/*

** 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.c,v 1.387 2008/07/28 19:34:53 drh Exp $

*/

#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;

sqlite3 *db = pParse->db;

zColl = sqlite3NameFromToken(db, pName);

if( pExpr && zColl ){

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

if( pColl ){

pExpr->pColl = pColl;

pExpr->flags |= EP_ExpCollate;

}

}

sqlite3DbFree(db, 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 P5 value that should be used for a binary comparison

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

*/

static u8 binaryCompareP5(Expr *pExpr1, Expr *pExpr2, int jumpIfNull){

u8 aff = (char)sqlite3ExprAffinity(pExpr2);

aff = sqlite3CompareAffinity(pExpr1, aff) | jumpIfNull;

return aff;

}

/*

** 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 the operands for a comparison operation. Before

** generating the code for each operand, set the EP_AnyAff

** flag on the expression so that it will be able to used a

** cached column value that has previously undergone an

** affinity change.

*/

static void codeCompareOperands(

Parse *pParse, /* Parsing and code generating context */

Expr *pLeft, /* The left operand */

int *pRegLeft, /* Register where left operand is stored */

int *pFreeLeft, /* Free this register when done */

Expr *pRight, /* The right operand */

int *pRegRight, /* Register where right operand is stored */

int *pFreeRight /* Write temp register for right operand there */

){

while( pLeft->op==TK_UPLUS ) pLeft = pLeft->pLeft;

pLeft->flags |= EP_AnyAff;

*pRegLeft = sqlite3ExprCodeTemp(pParse, pLeft, pFreeLeft);

while( pRight->op==TK_UPLUS ) pRight = pRight->pLeft;

pRight->flags |= EP_AnyAff;

*pRegRight = sqlite3ExprCodeTemp(pParse, pRight, pFreeRight);

}

/*

** 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 in1, int in2, /* Register holding operands */

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

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

){

int p5;

int addr;

CollSeq *p4;

p4 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);

p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);

addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,

(void*)p4, P4_COLLSEQ);

sqlite3VdbeChangeP5(pParse->pVdbe, p5);

if( (p5 & SQLITE_AFF_MASK)!=SQLITE_AFF_NONE ){

sqlite3ExprCacheAffinityChange(pParse, in1, 1);

sqlite3ExprCacheAffinityChange(pParse, in2, 1);

}

return addr;

}

#if SQLITE_MAX_EXPR_DEPTH>0

/*

** Check that argument nHeight is less than or equal to the maximum

** expression depth allowed. If it is not, leave an error message in

** pParse.

*/

static int checkExprHeight(Parse *pParse, int nHeight){

int rc = SQLITE_OK;

int mxHeight = pParse->db->aLimit[SQLITE_LIMIT_EXPR_DEPTH];

if( nHeight>mxHeight ){

sqlite3ErrorMsg(pParse,

"Expression tree is too large (maximum depth %d)", mxHeight

);

rc = SQLITE_ERROR;

}

return rc;

}

/* The following three functions, heightOfExpr(), heightOfExprList()

** and heightOfSelect(), are used to determine the maximum height

** of any expression tree referenced by the structure passed as the

** first argument.

**

** If this maximum height is greater than the current value pointed

** to by pnHeight, the second parameter, then set *pnHeight to that

** value.

*/

static void heightOfExpr(Expr *p, int *pnHeight){

if( p ){

if( p->nHeight>*pnHeight ){

*pnHeight = p->nHeight;

}

}

}

static void heightOfExprList(ExprList *p, int *pnHeight){

if( p ){

int i;

for(i=0; i<p->nExpr; i++){

heightOfExpr(p->a[i].pExpr, pnHeight);

}

}

}

static void heightOfSelect(Select *p, int *pnHeight){

if( p ){

heightOfExpr(p->pWhere, pnHeight);

heightOfExpr(p->pHaving, pnHeight);

heightOfExpr(p->pLimit, pnHeight);

heightOfExpr(p->pOffset, pnHeight);

heightOfExprList(p->pEList, pnHeight);

heightOfExprList(p->pGroupBy, pnHeight);

heightOfExprList(p->pOrderBy, pnHeight);

heightOfSelect(p->pPrior, pnHeight);

}

}

/*

** Set the Expr.nHeight variable in the structure passed as an

** argument. An expression with no children, Expr.pList or

** Expr.pSelect member has a height of 1. Any other expression

** has a height equal to the maximum height of any other

** referenced Expr plus one.

*/

static void exprSetHeight(Expr *p){

int nHeight = 0;

heightOfExpr(p->pLeft, &nHeight);

heightOfExpr(p->pRight, &nHeight);

heightOfExprList(p->pList, &nHeight);

heightOfSelect(p->pSelect, &nHeight);

p->nHeight = nHeight + 1;

}

/*

** Set the Expr.nHeight variable using the exprSetHeight() function. If

** the height is greater than the maximum allowed expression depth,

** leave an error in pParse.

*/

void sqlite3ExprSetHeight(Parse *pParse, Expr *p){

exprSetHeight(p);

checkExprHeight(pParse, p->nHeight);

}

/*

** Return the maximum height of any expression tree referenced

** by the select statement passed as an argument.

*/

int sqlite3SelectExprHeight(Select *p){

int nHeight = 0;

heightOfSelect(p, &nHeight);

return nHeight;

}

#else

#define checkExprHeight(x,y)

#define exprSetHeight(y)

#endif /* SQLITE_MAX_EXPR_DEPTH>0 */

/*

** 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 = 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(db, pLeft);

sqlite3ExprDelete(db, pRight);

return 0;

}

pNew->op = op;

pNew->pLeft = pLeft;

pNew->pRight = pRight;

pNew->iAgg = -1;

pNew->span.z = (u8*)"";

if( pToken ){

assert( pToken->dyn==0 );

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

}else if( pLeft ){

if( pRight ){

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

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;

}

}

exprSetHeight(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 */

){

Expr *p = sqlite3Expr(pParse->db, op, pLeft, pRight, pToken);

if( p ){

checkExprHeight(pParse, p->nHeight);

}

return p;

}

/*

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

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

** in the virtual machine. #N is the N-th register.

**

** 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;

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 */

}

p->iTable = atoi((char*)&pToken->z[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. Both tokens must be pointing

** at the same string.

*/

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

assert( pRight!=0 );

assert( pLeft!=0 );

if( pExpr ){

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

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

}

}

/*

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

** arguments.

*/

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

Expr *pNew;

sqlite3 *db = pParse->db;

assert( pToken );

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

if( pNew==0 ){

sqlite3ExprListDelete(db, 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(pParse, 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]);

testcase( i==0 );

testcase( i==1 );

testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );

testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );

if( i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){

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

db->aLimit[SQLITE_LIMIT_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 =

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>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){

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

}

}

/*

** Recursively delete an expression tree.

*/

void sqlite3ExprDelete(sqlite3 *db, Expr *p){

if( p==0 ) return;

if( p->span.dyn ) sqlite3DbFree(db, (char*)p->span.z);

if( p->token.dyn ) sqlite3DbFree(db, (char*)p->token.z);

sqlite3ExprDelete(db, p->pLeft);

sqlite3ExprDelete(db, p->pRight);

sqlite3ExprListDelete(db, p->pList);

sqlite3SelectDelete(db, p->pSelect);

sqlite3DbFree(db, 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 = 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 ) sqlite3DbFree(db, (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;

struct ExprList_item *pItem, *pOldItem;

int i;

if( p==0 ) return 0;

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

if( pNew==0 ) return 0;

pNew->iECursor = 0;

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

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

if( pItem==0 ){

sqlite3DbFree(db, pNew);

return 0;

}

pOldItem = p->a;

for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){

Expr *pNewExpr, *pOldExpr;

pItem->pExpr = pNewExpr = sqlite3ExprDup(db, pOldExpr = pOldItem->pExpr);

if( pOldExpr->span.z!=0 && pNewExpr ){

/* Always make a copy of the span for top-level expressions in the

** expression list. The logic in SELECT processing that determines

** the names of columns in the result set needs this information */

sqlite3TokenCopy(db, &pNewExpr->span, &pOldExpr->span);

}

assert( pNewExpr==0 || pNewExpr->span.z!=0

|| pOldExpr->span.z==0

|| db->mallocFailed );

pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

pItem->sortOrder = pOldItem->sortOrder;

pItem->isAgg = pOldItem->isAgg;

pItem->done = 0;

}

return pNew;

}

/*

** If cursors, triggers, views and subqueries are all omitted from

** the build, then none of the following routines, except for

** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes

** called with a NULL argument.

*/

#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \

|| !defined(SQLITE_OMIT_SUBQUERY)

SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p){

SrcList *pNew;

int i;

int nByte;

if( p==0 ) return 0;

nByte = sizeof(*p) + (p->nSrc>0 ? sizeof(p->a[0]) * (p->nSrc-1) : 0);

pNew = sqlite3DbMallocRaw(db, nByte );

if( pNew==0 ) return 0;

pNew->nSrc = pNew->nAlloc = p->nSrc;

for(i=0; i<p->nSrc; i++){

struct SrcList_item *pNewItem = &pNew->a[i];

struct SrcList_item *pOldItem = &p->a[i];

Table *pTab;

pNewItem->zDatabase = sqlite3DbStrDup(db, pOldItem->zDatabase);

pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);

pNewItem->jointype = pOldItem->jointype;

pNewItem->iCursor = pOldItem->iCursor;

pNewItem->isPopulated = pOldItem->isPopulated;

pTab = pNewItem->pTab = pOldItem->pTab;

if( pTab ){

pTab->nRef++;

}

pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect);

pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn);

pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing);

pNewItem->colUsed = pOldItem->colUsed;

}

return pNew;

}

IdList *sqlite3IdListDup(sqlite3 *db, IdList *p){

IdList *pNew;

int i;

if( p==0 ) return 0;

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

if( pNew==0 ) return 0;

pNew->nId = pNew->nAlloc = p->nId;

pNew->a = sqlite3DbMallocRaw(db, p->nId*sizeof(p->a[0]) );

if( pNew->a==0 ){

sqlite3DbFree(db, pNew);

return 0;

}

for(i=0; i<p->nId; i++){

struct IdList_item *pNewItem = &pNew->a[i];

struct IdList_item *pOldItem = &p->a[i];

pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);

pNewItem->idx = pOldItem->idx;

}

return pNew;

}

Select *sqlite3SelectDup(sqlite3 *db, Select *p){

Select *pNew;

if( p==0 ) return 0;

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

if( pNew==0 ) return 0;

pNew->isDistinct = p->isDistinct;

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

pNew->pSrc = sqlite3SrcListDup(db, p->pSrc);

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

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

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

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

pNew->op = p->op;

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

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

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

pNew->iLimit = 0;

pNew->iOffset = 0;

pNew->isResolved = p->isResolved;

pNew->isAgg = p->isAgg;

pNew->usesEphm = 0;

pNew->disallowOrderBy = 0;

pNew->pRightmost = 0;

pNew->addrOpenEphm[0] = -1;

pNew->addrOpenEphm[1] = -1;

pNew->addrOpenEphm[2] = -1;

return pNew;

}

#else

Select *sqlite3SelectDup(sqlite3 *db, Select *p){

assert( p==0 );

return 0;

}

#endif

/*

** Add a new element to the end of an expression list. If pList is

** initially NULL, then create a new expression list.

*/

ExprList *sqlite3ExprListAppend(

Parse *pParse, /* Parsing context */

ExprList *pList, /* List to which to append. Might be NULL */

Expr *pExpr, /* Expression to be appended */

Token *pName /* AS keyword for the expression */

){

sqlite3 *db = pParse->db;

if( pList==0 ){

pList = sqlite3DbMallocZero(db, sizeof(ExprList) );

if( pList==0 ){

goto no_mem;

}

assert( pList->nAlloc==0 );

}

if( pList->nAlloc<=pList->nExpr ){

struct ExprList_item *a;

int n = pList->nAlloc*2 + 4;

a = sqlite3DbRealloc(db, pList->a, n*sizeof(pList->a[0]));

if( a==0 ){

goto no_mem;

}

pList->a = a;

pList->nAlloc = n;

}

assert( pList->a!=0 );

if( pExpr || pName ){

struct ExprList_item *pItem = &pList->a[pList->nExpr++];

memset(pItem, 0, sizeof(*pItem));

pItem->zName = sqlite3NameFromToken(db, pName);

pItem->pExpr = pExpr;

}

return pList;

no_mem:

/* Avoid leaking memory if malloc has failed. */

sqlite3ExprDelete(db, pExpr);

sqlite3ExprListDelete(db, pList);

return 0;

}

/*

** If the expression list pEList contains more than iLimit elements,

** leave an error message in pParse.

*/

void sqlite3ExprListCheckLength(

Parse *pParse,

ExprList *pEList,

const char *zObject

){

int mx = pParse->db->aLimit[SQLITE_LIMIT_COLUMN];

testcase( pEList && pEList->nExpr==mx );

testcase( pEList && pEList->nExpr==mx+1 );

if( pEList && pEList->nExpr>mx ){

sqlite3ErrorMsg(pParse, "too many columns in %s", zObject);

}

}

/*

** Delete an entire expression list.

*/

void sqlite3ExprListDelete(sqlite3 *db, ExprList *pList){

int i;

struct ExprList_item *pItem;

if( pList==0 ) return;

assert( pList->a!=0 || (pList->nExpr==0 && pList->nAlloc==0) );

assert( pList->nExpr<=pList->nAlloc );

for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){

sqlite3ExprDelete(db, pItem->pExpr);

sqlite3DbFree(db, pItem->zName);

}

sqlite3DbFree(db, pList->a);

sqlite3DbFree(db, pList);

}

/*

** Walk an expression tree. Call xFunc for each node visited. xFunc

** is called on the node before xFunc is called on the nodes children.

**

** The return value from xFunc determines whether the tree walk continues.

** 0 means continue walking the tree. 1 means do not walk children

** of the current node but continue with siblings. 2 means abandon

** the tree walk completely.

**

** The return value from this routine is 1 to abandon the tree walk

** and 0 to continue.

**

** NOTICE: This routine does *not* descend into subqueries.

*/

static int walkExprList(ExprList *, int (*)(void *, Expr*), void *);

static int walkExprTree(Expr *pExpr, int (*xFunc)(void*,Expr*), void *pArg){

int rc;

if( pExpr==0 ) return 0;

rc = (*xFunc)(pArg, pExpr);

if( rc==0 ){

if( walkExprTree(pExpr->pLeft, xFunc, pArg) ) return 1;

if( walkExprTree(pExpr->pRight, xFunc, pArg) ) return 1;

if( walkExprList(pExpr->pList, xFunc, pArg) ) return 1;

}

return rc>1;

}

/*

** Call walkExprTree() for every expression in list p.

*/

static int walkExprList(ExprList *p, int (*xFunc)(void *, Expr*), void *pArg){

int i;

struct ExprList_item *pItem;

if( !p ) return 0;

for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){

if( walkExprTree(pItem->pExpr, xFunc, pArg) ) return 1;

}

return 0;

}

/*

** Call walkExprTree() for every expression in Select p, not including

** expressions that are part of sub-selects in any FROM clause or the LIMIT

** or OFFSET expressions..

*/

static int walkSelectExpr(Select *p, int (*xFunc)(void *, Expr*), void *pArg){

walkExprList(p->pEList, xFunc, pArg);

walkExprTree(p->pWhere, xFunc, pArg);

walkExprList(p->pGroupBy, xFunc, pArg);

walkExprTree(p->pHaving, xFunc, pArg);

walkExprList(p->pOrderBy, xFunc, pArg);

if( p->pPrior ){

walkSelectExpr(p->pPrior, xFunc, pArg);

}

return 0;

}

/*

** This routine is designed as an xFunc for walkExprTree().

**

** pArg is really a pointer to an integer. If we can tell by looking

** at pExpr that the expression that contains pExpr is not a constant

** expression, then set *pArg to 0 and return 2 to abandon the tree walk.

** If pExpr does does not disqualify the expression from being a constant

** then do nothing.

**

** After walking the whole tree, if no nodes are found that disqualify

** the expression as constant, then we assume the whole expression

** is constant. See sqlite3ExprIsConstant() for additional information.

*/

static int exprNodeIsConstant(void *pArg, Expr *pExpr){

int *pN = (int*)pArg;

/* If *pArg is 3 then any term of the expression that comes from

** the ON or USING clauses of a join disqualifies the expression

** from being considered constant. */

if( (*pN)==3 && ExprHasAnyProperty(pExpr, EP_FromJoin) ){

*pN = 0;

return 2;

}

switch( pExpr->op ){

/* Consider functions to be constant if all their arguments are constant

** and *pArg==2 */

case TK_FUNCTION:

if( (*pN)==2 ) return 0;

/* Fall through */

case TK_ID:

case TK_COLUMN:

case TK_DOT:

case TK_AGG_FUNCTION:

case TK_AGG_COLUMN:

#ifndef SQLITE_OMIT_SUBQUERY

case TK_SELECT:

case TK_EXISTS:

testcase( pExpr->op==TK_SELECT );

testcase( pExpr->op==TK_EXISTS );

#endif

testcase( pExpr->op==TK_ID );

testcase( pExpr->op==TK_COLUMN );

testcase( pExpr->op==TK_DOT );

testcase( pExpr->op==TK_AGG_FUNCTION );

testcase( pExpr->op==TK_AGG_COLUMN );

*pN = 0;

return 2;

case TK_IN:

if( pExpr->pSelect ){

*pN = 0;

return 2;

}

default:

return 0;

}

}

/*

** Walk an expression tree. Return 1 if the expression is constant

** and 0 if it involves variables or function calls.

**

** For the purposes of this function, a double-quoted string (ex: "abc")

** is considered a variable but a single-quoted string (ex: 'abc') is

** a constant.

*/

int sqlite3ExprIsConstant(Expr *p){

int isConst = 1;

walkExprTree(p, exprNodeIsConstant, &isConst);

return isConst;

}

/*

** Walk an expression tree. Return 1 if the expression is constant

** that does no originate from the ON or USING clauses of a join.

** Return 0 if it involves variables or function calls or terms from

** an ON or USING clause.

*/

int sqlite3ExprIsConstantNotJoin(Expr *p){

int isConst = 3;

walkExprTree(p, exprNodeIsConstant, &isConst);

return isConst!=0;

}

/*