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author | João Valverde <j@v6e.pt> | 2022-04-16 02:42:20 +0100 |
---|---|---|
committer | João Valverde <j@v6e.pt> | 2022-04-18 17:10:31 +0100 |
commit | fab32ea0cb5ccbce9327c861f4819b8a6e3980d9 (patch) | |
tree | a079ec80c18831281bf7cd1e6afb888bcbcdb9fc /.travis.yml | |
parent | 92c1519dfef8c42d3899e60beed226cd040a212e (diff) |
dfilter: Allow arithmetic expressions as function arguments
This allows writing moderately complex expressions, for example
a float epsilon test (#16483):
Filter: {abs(_ws.ftypes.double - 1) / max(abs(_ws.ftypes.double), abs(1))} < 0.01
Syntax tree:
0 TEST_LT:
1 OP_DIVIDE:
2 FUNCTION(abs#1):
3 OP_SUBTRACT:
4 FIELD(_ws.ftypes.double)
4 FVALUE(1 <FT_DOUBLE>)
2 FUNCTION(max#2):
3 FUNCTION(abs#1):
4 FIELD(_ws.ftypes.double)
3 FUNCTION(abs#1):
4 FVALUE(1 <FT_DOUBLE>)
1 FVALUE(0.01 <FT_DOUBLE>)
Instructions:
00000 READ_TREE _ws.ftypes.double -> reg#1
00001 IF_FALSE_GOTO 3
00002 SUBRACT reg#1 - 1 <FT_DOUBLE> -> reg#2
00003 STACK_PUSH reg#2
00004 CALL_FUNCTION abs(reg#2) -> reg#0
00005 STACK_POP 1
00006 IF_FALSE_GOTO 24
00007 READ_TREE _ws.ftypes.double -> reg#1
00008 IF_FALSE_GOTO 9
00009 STACK_PUSH reg#1
00010 CALL_FUNCTION abs(reg#1) -> reg#4
00011 STACK_POP 1
00012 IF_FALSE_GOTO 13
00013 STACK_PUSH reg#4
00014 STACK_PUSH 1 <FT_DOUBLE>
00015 CALL_FUNCTION abs(1 <FT_DOUBLE>) -> reg#5
00016 STACK_POP 1
00017 IF_FALSE_GOTO 18
00018 STACK_PUSH reg#5
00019 CALL_FUNCTION max(reg#5, reg#4) -> reg#3
00020 STACK_POP 2
00021 IF_FALSE_GOTO 24
00022 DIVIDE reg#0 / reg#3 -> reg#6
00023 ANY_LT reg#6 < 0.01 <FT_DOUBLE>
00024 RETURN
We now use a stack to pass arguments to the function. The
stack is implemented as a list of lists (list of registers).
Arguments may still be non-existent to functions (this is
a feature). Functions must check for nil arguments (NULL lists)
and handle that case.
It's somewhat complicated to allow literal values and test compatibility
for different types, both because of lack of type information with
unparsed/literal and also because it is an underdeveloped area in the
code. In my limited testing it was good enough and useful, further
enhancements are left for future work.
Diffstat (limited to '.travis.yml')
0 files changed, 0 insertions, 0 deletions