m & ((((sqlite3_int64)1)<<52)-1);
    a |= e<<52;
    if( isNeg ) a |= ((sqlite3_int64)1)<<63;
    memcpy(&r, &a, sizeof(r));
    sqlite3_result_double(context, r);
  }
}


#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_ieee_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  int rc = SQLITE_OK;
  SQLITE_EXTENSION_INIT2(pApi);
  (void)pzErrMsg;  /* Unused parameter */
  rc = sqlite3_create_function(db, "ieee754", 1, SQLITE_UTF8, 0,
                               ieee754func, 0, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "ieee754", 2, SQLITE_UTF8, 0,
                                 ieee754func, 0, 0);
  }
  return rc;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** The code in this file implements a compact but reasonably
** efficient regular-expression matcher for posix extended regular
** expressions against UTF8 text.
**
** This file is an SQLite extension.  It registers a single function
** named "regexp(A,B)" where A is the regular expression and B is the
** string to be matched.  By registering this function, SQLite will also
** then implement the "B regexp A" operator.  Note that with the function
** the regular expression comes first, but with the operator it comes
** second.
**
**  The following regular expression syntax is supported:
**
**     X*      zero or more occurrences of X
**     X+      one or more occurrences of X
**     X?      zero or one occurrences of X
**     X{p,q}  between p and q occurrences of X
**     (X)     match X
**     X|Y     X or Y

  $(TOP)/src/test_thread.c \
  $(TOP)/src/test_vfs.c \
  $(TOP)/src/test_wsd.c

# Extensions to be statically loaded.
#
TESTSRC += \
  $(TOP)/ext/misc/amatch.c \
  $(TOP)/ext/misc/closure.c \
  $(TOP)/ext/misc/fuzzer.c \
  $(TOP)/ext/misc/ieee754.c \
  $(TOP)/ext/misc/regexp.c \
  $(TOP)/ext/misc/spellfix.c \
  $(TOP)/ext/misc/wholenumber.c


#TESTSRC += $(TOP)/ext/fts2/fts2_tokenizer.c
#TESTSRC += $(TOP)/ext/fts3/fts3_tokenizer.c

*/
static int tclLoadStaticExtensionCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  extern int sqlite3_amatch_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_closure_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_fuzzer_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_ieee_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_regexp_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_spellfix_init(sqlite3*,char**,const sqlite3_api_routines*);
  extern int sqlite3_wholenumber_init(sqlite3*,char**,const sqlite3_api_routines*);
  static const struct {
    const char *zExtName;
    int (*pInit)(sqlite3*,char**,const sqlite3_api_routines*);
  } aExtension[] = {
    { "amatch",                sqlite3_amatch_init               },
    { "closure",               sqlite3_closure_init              },
    { "fuzzer",                sqlite3_fuzzer_init               },
    { "ieee754",               sqlite3_ieee_init                 },
    { "regexp",                sqlite3_regexp_init               },
    { "spellfix",              sqlite3_spellfix_init             },
    { "wholenumber",           sqlite3_wholenumber_init          },
  };
  sqlite3 *db;
  const char *zName;
  int i, rc;

# 2013-04-25
#
# 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.
#
#***********************************************************************
# 
# Test cases for transitive_closure virtual table.

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix closure01

load_static_extension db closure

do_execsql_test 1.0 {
  BEGIN;
  CREATE TABLE t1(x INTEGER PRIMARY KEY, y INTEGER);
  CREATE INDEX t1y ON t1(y);
  INSERT INTO t1(x) VALUES(1),(2);
  INSERT INTO t1(x) SELECT x+2 FROM t1;
  INSERT INTO t1(x) SELECT x+4 FROM t1;
  INSERT INTO t1(x) SELECT x+8 FROM t1;
  INSERT INTO t1(x) SELECT x+16 FROM t1;
  INSERT INTO t1(x) SELECT x+32 FROM t1;
  INSERT INTO t1(x) SELECT x+64 FROM t1;
  INSERT INTO t1(x) SELECT x+128 FROM t1;
  INSERT INTO t1(x) SELECT x+256 FROM t1;
  INSERT INTO t1(x) SELECT x+512 FROM t1;
  INSERT INTO t1(x) SELECT x+1024 FROM t1;
  INSERT INTO t1(x) SELECT x+2048 FROM t1;
  INSERT INTO t1(x) SELECT x+4096 FROM t1;
  INSERT INTO t1(x) SELECT x+8192 FROM t1;
  INSERT INTO t1(x) SELECT x+16384 FROM t1;
  INSERT INTO t1(x) SELECT x+32768 FROM t1;
  INSERT INTO t1(x) SELECT x+65536 FROM t1;
  UPDATE t1 SET y=x/2 WHERE x>1;
  COMMIT;
  CREATE VIRTUAL TABLE cx 
   USING transitive_closure(tablename=t1, idcolumn=x, parentcolumn=y);
} {}

# The entire table
do_execsql_test 1.1 {
  SELECT count(*), depth FROM cx WHERE root=1 GROUP BY depth ORDER BY 1;
} {/1 0 1 17 2 1 4 2 8 3 16 4 .* 65536 16/}

# descendents of 32768
do_execsql_test 1.2 {
  SELECT * FROM cx WHERE root=32768 ORDER BY id;
} {32768 0 65536 1 65537 1 131072 2}

# descendents of 16384
do_execsql_test 1.3 {
  SELECT * FROM cx WHERE root=16384 AND depth<=2 ORDER BY id;
} {16384 0 32768 1 32769 1 65536 2 65537 2 65538 2 65539 2}

# children of 16384
do_execsql_test 1.4 {
  SELECT id, depth, root, tablename, idcolumn, parentcolumn FROM cx
   WHERE root=16384
     AND depth=1
   ORDER BY id;
} {32768 1 {} t1 x y 32769 1 {} t1 x y}

# great-grandparent of 16384
do_execsql_test 1.5 {
  SELECT id, depth, root, tablename, idcolumn, parentcolumn FROM cx
   WHERE root=16384
     AND depth=3
     AND idcolumn='Y'
     AND parentcolumn='X';
} {2048 3 {} t1 Y X}

# depth<5
do_execsql_test 1.6 {
  SELECT count(*), depth FROM cx WHERE root=1 AND depth<5
   GROUP BY depth ORDER BY 1;
} {1 0 2 1 4 2 8 3 16 4}

# depth<=5
do_execsql_test 1.7 {
  SELECT count(*), depth FROM cx WHERE root=1 AND depth<=5
   GROUP BY depth ORDER BY 1;
} {1 0 2 1 4 2 8 3 16 4 32 5}

# depth==5
do_execsql_test 1.8 {
  SELECT count(*), depth FROM cx WHERE root=1 AND depth=5
   GROUP BY depth ORDER BY 1;
} {32 5}

# depth BETWEEN 3 AND 5
do_execsql_test 1.9 {
  SELECT count(*), depth FROM cx WHERE root=1 AND depth BETWEEN 3 AND 5
   GROUP BY depth ORDER BY 1;
} {8 3 16 4 32 5}

# depth==5 with min() and max()
do_execsql_test 1.10 {
  SELECT count(*), min(id), max(id) FROM cx WHERE root=1 AND depth=5;
} {32 32 63}

# Create a much smaller table t2 with only 32 elements 
db eval {
  CREATE TABLE t2(x INTEGER PRIMARY KEY, y INTEGER);
  INSERT INTO t2 SELECT x, y FROM t1 WHERE x<32;
  CREATE INDEX t2y ON t2(y);
  CREATE VIRTUAL TABLE c2 
   USING transitive_closure(tablename=t2, idcolumn=x, parentcolumn=y);
}

# t2 full-table
do_execsql_test 2.1 {
  SELECT count(*), min(id), max(id) FROM c2 WHERE root=1;
} {31 1 31}
# t2 root=10
do_execsql_test 2.2 {
  SELECT id FROM c2 WHERE root=10;
} {10 20 21}
# t2 root=11
do_execsql_test 2.3 {
  SELECT id FROM c2 WHERE root=12;
} {12 24 25}
# t2 root IN [10,12]
do_execsql_test 2.4 {
  SELECT id FROM c2 WHERE root IN (10,12) ORDER BY id;
} {10 12 20 21 24 25}
# t2 root IN [10,12] (sorted)
do_execsql_test 2.5 {
  SELECT id FROM c2 WHERE root IN (10,12) ORDER BY +id;
} {10 12 20 21 24 25}

# t2 c2up from 20
do_execsql_test 3.0 {
  CREATE VIRTUAL TABLE c2up USING transitive_closure(
    tablename = t2,
    idcolumn = y,
    parentcolumn = x
  );
  SELECT id FROM c2up WHERE root=20;
} {1 2 5 10 20}

# cx as c2up
do_execsql_test 3.1 {
  SELECT id FROM cx
   WHERE root=20
     AND tablename='t2'
     AND idcolumn='y'
     AND parentcolumn='x';
} {1 2 5 10 20}

# t2 first cousins of 20
do_execsql_test 3.2 {
  SELECT DISTINCT id FROM c2
   WHERE root IN (SELECT id FROM c2up
                   WHERE root=20 AND depth<=2)
   ORDER BY id;
} {5 10 11 20 21 22 23}

# t2 first cousins of 20
do_execsql_test 3.3 {
  SELECT id FROM c2
   WHERE root=(SELECT id FROM c2up
               WHERE root=20 AND depth=2)
     AND depth=2
  EXCEPT
  SELECT id FROM c2
   WHERE root=(SELECT id FROM c2up
               WHERE root=20 AND depth=1)
     AND depth<=1
   ORDER BY id;
} {22 23}

# missing tablename.
do_test 4.1 {
  catchsql {
    SELECT id FROM cx
     WHERE root=20
       AND tablename='t3'
       AND idcolumn='y'
       AND parentcolumn='x';
  }
} {1 {no such table: t3}}

# missing idcolumn
do_test 4.2 {
  catchsql {
    SELECT id FROM cx
     WHERE root=20
       AND tablename='t2'
       AND idcolumn='xyz'
       AND parentcolumn='x';
  }
} {1 {no such column: t2.xyz}}

# missing parentcolumn
do_test 4.3 {
  catchsql {
    SELECT id FROM cx
     WHERE root=20
       AND tablename='t2'
       AND idcolumn='x'
       AND parentcolumn='pqr';
  }
} {1 {no such column: t2.pqr}}

# generic closure
do_execsql_test 5.1 {
  CREATE VIRTUAL TABLE temp.closure USING transitive_closure;
  SELECT id FROM closure
   WHERE root=1
     AND depth=3
     AND tablename='t1'
     AND idcolumn='x'
     AND parentcolumn='y'
  ORDER BY id;
} {8 9 10 11 12 13 14 15}

finish_test