SQLite

    /* There are now 4 possibilities:
    **
    **     1. uPattern is an unescaped match-all character "%",
    **     2. uPattern is an unescaped match-one character "_",
    **     3. uPattern is an unescaped escape character, or
    **     4. uPattern is to be handled as an ordinary character
    */
    if( uPattern==MATCH_ALL && !prevEscape && uPattern!=(uint32_t)uEsc ){
      /* Case 1. */
      uint8_t c;

      /* Skip any MATCH_ALL or MATCH_ONE characters that follow a
      ** MATCH_ALL. For each MATCH_ONE, skip one character in the 
      ** test string.
      */

        if( icuLikeCompare(zPattern, zString, uEsc) ){
          return 1;
        }
        SQLITE_ICU_SKIP_UTF8(zString);
      }
      return 0;

    }else if( uPattern==MATCH_ONE && !prevEscape && uPattern!=(uint32_t)uEsc ){
      /* Case 2. */
      if( *zString==0 ) return 0;
      SQLITE_ICU_SKIP_UTF8(zString);

    }else if( uPattern==(uint32_t)uEsc && !prevEscape ){
      /* Case 3. */
      prevEscape = 1;

    }else{
      /* Case 4. */
      uint32_t uString;
      SQLITE_ICU_READ_UTF8(zString, uString);

  sqlite3_value **argv
){
  const unsigned char *zA, *zB;
  u32 escape;
  int nPat;
  sqlite3 *db = sqlite3_context_db_handle(context);
  struct compareInfo *pInfo = sqlite3_user_data(context);
  struct compareInfo backupInfo;

#ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
  if( sqlite3_value_type(argv[0])==SQLITE_BLOB
   || sqlite3_value_type(argv[1])==SQLITE_BLOB
  ){
#ifdef SQLITE_TEST
    sqlite3_like_count++;

    if( zEsc==0 ) return;
    if( sqlite3Utf8CharLen((char*)zEsc, -1)!=1 ){
      sqlite3_result_error(context, 
          "ESCAPE expression must be a single character", -1);
      return;
    }
    escape = sqlite3Utf8Read(&zEsc);
    if( escape==pInfo->matchAll || escape==pInfo->matchOne ){
      memcpy(&backupInfo, pInfo, sizeof(backupInfo));
      pInfo = &backupInfo;
      if( escape==pInfo->matchAll ) pInfo->matchAll = 0;
      if( escape==pInfo->matchOne ) pInfo->matchOne = 0;
    }
  }else{
    escape = pInfo->matchSet;
  }
  zB = sqlite3_value_text(argv[0]);
  zA = sqlite3_value_text(argv[1]);
  if( zA && zB ){
#ifdef SQLITE_TEST

  pDef = sqlite3FindFunction(db, pExpr->u.zToken, nExpr, SQLITE_UTF8, 0);
#ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
  if( pDef==0 ) return 0;
#endif
  if( NEVER(pDef==0) || (pDef->funcFlags & SQLITE_FUNC_LIKE)==0 ){
    return 0;
  }











  /* The memcpy() statement assumes that the wildcard characters are
  ** the first three statements in the compareInfo structure.  The
  ** asserts() that follow verify that assumption
  */
  memcpy(aWc, pDef->pUserData, 3);
  assert( (char*)&likeInfoAlt == (char*)&likeInfoAlt.matchAll );
  assert( &((char*)&likeInfoAlt)[1] == (char*)&likeInfoAlt.matchOne );
  assert( &((char*)&likeInfoAlt)[2] == (char*)&likeInfoAlt.matchSet );

  if( nExpr<3 ){
    aWc[3] = 0;
  }else{
    Expr *pEscape = pExpr->x.pList->a[2].pExpr;
    char *zEscape;
    if( pEscape->op!=TK_STRING ) return 0;
    zEscape = pEscape->u.zToken;
    if( zEscape[0]==0 || zEscape[1]!=0 ) return 0;
    if( zEscape[0]==aWc[0] ) return 0;
    if( zEscape[0]==aWc[1] ) return 0;
    aWc[3] = zEscape[0];
  }

  *pIsNocase = (pDef->funcFlags & SQLITE_FUNC_CASE)==0;
  return 1;
}

/*
** All of the FuncDef structures in the aBuiltinFunc[] array above
** to the global function hash table.  This occurs at start-time (as

  do_catchsql_test icu-5.5 {SELECT 'abc' REGEXP }   {1 {incomplete input}}
  do_catchsql_test icu-5.6 {SELECT 'abc' REGEXP, 1} {1 {near ",": syntax error}}
 
  do_malloc_test icu-6.10 -sqlbody {
    SELECT upper(char(0xfb04,0xdf,0xfb04,0xe8,0xfb04));
  }
}

# 2020-03-19
# The ESCAPE clause on LIKE takes precedence over wildcards
#
do_execsql_test idu-6.0 {
  DROP TABLE IF EXISTS t1;
  CREATE TABLE t1(id INTEGER PRIMARY KEY, x TEXT);
  INSERT INTO t1 VALUES
    (1,'abcde'),
    (2,'abc_'),
    (3,'abc__'),
    (4,'abc%'),
    (5,'abc%%');
  SELECT id FROM t1 WHERE x LIKE 'abc%%' ESCAPE '%';
} {4}
do_execsql_test icu-6.1 {
  SELECT id FROM t1 WHERE x LIKE 'abc__' ESCAPE '_';
} {2}

finish_test

}
do_execsql_test 16.1 {
  SELECT * FROM t1 WHERE a LIKE ' 1%';
} {{ 1x} { 1-}}
do_execsql_test 16.2 {
  SELECT * FROM t1 WHERE a LIKE ' 1-';
} {{ 1-}}

# 2020-03-19
# The ESCAPE clause on LIKE takes precedence over wildcards
#
do_execsql_test 17.0 {
  DROP TABLE IF EXISTS t1;
  CREATE TABLE t1(id INTEGER PRIMARY KEY, x TEXT);
  INSERT INTO t1 VALUES
    (1,'abcde'),
    (2,'abc_'),
    (3,'abc__'),
    (4,'abc%'),
    (5,'abc%%');
  SELECT id FROM t1 WHERE x LIKE 'abc%%' ESCAPE '%';
} {4}
do_execsql_test 17.1 {
  SELECT id FROM t1 WHERE x LIKE 'abc__' ESCAPE '_';
} {2}

finish_test

do_eqp_test like3-6.110 {
  SELECT * FROM t1 WHERE path LIKE 'a%';
} {
  QUERY PLAN
  `--SEARCH TABLE t1 USING PRIMARY KEY (path>? AND path<?)
}
do_eqp_test like3-6.120 {
  SELECT * FROM t1 WHERE path LIKE 'a%' ESCAPE 'x';
} {
  QUERY PLAN
  `--SEARCH TABLE t1 USING PRIMARY KEY (path>? AND path<?)
}
do_execsql_test like3-6.200 {
  DROP TABLE IF EXISTS t2;
  CREATE TABLE t2(path TEXT,x,y,z);
  CREATE INDEX t2path ON t2(path COLLATE nocase);
  CREATE INDEX t2path2 ON t2(path);
}
do_eqp_test like3-6.210 {
  SELECT * FROM t2 WHERE path LIKE 'a%';
} {
  QUERY PLAN
  `--SEARCH TABLE t2 USING INDEX t2path (path>? AND path<?)
}
do_eqp_test like3-6.220 {
  SELECT * FROM t2 WHERE path LIKE 'a%' ESCAPE '\';
} {
  QUERY PLAN
  `--SEARCH TABLE t2 USING INDEX t2path (path>? AND path<?)
}
db eval {PRAGMA case_sensitive_like=ON}
do_eqp_test like3-6.230 {
  SELECT * FROM t2 WHERE path LIKE 'a%';
} {
  QUERY PLAN
  `--SEARCH TABLE t2 USING INDEX t2path2 (path>? AND path<?)
}
do_eqp_test like3-6.240 {
  SELECT * FROM t2 WHERE path LIKE 'a%' ESCAPE '\';
} {
  QUERY PLAN
  `--SEARCH TABLE t2 USING INDEX t2path2 (path>? AND path<?)
}
}

finish_test