SQLite

/*
** Compile and run this standalone program in order to generate code that
** implements a function that will translate alphabetic identifiers into
** parser token codes.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>

/*
** A header comment placed at the beginning of generated code.
*/
static const char zHdr[] = 
  "/***** This file contains automatically generated code ******\n"
  "**\n"
  "** The code in this file has been automatically generated by\n"
  "**\n"
  "**     $Header: /home/drh/sqlite/trans/cvs/sqlite/sqlite/tool/mkkeywordhash.c,v 1.38 2009/06/09 14:27:41 drh Exp $\n"
  "**\n"
  "** The code in this file implements a function that determines whether\n"
  "** or not a given identifier is really an SQL keyword.  The same thing\n"
  "** might be implemented more directly using a hand-written hash table.\n"
  "** But by using this automatically generated code, the size of the code\n"
  "** is substantially reduced.  This is important for embedded applications\n"
  "** on platforms with limited memory.\n"

  int offset;          /* Offset to start of name string */
  int len;             /* Length of this keyword, not counting final \000 */
  int prefix;          /* Number of characters in prefix */
  int longestSuffix;   /* Longest suffix that is a prefix on another word */
  int iNext;           /* Index in aKeywordTable[] of next with same hash */
  int substrId;        /* Id to another keyword this keyword is embedded in */
  int substrOffset;    /* Offset into substrId for start of this keyword */
  char zOrigName[20];  /* Original keyword name before processing */
};

/*
** Define masks used to determine which keywords are allowed
*/
#ifdef SQLITE_OMIT_ALTERTABLE
#  define ALTER      0

  }
  nKeyword = j;

  /* Fill in the lengths of strings and hashes for all entries. */
  for(i=0; i<nKeyword; i++){
    Keyword *p = &aKeywordTable[i];
    p->len = strlen(p->zName);
    assert( p->len<sizeof(p->zOrigName) );
    strcpy(p->zOrigName, p->zName);
    totalLen += p->len;
    p->hash = (UpperToLower[(int)p->zName[0]]*4) ^
              (UpperToLower[(int)p->zName[p->len-1]]*3) ^ p->len;
    p->id = i+1;
  }

  /* Sort the table from shortest to longest keyword */

         "      (charMap(z[n-1])*3) ^\n"
         "      n) %% %d;\n", bestSize);
  printf("  for(i=((int)aHash[h])-1; i>=0; i=((int)aNext[i])-1){\n");
  printf("    if( aLen[i]==n &&"
                   " sqlite3StrNICmp(&zText[aOffset[i]],z,n)==0 ){\n");
  for(i=0; i<nKeyword; i++){
    printf("      testcase( i==%d ); /* %s */\n",
           i, aKeywordTable[i].zOrigName);
  }
  printf("      return aCode[i];\n");
  printf("    }\n");
  printf("  }\n");
  printf("  return TK_ID;\n");
  printf("}\n");
  printf("int sqlite3KeywordCode(const unsigned char *z, int n){\n");
  printf("  return keywordCode((char*)z, n);\n");
  printf("}\n");

  return 0;
}