aldas
commented
2 years ago So far what I have come up is to have 2 extra functions in DSL that must be used for those variables in expression that come from configuration.
v(<timeserieCode>)is equivalent just plain old parameter gettern(<timeserieCode>)is for cases when you need to use is as argument for some other function
and then we can do quite primitive regexp capture to get list of all referenced configuration variables.
this does not feel eloquent but seems to work
var timeserieRegexp = regexp.MustCompile(`(?:^|\W)[vn]\(([a-zA-Z0-9-_]{0,100})\)`)
func TestVariableSelector(t *testing.T) {
expression := `avg(n(me1_rpm)) + v(me2_rpm) + 0.5`
// ------------------ related timeserie capture start ---------------------
result := make([]string, 0)
matches := timeserieRegexp.FindAllStringSubmatch(expression, -1)
for _, match := range matches {
tmp := match[1]
if !containsString(result, tmp) {
result = append(result, tmp)
}
}
assert.Equal(t, []string{"me1_rpm", "me2_rpm"}, result)
// ------------------ related timeserie capture end ---------------------
value, err := gval.Evaluate(expression,
nil,
gval.VariableSelector(func(path gval.Evaluables) gval.Evaluable {
return func(c context.Context, v interface{}) (interface{}, error) {
keys, err := path.EvalStrings(c, v)
if err != nil {
return nil, err
}
return keys[0], nil
}
}),
// `avg(<timeserie>)` calculates average for timeserie from cache/database
gval.Function("avg", func(timeserieCode string) (interface{}, error) {
if timeserieCode == "me1_rpm" { // just for testing
return 5.0, nil
}
return 0.0, nil
}),
// `v(<timeserie>)` helps to identify all related timeseries used by their value
gval.Function("v", func(timeserieCode string) (interface{}, error) {
return 1.0, nil
}),
// `n(<timeserie>)` helps to identify all related timeseries used by their code
gval.Function("n", func(timeserieCode string) (interface{}, error) {
return timeserieCode, nil
}),
)
assert.NoError(t, err)
assert.Equal(t, 6.5, value)
}
func containsString(haystack []string, needle string) bool {
for _, v := range haystack {
if v == needle {
return true
}
}
return false
}
skyf0cker
generikvault
shivam-940
annlumia
I have expression
vtg_ground_speed_unit > 0 ? vtg_ground_speed_knots : vtg_ground_speed_kph.These variables (
vtg_ground_speed_unit,vtg_ground_speed_knots,vtg_ground_speed_kph) can only be from fixed list (coming from configuration file). So it would be nice if would be a way to get all variables from parsed expression so they could be validated against current configuration - to see if they exist or not.So far I have tried to create selector that captures all seen variables in "test evaluation".
Something like that:
but this has limitation as
vtg_ground_speed_kphwill not get captured as executing all paths from expression involves knowing how to provides values for getting true/false sides.Is there a way to traverse parsed tree without evaluation and pick all parts that are used as "variable"?