2.2.1.6 CPropertyRestriction

The CPropertyRestriction structure contains a property to get from each row, a comparison operator, and a constant. For each row, the value returned by the specific property in the row is compared against the constant to determine if it has the relationship specified by the _relop field. For the comparison to be true, the data types of the values must match.

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
_relop
_Property (variable)
...
_prval (variable)
...

_relop (4 bytes): A 32-bit unsigned integer specifying the relation to perform on the property. _relop MUST be one of the values in the following tables.

Value	Meaning
PRLT 0x00000000	A less-than comparison.
PRLE 0x00000001	A less-than-or-equal-to comparison.
PRGT 0x00000002	A greater-than comparison.
PRGE 0x00000003	A greater-than-or-equal-to comparison.
PREQ 0x00000004	An equality comparison.
PRNE 0x00000005	A not-equal comparison.
PRRE 0x00000006	A regular expression comparison.

For PRRE relations, regular expressions are expressed with a string that contains special symbols. Any character except an asterisk (*), period (.), question mark (?), or vertical bar (|) matches itself. A regular expression can be enclosed in a pair of quotation marks ("…"), and MUST be enclosed in quotation marks if the expression contains a space or a closing parenthesis.

The asterisk matches any number of characters. The period matches the end of a string. The question mark matches any one character. The vertical bar (|) is an escape character, which indicates special behavior for the characters shown in the following table. The following table explains the meanings of special characters in regular expressions.

Character	Meaning
(	An opening parenthesis opens a group. It MUST be followed by a matching closing parenthesis.
)	A closing parenthesis closes a group. It MUST be preceded by a matching opening parenthesis.
[	An opening bracket preceded (escaped) by a vertical bar opens a character class. It MUST be followed by a matching (nonescaped) closing square bracket.
{	An opening brace opens a counted match. It MUST be followed by a matching closing brace.
}	A closing brace closes a counted match. It MUST be preceded by a matching opening brace.
,	A comma separates OR clauses.
*	An asterisk matches zero or more occurrences of the preceding expression.
?	A question mark matches zero or one occurrence of the preceding expression.
+	A plus sign matches one or more occurrences of the preceding expression.
Other	All other characters match themselves.

The following table describes characters which, when located between brackets ([ ]), have special meanings.

Character	Meaning
^	A caret matches everything but following classes. (It MUST be the first character in the string.)
]	A closing bracket matches another closing bracket. It MAY be preceded only by a caret (^); otherwise, it closes the class.
-	A hyphen is a range operator. It is preceded and followed by normal characters.
Other	All other characters match themselves (or begin or end a range).

The following table describes the syntax used between braces ({ }).

Character	Meaning
{m}	Matches exactly m occurrences of the preceding expression (0 < m < 256).
{m,}	Matches at least m occurrences of the preceding expression (1 < m < 256).
{m, n}	Matches between m and n occurrences of the preceding expression, inclusive (0 < m < 256, 0 < n < 256).

To match the asterisk and question mark, enclose them in brackets. For example, [*]sample matches "*sample".

Value	Meaning
PRAllBits 0x00000007	A bitwise AND that returns the value equal to _prval.
PRSomeBits 0x00000008	A bitwise AND that returns a nonzero value.

For vector properties, the behavior of the relational operators depends on the result of a logical OR using a mask and the relational operator.

If there is no mask, then the restriction  is true if the relational operator holds between each element of a property value and the corresponding element in the _prval field. If, in addition, the two vectors have different lengths, then the vector lengths are compared using the relational operator.

If there is a mask, the possible values are as follows.

Value	Meaning
PRAll 0x00000100	The restriction is true if every element in a property value has the relationship with some element in the _prval field.
PRAny 0x00000200	The restriction is true if any element in the property value has the relationship with some element in the _prval field.

_Property (variable): A CFullPropSpec structure indicating the property on which to perform a match operation.

_prval (variable): A CBaseStorageVariant structure containing the value to relate to the property.