/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** An tokenizer for SQL
**
** This file contains C code that implements the sqlite3_complete() API.
** This code used to be part of the tokenizer.c source file.  But by
** separating it out, the code will be automatically omitted from
** static links that do not use it.
**
** $Id: complete.c,v 1.5 2007/08/21 19:33:56 drh Exp $
*/
#include "sqliteInt.h"
#ifndef SQLITE_OMIT_COMPLETE

/*
** This is defined in tokenize.c.  We just have to import the definition.
*/
extern const char sqlite3IsIdChar[];
#define IdChar(C)  (((c=C)&0x80)!=0 || (c>0x1f && sqlite3IsIdChar[c-0x20]))


/*
** Token types used by the sqlite3_complete() routine.  See the header
** comments on that procedure for additional information.
*/
#define tkSEMI    0
#define tkWS      1
#define tkOTHER   2
#define tkEXPLAIN 3
#define tkCREATE  4
#define tkTEMP    5
#define tkTRIGGER 6
#define tkEND     7

/*
** Return TRUE if the given SQL string ends in a semicolon.
**
** Special handling is require for CREATE TRIGGER statements.
** Whenever the CREATE TRIGGER keywords are seen, the statement
** must end with ";END;".
**
** This implementation uses a state machine with 7 states:
**
**   (0) START     At the beginning or end of an SQL statement.  This routine
**                 returns 1 if it ends in the START state and 0 if it ends
**                 in any other state.
**
**   (1) NORMAL    We are in the middle of statement which ends with a single
**                 semicolon.
**
**   (2) EXPLAIN   The keyword EXPLAIN has been seen at the beginning of 
**                 a statement.
**
**   (3) CREATE    The keyword CREATE has been seen at the beginning of a
**                 statement, possibly preceeded by EXPLAIN and/or followed by
**                 TEMP or TEMPORARY
**
**   (4) TRIGGER   We are in the middle of a trigger definition that must be
**                 ended by a semicolon, the keyword END, and another semicolon.
**
**   (5) SEMI      We've seen the first semicolon in the ";END;" that occurs at
**                 the end of a trigger definition.
**
**   (6) END       We've seen the ";END" of the ";END;" that occurs at the end
**                 of a trigger difinition.
**
** Transitions between states above are determined by tokens extracted
** from the input.  The following tokens are significant:
**
**   (0) tkSEMI      A semicolon.
**   (1) tkWS        Whitespace
**   (2) tkOTHER     Any other SQL token.
**   (3) tkEXPLAIN   The "explain" keyword.
**   (4) tkCREATE    The "create" keyword.
**   (5) tkTEMP      The "temp" or "temporary" keyword.
**   (6) tkTRIGGER   The "trigger" keyword.
**   (7) tkEND       The "end" keyword.
**
** Whitespace never causes a state transition and is always ignored.
**
** If we compile with SQLITE_OMIT_TRIGGER, all of the computation needed
** to recognize the end of a trigger can be omitted.  All we have to do
** is look for a semicolon that is not part of an string or comment.
*/
int sqlite3_complete(const char *zSql){
  u8 state = 0;   /* Current state, using numbers defined in header comment */
  u8 token;       /* Value of the next token */

#ifndef SQLITE_OMIT_TRIGGER
  /* A complex statement machine used to detect the end of a CREATE TRIGGER
  ** statement.  This is the normal case.
  */
  static const u8 trans[7][8] = {
                     /* Token:                                                */
     /* State:       **  SEMI  WS  OTHER EXPLAIN  CREATE  TEMP  TRIGGER  END  */
     /* 0   START: */ {    0,  0,     1,      2,      3,    1,       1,   1,  },
     /* 1  NORMAL: */ {    0,  1,     1,      1,      1,    1,       1,   1,  },
     /* 2 EXPLAIN: */ {    0,  2,     1,      1,      3,    1,       1,   1,  },
     /* 3  CREATE: */ {    0,  3,     1,      1,      1,    3,       4,   1,  },
     /* 4 TRIGGER: */ {    5,  4,     4,      4,      4,    4,       4,   4,  },
     /* 5    SEMI: */ {    5,  5,     4,      4,      4,    4,       4,   6,  },
     /* 6     END: */ {    0,  6,     4,      4,      4,    4,       4,   4,  },
  };
#else
  /* If triggers are not suppored by this compile then the statement machine
  ** used to detect the end of a statement is much simplier
  */
  static const u8 trans[2][3] = {
                     /* Token:           */
     /* State:       **  SEMI  WS  OTHER */
     /* 0   START: */ {    0,  0,     1, },
     /* 1  NORMAL: */ {    0,  1,     1, },
  };
#endif /* SQLITE_OMIT_TRIGGER */

  while( *zSql ){
    switch( *zSql ){
      case ';': {  /* A semicolon */
        token = tkSEMI;
        break;
      }
      case ' ':
      case '\r':
      case '\t':
      case '\n':
      case '\f': {  /* White space is ignored */
        token = tkWS;
        break;
      }
      case '/': {   /* C-style comments */
        if( zSql[1]!='*' ){
          token = tkOTHER;
          break;
        }
        zSql += 2;
        while( zSql[0] && (zSql[0]!='*' || zSql[1]!='/') ){ zSql++; }
        if( zSql[0]==0 ) return 0;
        zSql++;
        token = tkWS;
        break;
      }
      case '-': {   /* SQL-style comments from "--" to end of line */
        if( zSql[1]!='-' ){
          token = tkOTHER;
          break;
        }
        while( *zSql && *zSql!='\n' ){ zSql++; }
        if( *zSql==0 ) return state==0;
        token = tkWS;
        break;
      }
      case '[': {   /* Microsoft-style identifiers in [...] */
        zSql++;
        while( *zSql && *zSql!=']' ){ zSql++; }
        if( *zSql==0 ) return 0;
        token = tkOTHER;
        break;
      }
      case '`':     /* Grave-accent quoted symbols used by MySQL */
      case '"':     /* single- and double-quoted strings */
      case '\'': {
        int c = *zSql;
        zSql++;
        while( *zSql && *zSql!=c ){ zSql++; }
        if( *zSql==0 ) return 0;
        token = tkOTHER;
        break;
      }
      default: {
        int c;
        if( IdChar((u8)*zSql) ){
          /* Keywords and unquoted identifiers */
          int nId;
          for(nId=1; IdChar(zSql[nId]); nId++){}
#ifdef SQLITE_OMIT_TRIGGER
          token = tkOTHER;
#else
          switch( *zSql ){
            case 'c': case 'C': {
              if( nId==6 && sqlite3StrNICmp(zSql, "create", 6)==0 ){
                token = tkCREATE;
              }else{
                token = tkOTHER;
              }
              break;
            }
            case 't': case 'T': {
              if( nId==7 && sqlite3StrNICmp(zSql, "trigger", 7)==0 ){
                token = tkTRIGGER;
              }else if( nId==4 && sqlite3StrNICmp(zSql, "temp", 4)==0 ){
                token = tkTEMP;
              }else if( nId==9 && sqlite3StrNICmp(zSql, "temporary", 9)==0 ){
                token = tkTEMP;
              }else{
                token = tkOTHER;
              }
              break;
            }
            case 'e':  case 'E': {
              if( nId==3 && sqlite3StrNICmp(zSql, "end", 3)==0 ){
                token = tkEND;
              }else
#ifndef SQLITE_OMIT_EXPLAIN
              if( nId==7 && sqlite3StrNICmp(zSql, "explain", 7)==0 ){
                token = tkEXPLAIN;
              }else
#endif
              {
                token = tkOTHER;
              }
              break;
            }
            default: {
              token = tkOTHER;
              break;
            }
          }
#endif /* SQLITE_OMIT_TRIGGER */
          zSql += nId-1;
        }else{
          /* Operators and special symbols */
          token = tkOTHER;
        }
        break;
      }
    }
    state = trans[state][token];
    zSql++;
  }
  return state==0;
}

#ifndef SQLITE_OMIT_UTF16
/*
** This routine is the same as the sqlite3_complete() routine described
** above, except that the parameter is required to be UTF-16 encoded, not
** UTF-8.
*/
int sqlite3_complete16(const void *zSql){
  sqlite3_value *pVal;
  char const *zSql8;
  int rc = SQLITE_NOMEM;

  pVal = sqlite3ValueNew(0);
  sqlite3ValueSetStr(pVal, -1, zSql, SQLITE_UTF16NATIVE, SQLITE_STATIC);
  zSql8 = sqlite3ValueText(pVal, SQLITE_UTF8);
  if( zSql8 ){
    rc = sqlite3_complete(zSql8);
  }
  sqlite3ValueFree(pVal);
  return sqlite3ApiExit(0, rc);
}
#endif /* SQLITE_OMIT_UTF16 */
#endif /* SQLITE_OMIT_COMPLETE */
