CURSOR/DOWHILE-PREFIXED
Fetching cursor walker for a range of keys starting with a prefix.
Input stack: prefix closure
Output stack:
CURSOR/DOWHILE-PREFIXED will start the cursor from the first key that is
equal or grater than prefix and execute closure while it leaves 1 on the
top of the stack, invoking CURSOR/NEXT on the cursor after each run. The closure
should be written with an expectation of the cursor on top of the stack.
PumpkinDB> ["a" HLC CONCAT 0 ASSOC
"testkey" HLC CONCAT 1 ASSOC
"testkey" HLC CONCAT 2 ASSOC
"testkey" HLC CONCAT 3 ASSOC
"z" HLC CONCAT 4 ASSOC
COMMIT] WRITE
["testkey" [CURSOR/VAL TRUE] CURSOR/DOWHILE-PREFIXED] READ
0x01 0x02 0x03
Allocation
Allocates for closure composition
Errors
NoTransaction error if there's no current write transaction
InvalidValue error if the cursor identifier is incorrect or expired
Tests
cursor_dowhile_prefixed :
["a" HLC CONCAT 0 ASSOC
"testkey" HLC CONCAT 1 ASSOC
"testkey" HLC CONCAT 2 ASSOC
"testkey" HLC CONCAT 3 ASSOC
"z" HLC CONCAT 4 ASSOC
COMMIT] WRITE
["testkey" [CURSOR/VAL TRUE] CURSOR/DOWHILE-PREFIXED] READ
3 WRAP [1 2 3] EQUAL?.
nextkey_short : ["key" HLC CONCAT 1 ASSOC
"key" HLC CONCAT 2 ASSOC
"key" HLC CONCAT 3 ASSOC
"z" 4 ASSOC COMMIT] WRITE
["key" [CURSOR/VAL TRUE] CURSOR/DOWHILE-PREFIXED] READ
3 WRAP [1 2 3] EQUAL?.