/*

** 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.

**

*************************************************************************

** This file contains routines used for analyzing expressions and

** for generating VDBE code that evaluates expressions in SQLite.

**

** $Id: expr.cpp 1282 2008-11-13 09:31:33Z LarsPson $

*/

#include "sqliteInt.h"

#include <ctype.h>

/*

** Return the 'affinity' of the expression pExpr if any.

**

** If pExpr is a column, a reference to a column via an 'AS' alias,

** or a sub-select with a column as the return value, then the 

** affinity of that column is returned. Otherwise, 0x00 is returned,

** indicating no affinity for the expression.

**

** i.e. the WHERE clause expresssions in the following statements all

** have an affinity:

**

** CREATE TABLE t1(a);

** SELECT * FROM t1 WHERE a;

** SELECT a AS b FROM t1 WHERE b;

** SELECT * FROM t1 WHERE (select a from t1);

*/

char sqlite3ExprAffinity(Expr *pExpr){

  int op = pExpr->op;

  if( op==TK_SELECT ){

    return sqlite3ExprAffinity(pExpr->pSelect->pEList->a[0].pExpr);

  }

#ifndef SQLITE_OMIT_CAST

  if( op==TK_CAST ){

    return sqlite3AffinityType(&pExpr->token);

  }

#endif

  return pExpr->affinity;

}

/*

** Set the collating sequence for expression pExpr to be the collating

** sequence named by pToken.   Return a pointer to the revised expression.

** The collating sequence is marked as "explicit" using the EP_ExpCollate

** flag.  An explicit collating sequence will override implicit

** collating sequences.

*/

Expr *sqlite3ExprSetColl(Parse *pParse, Expr *pExpr, Token *pName){

  char *zColl = 0;            /* Dequoted name of collation sequence */

  CollSeq *pColl;

  zColl = sqlite3NameFromToken(pParse->db, pName);

  if( pExpr && zColl ){

    pColl = sqlite3LocateCollSeq(pParse, zColl, -1);

    if( pColl ){

      pExpr->pColl = pColl;

      pExpr->flags |= EP_ExpCollate;

    }

  }

  sqlite3_free(zColl);

  return pExpr;

}

/*

** Return the default collation sequence for the expression pExpr. If

** there is no default collation type, return 0.

*/

CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){

  CollSeq *pColl = 0;

  if( pExpr ){

    int op;

    pColl = pExpr->pColl;

    op = pExpr->op;

    if( (op==TK_CAST || op==TK_UPLUS) && !pColl ){

      return sqlite3ExprCollSeq(pParse, pExpr->pLeft);

    }

  }

  if( sqlite3CheckCollSeq(pParse, pColl) ){ 

    pColl = 0;

  }

  return pColl;

}

/*

** pExpr is an operand of a comparison operator.  aff2 is the

** type affinity of the other operand.  This routine returns the

** type affinity that should be used for the comparison operator.

*/

char sqlite3CompareAffinity(Expr *pExpr, char aff2){

  char aff1 = sqlite3ExprAffinity(pExpr);

  if( aff1 && aff2 ){

    /* Both sides of the comparison are columns. If one has numeric

    ** affinity, use that. Otherwise use no affinity.

    */

    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){

      return SQLITE_AFF_NUMERIC;

    }else{

      return SQLITE_AFF_NONE;

    }

  }else if( !aff1 && !aff2 ){

    /* Neither side of the comparison is a column.  Compare the

    ** results directly.

    */

    return SQLITE_AFF_NONE;

  }else{

    /* One side is a column, the other is not. Use the columns affinity. */

    assert( aff1==0 || aff2==0 );

    return (aff1 + aff2);

  }

}

/*

** pExpr is a comparison operator.  Return the type affinity that should

** be applied to both operands prior to doing the comparison.

*/

static char comparisonAffinity(Expr *pExpr){

  char aff;

  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||

          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||

          pExpr->op==TK_NE );

  assert( pExpr->pLeft );

  aff = sqlite3ExprAffinity(pExpr->pLeft);

  if( pExpr->pRight ){

    aff = sqlite3CompareAffinity(pExpr->pRight, aff);

  }

  else if( pExpr->pSelect ){

    aff = sqlite3CompareAffinity(pExpr->pSelect->pEList->a[0].pExpr, aff);

  }

  else if( !aff ){

    aff = SQLITE_AFF_NONE;

  }

  return aff;

}

/*

** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.

** idx_affinity is the affinity of an indexed column. Return true

** if the index with affinity idx_affinity may be used to implement

** the comparison in pExpr.

*/

int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){

  char aff = comparisonAffinity(pExpr);

  switch( aff ){

    case SQLITE_AFF_NONE:

      return 1;

    case SQLITE_AFF_TEXT:

      return idx_affinity==SQLITE_AFF_TEXT;

    default:

      return sqlite3IsNumericAffinity(idx_affinity);

  }

}

/*

** Return the P1 value that should be used for a binary comparison

** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.

** If jumpIfNull is true, then set the low byte of the returned

** P1 value to tell the opcode to jump if either expression

** evaluates to NULL.

*/

static int binaryCompareP1(Expr *pExpr1, Expr *pExpr2, int jumpIfNull){

  char aff = sqlite3ExprAffinity(pExpr2);

  return ((int)sqlite3CompareAffinity(pExpr1, aff))+(jumpIfNull?0x100:0);

}

/*

** Return a pointer to the collation sequence that should be used by

** a binary comparison operator comparing pLeft and pRight.

**

** If the left hand expression has a collating sequence type, then it is

** used. Otherwise the collation sequence for the right hand expression

** is used, or the default (BINARY) if neither expression has a collating

** type.

**

** Argument pRight (but not pLeft) may be a null pointer. In this case,

** it is not considered.

*/

CollSeq *sqlite3BinaryCompareCollSeq(

  Parse *pParse, 

  Expr *pLeft, 

  Expr *pRight

){

  CollSeq *pColl;

  assert( pLeft );

  if( pLeft->flags & EP_ExpCollate ){

    assert( pLeft->pColl );

    pColl = pLeft->pColl;

  }else if( pRight && pRight->flags & EP_ExpCollate ){

    assert( pRight->pColl );

    pColl = pRight->pColl;

  }else{

    pColl = sqlite3ExprCollSeq(pParse, pLeft);

    if( !pColl ){

      pColl = sqlite3ExprCollSeq(pParse, pRight);

    }

  }

  return pColl;

}

/*

** Generate code for a comparison operator.

*/

static int codeCompare(

  Parse *pParse,    /* The parsing (and code generating) context */

  Expr *pLeft,      /* The left operand */

  Expr *pRight,     /* The right operand */

  int opcode,       /* The comparison opcode */

  int dest,         /* Jump here if true.  */

  int jumpIfNull    /* If true, jump if either operand is NULL */

){

  int p1 = binaryCompareP1(pLeft, pRight, jumpIfNull);

  CollSeq *p3 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);

  return sqlite3VdbeOp3(pParse->pVdbe, opcode, p1, dest, (const char*)p3, P3_COLLSEQ);

}

/*

** Construct a new expression node and return a pointer to it.  Memory

** for this node is obtained from sqlite3_malloc().  The calling function

** is responsible for making sure the node eventually gets freed.

*/

Expr *sqlite3Expr(

  sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */

  int op,                 /* Expression opcode */

  Expr *pLeft,            /* Left operand */

  Expr *pRight,           /* Right operand */

  const Token *pToken     /* Argument token */

){

  Expr *pNew;

  pNew = (Expr*)sqlite3DbMallocZero(db, sizeof(Expr));

  if( pNew==0 ){

    /* When malloc fails, delete pLeft and pRight. Expressions passed to 

    ** this function must always be allocated with sqlite3Expr() for this 

    ** reason. 

    */

    sqlite3ExprDelete(pLeft);

    sqlite3ExprDelete(pRight);

    return 0;

  }

  pNew->op = op;

  pNew->pLeft = pLeft;

  pNew->pRight = pRight;

  pNew->iAgg = -1;

  if( pToken ){

    assert( pToken->dyn==0 );

    pNew->span = pNew->token = *pToken;

  }else if( pLeft ){

    if( pRight ){

      sqlite3ExprSpan(pNew, &pLeft->span, &pRight->span);

      if( pRight->flags & EP_ExpCollate ){

        pNew->flags |= EP_ExpCollate;

        pNew->pColl = pRight->pColl;

      }

    }

    if( pLeft->flags & EP_ExpCollate ){

      pNew->flags |= EP_ExpCollate;

      pNew->pColl = pLeft->pColl;

    }

  }

  sqlite3ExprSetHeight(pNew);

  return pNew;

}

/*

** Works like sqlite3Expr() except that it takes an extra Parse*

** argument and notifies the associated connection object if malloc fails.

*/

Expr *sqlite3PExpr(

  Parse *pParse,          /* Parsing context */

  int op,                 /* Expression opcode */

  Expr *pLeft,            /* Left operand */

  Expr *pRight,           /* Right operand */

  const Token *pToken     /* Argument token */

){

  return sqlite3Expr(pParse->db, op, pLeft, pRight, pToken);

}

/*

** When doing a nested parse, you can include terms in an expression

** that look like this:   #0 #1 #2 ...  These terms refer to elements

** on the stack.  "#0" means the top of the stack.

** "#1" means the next down on the stack.  And so forth.

**

** This routine is called by the parser to deal with on of those terms.

** It immediately generates code to store the value in a memory location.

** The returns an expression that will code to extract the value from

** that memory location as needed.

*/

Expr *sqlite3RegisterExpr(Parse *pParse, Token *pToken){

  Vdbe *v = pParse->pVdbe;

  Expr *p;

  int depth;

  if( pParse->nested==0 ){

    sqlite3ErrorMsg(pParse, "near \"%T\": syntax error", pToken);

    return sqlite3PExpr(pParse, TK_NULL, 0, 0, 0);

  }

  if( v==0 ) return 0;

  p = sqlite3PExpr(pParse, TK_REGISTER, 0, 0, pToken);

  if( p==0 ){

    return 0;  /* Malloc failed */

  }

  depth = atoi((char*)&pToken->z[1]);

  p->iTable = pParse->nMem++;

  sqlite3VdbeAddOp(v, OP_Dup, depth, 0);

  sqlite3VdbeAddOp(v, OP_MemStore, p->iTable, 1);

  return p;

}

/*

** Join two expressions using an AND operator.  If either expression is

** NULL, then just return the other expression.

*/

Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){

  if( pLeft==0 ){

    return pRight;

  }else if( pRight==0 ){

    return pLeft;

  }else{

    return sqlite3Expr(db, TK_AND, pLeft, pRight, 0);

  }

}

/*

** Set the Expr.span field of the given expression to span all

** text between the two given tokens.

*/

void sqlite3ExprSpan(Expr *pExpr, Token *pLeft, Token *pRight){

  assert( pRight!=0 );

  assert( pLeft!=0 );

  if( pExpr && pRight->z && pLeft->z ){

    assert( pLeft->dyn==0 || pLeft->z[pLeft->n]==0 );

    if( pLeft->dyn==0 && pRight->dyn==0 ){

      pExpr->span.z = pLeft->z;

      pExpr->span.n = pRight->n + (pRight->z - pLeft->z);

    }else{

      pExpr->span.z = 0;

    }

  }

}

/*

** Construct a new expression node for a function with multiple

** arguments.

*/

Expr *sqlite3ExprFunction(Parse *pParse, ExprList *pList, Token *pToken){

  Expr *pNew;

  assert( pToken );

  pNew = (Expr*)sqlite3DbMallocZero(pParse->db, sizeof(Expr) );

  if( pNew==0 ){

    sqlite3ExprListDelete(pList); /* Avoid leaking memory when malloc fails */

    return 0;

  }

  pNew->op = TK_FUNCTION;

  pNew->pList = pList;

  assert( pToken->dyn==0 );

  pNew->token = *pToken;

  pNew->span = pNew->token;

  sqlite3ExprSetHeight(pNew);

  return pNew;

}

/*

** Assign a variable number to an expression that encodes a wildcard

** in the original SQL statement.  

**

** Wildcards consisting of a single "?" are assigned the next sequential

** variable number.

**

** Wildcards of the form "?nnn" are assigned the number "nnn".  We make

** sure "nnn" is not too be to avoid a denial of service attack when

** the SQL statement comes from an external source.

**

** Wildcards of the form ":aaa" or "$aaa" are assigned the same number

** as the previous instance of the same wildcard.  Or if this is the first

** instance of the wildcard, the next sequenial variable number is

** assigned.

*/

void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr){

  Token *pToken;

  sqlite3 *db = pParse->db;

  if( pExpr==0 ) return;

  pToken = &pExpr->token;

  assert( pToken->n>=1 );

  assert( pToken->z!=0 );

  assert( pToken->z[0]!=0 );

  if( pToken->n==1 ){

    /* Wildcard of the form "?".  Assign the next variable number */

    pExpr->iTable = ++pParse->nVar;

  }else if( pToken->z[0]=='?' ){

    /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and

    ** use it as the variable number */

    int i;

    pExpr->iTable = i = atoi((char*)&pToken->z[1]);

    if( i<1 || i>SQLITE_MAX_VARIABLE_NUMBER ){

      sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",

          SQLITE_MAX_VARIABLE_NUMBER);

    }

    if( i>pParse->nVar ){

      pParse->nVar = i;

    }

  }else{

    /* Wildcards of the form ":aaa" or "$aaa".  Reuse the same variable

    ** number as the prior appearance of the same name, or if the name

    ** has never appeared before, reuse the same variable number

    */

    int i, n;

    n = pToken->n;

    for(i=0; i<pParse->nVarExpr; i++){

      Expr *pE;

      if( (pE = pParse->apVarExpr[i])!=0

          && pE->token.n==n

          && memcmp(pE->token.z, pToken->z, n)==0 ){

        pExpr->iTable = pE->iTable;

        break;

      }

    }

    if( i>=pParse->nVarExpr ){

      pExpr->iTable = ++pParse->nVar;

      if( pParse->nVarExpr>=pParse->nVarExprAlloc-1 ){

        pParse->nVarExprAlloc += pParse->nVarExprAlloc + 10;

        pParse->apVarExpr =

            (Expr**)sqlite3DbReallocOrFree(

              db,

              pParse->apVarExpr,

              pParse->nVarExprAlloc*sizeof(pParse->apVarExpr[0])

            );

      }

      if( !db->mallocFailed ){

        assert( pParse->apVarExpr!=0 );

        pParse->apVarExpr[pParse->nVarExpr++] = pExpr;

      }

    }

  } 

  if( !pParse->nErr && pParse->nVar>SQLITE_MAX_VARIABLE_NUMBER ){

    sqlite3ErrorMsg(pParse, "too many SQL variables");

  }

}

/*

** Recursively delete an expression tree.

*/

void sqlite3ExprDelete(Expr *p){

  if( p==0 ) return;

  if( p->span.dyn ) sqlite3_free((char*)p->span.z);

  if( p->token.dyn ) sqlite3_free((char*)p->token.z);

  sqlite3ExprDelete(p->pLeft);

  sqlite3ExprDelete(p->pRight);

  sqlite3ExprListDelete(p->pList);

  sqlite3SelectDelete(p->pSelect);

  sqlite3_free(p);

}

/*

** The Expr.token field might be a string literal that is quoted.

** If so, remove the quotation marks.

*/

void sqlite3DequoteExpr(sqlite3 *db, Expr *p){

  if( ExprHasAnyProperty(p, EP_Dequoted) ){

    return;

  }

  ExprSetProperty(p, EP_Dequoted);

  if( p->token.dyn==0 ){

    sqlite3TokenCopy(db, &p->token, &p->token);

  }

  sqlite3Dequote((char*)p->token.z);

}

/*

** The following group of routines make deep copies of expressions,

** expression lists, ID lists, and select statements.  The copies can

** be deleted (by being passed to their respective ...Delete() routines)

** without effecting the originals.

**

** The expression list, ID, and source lists return by sqlite3ExprListDup(),

** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded 

** by subsequent calls to sqlite*ListAppend() routines.

**

** Any tables that the SrcList might point to are not duplicated.

*/

Expr *sqlite3ExprDup(sqlite3 *db, Expr *p){

  Expr *pNew;

  if( p==0 ) return 0;

  pNew = (Expr*)sqlite3DbMallocRaw(db, sizeof(*p) );

  if( pNew==0 ) return 0;

  memcpy(pNew, p, sizeof(*pNew));

  if( p->token.z!=0 ){

    pNew->token.z = (u8*)sqlite3DbStrNDup(db, (char*)p->token.z, p->token.n);

    pNew->token.dyn = 1;

  }else{

    assert( pNew->token.z==0 );

  }

  pNew->span.z = 0;

  pNew->pLeft = sqlite3ExprDup(db, p->pLeft);

  pNew->pRight = sqlite3ExprDup(db, p->pRight);

  pNew->pList = sqlite3ExprListDup(db, p->pList);

  pNew->pSelect = sqlite3SelectDup(db, p->pSelect);

  return pNew;

}

void sqlite3TokenCopy(sqlite3 *db, Token *pTo, Token *pFrom){

  if( pTo->dyn ) sqlite3_free((char*)pTo->z);

  if( pFrom->z ){

    pTo->n = pFrom->n;

    pTo->z = (u8*)sqlite3DbStrNDup(db, (char*)pFrom->z, pFrom->n);

    pTo->dyn = 1;

  }else{

    pTo->z = 0;

  }

}

ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p){

  ExprList *pNew;

  ExprList::ExprList_item *pItem, *pOldItem;

  int i;

  if( p==0 ) return 0;

  pNew = (ExprList*)sqlite3DbMallocRaw(db, sizeof(*pNew) );

  if( pNew==0 ) return 0;

  pNew->iECursor = 0;

  pNew->nExpr = pNew->nAlloc = p->nExpr;

  pNew->a = pItem = (ExprList::ExprList_item*)sqlite3DbMallocRaw(db,  p->nExpr*sizeof(p->a[0]) );

  if( pItem==0 ){

    sqlite3_free(pNew);