vendor/sqlite3/sqlite-3370100

1 files changed, 300 insertions, 0 deletions

diff --git a/ext/misc/stmt.c b/ext/misc/stmt.c
new file mode 100644
index 000000000000..876b0e5cb60f
--- /dev/null
+++ b/ext/misc/stmt.c
@@ -0,0 +1,300 @@
+/*
+** 2017-05-31
+**
+** 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 an eponymous virtual table that returns information
+** about all prepared statements for the database connection.
+**
+** Usage example:
+**
+**     .load ./stmt
+**     .mode line
+**     .header on
+**     SELECT * FROM stmt;
+*/
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_STMTVTAB)
+#if !defined(SQLITEINT_H)
+#include "sqlite3ext.h"
+#endif
+SQLITE_EXTENSION_INIT1
+#include <assert.h>
+#include <string.h>
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+/* stmt_vtab is a subclass of sqlite3_vtab which will
+** serve as the underlying representation of a stmt virtual table
+*/
+typedef struct stmt_vtab stmt_vtab;
+struct stmt_vtab {
+  sqlite3_vtab base;  /* Base class - must be first */
+  sqlite3 *db;        /* Database connection for this stmt vtab */
+};
+
+/* stmt_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 stmt_cursor stmt_cursor;
+struct stmt_cursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  sqlite3 *db;               /* Database connection for this cursor */
+  sqlite3_stmt *pStmt;       /* Statement cursor is currently pointing at */
+  sqlite3_int64 iRowid;      /* The rowid */
+};
+
+/*
+** The stmtConnect() method is invoked to create a new
+** stmt_vtab that describes the stmt virtual table.
+**
+** Think of this routine as the constructor for stmt_vtab objects.
+**
+** All this routine needs to do is:
+**
+**    (1) Allocate the stmt_vtab object and initialize all fields.
+**
+**    (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the
+**        result set of queries against stmt will look like.
+*/
+static int stmtConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  stmt_vtab *pNew;
+  int rc;
+
+/* Column numbers */
+#define STMT_COLUMN_SQL     0   /* SQL for the statement */
+#define STMT_COLUMN_NCOL    1   /* Number of result columns */
+#define STMT_COLUMN_RO      2   /* True if read-only */
+#define STMT_COLUMN_BUSY    3   /* True if currently busy */
+#define STMT_COLUMN_NSCAN   4   /* SQLITE_STMTSTATUS_FULLSCAN_STEP */
+#define STMT_COLUMN_NSORT   5   /* SQLITE_STMTSTATUS_SORT */
+#define STMT_COLUMN_NAIDX   6   /* SQLITE_STMTSTATUS_AUTOINDEX */
+#define STMT_COLUMN_NSTEP   7   /* SQLITE_STMTSTATUS_VM_STEP */
+#define STMT_COLUMN_REPREP  8   /* SQLITE_STMTSTATUS_REPREPARE */
+#define STMT_COLUMN_RUN     9   /* SQLITE_STMTSTATUS_RUN */
+#define STMT_COLUMN_MEM    10   /* SQLITE_STMTSTATUS_MEMUSED */
+
+
+  rc = sqlite3_declare_vtab(db,
+     "CREATE TABLE x(sql,ncol,ro,busy,nscan,nsort,naidx,nstep,"
+                    "reprep,run,mem)");
+  if( rc==SQLITE_OK ){
+    pNew = sqlite3_malloc( sizeof(*pNew) );
+    *ppVtab = (sqlite3_vtab*)pNew;
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(*pNew));
+    pNew->db = db;
+  }
+  return rc;
+}
+
+/*
+** This method is the destructor for stmt_cursor objects.
+*/
+static int stmtDisconnect(sqlite3_vtab *pVtab){
+  sqlite3_free(pVtab);
+  return SQLITE_OK;
+}
+
+/*
+** Constructor for a new stmt_cursor object.
+*/
+static int stmtOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  stmt_cursor *pCur;
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  pCur->db = ((stmt_vtab*)p)->db;
+  *ppCursor = &pCur->base;
+  return SQLITE_OK;
+}
+
+/*
+** Destructor for a stmt_cursor.
+*/
+static int stmtClose(sqlite3_vtab_cursor *cur){
+  sqlite3_free(cur);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance a stmt_cursor to its next row of output.
+*/
+static int stmtNext(sqlite3_vtab_cursor *cur){
+  stmt_cursor *pCur = (stmt_cursor*)cur;
+  pCur->iRowid++;
+  pCur->pStmt = sqlite3_next_stmt(pCur->db, pCur->pStmt);
+  return SQLITE_OK;
+}
+
+/*
+** Return values of columns for the row at which the stmt_cursor
+** is currently pointing.
+*/
+static int stmtColumn(
+  sqlite3_vtab_cursor *cur,   /* The cursor */
+  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
+  int i                       /* Which column to return */
+){
+  stmt_cursor *pCur = (stmt_cursor*)cur;
+  switch( i ){
+    case STMT_COLUMN_SQL: {
+      sqlite3_result_text(ctx, sqlite3_sql(pCur->pStmt), -1, SQLITE_TRANSIENT);
+      break;
+    }
+    case STMT_COLUMN_NCOL: {
+      sqlite3_result_int(ctx, sqlite3_column_count(pCur->pStmt));
+      break;
+    }
+    case STMT_COLUMN_RO: {
+      sqlite3_result_int(ctx, sqlite3_stmt_readonly(pCur->pStmt));
+      break;
+    }
+    case STMT_COLUMN_BUSY: {
+      sqlite3_result_int(ctx, sqlite3_stmt_busy(pCur->pStmt));
+      break;
+    }
+    default: {
+      assert( i==STMT_COLUMN_MEM );
+      i = SQLITE_STMTSTATUS_MEMUSED + 
+            STMT_COLUMN_NSCAN - SQLITE_STMTSTATUS_FULLSCAN_STEP;
+      /* Fall thru */
+    }
+    case STMT_COLUMN_NSCAN:
+    case STMT_COLUMN_NSORT:
+    case STMT_COLUMN_NAIDX:
+    case STMT_COLUMN_NSTEP:
+    case STMT_COLUMN_REPREP:
+    case STMT_COLUMN_RUN: {
+      sqlite3_result_int(ctx, sqlite3_stmt_status(pCur->pStmt,
+                      i-STMT_COLUMN_NSCAN+SQLITE_STMTSTATUS_FULLSCAN_STEP, 0));
+      break;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Return the rowid for the current row.  In this implementation, the
+** rowid is the same as the output value.
+*/
+static int stmtRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  stmt_cursor *pCur = (stmt_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 stmtEof(sqlite3_vtab_cursor *cur){
+  stmt_cursor *pCur = (stmt_cursor*)cur;
+  return pCur->pStmt==0;
+}
+
+/*
+** This method is called to "rewind" the stmt_cursor object back
+** to the first row of output.  This method is always called at least
+** once prior to any call to stmtColumn() or stmtRowid() or 
+** stmtEof().
+*/
+static int stmtFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  stmt_cursor *pCur = (stmt_cursor *)pVtabCursor;
+  pCur->pStmt = 0;
+  pCur->iRowid = 0;
+  return stmtNext(pVtabCursor);
+}
+
+/*
+** SQLite will invoke this method one or more times while planning a query
+** that uses the stmt virtual table.  This routine needs to create
+** a query plan for each invocation and compute an estimated cost for that
+** plan.
+*/
+static int stmtBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  pIdxInfo->estimatedCost = (double)500;
+  pIdxInfo->estimatedRows = 500;
+  return SQLITE_OK;
+}
+
+/*
+** This following structure defines all the methods for the 
+** stmt virtual table.
+*/
+static sqlite3_module stmtModule = {
+  0,                         /* iVersion */
+  0,                         /* xCreate */
+  stmtConnect,               /* xConnect */
+  stmtBestIndex,             /* xBestIndex */
+  stmtDisconnect,            /* xDisconnect */
+  0,                         /* xDestroy */
+  stmtOpen,                  /* xOpen - open a cursor */
+  stmtClose,                 /* xClose - close a cursor */
+  stmtFilter,                /* xFilter - configure scan constraints */
+  stmtNext,                  /* xNext - advance a cursor */
+  stmtEof,                   /* xEof - check for end of scan */
+  stmtColumn,                /* xColumn - read data */
+  stmtRowid,                 /* xRowid - read data */
+  0,                         /* xUpdate */
+  0,                         /* xBegin */
+  0,                         /* xSync */
+  0,                         /* xCommit */
+  0,                         /* xRollback */
+  0,                         /* xFindMethod */
+  0,                         /* xRename */
+  0,                         /* xSavepoint */
+  0,                         /* xRelease */
+  0,                         /* xRollbackTo */
+  0,                         /* xShadowName */
+};
+
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+int sqlite3StmtVtabInit(sqlite3 *db){
+  int rc = SQLITE_OK;
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  rc = sqlite3_create_module(db, "sqlite_stmt", &stmtModule, 0);
+#endif
+  return rc;
+}
+
+#ifndef SQLITE_CORE
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_stmt_init(
+  sqlite3 *db, 
+  char **pzErrMsg, 
+  const sqlite3_api_routines *pApi
+){
+  int rc = SQLITE_OK;
+  SQLITE_EXTENSION_INIT2(pApi);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  rc = sqlite3StmtVtabInit(db);
+#endif
+  return rc;
+}
+#endif /* SQLITE_CORE */
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_STMTVTAB) */