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expr.c
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4116 lines (3923 loc) · 137 KB
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/*
** 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.
*/
#include "sqliteInt.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 ){
assert( pExpr->flags&EP_xIsSelect );
return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
}
#ifndef SQLITE_OMIT_CAST
if( op==TK_CAST ){
assert( !ExprHasProperty(pExpr, EP_IntValue) );
return sqlite3AffinityType(pExpr->u.zToken);
}
#endif
if( (op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER)
&& pExpr->pTab!=0
){
/* op==TK_REGISTER && pExpr->pTab!=0 happens when pExpr was originally
** a TK_COLUMN but was previously evaluated and cached in a register */
int j = pExpr->iColumn;
if( j<0 ) return SQLITE_AFF_INTEGER;
assert( pExpr->pTab && j<pExpr->pTab->nCol );
return pExpr->pTab->aCol[j].affinity;
}
return pExpr->affinity;
}
/*
** Set the explicit collating sequence for an expression to the
** collating sequence supplied in the second argument.
*/
Expr *sqlite3ExprSetColl(Expr *pExpr, CollSeq *pColl){
if( pExpr && pColl ){
pExpr->pColl = pColl;
pExpr->flags |= EP_ExpCollate;
}
return pExpr;
}
/*
** 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 *sqlite3ExprSetCollByToken(Parse *pParse, Expr *pExpr, Token *pCollName){
char *zColl = 0; /* Dequoted name of collation sequence */
CollSeq *pColl;
sqlite3 *db = pParse->db;
zColl = sqlite3NameFromToken(db, pCollName);
pColl = sqlite3LocateCollSeq(pParse, zColl);
sqlite3ExprSetColl(pExpr, pColl);
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;
Expr *p = pExpr;
while( p ){
int op;
pColl = p->pColl;
if( pColl ) break;
op = p->op;
if( p->pTab!=0 && (
op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER || op==TK_TRIGGER
)){
/* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
** a TK_COLUMN but was previously evaluated and cached in a register */
const char *zColl;
int j = p->iColumn;
if( j>=0 ){
sqlite3 *db = pParse->db;
zColl = p->pTab->aCol[j].zColl;
pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
pExpr->pColl = pColl;
}
break;
}
if( op!=TK_CAST && op!=TK_UPLUS ){
break;
}
p = p->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 || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
assert( pExpr->pLeft );
aff = sqlite3ExprAffinity(pExpr->pLeft);
if( pExpr->pRight ){
aff = sqlite3CompareAffinity(pExpr->pRight, aff);
}else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
aff = sqlite3CompareAffinity(pExpr->x.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 = (u8)sqlite3CompareAffinity(pExpr1, aff) | (u8)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 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, (u8)p5);
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.
*/
int sqlite3ExprCheckHeight(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);
if( ExprHasProperty(p, EP_xIsSelect) ){
heightOfSelect(p->x.pSelect, &nHeight);
}else{
heightOfExprList(p->x.pList, &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);
sqlite3ExprCheckHeight(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 exprSetHeight(y)
#endif /* SQLITE_MAX_EXPR_DEPTH>0 */
/*
** This routine is the core allocator for Expr nodes.
**
** Construct a new expression node and return a pointer to it. Memory
** for this node and for the pToken argument is a single allocation
** obtained from sqlite3DbMalloc(). The calling function
** is responsible for making sure the node eventually gets freed.
**
** If dequote is true, then the token (if it exists) is dequoted.
** If dequote is false, no dequoting is performance. The deQuote
** parameter is ignored if pToken is NULL or if the token does not
** appear to be quoted. If the quotes were of the form "..." (double-quotes)
** then the EP_DblQuoted flag is set on the expression node.
**
** Special case: If op==TK_INTEGER and pToken points to a string that
** can be translated into a 32-bit integer, then the token is not
** stored in u.zToken. Instead, the integer values is written
** into u.iValue and the EP_IntValue flag is set. No extra storage
** is allocated to hold the integer text and the dequote flag is ignored.
*/
Expr *sqlite3ExprAlloc(
sqlite3 *db, /* Handle for sqlite3DbMallocZero() (may be null) */
int op, /* Expression opcode */
const Token *pToken, /* Token argument. Might be NULL */
int dequote /* True to dequote */
){
Expr *pNew;
int nExtra = 0;
int iValue = 0;
if( pToken ){
if( op!=TK_INTEGER || pToken->z==0
|| sqlite3GetInt32(pToken->z, &iValue)==0 ){
nExtra = pToken->n+1;
assert( iValue>=0 );
}
}
pNew = sqlite3DbMallocZero(db, sizeof(Expr)+nExtra);
if( pNew ){
pNew->op = (u8)op;
pNew->iAgg = -1;
if( pToken ){
if( nExtra==0 ){
pNew->flags |= EP_IntValue;
pNew->u.iValue = iValue;
}else{
int c;
pNew->u.zToken = (char*)&pNew[1];
assert( pToken->z!=0 || pToken->n==0 );
if( pToken->n ) memcpy(pNew->u.zToken, pToken->z, pToken->n);
pNew->u.zToken[pToken->n] = 0;
if( dequote && nExtra>=3
&& ((c = pToken->z[0])=='\'' || c=='"' || c=='[' || c=='`') ){
sqlite3Dequote(pNew->u.zToken);
if( c=='"' ) pNew->flags |= EP_DblQuoted;
}
}
}
#if SQLITE_MAX_EXPR_DEPTH>0
pNew->nHeight = 1;
#endif
}
return pNew;
}
/*
** Allocate a new expression node from a zero-terminated token that has
** already been dequoted.
*/
Expr *sqlite3Expr(
sqlite3 *db, /* Handle for sqlite3DbMallocZero() (may be null) */
int op, /* Expression opcode */
const char *zToken /* Token argument. Might be NULL */
){
Token x;
x.z = zToken;
x.n = zToken ? sqlite3Strlen30(zToken) : 0;
return sqlite3ExprAlloc(db, op, &x, 0);
}
/*
** Attach subtrees pLeft and pRight to the Expr node pRoot.
**
** If pRoot==NULL that means that a memory allocation error has occurred.
** In that case, delete the subtrees pLeft and pRight.
*/
void sqlite3ExprAttachSubtrees(
sqlite3 *db,
Expr *pRoot,
Expr *pLeft,
Expr *pRight
){
if( pRoot==0 ){
assert( db->mallocFailed );
sqlite3ExprDelete(db, pLeft);
sqlite3ExprDelete(db, pRight);
}else{
if( pRight ){
pRoot->pRight = pRight;
if( pRight->flags & EP_ExpCollate ){
pRoot->flags |= EP_ExpCollate;
pRoot->pColl = pRight->pColl;
}
}
if( pLeft ){
pRoot->pLeft = pLeft;
if( pLeft->flags & EP_ExpCollate ){
pRoot->flags |= EP_ExpCollate;
pRoot->pColl = pLeft->pColl;
}
}
exprSetHeight(pRoot);
}
}
/*
** Allocate a Expr node which joins as many as two subtrees.
**
** One or both of the subtrees can be NULL. Return a pointer to the new
** Expr node. Or, if an OOM error occurs, set pParse->db->mallocFailed,
** free the subtrees and return NULL.
*/
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;
if( op==TK_AND && pLeft && pRight ){
/* Take advantage of short-circuit false optimization for AND */
p = sqlite3ExprAnd(pParse->db, pLeft, pRight);
}else{
p = sqlite3ExprAlloc(pParse->db, op, pToken, 1);
sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
}
if( p ) {
sqlite3ExprCheckHeight(pParse, p->nHeight);
}
return p;
}
/*
** Return 1 if an expression must be FALSE in all cases and 0 if the
** expression might be true. This is an optimization. If is OK to
** return 0 here even if the expression really is always false (a
** false negative). But it is a bug to return 1 if the expression
** might be true in some rare circumstances (a false positive.)
**
** Note that if the expression is part of conditional for a
** LEFT JOIN, then we cannot determine at compile-time whether or not
** is it true or false, so always return 0.
*/
static int exprAlwaysFalse(Expr *p){
int v = 0;
if( ExprHasProperty(p, EP_FromJoin) ) return 0;
if( !sqlite3ExprIsInteger(p, &v) ) return 0;
return v==0;
}
/*
** Join two expressions using an AND operator. If either expression is
** NULL, then just return the other expression.
**
** If one side or the other of the AND is known to be false, then instead
** of returning an AND expression, just return a constant expression with
** a value of false.
*/
Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){
if( pLeft==0 ){
return pRight;
}else if( pRight==0 ){
return pLeft;
}else if( exprAlwaysFalse(pLeft) || exprAlwaysFalse(pRight) ){
sqlite3ExprDelete(db, pLeft);
sqlite3ExprDelete(db, pRight);
return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
}else{
Expr *pNew = sqlite3ExprAlloc(db, TK_AND, 0, 0);
sqlite3ExprAttachSubtrees(db, pNew, pLeft, pRight);
return pNew;
}
}
/*
** 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 = sqlite3ExprAlloc(db, TK_FUNCTION, pToken, 1);
if( pNew==0 ){
sqlite3ExprListDelete(db, pList); /* Avoid memory leak when malloc fails */
return 0;
}
pNew->x.pList = pList;
assert( !ExprHasProperty(pNew, EP_xIsSelect) );
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", "@aaa", or "$aaa" are assigned the same number
** as the previous instance of the same wildcard. Or if this is the first
** instance of the wildcard, the next sequenial variable number is
** assigned.
*/
void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr){
sqlite3 *db = pParse->db;
const char *z;
if( pExpr==0 ) return;
assert( !ExprHasAnyProperty(pExpr, EP_IntValue|EP_Reduced|EP_TokenOnly) );
z = pExpr->u.zToken;
assert( z!=0 );
assert( z[0]!=0 );
if( z[1]==0 ){
/* Wildcard of the form "?". Assign the next variable number */
assert( z[0]=='?' );
pExpr->iColumn = (ynVar)(++pParse->nVar);
}else{
ynVar x = 0;
u32 n = sqlite3Strlen30(z);
if( z[0]=='?' ){
/* Wildcard of the form "?nnn". Convert "nnn" to an integer and
** use it as the variable number */
i64 i;
int bOk = 0==sqlite3Atoi64(&z[1], &i, n-1, SQLITE_UTF8);
pExpr->iColumn = x = (ynVar)i;
testcase( i==0 );
testcase( i==1 );
testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );
testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );
if( bOk==0 || i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",
db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]);
x = 0;
}
if( i>pParse->nVar ){
pParse->nVar = (int)i;
}
}else{
/* Wildcards like ":aaa", "$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
*/
ynVar i;
for(i=0; i<pParse->nzVar; i++){
if( pParse->azVar[i] && memcmp(pParse->azVar[i],z,n+1)==0 ){
pExpr->iColumn = x = (ynVar)i+1;
break;
}
}
if( x==0 ) x = pExpr->iColumn = (ynVar)(++pParse->nVar);
}
if( x>0 ){
if( x>pParse->nzVar ){
char **a;
a = sqlite3DbRealloc(db, pParse->azVar, x*sizeof(a[0]));
if( a==0 ) return; /* Error reported through db->mallocFailed */
pParse->azVar = a;
memset(&a[pParse->nzVar], 0, (x-pParse->nzVar)*sizeof(a[0]));
pParse->nzVar = x;
}
if( z[0]!='?' || pParse->azVar[x-1]==0 ){
sqlite3DbFree(db, pParse->azVar[x-1]);
pParse->azVar[x-1] = sqlite3DbStrNDup(db, z, n);
}
}
}
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;
/* Sanity check: Assert that the IntValue is non-negative if it exists */
assert( !ExprHasProperty(p, EP_IntValue) || p->u.iValue>=0 );
if( !ExprHasAnyProperty(p, EP_TokenOnly) ){
sqlite3ExprDelete(db, p->pLeft);
sqlite3ExprDelete(db, p->pRight);
if( !ExprHasProperty(p, EP_Reduced) && (p->flags2 & EP2_MallocedToken)!=0 ){
sqlite3DbFree(db, p->u.zToken);
}
if( ExprHasProperty(p, EP_xIsSelect) ){
sqlite3SelectDelete(db, p->x.pSelect);
}else{
sqlite3ExprListDelete(db, p->x.pList);
}
}
if( !ExprHasProperty(p, EP_Static) ){
sqlite3DbFree(db, p);
}
}
/*
** Return the number of bytes allocated for the expression structure
** passed as the first argument. This is always one of EXPR_FULLSIZE,
** EXPR_REDUCEDSIZE or EXPR_TOKENONLYSIZE.
*/
static int exprStructSize(Expr *p){
if( ExprHasProperty(p, EP_TokenOnly) ) return EXPR_TOKENONLYSIZE;
if( ExprHasProperty(p, EP_Reduced) ) return EXPR_REDUCEDSIZE;
return EXPR_FULLSIZE;
}
/*
** The dupedExpr*Size() routines each return the number of bytes required
** to store a copy of an expression or expression tree. They differ in
** how much of the tree is measured.
**
** dupedExprStructSize() Size of only the Expr structure
** dupedExprNodeSize() Size of Expr + space for token
** dupedExprSize() Expr + token + subtree components
**
***************************************************************************
**
** The dupedExprStructSize() function returns two values OR-ed together:
** (1) the space required for a copy of the Expr structure only and
** (2) the EP_xxx flags that indicate what the structure size should be.
** The return values is always one of:
**
** EXPR_FULLSIZE
** EXPR_REDUCEDSIZE | EP_Reduced
** EXPR_TOKENONLYSIZE | EP_TokenOnly
**
** The size of the structure can be found by masking the return value
** of this routine with 0xfff. The flags can be found by masking the
** return value with EP_Reduced|EP_TokenOnly.
**
** Note that with flags==EXPRDUP_REDUCE, this routines works on full-size
** (unreduced) Expr objects as they or originally constructed by the parser.
** During expression analysis, extra information is computed and moved into
** later parts of teh Expr object and that extra information might get chopped
** off if the expression is reduced. Note also that it does not work to
** make a EXPRDUP_REDUCE copy of a reduced expression. It is only legal
** to reduce a pristine expression tree from the parser. The implementation
** of dupedExprStructSize() contain multiple assert() statements that attempt
** to enforce this constraint.
*/
static int dupedExprStructSize(Expr *p, int flags){
int nSize;
assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
if( 0==(flags&EXPRDUP_REDUCE) ){
nSize = EXPR_FULLSIZE;
}else{
assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) );
assert( !ExprHasProperty(p, EP_FromJoin) );
assert( (p->flags2 & EP2_MallocedToken)==0 );
assert( (p->flags2 & EP2_Irreducible)==0 );
if( p->pLeft || p->pRight || p->pColl || p->x.pList ){
nSize = EXPR_REDUCEDSIZE | EP_Reduced;
}else{
nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
}
}
return nSize;
}
/*
** This function returns the space in bytes required to store the copy
** of the Expr structure and a copy of the Expr.u.zToken string (if that
** string is defined.)
*/
static int dupedExprNodeSize(Expr *p, int flags){
int nByte = dupedExprStructSize(p, flags) & 0xfff;
if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
nByte += sqlite3Strlen30(p->u.zToken)+1;
}
return ROUND8(nByte);
}
/*
** Return the number of bytes required to create a duplicate of the
** expression passed as the first argument. The second argument is a
** mask containing EXPRDUP_XXX flags.
**
** The value returned includes space to create a copy of the Expr struct
** itself and the buffer referred to by Expr.u.zToken, if any.
**
** If the EXPRDUP_REDUCE flag is set, then the return value includes
** space to duplicate all Expr nodes in the tree formed by Expr.pLeft
** and Expr.pRight variables (but not for any structures pointed to or
** descended from the Expr.x.pList or Expr.x.pSelect variables).
*/
static int dupedExprSize(Expr *p, int flags){
int nByte = 0;
if( p ){
nByte = dupedExprNodeSize(p, flags);
if( flags&EXPRDUP_REDUCE ){
nByte += dupedExprSize(p->pLeft, flags) + dupedExprSize(p->pRight, flags);
}
}
return nByte;
}
/*
** This function is similar to sqlite3ExprDup(), except that if pzBuffer
** is not NULL then *pzBuffer is assumed to point to a buffer large enough
** to store the copy of expression p, the copies of p->u.zToken
** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
** if any. Before returning, *pzBuffer is set to the first byte passed the
** portion of the buffer copied into by this function.
*/
static Expr *exprDup(sqlite3 *db, Expr *p, int flags, u8 **pzBuffer){
Expr *pNew = 0; /* Value to return */
if( p ){
const int isReduced = (flags&EXPRDUP_REDUCE);
u8 *zAlloc;
u32 staticFlag = 0;
assert( pzBuffer==0 || isReduced );
/* Figure out where to write the new Expr structure. */
if( pzBuffer ){
zAlloc = *pzBuffer;
staticFlag = EP_Static;
}else{
zAlloc = sqlite3DbMallocRaw(db, dupedExprSize(p, flags));
}
pNew = (Expr *)zAlloc;
if( pNew ){
/* Set nNewSize to the size allocated for the structure pointed to
** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
** by the copy of the p->u.zToken string (if any).
*/
const unsigned nStructSize = dupedExprStructSize(p, flags);
const int nNewSize = nStructSize & 0xfff;
int nToken;
if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
nToken = sqlite3Strlen30(p->u.zToken) + 1;
}else{
nToken = 0;
}
if( isReduced ){
assert( ExprHasProperty(p, EP_Reduced)==0 );
memcpy(zAlloc, p, nNewSize);
}else{
int nSize = exprStructSize(p);
memcpy(zAlloc, p, nSize);
memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize);
}
/* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static);
pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
pNew->flags |= staticFlag;
/* Copy the p->u.zToken string, if any. */
if( nToken ){
char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
memcpy(zToken, p->u.zToken, nToken);
}
if( 0==((p->flags|pNew->flags) & EP_TokenOnly) ){
/* Fill in the pNew->x.pSelect or pNew->x.pList member. */
if( ExprHasProperty(p, EP_xIsSelect) ){
pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, isReduced);
}else{
pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, isReduced);
}
}
/* Fill in pNew->pLeft and pNew->pRight. */
if( ExprHasAnyProperty(pNew, EP_Reduced|EP_TokenOnly) ){
zAlloc += dupedExprNodeSize(p, flags);
if( ExprHasProperty(pNew, EP_Reduced) ){
pNew->pLeft = exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc);
pNew->pRight = exprDup(db, p->pRight, EXPRDUP_REDUCE, &zAlloc);
}
if( pzBuffer ){
*pzBuffer = zAlloc;
}
}else{
pNew->flags2 = 0;
if( !ExprHasAnyProperty(p, EP_TokenOnly) ){
pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
pNew->pRight = sqlite3ExprDup(db, p->pRight, 0);
}
}
}
}
return pNew;
}
/*
** 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.
**
** The flags parameter contains a combination of the EXPRDUP_XXX flags.
** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
** truncated version of the usual Expr structure that will be stored as
** part of the in-memory representation of the database schema.
*/
Expr *sqlite3ExprDup(sqlite3 *db, Expr *p, int flags){
return exprDup(db, p, flags, 0);
}
ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
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 = i = p->nExpr;
if( (flags & EXPRDUP_REDUCE)==0 ) for(i=1; i<p->nExpr; i+=i){}
pNew->a = pItem = sqlite3DbMallocRaw(db, i*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 *pOldExpr = pOldItem->pExpr;
pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags);
pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
pItem->zSpan = sqlite3DbStrDup(db, pOldItem->zSpan);
pItem->sortOrder = pOldItem->sortOrder;
pItem->done = 0;
pItem->iOrderByCol = pOldItem->iOrderByCol;
pItem->iAlias = pOldItem->iAlias;
}
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, int flags){
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->addrFillSub = pOldItem->addrFillSub;
pNewItem->regReturn = pOldItem->regReturn;
pNewItem->isCorrelated = pOldItem->isCorrelated;
pNewItem->zIndex = sqlite3DbStrDup(db, pOldItem->zIndex);
pNewItem->notIndexed = pOldItem->notIndexed;
pNewItem->pIndex = pOldItem->pIndex;
pTab = pNewItem->pTab = pOldItem->pTab;
if( pTab ){
pTab->nRef++;
}
pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);
pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn, flags);
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 = p->nId;
pNew->a = sqlite3DbMallocRaw(db, p->nId*sizeof(p->a[0]) );
if( pNew->a==0 ){
sqlite3DbFree(db, pNew);
return 0;
}
/* Note that because the size of the allocation for p->a[] is not
** necessarily a power of two, sqlite3IdListAppend() may not be called
** on the duplicate created by this function. */
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, int flags){
Select *pNew, *pPrior;
if( p==0 ) return 0;
pNew = sqlite3DbMallocRaw(db, sizeof(*p) );
if( pNew==0 ) return 0;
pNew->pEList = sqlite3ExprListDup(db, p->pEList, flags);
pNew->pSrc = sqlite3SrcListDup(db, p->pSrc, flags);
pNew->pWhere = sqlite3ExprDup(db, p->pWhere, flags);
pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy, flags);
pNew->pHaving = sqlite3ExprDup(db, p->pHaving, flags);
pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, flags);
pNew->op = p->op;
pNew->pPrior = pPrior = sqlite3SelectDup(db, p->pPrior, flags);
if( pPrior ) pPrior->pNext = pNew;
pNew->pNext = 0;
pNew->pLimit = sqlite3ExprDup(db, p->pLimit, flags);
pNew->pOffset = sqlite3ExprDup(db, p->pOffset, flags);
pNew->iLimit = 0;
pNew->iOffset = 0;
pNew->selFlags = p->selFlags & ~SF_UsesEphemeral;
pNew->pRightmost = 0;
pNew->addrOpenEphm[0] = -1;
pNew->addrOpenEphm[1] = -1;