From: drh <drh@noemail.net>
Date: Mon, 25 Oct 2004 20:33:44 +0000 (+0000)
Subject: Minor optimizations in the pragma module. (CVS 2029)
X-Git-Tag: version-3.1.0~228
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=722e95ac65d681835cb1477027147532126e8651;p=thirdparty%2Fsqlite.git

Minor optimizations in the pragma module. (CVS 2029)

FossilOrigin-Name: 63efd50a1608eb4ccac44a233c0f77c3956f9fa0
---

diff --git a/manifest b/manifest
index 147f1b1641..5f4e35ecc7 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Tighter\sencoding\sof\sthe\skeyword\shash\stable\sin\sthe\stokenizer.\s(CVS\s2028)
-D 2004-10-23T05:10:18
+C Minor\soptimizations\sin\sthe\spragma\smodule.\s(CVS\s2029)
+D 2004-10-25T20:33:44
 F Makefile.in 52c1cc106cad9148d4b7cb387b458e82dc86b339
 F Makefile.linux-gcc a9e5a0d309fa7c38e7c14d3ecf7690879d3a5457
 F README a01693e454a00cc117967e3f9fdab2d4d52e9bc1
@@ -20,7 +20,7 @@ F ltmain.sh f6b283068efa69f06eb8aa1fe4bddfdbdeb35826
 F main.mk bf65bb9f839aa8777796c9846816be590a7cd4b0
 F mkdll.sh 468d4f41d3ea98221371df4825cfbffbaac4d7e4
 F mkopcodec.awk 80311cdeb16d78017cc62e4ad6c6d008e5fe0e17
-F mkopcodeh.awk 877459a51b4c75a99d7336159790aca51e4c2cad
+F mkopcodeh.awk 4090944e4de0a2ccb99aa0083290f73bce4db406
 F mkso.sh 7b67da1d63070875ba948e749aee9ef50ce36e3d
 F publish.sh 72bde067dda3fc2d33e92f20253b924e3b97da30
 F spec.template b2f6c4e488cbc3b993a57deba22cbc36203c4da3
@@ -56,7 +56,7 @@ F src/os_win.h 41a946bea10f61c158ce8645e7646b29d44f122b
 F src/pager.c cc2e7fb3d7913862d7b1170f923d2dcfdbac3bed
 F src/pager.h 774d1973acbda341827d21b0da0150575d69f7d9
 F src/parse.y 8d97a91cba7e35b5eaac064c9f6e597dc6442b29
-F src/pragma.c 2b65e0150ca1af8041c3db95e7b1c41dc51a3e95
+F src/pragma.c 263e20f7640df1e7937f1c71372fa286356aaf09
 F src/printf.c 7a92adc00b758cd5ce087dae80181a8bbdb70ed2
 F src/random.c eff68e3f257e05e81eae6c4d50a51eb88beb4ff3
 F src/select.c de51ec24aef0d5370819dac6c2613460effac42c
@@ -252,7 +252,7 @@ F www/tclsqlite.tcl 560ecd6a916b320e59f2917317398f3d59b7cc25
 F www/vdbe.tcl 59288db1ac5c0616296b26dce071c36cb611dfe9
 F www/version3.tcl 092a01f5ef430d2c4acc0ae558d74c4bb89638a0
 F www/whentouse.tcl fdacb0ba2d39831e8a6240d05a490026ad4c4e4c
-P 39f7870a54d90d5163fcad3f08cd63699c4bb567
-R f3fcd5be76f79a1c63d8d5fffbad49dd
+P 7b9886f8d4db366bc7dbf25495f0d3b907d25689
+R e866ede2f03d84f2dce38e1442866c10
 U drh
-Z 91960f90f1e7a02a6b795447e3b7377d
+Z 5a8b8e324cda1249d7cb76835accaa40
diff --git a/manifest.uuid b/manifest.uuid
index 836ed52f45..e7ace73758 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-7b9886f8d4db366bc7dbf25495f0d3b907d25689
\ No newline at end of file
+63efd50a1608eb4ccac44a233c0f77c3956f9fa0
\ No newline at end of file
diff --git a/mkopcodeh.awk b/mkopcodeh.awk
index ead07d5ff9..44a12cc242 100644
--- a/mkopcodeh.awk
+++ b/mkopcodeh.awk
@@ -1,5 +1,7 @@
 #!/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.  
@@ -12,6 +14,15 @@
 # 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_/ {
diff --git a/src/pragma.c b/src/pragma.c
index dbe00f70cd..d238d4264f 100644
--- a/src/pragma.c
+++ b/src/pragma.c
@@ -11,7 +11,7 @@
 *************************************************************************
 ** This file contains code used to implement the PRAGMA command.
 **
-** $Id: pragma.c,v 1.71 2004/10/22 20:29:22 drh Exp $
+** $Id: pragma.c,v 1.72 2004/10/25 20:33:44 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -21,22 +21,6 @@
 # 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 
@@ -47,30 +31,32 @@ static int getBoolean(const u8 *z){
 ** 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) ){
+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);
   }
-  for(i=0; i<sizeof(aKey)/sizeof(aKey[0]); i++){
-    if( sqlite3StrICmp(z,aKey[i].zWord)==0 ) return aKey[i].val;
+  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
@@ -130,7 +116,7 @@ static void returnSingleInt(Parse *pParse, const char *zLabel, int value){
 ** Also, implement the pragma.
 */
 static int flagPragma(Parse *pParse, const char *zLeft, const char *zRight){
-  static const struct {
+  static const struct sPragmaType {
     const char *zName;  /* Name of the pragma */
     int mask;           /* Mask for the db->flags value */
   } aPragma[] = {
@@ -141,24 +127,24 @@ static int flagPragma(Parse *pParse, const char *zLeft, const char *zRight){
     { "short_column_names",       SQLITE_ShortColNames },
     { "count_changes",            SQLITE_CountRows     },
     { "empty_result_callbacks",   SQLITE_NullCallback  },
-/* The following is VERY experimental */
+    /* 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 ){
+  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,
-               aPragma[i].zName, (db->flags&aPragma[i].mask)!=0);
+          returnSingleInt(pParse, p->zName, (db->flags & p->mask)!=0 );
         }
       }else if( getBoolean(zRight) ){
-        db->flags |= aPragma[i].mask;
+        db->flags |= p->mask;
       }else{
-        db->flags &= ~aPragma[i].mask;
+        db->flags &= ~p->mask;
       }
       return 1;
     }