CFLT onsite prep -- variadic function

variadic_func.py

# variadic function call
"""
Note:
If a function is marked as isVariadic=true, then the last argument can occur one or more number of times.
Example:
FuncA: [String, Integer, Integer]; isVariadic = false
FuncB: [String, Integer]; isVariadic = true
FuncC: [Integer]; isVariadic = true
FuncD: [Integer, Integer]; isVariadic = true
FuncE: [Integer, Integer, Integer]; isVariadic = false
FuncF: [String]; isVariadic = false
FuncG: [Integer]; isVariadic = false
findMatches({String}) -> [FuncF]
findMatches({Integer}) -> [FuncC, FuncG]
findMatches({Integer, Integer, Integer, Integer}) -> [FuncC, FuncD]
findMatches({Integer, Integer, Integer}) -> [FuncC, FuncD, FuncE]
findMatches({String, Integer, Integer, Integer}) -> [FuncB]
findMatches({String, Integer, Integer}) -> [FuncA, FuncB]
algo
variadic_types = <rep, function>
nonvariadic_types = <rep, function>
check for match in non variadic types: direct convert
check for match in variadic type (int, int, int, int) -> reduced to (int)
"""
from collections import defaultdict
class Function:
    def __init__ (self, name, argtypes, isvariadic):
        self.name = name
        self.argtypes = argtypes
        self.isvariadic = isvariadic
    
    def __repr__ (self):
        return self.name

class FunctionLibrary:

    def register(self, functionset):# k functions, each avg to n overall kn 
        self.variadic_lib = defaultdict(list)
        self.nonvariadic_lib = defaultdict(list)
        for func in functionset:
            if func.isvariadic:
                self.variadic_lib[tuple(func.argtypes)].append(func)
            else:
                self.nonvariadic_lib[tuple(func.argtypes)].append(func)
    
    def findMatches(self, argtypes): # k args ~ k ^2
        # input: list of args, output list of functions 
        search_key = tuple(argtypes)
        result = []
        result += self.nonvariadic_lib[search_key]
        result += self.variadic_lib[search_key]
        # check for non variadic
        i = 0
        for i in range(len(argtypes) - 2, -1, -1):
            if argtypes[i] != argtypes[i+1]:
                break
            reduced_key = tuple(argtypes[:i+1])
            result += self.variadic_lib[reduced_key]
        return result