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Overview
Comment:Minor optimizations in the pragma module. (CVS 2029)
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SHA1:63efd50a1608eb4ccac44a233c0f77c3956f9fa0
User & Date: drh 2004-10-25 20:33:44
Context
2004-10-26
00:08
Fix a bug in the ".databases" command of the command-line shell. Ticket #973 (CVS 2030) check-in: 507d8e6f user: drh tags: trunk
2004-10-25
20:33
Minor optimizations in the pragma module. (CVS 2029) check-in: 63efd50a user: drh tags: trunk
2004-10-23
05:10
Tighter encoding of the keyword hash table in the tokenizer. (CVS 2028) check-in: 7b9886f8 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to mkopcodeh.awk.

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#!/usr/bin/awk -f


#
# This AWK script scans a concatenation of the parse.h output file from the
# parser and the vdbe.c source file in order to generate the opcodes numbers
# for all opcodes.  
#
# The lines of the vdbe.c that we are interested in are of the form:
#
#       case OP_aaaa:      /* same as TK_bbbbb */
#
# The TK_ comment is optional.  If it is present, then the value assigned to
# the OP_ is the same as the TK_ value.  If missing, the OP_ value is assigned
# a small integer that is different from every other OP_ value.









#

# Remember the TK_ values from the parse.h file
/^#define TK_/ {
  tk[$2] = $3
}


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#!/usr/bin/awk -f
#
# Generate the file opcodes.h.
#
# This AWK script scans a concatenation of the parse.h output file from the
# parser and the vdbe.c source file in order to generate the opcodes numbers
# for all opcodes.  
#
# The lines of the vdbe.c that we are interested in are of the form:
#
#       case OP_aaaa:      /* same as TK_bbbbb */
#
# The TK_ comment is optional.  If it is present, then the value assigned to
# the OP_ is the same as the TK_ value.  If missing, the OP_ value is assigned
# a small integer that is different from every other OP_ value.
#
# We go to the trouble of making some OP_ value the same as TK_ values
# as an optimization.  During parsing, things like expression operators
# are coded with TK_ values such as TK_ADD, TK_DIVIDE, and so forth.  Later
# during code generation, we need to generate corresponding opcodes like
# OP_Add and OP_Divide.  By making TK_ADD==OP_Add and TK_DIVIDE==OP_Divide,
# code to translation from one to the other is avoided.  This makes the
# code generator run (infinitesimally) faster and more importantly it makes
# the total library smaller.
#

# Remember the TK_ values from the parse.h file
/^#define TK_/ {
  tk[$2] = $3
}

Changes to src/pragma.c.

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**    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 used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.71 2004/10/22 20:29:22 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"
#endif

/*
** Interpret the given string as a boolean value.
*/
static int getBoolean(const u8 *z){
  static const u8 *azTrue[] = { "yes", "on", "true" };
  int i;
  if( z[0]==0 ) return 0;
  if( sqlite3IsNumber(z, 0, SQLITE_UTF8) ){
    return atoi(z);
  }
  for(i=0; i<sizeof(azTrue)/sizeof(azTrue[0]); i++){
    if( sqlite3StrICmp(z,azTrue[i])==0 ) return 1;
  }
  return 0;
}

/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.
**
** Note that the values returned are one less that the values that
** should be passed into sqlite3BtreeSetSafetyLevel().  The is done
** to support legacy SQL code.  The safety level used to be boolean
** and older scripts may have used numbers 0 for OFF and 1 for ON.
*/
static int getSafetyLevel(u8 *z){
  static const struct {
    const u8 *zWord;
    int val;
  } aKey[] = {
    { "no",    0 },
    { "off",   0 },
    { "false", 0 },
    { "yes",   1 },
    { "on",    1 },
    { "true",  1 },
    { "full",  2 },
  };
  int i;
  if( z[0]==0 ) return 1;
  if( sqlite3IsNumber(z, 0, SQLITE_UTF8) ){
    return atoi(z);
  }
  for(i=0; i<sizeof(aKey)/sizeof(aKey[0]); i++){
    if( sqlite3StrICmp(z,aKey[i].zWord)==0 ) return aKey[i].val;
  }
  return 1;
}








/*
** Interpret the given string as a temp db location. Return 1 for file
** backed temporary databases, 2 for the Red-Black tree in memory database
** and 0 to use the compile-time default.
*/
static int getTempStore(const char *z){
................................................................................

/*
** Check to see if zRight and zLeft refer to a pragma that queries
** or changes one of the flags in db->flags.  Return 1 if so and 0 if not.
** Also, implement the pragma.
*/
static int flagPragma(Parse *pParse, const char *zLeft, const char *zRight){
  static const struct {
    const char *zName;  /* Name of the pragma */
    int mask;           /* Mask for the db->flags value */
  } aPragma[] = {
    { "vdbe_trace",               SQLITE_VdbeTrace     },
    { "sql_trace",                SQLITE_SqlTrace      },
    { "vdbe_listing",             SQLITE_VdbeListing   },
    { "full_column_names",        SQLITE_FullColNames  },
    { "short_column_names",       SQLITE_ShortColNames },
    { "count_changes",            SQLITE_CountRows     },
    { "empty_result_callbacks",   SQLITE_NullCallback  },
/* The following is VERY experimental */
    { "writable_schema",          SQLITE_WriteSchema   },
  };
  int i;

  for(i=0; i<sizeof(aPragma)/sizeof(aPragma[0]); i++){
    if( sqlite3StrICmp(zLeft, aPragma[i].zName)==0 ){
      sqlite3 *db = pParse->db;
      Vdbe *v;
      if( zRight==0 ){
        v = sqlite3GetVdbe(pParse);
        if( v ){
          returnSingleInt(pParse,
               aPragma[i].zName, (db->flags&aPragma[i].mask)!=0);
        }
      }else if( getBoolean(zRight) ){
        db->flags |= aPragma[i].mask;
      }else{
        db->flags &= ~aPragma[i].mask;
      }
      return 1;
    }
  }
  return 0;
}








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**    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 used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.72 2004/10/25 20:33:44 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"
#endif

















/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.
**
** Note that the values returned are one less that the values that
** should be passed into sqlite3BtreeSetSafetyLevel().  The is done
** to support legacy SQL code.  The safety level used to be boolean
** and older scripts may have used numbers 0 for OFF and 1 for ON.
*/
static int getSafetyLevel(const u8 *z){
                             /* 123456789 123456789 */
  static const char zText[] = "onoffalseyestruefull";
  static const u8 iOffset[] = {0, 1, 2, 4, 9, 12, 16};
  static const u8 iLength[] = {2, 2, 3, 5, 3, 4, 4};
  static const u8 iValue[] =  {1, 0, 0, 0, 1, 1, 2};
  int i, n;
  if( isdigit(*z) ){
    return atoi(z);
  }
  n = strlen(z);
  for(i=0; i<sizeof(iLength); i++){
    if( iLength[i]==n && sqlite3StrNICmp(&zText[iOffset[i]],z,n)==0 ){
      return iValue[i];
    }





  }
  return 1;
}

/*
** Interpret the given string as a boolean value.
*/
static int getBoolean(const u8 *z){
  return getSafetyLevel(z)&1;
}

/*
** Interpret the given string as a temp db location. Return 1 for file
** backed temporary databases, 2 for the Red-Black tree in memory database
** and 0 to use the compile-time default.
*/
static int getTempStore(const char *z){
................................................................................

/*
** Check to see if zRight and zLeft refer to a pragma that queries
** or changes one of the flags in db->flags.  Return 1 if so and 0 if not.
** Also, implement the pragma.
*/
static int flagPragma(Parse *pParse, const char *zLeft, const char *zRight){
  static const struct sPragmaType {
    const char *zName;  /* Name of the pragma */
    int mask;           /* Mask for the db->flags value */
  } aPragma[] = {
    { "vdbe_trace",               SQLITE_VdbeTrace     },
    { "sql_trace",                SQLITE_SqlTrace      },
    { "vdbe_listing",             SQLITE_VdbeListing   },
    { "full_column_names",        SQLITE_FullColNames  },
    { "short_column_names",       SQLITE_ShortColNames },
    { "count_changes",            SQLITE_CountRows     },
    { "empty_result_callbacks",   SQLITE_NullCallback  },
    /* The following is VERY experimental */
    { "writable_schema",          SQLITE_WriteSchema   },
  };
  int i;
  const struct sPragmaType *p;
  for(i=0, p=aPragma; i<sizeof(aPragma)/sizeof(aPragma[0]); i++, p++){
    if( sqlite3StrICmp(zLeft, p->zName)==0 ){
      sqlite3 *db = pParse->db;
      Vdbe *v;
      if( zRight==0 ){
        v = sqlite3GetVdbe(pParse);
        if( v ){
          returnSingleInt(pParse, p->zName, (db->flags & p->mask)!=0 );

        }
      }else if( getBoolean(zRight) ){
        db->flags |= p->mask;
      }else{
        db->flags &= ~p->mask;
      }
      return 1;
    }
  }
  return 0;
}