Infrastructure for the bytecode() table-valued function. The function itself

is not yet implemented.

FossilOrigin-Name: 2795f0d633577e0de66b389d9e8e44c55e85975bdc62f1a0b8f93959d19b22bf

4 files changed, 235 insertions, 0 deletions

diff --git a/src/ctime.c b/src/ctime.c
index 7a2ace931..b104b35db 100644
--- a/src/ctime.c
+++ b/src/ctime.c
@@ -193,6 +193,9 @@ static const char * const sqlite3azCompileOpt[] = {
 #if SQLITE_ENABLE_BATCH_ATOMIC_WRITE
   "ENABLE_BATCH_ATOMIC_WRITE",
 #endif
+#if SQLITE_ENABLE_BYTECODE_VTAB
+  "ENABLE_BYTECODE_VTAB",
+#endif
 #if SQLITE_ENABLE_CEROD
   "ENABLE_CEROD=" CTIMEOPT_VAL(SQLITE_ENABLE_CEROD),
 #endif
diff --git a/src/main.c b/src/main.c
index 98e030fad..24cbe8bdb 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3346,6 +3346,12 @@ static int openDatabase(
   }
 #endif
 
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+  if( !db->mallocFailed && rc==SQLITE_OK){
+    rc = sqlite3VdbeBytecodeVtabInit(db);
+  }
+#endif
+
 #ifdef SQLITE_ENABLE_INTERNAL_FUNCTIONS
   /* Testing use only!!! The -DSQLITE_ENABLE_INTERNAL_FUNCTIONS=1 compile-time
   ** option gives access to internal functions by default.  
diff --git a/src/vdbe.h b/src/vdbe.h
index 482331eff..38b43eb71 100644
--- a/src/vdbe.h
+++ b/src/vdbe.h
@@ -290,6 +290,9 @@ void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
 int sqlite3VdbeHasSubProgram(Vdbe*);
 
 int sqlite3NotPureFunc(sqlite3_context*);
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+int sqlite3VdbeBytecodeVtabInit(sqlite3*);
+#endif
 
 /* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
 ** each VDBE opcode.
diff --git a/src/vdbevtab.c b/src/vdbevtab.c
new file mode 100644
index 000000000..b2994cb25
--- /dev/null
+++ b/src/vdbevtab.c
@@ -0,0 +1,223 @@
+/*
+** 2020-03-23
+**
+** 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 implements virtual-tables for examining the bytecode content
+** of a prepared statement.
+*/
+#ifdef SQLITE_ENABLE_BYTECODE_VTAB
+#include "sqliteInt.h"
+#include "vdbeInt.h"
+
+/* An instance of the bytecode() table-valued function.
+*/
+typedef struct bytecodevtab_vtab bytecodevtab_vtab;
+struct bytecodevtab_vtab {
+  sqlite3_vtab base;     /* Base class - must be first */
+  sqlite3_stmt *pStmt;   /* The statement whose bytecode is to be displayed */
+};
+
+/* A cursor for scanning through the bytecode
+*/
+typedef struct bytecodevtab_cursor bytecodevtab_cursor;
+struct bytecodevtab_cursor {
+  sqlite3_vtab_cursor base;  /* Base class - must be first */
+  sqlite3_int64 iRowid;      /* The rowid */
+};
+
+/*
+** Create a new bytecode() table-valued function.
+*/
+static int bytecodevtabConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  bytecodevtab_vtab *pNew;
+  int rc;
+
+  rc = sqlite3_declare_vtab(db,
+         "CREATE TABLE x("
+           "addr INT,"
+           "opcode TEXT,"
+           "p1 INT,"
+           "p2 INT,"
+           "p3 INT,"
+           "p4 TEXT,"
+           "p5 INT,"
+           "comment TEXT,"
+           "subprog TEXT," 
+           "stmt HIDDEN"
+         ");"
+       );
+  if( rc==SQLITE_OK ){
+    pNew = sqlite3_malloc( sizeof(*pNew) );
+    *ppVtab = (sqlite3_vtab*)pNew;
+    if( pNew==0 ) return SQLITE_NOMEM;
+    memset(pNew, 0, sizeof(*pNew));
+  }
+  return rc;
+}
+
+/*
+** This method is the destructor for bytecodevtab_vtab objects.
+*/
+static int bytecodevtabDisconnect(sqlite3_vtab *pVtab){
+  bytecodevtab_vtab *p = (bytecodevtab_vtab*)pVtab;
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Constructor for a new bytecodevtab_cursor object.
+*/
+static int bytecodevtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
+  bytecodevtab_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 bytecodevtab_cursor.
+*/
+static int bytecodevtabClose(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  sqlite3_free(pCur);
+  return SQLITE_OK;
+}
+
+
+/*
+** Advance a bytecodevtab_cursor to its next row of output.
+*/
+static int bytecodevtabNext(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  pCur->iRowid++;
+  return SQLITE_OK;
+}
+
+/*
+** Return values of columns for the row at which the bytecodevtab_cursor
+** is currently pointing.
+*/
+static int bytecodevtabColumn(
+  sqlite3_vtab_cursor *cur,   /* The cursor */
+  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
+  int i                       /* Which column to return */
+){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+#if 0
+  switch( i ){
+    case TEMPLATEVTAB_A:
+      sqlite3_result_int(ctx, 1000 + pCur->iRowid);
+      break;
+    default:
+      assert( i==TEMPLATEVTAB_B );
+      sqlite3_result_int(ctx, 2000 + pCur->iRowid);
+      break;
+  }
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Return the rowid for the current row.  In this implementation, the
+** rowid is the same as the output value.
+*/
+static int bytecodevtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  bytecodevtab_cursor *pCur = (bytecodevtab_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 bytecodevtabEof(sqlite3_vtab_cursor *cur){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
+  return pCur->iRowid>=10;
+}
+
+/*
+** This method is called to "rewind" the bytecodevtab_cursor object back
+** to the first row of output.  This method is always called at least
+** once prior to any call to bytecodevtabColumn() or bytecodevtabRowid() or 
+** bytecodevtabEof().
+*/
+static int bytecodevtabFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  bytecodevtab_cursor *pCur = (bytecodevtab_cursor *)pVtabCursor;
+  pCur->iRowid = 1;
+  return SQLITE_OK;
+}
+
+/*
+** SQLite will invoke this method one or more times while planning a query
+** that uses the virtual table.  This routine needs to create
+** a query plan for each invocation and compute an estimated cost for that
+** plan.
+*/
+static int bytecodevtabBestIndex(
+  sqlite3_vtab *tab,
+  sqlite3_index_info *pIdxInfo
+){
+  pIdxInfo->estimatedCost = (double)10;
+  pIdxInfo->estimatedRows = 10;
+  return SQLITE_OK;
+}
+
+/*
+** This following structure defines all the methods for the 
+** virtual table.
+*/
+static sqlite3_module bytecodevtabModule = {
+  /* iVersion    */ 0,
+  /* xCreate     */ 0,
+  /* xConnect    */ bytecodevtabConnect,
+  /* xBestIndex  */ bytecodevtabBestIndex,
+  /* xDisconnect */ bytecodevtabDisconnect,
+  /* xDestroy    */ 0,
+  /* xOpen       */ bytecodevtabOpen,
+  /* xClose      */ bytecodevtabClose,
+  /* xFilter     */ bytecodevtabFilter,
+  /* xNext       */ bytecodevtabNext,
+  /* xEof        */ bytecodevtabEof,
+  /* xColumn     */ bytecodevtabColumn,
+  /* xRowid      */ bytecodevtabRowid,
+  /* xUpdate     */ 0,
+  /* xBegin      */ 0,
+  /* xSync       */ 0,
+  /* xCommit     */ 0,
+  /* xRollback   */ 0,
+  /* xFindMethod */ 0,
+  /* xRename     */ 0,
+  /* xSavepoint  */ 0,
+  /* xRelease    */ 0,
+  /* xRollbackTo */ 0,
+  /* xShadowName */ 0
+};
+
+
+int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){
+  int rc;
+  rc = sqlite3_create_module(db, "bytecodevtab", &bytecodevtabModule, 0);
+  return rc;
+}
+#endif /* SQLITE_ENABLE_BYTECODE_VTAB */