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Add commentary to the ExprList object to explain how zSpan is overloaded.

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Add test cases for the new name resolution functionality.

FossilOrigin-Name: 3e7d84db7861911c9b2c7dcdabe0b213bf483d79
This commit is contained in:
drh
2012-12-19 13:41:03 +00:00
parent 8f25d18b21
commit 0dde4739f3
4 changed files with 101 additions and 17 deletions
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22
src/sqliteInt.h
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@@ -1771,18 +1771,26 @@ struct Expr {
** list of "ID = expr" items in an UPDATE. A list of expressions can
** also be used as the argument to a function, in which case the a.zName
** field is not used.
**
** By default the Expr.zSpan field holds a human-readable description of
** the expression that is used in the generation of error messages and
** column labels. In this case, Expr.zSpan is typically the text of a
** column expression as it exists in a SELECT statement. However, if
** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name
** of the table to which the column of a FROM-clause subquery refers.
*/
struct ExprList {
int nExpr; /* Number of expressions on the list */
int iECursor; /* VDBE Cursor associated with this ExprList */
struct ExprList_item { /* For each expression in the list */
Expr *pExpr; /* The list of expressions */
char *zName; /* Token associated with this expression */
char *zSpan; /* Original text of the expression */
u8 sortOrder; /* 1 for DESC or 0 for ASC */
u8 done; /* A flag to indicate when processing is finished */
u16 iOrderByCol; /* For ORDER BY, column number in result set */
u16 iAlias; /* Index into Parse.aAlias[] for zName */
Expr *pExpr; /* The list of expressions */
char *zName; /* Token associated with this expression */
char *zSpan; /* Original text of the expression */
u8 sortOrder; /* 1 for DESC or 0 for ASC */
unsigned done :1; /* A flag to indicate when processing is finished */
unsigned bSpanIsTab :1; /* zSpan holds table name, not the span */
u16 iOrderByCol; /* For ORDER BY, column number in result set */
u16 iAlias; /* Index into Parse.aAlias[] for zName */
} *a; /* Alloc a power of two greater or equal to nExpr */
};