str_to_keyvalue

Retrieve and discard the (key,value) pairs present in a given string/list.

%str_to_keyvalue(str, key=, value=, _key_, _value_=, _item_=, _str_=, op=%quote(=), sep=%quote( ));

Arguments

• str : strings of items that may be defined as (key,value) pairs of the form A&opB where op is defined below;
• key : (option) string(s) defining the keys to look for in the input string; a key is defined as the left-hand side of the (key,value) pair A&opB, i.e. A; when passed, only those (key,value) pairs associated to keys in key are retrieved; when not passed (i.e. left blank), the macro retrieves all possible keys present in the input string;
• value : (option) string(s) defining the values to look for in the input string; a value is defined as the right-hand side of the (key,value) pair A&opB, i.e. B; when passed, the values retrieved from the input string are matched against those in value; by default, value is not considered;
• op : (option) separator character of (key,value) pairs in input string str; default: op=quote(=);
• sep : (option) character/string separator in input list; default: %quote( ), i.e. sep is blank.

Returns

• _key_ : (option) name of the variable storing the (list of) key(s) found in (key,value) pairs present of str and that match the criteria on key and value parameters above;
• _value_ : (option) ibid with value(s);
• _item_ : (option) name of the variable storing the (key,value) zipped pairs that match the criteria on key and value parameters above;
• _str_ : (option) updated string from which all (key,value) pairs that macth the criteria on key and value parameters are discarded.

Examples

Let us consider the following simple examples:

%let str=A, B, K=C, D;
%let ovalue=;
%let ostr=;
%let oitem=;
%str_to_keyvalue(%quote(&str), key=K, _value_=ovalue, _str_=ostr, _item_=oitem, sep=%quote(,));

which sets: ovalue=C, item=K=C and ostr=A,B,D. Let us also consider the following case:

%let str=A, B, K1=C, D, K2=E, K3=, F, K4=G;
%let okey=;
%let ovalue=;
%let ostr=;
%let oitem=;
%str_to_keyvalue(%quote(&str), value=C F G, _value_=ovalue, _key_=okey, _str_=ostr, _item_=oitem, sep=%quote(,));

sets: ovalue=C G, okey=K1 K4, item=K1=C,K4=G and ostr=A,B,D,K2=E,K3=,F, while

%str_to_keyvalue(%quote(&str), _value_=ovalue, _key_=okey, _str_=ostr, _item_=oitem, sep=%quote(,));

sets: ovalue=C E _EMPTY_ G, okey=K1 K2 K3 K4, item=K1=C,K2=E,K3=,K4=G and ostr=A,B,D,F.

Run macro %_example_str_to_keyvalue for more examples.

Notes

1. This macro assumes that the (key,value) pairs in the input string parameter str are unique!
2. Zipped (key,value) pairs returned through _item_ are built using %list_append.
3. Output updated lists are (blank) compressed.

See also

%list_append.