/*
** 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>

/*
** All the keywords of the SQL language are stored as in a hash
** table composed of instances of the following structure.
*/
typedef struct Keyword Keyword;
struct Keyword {
  char *zName;         /* The keyword name */
  char *zTokenType;    /* Token value for this keyword */
  int mask;            /* Code this keyword if non-zero */
  int id;              /* Unique ID for this record */
  int hash;            /* Hash on the keyword */
  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 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 */
};

/*
** Define masks used to determine which keywords are allowed
*/
#ifdef SQLITE_OMIT_ALTERTABLE
#  define ALTER      0
#else
#  define ALTER      0x00000001
#endif
#define ALWAYS       0x00000002
#ifdef SQLITE_OMIT_ANALYZE
#  define ANALYZE    0
#else
#  define ANALYZE    0x00000004
#endif
#ifdef SQLITE_OMIT_ATTACH
#  define ATTACH     0
#else
#  define ATTACH     0x00000008
#endif
#ifdef SQLITE_OMIT_AUTOINCREMENT
#  define AUTOINCR   0
#else
#  define AUTOINCR   0x00000010
#endif
#ifdef SQLITE_OMIT_CAST
#  define CAST       0
#else
#  define CAST       0x00000020
#endif
#ifdef SQLITE_OMIT_COMPOUND_SELECT
#  define COMPOUND   0
#else
#  define COMPOUND   0x00000040
#endif
#ifdef SQLITE_OMIT_CONFLICT_CLAUSE
#  define CONFLICT   0
#else
#  define CONFLICT   0x00000080
#endif
#ifdef SQLITE_OMIT_EXPLAIN
#  define EXPLAIN    0
#else
#  define EXPLAIN    0x00000100
#endif
#ifdef SQLITE_OMIT_FOREIGN_KEY
#  define FKEY       0
#else
#  define FKEY       0x00000200
#endif
#ifdef SQLITE_OMIT_PRAGMA
#  define PRAGMA     0
#else
#  define PRAGMA     0x00000400
#endif
#ifdef SQLITE_OMIT_REINDEX
#  define REINDEX    0
#else
#  define REINDEX    0x00000800
#endif
#ifdef SQLITE_OMIT_SUBQUERY
#  define SUBQUERY   0
#else
#  define SUBQUERY   0x00001000
#endif
#ifdef SQLITE_OMIT_TRIGGER
#  define TRIGGER    0
#else
#  define TRIGGER    0x00002000
#endif
#ifdef SQLITE_OMIT_VACUUM
#  define VACUUM     0
#else
#  define VACUUM     0x00004000
#endif
#ifdef SQLITE_OMIT_VIEW
#  define VIEW       0
#else
#  define VIEW       0x00008000
#endif
#ifdef SQLITE_OMIT_VIRTUALTABLE
#  define VTAB       0
#else
#  define VTAB       0x00010000
#endif

/*
** These are the keywords
*/
static Keyword aKeywordTable[] = {
  { "ABORT",            "TK_ABORT",        CONFLICT|TRIGGER       },
  { "ADD",              "TK_ADD",          ALTER                  },
  { "AFTER",            "TK_AFTER",        TRIGGER                },
  { "ALL",              "TK_ALL",          ALWAYS                 },
  { "ALTER",            "TK_ALTER",        ALTER                  },
  { "ANALYZE",          "TK_ANALYZE",      ANALYZE                },
  { "AND",              "TK_AND",          ALWAYS                 },
  { "AS",               "TK_AS",           ALWAYS                 },
  { "ASC",              "TK_ASC",          ALWAYS                 },
  { "ATTACH",           "TK_ATTACH",       ATTACH                 },
  { "AUTOINCREMENT",    "TK_AUTOINCR",     AUTOINCR               },
  { "BEFORE",           "TK_BEFORE",       TRIGGER                },
  { "BEGIN",            "TK_BEGIN",        ALWAYS                 },
  { "BETWEEN",          "TK_BETWEEN",      ALWAYS                 },
  { "BY",               "TK_BY",           ALWAYS                 },
  { "CASCADE",          "TK_CASCADE",      FKEY                   },
  { "CASE",             "TK_CASE",         ALWAYS                 },
  { "CAST",             "TK_CAST",         CAST                   },
  { "CHECK",            "TK_CHECK",        ALWAYS                 },
  { "COLLATE",          "TK_COLLATE",      ALWAYS                 },
  { "COLUMN",           "TK_COLUMNKW",     ALTER                  },
  { "COMMIT",           "TK_COMMIT",       ALWAYS                 },
  { "CONFLICT",         "TK_CONFLICT",     CONFLICT               },
  { "CONSTRAINT",       "TK_CONSTRAINT",   ALWAYS                 },
  { "CREATE",           "TK_CREATE",       ALWAYS                 },
  { "CROSS",            "TK_JOIN_KW",      ALWAYS                 },
  { "CURRENT_DATE",     "TK_CTIME_KW",     ALWAYS                 },
  { "CURRENT_TIME",     "TK_CTIME_KW",     ALWAYS                 },
  { "CURRENT_TIMESTAMP","TK_CTIME_KW",     ALWAYS                 },
  { "DATABASE",         "TK_DATABASE",     ATTACH                 },
  { "DEFAULT",          "TK_DEFAULT",      ALWAYS                 },
  { "DEFERRED",         "TK_DEFERRED",     ALWAYS                 },
  { "DEFERRABLE",       "TK_DEFERRABLE",   FKEY                   },
  { "DELETE",           "TK_DELETE",       ALWAYS                 },
  { "DESC",             "TK_DESC",         ALWAYS                 },
  { "DETACH",           "TK_DETACH",       ATTACH                 },
  { "DISTINCT",         "TK_DISTINCT",     ALWAYS                 },
  { "DROP",             "TK_DROP",         ALWAYS                 },
  { "END",              "TK_END",          ALWAYS                 },
  { "EACH",             "TK_EACH",         TRIGGER                },
  { "ELSE",             "TK_ELSE",         ALWAYS                 },
  { "ESCAPE",           "TK_ESCAPE",       ALWAYS                 },
  { "EXCEPT",           "TK_EXCEPT",       COMPOUND               },
  { "EXCLUSIVE",        "TK_EXCLUSIVE",    ALWAYS                 },
  { "EXISTS",           "TK_EXISTS",       ALWAYS                 },
  { "EXPLAIN",          "TK_EXPLAIN",      EXPLAIN                },
  { "FAIL",             "TK_FAIL",         CONFLICT|TRIGGER       },
  { "FOR",              "TK_FOR",          TRIGGER                },
  { "FOREIGN",          "TK_FOREIGN",      FKEY                   },
  { "FROM",             "TK_FROM",         ALWAYS                 },
  { "FULL",             "TK_JOIN_KW",      ALWAYS                 },
  { "GLOB",             "TK_LIKE_KW",      ALWAYS                 },
  { "GROUP",            "TK_GROUP",        ALWAYS                 },
  { "HAVING",           "TK_HAVING",       ALWAYS                 },
  { "IF",               "TK_IF",           ALWAYS                 },
  { "IGNORE",           "TK_IGNORE",       CONFLICT|TRIGGER       },
  { "IMMEDIATE",        "TK_IMMEDIATE",    ALWAYS                 },
  { "IN",               "TK_IN",           ALWAYS                 },
  { "INDEX",            "TK_INDEX",        ALWAYS                 },
  { "INITIALLY",        "TK_INITIALLY",    FKEY                   },
  { "INNER",            "TK_JOIN_KW",      ALWAYS                 },
  { "INSERT",           "TK_INSERT",       ALWAYS                 },
  { "INSTEAD",          "TK_INSTEAD",      TRIGGER                },
  { "INTERSECT",        "TK_INTERSECT",    COMPOUND               },
  { "INTO",             "TK_INTO",         ALWAYS                 },
  { "IS",               "TK_IS",           ALWAYS                 },
  { "ISNULL",           "TK_ISNULL",       ALWAYS                 },
  { "JOIN",             "TK_JOIN",         ALWAYS                 },
  { "KEY",              "TK_KEY",          ALWAYS                 },
  { "LEFT",             "TK_JOIN_KW",      ALWAYS                 },
  { "LIKE",             "TK_LIKE_KW",      ALWAYS                 },
  { "LIMIT",            "TK_LIMIT",        ALWAYS                 },
  { "MATCH",            "TK_MATCH",        ALWAYS                 },
  { "NATURAL",          "TK_JOIN_KW",      ALWAYS                 },
  { "NOT",              "TK_NOT",          ALWAYS                 },
  { "NOTNULL",          "TK_NOTNULL",      ALWAYS                 },
  { "NULL",             "TK_NULL",         ALWAYS                 },
  { "OF",               "TK_OF",           ALWAYS                 },
  { "OFFSET",           "TK_OFFSET",       ALWAYS                 },
  { "ON",               "TK_ON",           ALWAYS                 },
  { "OR",               "TK_OR",           ALWAYS                 },
  { "ORDER",            "TK_ORDER",        ALWAYS                 },
  { "OUTER",            "TK_JOIN_KW",      ALWAYS                 },
  { "PRAGMA",           "TK_PRAGMA",       PRAGMA                 },
  { "PRIMARY",          "TK_PRIMARY",      ALWAYS                 },
  { "RAISE",            "TK_RAISE",        TRIGGER                },
  { "REFERENCES",       "TK_REFERENCES",   FKEY                   },
  { "REGEXP",           "TK_LIKE_KW",      ALWAYS                 },
  { "REINDEX",          "TK_REINDEX",      REINDEX                },
  { "RENAME",           "TK_RENAME",       ALTER                  },
  { "REPLACE",          "TK_REPLACE",      CONFLICT               },
  { "RESTRICT",         "TK_RESTRICT",     FKEY                   },
  { "RIGHT",            "TK_JOIN_KW",      ALWAYS                 },
  { "ROLLBACK",         "TK_ROLLBACK",     ALWAYS                 },
  { "ROW",              "TK_ROW",          TRIGGER                },
  { "SELECT",           "TK_SELECT",       ALWAYS                 },
  { "SET",              "TK_SET",          ALWAYS                 },
  { "STATEMENT",        "TK_STATEMENT",    TRIGGER                },
  { "TABLE",            "TK_TABLE",        ALWAYS                 },
  { "TEMP",             "TK_TEMP",         ALWAYS                 },
  { "TEMPORARY",        "TK_TEMP",         ALWAYS                 },
  { "THEN",             "TK_THEN",         ALWAYS                 },
  { "TO",               "TK_TO",           ALTER                  },
  { "TRANSACTION",      "TK_TRANSACTION",  ALWAYS                 },
  { "TRIGGER",          "TK_TRIGGER",      TRIGGER                },
  { "UNION",            "TK_UNION",        COMPOUND               },
  { "UNIQUE",           "TK_UNIQUE",       ALWAYS                 },
  { "UPDATE",           "TK_UPDATE",       ALWAYS                 },
  { "USING",            "TK_USING",        ALWAYS                 },
  { "VACUUM",           "TK_VACUUM",       VACUUM                 },
  { "VALUES",           "TK_VALUES",       ALWAYS                 },
  { "VIEW",             "TK_VIEW",         VIEW                   },
  { "VIRTUAL",          "TK_VIRTUAL",      VTAB                   },
  { "WHEN",             "TK_WHEN",         ALWAYS                 },
  { "WHERE",            "TK_WHERE",        ALWAYS                 },
};

/* Number of keywords */
static int NKEYWORD = (sizeof(aKeywordTable)/sizeof(aKeywordTable[0]));

/* An array to map all upper-case characters into their corresponding
** lower-case character. 
*/
const unsigned char sqlite3UpperToLower[] = {
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
     18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
     36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
     54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
    104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
    122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
    108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
    126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
    162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
    180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
    198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
    216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
    234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
    252,253,254,255
};
#define UpperToLower sqlite3UpperToLower

/*
** Comparision function for two Keyword records
*/
static int keywordCompare1(const void *a, const void *b){
  const Keyword *pA = (Keyword*)a;
  const Keyword *pB = (Keyword*)b;
  int n = pA->len - pB->len;
  if( n==0 ){
    n = strcmp(pA->zName, pB->zName);
  }
  return n;
}
static int keywordCompare2(const void *a, const void *b){
  const Keyword *pA = (Keyword*)a;
  const Keyword *pB = (Keyword*)b;
  int n = strcmp(pA->zName, pB->zName);
  return n;
}
static int keywordCompare3(const void *a, const void *b){
  const Keyword *pA = (Keyword*)a;
  const Keyword *pB = (Keyword*)b;
  int n = pA->offset - pB->offset;
  return n;
}

/*
** Return a KeywordTable entry with the given id
*/
static Keyword *findById(int id){
  int i;
  for(i=0; i<NKEYWORD; i++){
    if( aKeywordTable[i].id==id ) break;
  }
  return &aKeywordTable[i];
}

/*
** This routine does the work.  The generated code is printed on standard
** output.
*/
int main(int argc, char **argv){
  int i, j, k, h;
  int bestSize, bestCount;
  int count;
  int nChar;
  int aHash[1000];  /* 1000 is much bigger than NKEYWORD */

  /* Remove entries from the list of keywords that have mask==0 */
  for(i=j=0; i<NKEYWORD; i++){
    if( aKeywordTable[i].mask==0 ) continue;
    if( j<i ){
      aKeywordTable[j] = aKeywordTable[i];
    }
    j++;
  }
  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);
    p->hash = (UpperToLower[p->zName[0]]*4) ^
              (UpperToLower[p->zName[p->len-1]]*3) ^ p->len;
    p->id = i+1;
  }

  /* Sort the table from shortest to longest keyword */
  qsort(aKeywordTable, NKEYWORD, sizeof(aKeywordTable[0]), keywordCompare1);

  /* Look for short keywords embedded in longer keywords */
  for(i=NKEYWORD-2; i>=0; i--){
    Keyword *p = &aKeywordTable[i];
    for(j=NKEYWORD-1; j>i && p->substrId==0; j--){
      Keyword *pOther = &aKeywordTable[j];
      if( pOther->substrId ) continue;
      if( pOther->len<=p->len ) continue;
      for(k=0; k<=pOther->len-p->len; k++){
        if( memcmp(p->zName, &pOther->zName[k], p->len)==0 ){
          p->substrId = pOther->id;
          p->substrOffset = k;
          break;
        }
      }
    }
  }

  /* Sort the table into alphabetical order */
  qsort(aKeywordTable, NKEYWORD, sizeof(aKeywordTable[0]), keywordCompare2);

  /* Fill in the offset for all entries */
  nChar = 0;
  for(i=0; i<NKEYWORD; i++){
    Keyword *p = &aKeywordTable[i];
    if( p->offset>0 || p->substrId ) continue;
    p->offset = nChar;
    nChar += p->len;
    for(k=p->len-1; k>=1; k--){
      for(j=i+1; j<NKEYWORD; j++){
        Keyword *pOther = &aKeywordTable[j];
        if( pOther->offset>0 || pOther->substrId ) continue;
        if( pOther->len<=k ) continue;
        if( memcmp(&p->zName[p->len-k], pOther->zName, k)==0 ){
          p = pOther;
          p->offset = nChar - k;
          nChar = p->offset + p->len;
          p->zName += k;
          p->len -= k;
          p->prefix = k;
          j = i;
          k = p->len;
        }
      }
    }
  }
  for(i=0; i<NKEYWORD; i++){
    Keyword *p = &aKeywordTable[i];
    if( p->substrId ){
      p->offset = findById(p->substrId)->offset + p->substrOffset;
    }
  }

  /* Sort the table by offset */
  qsort(aKeywordTable, NKEYWORD, sizeof(aKeywordTable[0]), keywordCompare3);

  /* Figure out how big to make the hash table in order to minimize the
  ** number of collisions */
  bestSize = NKEYWORD;
  bestCount = NKEYWORD*NKEYWORD;
  for(i=NKEYWORD/2; i<=2*NKEYWORD; i++){
    for(j=0; j<i; j++) aHash[j] = 0;
    for(j=0; j<NKEYWORD; j++){
      h = aKeywordTable[j].hash % i;
      aHash[h] *= 2;
      aHash[h]++;
    }
    for(j=count=0; j<i; j++) count += aHash[j];
    if( count<bestCount ){
      bestCount = count;
      bestSize = i;
    }
  }

  /* Compute the hash */
  for(i=0; i<bestSize; i++) aHash[i] = 0;
  for(i=0; i<NKEYWORD; i++){
    h = aKeywordTable[i].hash % bestSize;
    aKeywordTable[i].iNext = aHash[h];
    aHash[h] = i+1;
  }

  /* Begin generating code */
  printf("/* Hash score: %d */\n", bestCount);
  printf("static int keywordCode(const char *z, int n){\n");

  printf("  static const char zText[%d] =\n", nChar+1);
  for(i=j=0; i<NKEYWORD; i++){
    Keyword *p = &aKeywordTable[i];
    if( p->substrId ) continue;
    if( j==0 ) printf("    \"");
    printf("%s", p->zName);
    j += p->len;
    if( j>60 ){
      printf("\"\n");
      j = 0;
    }
  }
  printf("%s;\n", j>0 ? "\"" : "  ");

  printf("  static const unsigned char aHash[%d] = {\n", bestSize);
  for(i=j=0; i<bestSize; i++){
    if( j==0 ) printf("    ");
    printf(" %3d,", aHash[i]);
    j++;
    if( j>12 ){
      printf("\n");
      j = 0;
    }
  }
  printf("%s  };\n", j==0 ? "" : "\n");    

  printf("  static const unsigned char aNext[%d] = {\n", NKEYWORD);
  for(i=j=0; i<NKEYWORD; i++){
    if( j==0 ) printf("    ");
    printf(" %3d,", aKeywordTable[i].iNext);
    j++;
    if( j>12 ){
      printf("\n");
      j = 0;
    }
  }
  printf("%s  };\n", j==0 ? "" : "\n");    

  printf("  static const unsigned char aLen[%d] = {\n", NKEYWORD);
  for(i=j=0; i<NKEYWORD; i++){
    if( j==0 ) printf("    ");
    printf(" %3d,", aKeywordTable[i].len+aKeywordTable[i].prefix);
    j++;
    if( j>12 ){
      printf("\n");
      j = 0;
    }
  }
  printf("%s  };\n", j==0 ? "" : "\n");    

  printf("  static const unsigned short int aOffset[%d] = {\n", NKEYWORD);
  for(i=j=0; i<NKEYWORD; i++){
    if( j==0 ) printf("    ");
    printf(" %3d,", aKeywordTable[i].offset);
    j++;
    if( j>12 ){
      printf("\n");
      j = 0;
    }
  }
  printf("%s  };\n", j==0 ? "" : "\n");

  printf("  static const unsigned char aCode[%d] = {\n", NKEYWORD);
  for(i=j=0; i<NKEYWORD; i++){
    char *zToken = aKeywordTable[i].zTokenType;
    if( j==0 ) printf("    ");
    printf("%s,%*s", zToken, (int)(14-strlen(zToken)), "");
    j++;
    if( j>=5 ){
      printf("\n");
      j = 0;
    }
  }
  printf("%s  };\n", j==0 ? "" : "\n");

  printf("  int h, i;\n");
  printf("  if( n<2 ) return TK_ID;\n");
  printf("  h = ((charMap(z[0])*4) ^\n"
         "      (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");
  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;
}
