[sql] Import SQLite 3.17.0.

third_party/sqlite/src/ext/misc/carray.c

+/*
+** 2016-06-29
+**
+** 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 demonstrates how to create a table-valued-function that
+** returns the values in a C-language array.
+** Examples:
+**
+**      SELECT * FROM carray($ptr,5)
+**
+** The query above returns 5 integers contained in a C-language array
+** at the address $ptr.  $ptr is a pointer to the array of integers that
+** has been cast to an integer.
+**
+** There is an optional third parameter to determine the datatype of
+** the C-language array.  Allowed values of the third parameter are
+** 'int32', 'int64', 'double', 'char*'.  Example:
+**
+**      SELECT * FROM carray($ptr,10,'char*');
+**
+** HOW IT WORKS
+**
+** The carray "function" is really a virtual table with the
+** following schema:
+**
+**     CREATE TABLE carray(
+**       value,
+**       pointer HIDDEN,
+**       count HIDDEN,
+**       ctype TEXT HIDDEN
+**     );
+**
+** If the hidden columns "pointer" and "count" are unconstrained, then 
+** the virtual table has no rows.  Otherwise, the virtual table interprets
+** the integer value of "pointer" as a pointer to the array and "count"
+** as the number of elements in the array.  The virtual table steps through
+** the array, element by element.
+*/
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+#include <assert.h>
+#include <string.h>
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+/*
+** Allowed datatypes
+*/
+#define CARRAY_INT32    0
+#define CARRAY_INT64    1
+#define CARRAY_DOUBLE   2
+#define CARRAY_TEXT     3
+
+/*
+** Names of types
+*/
+static const char *azType[] = { "int32", "int64", "double", "char*" };
+
+
+/* carray_cursor is a subclass of sqlite3_vtab_cursor which will
+** serve as the underlying representation of a cursor that scans
+** over rows of the result
+*/
+typedef struct carray_cursor carray_cursor;
+struct carray_cursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  sqlite3_int64 iRowid;      /* The rowid */
+  sqlite3_int64 iPtr;        /* Pointer to array of values */
+  sqlite3_int64 iCnt;        /* Number of integers in the array */
+  unsigned char eType;       /* One of the CARRAY_type values */
+};
+
+/*
+** The carrayConnect() method is invoked to create a new
+** carray_vtab that describes the carray virtual table.
+**
+** Think of this routine as the constructor for carray_vtab objects.
+**
+** All this routine needs to do is:
+**
+**    (1) Allocate the carray_vtab object and initialize all fields.
+**
+**    (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the
+**        result set of queries against carray will look like.
+*/
+static int carrayConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  sqlite3_vtab *pNew;
+  int rc;
+
+/* Column numbers */
+#define CARRAY_COLUMN_VALUE   0
+#define CARRAY_COLUMN_POINTER 1
+#define CARRAY_COLUMN_COUNT   2
+#define CARRAY_COLUMN_CTYPE   3
+
+  rc = sqlite3_declare_vtab(db,
+     "CREATE TABLE x(value,pointer hidden,count hidden,ctype hidden)");
+  if( rc==SQLITE_OK ){
+    pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(*pNew));
+  }
+  return rc;
+}
+
+/*
+** This method is the destructor for carray_cursor objects.
+*/
+static int carrayDisconnect(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** Constructor for a new carray_cursor object.
+*/
+static int carrayOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  carray_cursor *pCur;
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  *ppCursor = &pCur->base;
+  return SQLITE_OK;
+}
+
+/*
+** Destructor for a carray_cursor.
+*/
+static int carrayClose(sqlite3_vtab_cursor *cur){
+  sqlite3_free(cur);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance a carray_cursor to its next row of output.
+*/
+static int carrayNext(sqlite3_vtab_cursor *cur){
+  carray_cursor *pCur = (carray_cursor*)cur;
+  pCur->iRowid++;
+  return SQLITE_OK;
+}
+
+/*
+** Return values of columns for the row at which the carray_cursor
+** is currently pointing.
+*/
+static int carrayColumn(
+  sqlite3_vtab_cursor *cur,   /* The cursor */
+  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
+  int i                       /* Which column to return */
+){
+  carray_cursor *pCur = (carray_cursor*)cur;
+  sqlite3_int64 x = 0;
+  switch( i ){
+    case CARRAY_COLUMN_POINTER:   x = pCur->iPtr;   break;
+    case CARRAY_COLUMN_COUNT:     x = pCur->iCnt;   break;
+    case CARRAY_COLUMN_CTYPE: {
+      sqlite3_result_text(ctx, azType[pCur->eType], -1, SQLITE_STATIC);
+      return SQLITE_OK;
+    }
+    default: {
+      switch( pCur->eType ){
+        case CARRAY_INT32: {
+          int *p = (int*)pCur->iPtr;
+          sqlite3_result_int(ctx, p[pCur->iRowid-1]);
+          return SQLITE_OK;
+        }
+        case CARRAY_INT64: {
+          sqlite3_int64 *p = (sqlite3_int64*)pCur->iPtr;
+          sqlite3_result_int64(ctx, p[pCur->iRowid-1]);
+          return SQLITE_OK;
+        }
+        case CARRAY_DOUBLE: {
+          double *p = (double*)pCur->iPtr;
+          sqlite3_result_double(ctx, p[pCur->iRowid-1]);
+          return SQLITE_OK;
+        }
+        case CARRAY_TEXT: {
+          const char **p = (const char**)pCur->iPtr;
+          sqlite3_result_text(ctx, p[pCur->iRowid-1], -1, SQLITE_TRANSIENT);
+          return SQLITE_OK;
+        }
+      }
+    }
+  }
+  sqlite3_result_int64(ctx, x);
+  return SQLITE_OK;
+}
+
+/*
+** Return the rowid for the current row.  In this implementation, the
+** rowid is the same as the output value.
+*/
+static int carrayRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  carray_cursor *pCur = (carray_cursor*)cur;
+  *pRowid = pCur->iRowid;
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the cursor has been moved off of the last
+** row of output.
+*/
+static int carrayEof(sqlite3_vtab_cursor *cur){
+  carray_cursor *pCur = (carray_cursor*)cur;
+  return pCur->iRowid>pCur->iCnt;
+}
+
+/*
+** This method is called to "rewind" the carray_cursor object back
+** to the first row of output.
+*/
+static int carrayFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  carray_cursor *pCur = (carray_cursor *)pVtabCursor;
+  if( idxNum ){
+    pCur->iPtr = sqlite3_value_int64(argv[0]);
+    pCur->iCnt = sqlite3_value_int64(argv[1]);
+    if( idxNum<3 ){
+      pCur->eType = CARRAY_INT32;
+    }else{
+      unsigned char i;
+      const char *zType = (const char*)sqlite3_value_text(argv[2]);
+      for(i=0; i<sizeof(azType)/sizeof(azType[0]); i++){
+        if( sqlite3_stricmp(zType, azType[i])==0 ) break;
+      }
+      if( i>=sizeof(azType)/sizeof(azType[0]) ){
+        pVtabCursor->pVtab->zErrMsg = sqlite3_mprintf(
+          "unknown datatype: %Q", zType);
+        return SQLITE_ERROR;
+      }else{
+        pCur->eType = i;
+      }
+    }
+  }else{
+    pCur->iPtr = 0;
+    pCur->iCnt = 0;
+  }
+  pCur->iRowid = 1;
+  return SQLITE_OK;
+}
+
+/*
+** SQLite will invoke this method one or more times while planning a query
+** that uses the carray virtual table.  This routine needs to create
+** a query plan for each invocation and compute an estimated cost for that
+** plan.
+**
+** In this implementation idxNum is used to represent the
+** query plan.  idxStr is unused.
+**
+** idxNum is 2 if the pointer= and count= constraints exist,
+** 3 if the ctype= constraint also exists, and is 0 otherwise.
+** If idxNum is 0, then carray becomes an empty table.
+*/
+static int carrayBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  int i;                 /* Loop over constraints */
+  int ptrIdx = -1;       /* Index of the pointer= constraint, or -1 if none */
+  int cntIdx = -1;       /* Index of the count= constraint, or -1 if none */
+  int ctypeIdx = -1;     /* Index of the ctype= constraint, or -1 if none */
+
+  const struct sqlite3_index_constraint *pConstraint;
+  pConstraint = pIdxInfo->aConstraint;
+  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
+    if( pConstraint->usable==0 ) continue;
+    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
+    switch( pConstraint->iColumn ){
+      case CARRAY_COLUMN_POINTER:
+        ptrIdx = i;
+        break;
+      case CARRAY_COLUMN_COUNT:
+        cntIdx = i;
+        break;
+      case CARRAY_COLUMN_CTYPE:
+        ctypeIdx = i;
+        break;
+    }
+  }
+  if( ptrIdx>=0 && cntIdx>=0 ){
+    pIdxInfo->aConstraintUsage[ptrIdx].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[ptrIdx].omit = 1;
+    pIdxInfo->aConstraintUsage[cntIdx].argvIndex = 2;
+    pIdxInfo->aConstraintUsage[cntIdx].omit = 1;
+    pIdxInfo->estimatedCost = (double)1;
+    pIdxInfo->estimatedRows = 100;
+    pIdxInfo->idxNum = 2;
+    if( ctypeIdx>=0 ){
+      pIdxInfo->aConstraintUsage[ctypeIdx].argvIndex = 3;
+      pIdxInfo->aConstraintUsage[ctypeIdx].omit = 1;
+      pIdxInfo->idxNum = 3;
+    }
+  }else{
+    pIdxInfo->estimatedCost = (double)2147483647;
+    pIdxInfo->estimatedRows = 2147483647;
+    pIdxInfo->idxNum = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** This following structure defines all the methods for the 
+** carray virtual table.
+*/
+static sqlite3_module carrayModule = {
+  0,                         /* iVersion */
+  0,                         /* xCreate */
+  carrayConnect,             /* xConnect */
+  carrayBestIndex,           /* xBestIndex */
+  carrayDisconnect,          /* xDisconnect */
+  0,                         /* xDestroy */
+  carrayOpen,                /* xOpen - open a cursor */
+  carrayClose,               /* xClose - close a cursor */
+  carrayFilter,              /* xFilter - configure scan constraints */
+  carrayNext,                /* xNext - advance a cursor */
+  carrayEof,                 /* xEof - check for end of scan */
+  carrayColumn,              /* xColumn - read data */
+  carrayRowid,               /* xRowid - read data */
+  0,                         /* xUpdate */
+  0,                         /* xBegin */
+  0,                         /* xSync */
+  0,                         /* xCommit */
+  0,                         /* xRollback */
+  0,                         /* xFindMethod */
+  0,                         /* xRename */
+};
+
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_carray_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  int rc = SQLITE_OK;
+  SQLITE_EXTENSION_INIT2(pApi);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  rc = sqlite3_create_module(db, "carray", &carrayModule, 0);
+#endif
+  return rc;
+}