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| ''' | |
| STRING OPERATORS | |
| This file contains Python classes that define the string operators for program synthesis. | |
| ''' | |
| ''' | |
| CLASS DEFINITIONS | |
| ''' | |
| class StringVariable: | |
| ''' | |
| Class to represent an string variable. Note that position is the position of the variable in the input. | |
| For example, if the input is ["a", "b", "c"] and the variable is the third element (i.e., "c"), then position = 2. | |
| ''' | |
| def __init__(self, position): | |
| self.position = position # zero-indexed position of the variable in the arguments to program | |
| self.type = str # type of the variable | |
| self.weight = 1 # weight of the variable | |
| def evaluate(self, input = None): | |
| # check that input is not None | |
| if input is None: | |
| raise ValueError("Input is None.") | |
| # check that input is a list | |
| if type(input) != list: | |
| raise ValueError("Input is not a list.") | |
| # check that input is not empty | |
| if len(input) == 0: | |
| raise ValueError("Input is empty.") | |
| # check that position is valid | |
| if self.position >= len(input): | |
| raise ValueError(f"Position {self.position} is out of range for input of length {len(input)}.") | |
| return input[self.position] | |
| def str(self): | |
| return f"x{self.position}" | |
| class StringConstant: | |
| ''' | |
| Class to represent an string constant. | |
| ''' | |
| def __init__(self, value): | |
| self.value = value # value of the constant | |
| self.type = str # type of the constant | |
| self.weight = 1 # weight of the constant | |
| def evaluate(self, input = None): | |
| return self.value | |
| def str(self): | |
| return str(self.value) | |
| class Concatenate: | |
| ''' | |
| Operator to concatenate two string values. | |
| ''' | |
| def __init__(self): | |
| self.arity = 2 # number of arguments | |
| self.arg_types = [str, str] # argument types | |
| self.return_type = str # return type | |
| self.weight = 1 # weight | |
| def evaluate(self, x, y, input = None): | |
| return x + y | |
| def str(self, x, y): | |
| return f"Concat({x}, {y})" | |
| class Left: | |
| ''' | |
| Operator to get left substring. | |
| ''' | |
| def __init__(self): | |
| self.arity = 2 # number of arguments | |
| self.arg_types = [str, int] # argument types | |
| self.return_type = str # return type | |
| self.weight = 1 # weight | |
| def evaluate(self, x, y, input = None): | |
| return x[:y] | |
| def str(self, x, y): | |
| return f"Left({x}, {y})" | |
| class Right: | |
| ''' | |
| Operator to get right substring. | |
| ''' | |
| def __init__(self): | |
| self.arity = 2 # number of arguments | |
| self.arg_types = [str, int] # argument types | |
| self.return_type = str # return type | |
| self.weight = 1 # weight | |
| def evaluate(self, x, y, input = None): | |
| return x[(y * -1):] | |
| def str(self, x, y): | |
| return f"Right({x}, {y})" | |
| ''' | |
| GLOBAL CONSTANTS | |
| ''' | |
| # define operators | |
| string_operators = [Concatenate(), Left(), Right()] |