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Overview
Comment:Simplification to the logic underlying PRAGMA case_sensitive_like.
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SHA3-256: ef0015fde4c87e992ffd3d7dea8586951bdd65ff98d30d436b126b85b1cc9c74
User & Date: drh 2019-05-08 19:32:33
Context
2019-05-08
19:55
Fix another pattern for which the LIKE optimization does not work for a non-TEXT affinity. Case found by Manuel Rigger. check-in: 74020110 user: drh tags: trunk
19:32
Simplification to the logic underlying PRAGMA case_sensitive_like. check-in: ef0015fd user: drh tags: trunk
19:06
Avoid an excess register allocation in UPDATE, when possible. This improves speed (slightly) and reduces the code footprint. check-in: 8658574e user: drh tags: trunk
Changes
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Changes to src/func.c.

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  int rc = sqlite3_overload_function(db, "MATCH", 2);
  assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
  if( rc==SQLITE_NOMEM ){
    sqlite3OomFault(db);
  }
}

/*
** Set the LIKEOPT flag on the 2-argument function with the given name.
*/
static void setLikeOptFlag(sqlite3 *db, const char *zName, u8 flagVal){
  FuncDef *pDef;
  pDef = sqlite3FindFunction(db, zName, 2, SQLITE_UTF8, 0);
  if( ALWAYS(pDef) ){
    pDef->funcFlags |= flagVal;
  }
  pDef = sqlite3FindFunction(db, zName, 3, SQLITE_UTF8, 0);
  if( pDef ){
    pDef->funcFlags |= flagVal;
  }
}

/*
** Re-register the built-in LIKE functions.  The caseSensitive
** parameter determines whether or not the LIKE operator is case
** sensitive.
*/
void sqlite3RegisterLikeFunctions(sqlite3 *db, int caseSensitive){
  struct compareInfo *pInfo;

  if( caseSensitive ){
    pInfo = (struct compareInfo*)&likeInfoAlt;

  }else{
    pInfo = (struct compareInfo*)&likeInfoNorm;

  }
  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
  setLikeOptFlag(db, "like", 
      caseSensitive ? (SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE) : SQLITE_FUNC_LIKE);
}

/*
** pExpr points to an expression which implements a function.  If
** it is appropriate to apply the LIKE optimization to that function
** then set aWc[0] through aWc[2] to the wildcard characters and the
** escape character and then return TRUE.  If the function is not a 







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  int rc = sqlite3_overload_function(db, "MATCH", 2);
  assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
  if( rc==SQLITE_NOMEM ){
    sqlite3OomFault(db);
  }
}
















/*
** Re-register the built-in LIKE functions.  The caseSensitive
** parameter determines whether or not the LIKE operator is case
** sensitive.
*/
void sqlite3RegisterLikeFunctions(sqlite3 *db, int caseSensitive){
  struct compareInfo *pInfo;
  int flags;
  if( caseSensitive ){
    pInfo = (struct compareInfo*)&likeInfoAlt;
    flags = SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE;
  }else{
    pInfo = (struct compareInfo*)&likeInfoNorm;
    flags = SQLITE_FUNC_LIKE;
  }
  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0, 0, 0, 0);
  sqlite3FindFunction(db, "like", 2, SQLITE_UTF8, 0)->funcFlags |= flags;
  sqlite3FindFunction(db, "like", 3, SQLITE_UTF8, 0)->funcFlags |= flags;
}

/*
** pExpr points to an expression which implements a function.  If
** it is appropriate to apply the LIKE optimization to that function
** then set aWc[0] through aWc[2] to the wildcard characters and the
** escape character and then return TRUE.  If the function is not a 

Changes to test/e_expr.test.

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do_test         e_expr-15.1.4 { set likeargs } {def abc X}
db close
sqlite3 db test.db

# EVIDENCE-OF: R-22868-25880 The LIKE operator can be made case
# sensitive using the case_sensitive_like pragma.
#
do_execsql_test e_expr-16.1.1 { SELECT 'abcxyz' LIKE 'ABC%' } 1

do_execsql_test e_expr-16.1.2 { PRAGMA case_sensitive_like = 1 } {}
do_execsql_test e_expr-16.1.3 { SELECT 'abcxyz' LIKE 'ABC%' } 0

do_execsql_test e_expr-16.1.4 { SELECT 'ABCxyz' LIKE 'ABC%' } 1

do_execsql_test e_expr-16.1.5 { PRAGMA case_sensitive_like = 0 } {}
do_execsql_test e_expr-16.1.6 { SELECT 'abcxyz' LIKE 'ABC%' } 1

do_execsql_test e_expr-16.1.7 { SELECT 'ABCxyz' LIKE 'ABC%' } 1


# EVIDENCE-OF: R-52087-12043 The GLOB operator is similar to LIKE but
# uses the Unix file globbing syntax for its wildcards.
#
# EVIDENCE-OF: R-09813-17279 Also, GLOB is case sensitive, unlike LIKE.
#
do_execsql_test e_expr-17.1.1 { SELECT 'abcxyz' GLOB 'abc%' } 0







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do_test         e_expr-15.1.4 { set likeargs } {def abc X}
db close
sqlite3 db test.db

# EVIDENCE-OF: R-22868-25880 The LIKE operator can be made case
# sensitive using the case_sensitive_like pragma.
#
do_execsql_test e_expr-16.1.1  { SELECT 'abcxyz' LIKE 'ABC%' } 1
do_execsql_test e_expr-16.1.1b { SELECT 'abc%xyz' LIKE 'ABC\%x%' ESCAPE '\' } 1
do_execsql_test e_expr-16.1.2  { PRAGMA case_sensitive_like = 1 } {}
do_execsql_test e_expr-16.1.3  { SELECT 'abcxyz' LIKE 'ABC%' } 0
do_execsql_test e_expr-16.1.3b { SELECT 'abc%xyz' LIKE 'ABC\%X%' ESCAPE '\' } 0
do_execsql_test e_expr-16.1.4  { SELECT 'ABCxyz' LIKE 'ABC%' } 1
do_execsql_test e_expr-16.1.4b { SELECT 'ABC%xyz' LIKE 'ABC\%x%' ESCAPE '\' } 1
do_execsql_test e_expr-16.1.5  { PRAGMA case_sensitive_like = 0 } {}
do_execsql_test e_expr-16.1.6  { SELECT 'abcxyz' LIKE 'ABC%' } 1
do_execsql_test e_expr-16.1.6b { SELECT 'abc%xyz' LIKE 'ABC\%X%' ESCAPE '\' } 1
do_execsql_test e_expr-16.1.7  { SELECT 'ABCxyz' LIKE 'ABC%' } 1
do_execsql_test e_expr-16.1.7b { SELECT 'ABC%xyz' LIKE 'ABC\%X%' ESCAPE '\' } 1

# EVIDENCE-OF: R-52087-12043 The GLOB operator is similar to LIKE but
# uses the Unix file globbing syntax for its wildcards.
#
# EVIDENCE-OF: R-09813-17279 Also, GLOB is case sensitive, unlike LIKE.
#
do_execsql_test e_expr-17.1.1 { SELECT 'abcxyz' GLOB 'abc%' } 0