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Overview
Comment:Simplification to the grammar rules for window functions. Fix a memory leak that can follow an OOM while parsing a comma-separated list of window definitions.
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SHA3-256: a568f9c9db594f3b194c6e870305c9d6f2392ce6bc8ac00e9688883e97560fff
User & Date: drh 2018-07-09 16:24:00.700
Context
2018-07-09
17:33
Remove redundant branches in window function processing. (check-in: 8fdaf3f37e user: drh tags: trunk)
16:24
Simplification to the grammar rules for window functions. Fix a memory leak that can follow an OOM while parsing a comma-separated list of window definitions. (check-in: a568f9c9db user: drh tags: trunk)
13:31
Throw an error if the second argument passed to nth_value() is not a positive integer. (check-in: 1a06e57a0b user: dan tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/parse.y.
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// These must be at the end of this file. Specifically, the rules that
// introduce tokens WINDOW, OVER and FILTER must appear last. This causes 
// the integer values assigned to these tokens to be larger than all other 
// tokens that may be output by the tokenizer except TK_SPACE and TK_ILLEGAL.
//
%ifndef SQLITE_OMIT_WINDOWFUNC
%type windowdefn_list {Window*}
%destructor windowdefn_list {sqlite3WindowDelete(pParse->db, $$);}
windowdefn_list(A) ::= windowdefn(Z). { A = Z; }
windowdefn_list(A) ::= windowdefn_list(Y) COMMA windowdefn(Z). {

  if( Z ) Z->pNextWin = Y;
  A = Z;
}

%type windowdefn {Window*}
%destructor windowdefn {sqlite3WindowDelete(pParse->db, $$);}
windowdefn(A) ::= nm(X) AS window(Y). {
  if( Y ){
    Y->zName = sqlite3DbStrNDup(pParse->db, X.z, X.n);
  }
  A = Y;
}

%type window {Window*}
%destructor window {sqlite3WindowDelete(pParse->db, $$);}

%type frame_opt {Window*}
%destructor frame_opt {sqlite3WindowDelete(pParse->db, $$);}

%type window_or_nm {Window*}
%destructor window_or_nm {
sqlite3WindowDelete(pParse->db, $$);}

%type part_opt {ExprList*}
%destructor part_opt {sqlite3ExprListDelete(pParse->db, $$);}

%type filter_opt {Expr*}
%destructor filter_opt {sqlite3ExprDelete(pParse->db, $$);}

%type range_or_rows {int}

%type frame_bound {struct FrameBound}
%destructor frame_bound {sqlite3ExprDelete(pParse->db, $$.pExpr);}
%type frame_bound_s {struct FrameBound}
%destructor frame_bound_s {sqlite3ExprDelete(pParse->db, $$.pExpr);}
%type frame_bound_e {struct FrameBound}
%destructor frame_bound_e {sqlite3ExprDelete(pParse->db, $$.pExpr);}

window_or_nm(A) ::= window(Z). {A = Z;}
window_or_nm(A) ::= nm(Z). {
  A = (Window*)sqlite3DbMallocZero(pParse->db, sizeof(Window));
  if( A ){
    A->zName = sqlite3DbStrNDup(pParse->db, Z.z, Z.n);
  }
}

window(A) ::= LP part_opt(X) orderby_opt(Y) frame_opt(Z) RP. {
  A = Z;
  if( A ){
    A->pPartition = X;
    A->pOrderBy = Y;
  }
}

part_opt(A) ::= PARTITION BY exprlist(X). { A = X; }
part_opt(A) ::= .                         { A = 0; }







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// These must be at the end of this file. Specifically, the rules that
// introduce tokens WINDOW, OVER and FILTER must appear last. This causes 
// the integer values assigned to these tokens to be larger than all other 
// tokens that may be output by the tokenizer except TK_SPACE and TK_ILLEGAL.
//
%ifndef SQLITE_OMIT_WINDOWFUNC
%type windowdefn_list {Window*}
%destructor windowdefn_list {sqlite3WindowListDelete(pParse->db, $$);}
windowdefn_list(A) ::= windowdefn(Z). { A = Z; }
windowdefn_list(A) ::= windowdefn_list(Y) COMMA windowdefn(Z). {
  assert( Z!=0 );
  Z->pNextWin = Y;
  A = Z;
}

%type windowdefn {Window*}
%destructor windowdefn {sqlite3WindowDelete(pParse->db, $$);}
windowdefn(A) ::= nm(X) AS window(Y). {
  if( ALWAYS(Y) ){
    Y->zName = sqlite3DbStrNDup(pParse->db, X.z, X.n);
  }
  A = Y;
}

%type window {Window*}
%destructor window {sqlite3WindowDelete(pParse->db, $$);}

%type frame_opt {Window*}
%destructor frame_opt {sqlite3WindowDelete(pParse->db, $$);}





%type part_opt {ExprList*}
%destructor part_opt {sqlite3ExprListDelete(pParse->db, $$);}

%type filter_opt {Expr*}
%destructor filter_opt {sqlite3ExprDelete(pParse->db, $$);}

%type range_or_rows {int}

%type frame_bound {struct FrameBound}
%destructor frame_bound {sqlite3ExprDelete(pParse->db, $$.pExpr);}
%type frame_bound_s {struct FrameBound}
%destructor frame_bound_s {sqlite3ExprDelete(pParse->db, $$.pExpr);}
%type frame_bound_e {struct FrameBound}
%destructor frame_bound_e {sqlite3ExprDelete(pParse->db, $$.pExpr);}









window(A) ::= LP part_opt(X) orderby_opt(Y) frame_opt(Z) RP. {
  A = Z;
  if( ALWAYS(A) ){
    A->pPartition = X;
    A->pOrderBy = Y;
  }
}

part_opt(A) ::= PARTITION BY exprlist(X). { A = X; }
part_opt(A) ::= .                         { A = 0; }
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frame_bound_e(A) ::= UNBOUNDED FOLLOWING. {A.eType = TK_UNBOUNDED; A.pExpr = 0;}

frame_bound(A) ::= expr(X) PRECEDING.   { A.eType = TK_PRECEDING; A.pExpr = X; }
frame_bound(A) ::= CURRENT ROW.         { A.eType = TK_CURRENT  ; A.pExpr = 0; }
frame_bound(A) ::= expr(X) FOLLOWING.   { A.eType = TK_FOLLOWING; A.pExpr = X; }

%type windowdefn_opt {Window*}
%destructor windowdefn_opt {sqlite3WindowDelete(pParse->db, $$);}
windowdefn_opt(A) ::= . { A = 0; }
windowdefn_opt(A) ::= WINDOW windowdefn_list(B). { A = B; }

%type over_opt {Window*}
%destructor over_opt {sqlite3WindowDelete(pParse->db, $$);}
over_opt(A) ::= . { A = 0; }
over_opt(A) ::= filter_opt(W) OVER window_or_nm(Z). {
  A = Z;

  if( A ) A->pFilter = W;









}

filter_opt(A) ::= .                            { A = 0; }
filter_opt(A) ::= FILTER LP WHERE expr(X) RP.  { A = X; }
%endif // SQLITE_OMIT_WINDOWFUNC








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frame_bound_e(A) ::= UNBOUNDED FOLLOWING. {A.eType = TK_UNBOUNDED; A.pExpr = 0;}

frame_bound(A) ::= expr(X) PRECEDING.   { A.eType = TK_PRECEDING; A.pExpr = X; }
frame_bound(A) ::= CURRENT ROW.         { A.eType = TK_CURRENT  ; A.pExpr = 0; }
frame_bound(A) ::= expr(X) FOLLOWING.   { A.eType = TK_FOLLOWING; A.pExpr = X; }

%type windowdefn_opt {Window*}
%destructor windowdefn_opt {sqlite3WindowListDelete(pParse->db, $$);}
windowdefn_opt(A) ::= . { A = 0; }
windowdefn_opt(A) ::= WINDOW windowdefn_list(B). { A = B; }

%type over_opt {Window*}
%destructor over_opt {sqlite3WindowDelete(pParse->db, $$);}
over_opt(A) ::= . { A = 0; }
over_opt(A) ::= filter_opt(W) OVER window(Z). {
  A = Z;
  assert( A!=0 );
  A->pFilter = W;
}
over_opt(A) ::= filter_opt(W) OVER nm(Z). {
  A = (Window*)sqlite3DbMallocZero(pParse->db, sizeof(Window));
  if( A ){
    A->zName = sqlite3DbStrNDup(pParse->db, Z.z, Z.n);
    A->pFilter = W;
  }else{
    sqlite3ExprDelete(pParse->db, W);
  }
}

filter_opt(A) ::= .                            { A = 0; }
filter_opt(A) ::= FILTER LP WHERE expr(X) RP.  { A = X; }
%endif // SQLITE_OMIT_WINDOWFUNC