pySFeel Documentation

the sFeelParse function

class pySFeel.SFeelParser
sFeelParse(text)

Parse S-FEEL text

This routine parses the passed text, which must be valid S-FEEL

Parameters:param1 (str) – The S-FEEL text to be parsed
Returns:(status, value)

’status’ is alist of any parsing errors.

’value’ is the Python native value of the parsed S-FEEL text.

For an assignment statement the ‘value’ will be the Python native value assigned to the named variable.

For all other expressions the ‘value’ will be the Python native value of the S-FEEL expression.
Return type:tuple

Data Types

pySFeel converts S-FEEL data into the nearest equivalent Python native data type.

S-Feel data type Python native data type
number float
string str
boolean bool
days and time duration datetime.timedelta
year and months duration int
time datetime.time
date datetime.date
date and time datetime.datetime
List list
Context dict
Range tuple(end0, low0, high1, end1)
  where end0 is ‘[’ or ‘(’ and end1 is ‘)’ or ‘]’
Literal strings (@”PT5H”) are implemented as both literal strings (@”PT5H”) and as bare strings (PT5H).
@”PT5H” > @”PT4H” can be written as PT5H > PT4H and would return True
NOTE: For safety, enclose ‘codes’ in double quotes.
The ICD-10 code P04D, if not enclosed in double qoutes, will be interpreted as a day and time duration of 4 days.
The AN-SNAP code if 499A will throw a syntax error if not enclosed in double quotes, as ‘499’ will be interpreted as a number that should be followed by an operator.

List and Context Filters

pySFeel supports List and Context filters with one deviation from the standard - the dot operator requires the List to be enclosed in brackets.

Hence, fred.y is not the ‘y’ filter on the List of Contexts named ‘fred’ (as fred.y is a valid name).
However (fred).y is the ‘y’ filter on the List of Contexts named fred.

Assignment and Variable names

There’s one extension - an assignment operator (<-) which will store a Python internal value against a named variable. Named variables are valid in S-FEEL expressions in pySFeel.

fred <- 7 bill <- 9 fred = bill

This will return False

fred <- [{x:1,y:2},{x:2,y:3}] (fred).y

This will return [2,3]

Dot operators

All the dot operators are supported, however ‘.time offset’, ‘.start included’ and ‘.end included’ can be ambiguous (because of the embedded space). Hence the variants ‘.time_offset’, ‘.start_included’, ‘.end_included’ are supported.

thisDateTime.time offset

will fail because thisDateTime.time looks like a valid FEEL variable name. However the following two alternatives will work

thisDateTime.time_offset (thisDateTime).time offset

Usage

import pySFeel
parser = pySFeel.SFeelParser()
sfeelText = '7.3 in [2.0 .. 9.1]'
(status, retVal) = parser.sFeelParse(sfeelText)
if 'errors' in status:
    print('With errors:', status['errors'])
  • retVal will be True
  • The dictonary ‘status’ will have the key ‘errors’ if you have errors in your sfeelText.
  • status[‘errors’] is a list of strings. It may help in diagnosing your S-FEEL syntax errors.

Built-in Functions

pySFeel has support all the standard FEEL built-in functions with some differences because pySFeel is a Python implementation.

Name(paramters) Parameter Domain pySFeel implementation notes
date(from) date string Uses dateutil.parser - strict ISO format is not required. pySFeel will convert a string that is in ISO format into a datetime.date, datetime.time or datetime.datetime
date(from) date and time Truncates datetime.datetime to datetime.date
date(year,month,day) year,month,day are numbers  
date and time(date,time) date is a date or date time; time is a time  
date and time(from) date time string Uses dateutil.parser - strict ISO format is not required. pySFeel will convert a string that is in ISO format into a datetime.date, datetime.time or datetime.datetime
time(from) time string Uses dateutil.parser - strict ISO format is not required. pySFeel will convert a string that is in ISO format into a datetime.date, datetime.time or datetime.datetime
time(from) time, date and time  
number(from,grouping, separator,decimal separator) string,string, string pySFeel does the approriate rounding, but the returned value is a float. Trailing zeros are not retained.
string(from) non null  
duration(from) duration string  
years and months duration(from, to) both are date or both are date and time  
not(negand) boolean  
substring(string,start, position,length?) string,number  
string length(string) string  
upper case(string) string  
lower case(string) string  
substring before (string,match) string,string  
substring after (string,match) string,string  
replace(input,pattern, replacement,flags?) string  
contains(string,match) string  
starts with(string,match) string  
ends with(string,match) string  
matches(input,pattern, flags?) string  
split(string,delimiter) string  
list contains(list,element) list,any element of the semantic domain  
count(list) list  
min(list) min(C1,…,Cn),N>0 max(list) max(C1,…,Cn),N>0 non-empty list of comparable items or argument list of one or more comparable items  
sum(list) sum(N1,…,Nn),N>0 list of 0 or more numbers or argument list of one or more numbers  
mean(list) mean(N1,…,Nn),N>0 non-empty list of numbers or argument list of one or more numbers  
all(list) all(B1,…,Bn),N>0 list of Boolean items of argument list of one or more Boolean items  
any(list) any(B1,…,Bn),N>0 list of Boolean items of argument list of one or more Boolean items  
sublist(list,start position, length?) list,number, number  
append(list,item…) list,any element  
concatenate(list…) list  
insert before(list,position, newItem) list,number,any element  
remove(list,position) list,number  
reverse(list) list  
index of(list,match) list,any element  
union(list,…) list  
distinct values(list) list  
flattern(list) list  
product(list) product(N1,…,Nn) list is a list of numbers. N1..Nn are numbers  
median(list) median(N1,…,Nn) list is a list of numbers. N1..Nn are numbers  
stddev(list) stddev(N1,…,Nn) list is a list of numbers. N1..Nn are numbers  
mode(list) mode(N1,…,Nn) list is a list of numbers. N1..Nn are numbers  
deciman(n,scale) number,number pySFeel does the approriate rounding, but the returned value is a float. Trailing zeros are not retained.
floor(n) number  
ceiling(n) number  
abs(n) number  
modulo(dividend,divisor) number,number  
sqrt(n) number  
log(n) number  
exp(n) number  
odd(n) number  
even(n) number  
is(expr, expr) expr, expr  
before(range, range) range, range  
after(range, range) range, range  
meets(range, range) range, range  
met by(range, range) range, range  
overlaps(range, range) range, range  
overlaps before(range, range) range, range  
overlaps after(range, range) range, range  
finishes(range, range) range, range  
finished by(range, range) range, range  
includes(range, range) range, range  
during(range, range) range, range  
starts(range, range) range, range  
started by(range, range range, range  
coincides(range, range) range, range  
day of year(date) date, date and time  
day of week(date) date, date and time  
month of year(date) date, date and time  
week of year(date) date, date and time  
sort(list, function(x,y) expr) list  
now()    
today()    

Note: The support for the sort() function is very, very limited. Only the anonymous form is supported (function is defined within the sort call). Also, ‘expr’ is limited to ‘name0 < name1’ or ‘name0 > name1’ (ascending or decending). However, list can be a list of Contexts, in which case name0 and name1 must be ‘name0.attr’ and ‘name1.attr’ and ‘attr’ must be the same attribute for both ‘name0’ and ‘name1’.

Note: The support for ‘some/every in … satifies expression’ is also limited in that ‘expression’ must be ‘name relop expr’ or ‘odd(name)’ or ‘even(name)’. Again, the ‘name.attr’ form is suported where a list of Contexts is being tested.

Indices and tables