from __future__ import annotations
from typing import TYPE_CHECKING, Any, Optional, Union
import gamspy._algebra.condition as condition
import gamspy._algebra.domain as domain
import gamspy._algebra.operable as operable
import gamspy._algebra.operation as operation
import gamspy._symbols as symbols
import gamspy._symbols.implicits as implicits
import gamspy.utils as utils
from gamspy._extrinsic import ExtrinsicFunction
from gamspy.exceptions import ValidationError
from gamspy.math.misc import MathOp
if TYPE_CHECKING:
import gamspy._algebra.expression as expression
from gamspy import Variable
from gamspy._algebra.operation import Operation
from gamspy._symbols.implicits.implicit_symbol import ImplicitSymbol
from gamspy._symbols.symbol import Symbol
OperandType = Optional[
Union[
int,
float,
str,
Operation,
expression.Expression,
Symbol,
ImplicitSymbol,
MathOp,
]
]
GMS_MAX_LINE_LENGTH = 80000
LINE_LENGTH_OFFSET = 79000
[docs]
class Expression(operable.Operable):
"""
Expression of two operands and an operation.
Parameters
----------
left: str | int | float | Parameter | Variable | None
Left operand
data: str
Operation
right: str | int | float | Parameter | Variable | None
Right operand
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, name="a")
>>> b = gp.Parameter(m, name="b")
>>> expression = a * b
>>> expression.gamsRepr()
'(a * b)'
"""
def __init__(
self,
left: OperandType,
data: str | MathOp | ExtrinsicFunction,
right: OperandType,
):
self.left = left
self.data = data
self.right = right
if data == "=" and isinstance(right, Expression):
right._fix_equalities()
self.representation = self._create_representation()
self.where = condition.Condition(self)
def _create_representation(self) -> str:
left_str, right_str = self._get_operand_representations()
out_str = self._create_output_str(left_str, right_str)
# Adapt to GAMS quirks
if isinstance(self.left, (domain.Domain, symbols.Set, symbols.Alias)):
return out_str[1:-1]
if self.data in ["=", ".."] and out_str[0] == "(":
# (voycap(j,k)$vc(j,k)).. sum(.) -> not valid
# voycap(j,k)$vc(j,k).. sum(.) -> valid
match_index = utils._get_matching_paranthesis_indices(out_str)
out_str = out_str[1:match_index] + out_str[match_index + 1 :]
return out_str
def _get_operand_representations(self) -> tuple[str, str]:
if isinstance(self.left, float):
self.left = utils._map_special_values(self.left)
if isinstance(self.right, float):
self.right = utils._map_special_values(self.right)
if self.left is None:
left_str = ""
else:
left_str = (
str(self.left)
if isinstance(self.left, (int, float, str))
else self.left.gamsRepr()
)
if self.right is None:
right_str = ""
else:
right_str = (
str(self.right)
if isinstance(self.right, (int, float, str))
else self.right.gamsRepr()
)
# ((((ord(n) - 1) / 10) * -1) + ((ord(n) / 10) * 0)); -> not valid
# ((((ord(n) - 1) / 10) * (-1)) + ((ord(n) / 10) * 0)); -> valid
if isinstance(self.left, (int, float)) and self.left < 0:
left_str = f"({left_str})"
if isinstance(self.right, (int, float)) and self.right < 0:
right_str = f"({right_str})"
return left_str, right_str
def _create_output_str(self, left_str: str, right_str: str) -> str:
# get around 80000 line length limitation in GAMS
length = len(left_str) + len(self.data) + len(right_str)
if length >= GMS_MAX_LINE_LENGTH - LINE_LENGTH_OFFSET:
out_str = f"{left_str} {self.data}\n {right_str}"
else:
out_str = f"{left_str} {self.data} {right_str}"
if self.data in ["..", "="]:
return f"{out_str};"
if self.data in ["=g=", "=l=", "=e=", "=n=", "=x=", "=c=", "=b="]:
return out_str
return f"({out_str})"
def __eq__(self, other): # type: ignore
return Expression(self, "=e=", other)
def __ne__(self, other): # type: ignore
return Expression(self, "ne", other)
def __neg__(self):
return Expression(None, "-", self)
def __bool__(self):
raise ValidationError(
"An expression cannot be used as a truth value. If you are "
"trying to generate an expression, use binary operators "
"instead (e.g. &, |, ^). For more details, see: "
"https://gamspy.readthedocs.io/en/latest/user/gamspy_for_gams_users.html#logical-operations"
)
def _replace_operator(self, operator: str):
self.data = operator
self.representation = self._create_representation()
[docs]
def gamsRepr(self) -> str:
"""
Representation of this Expression in GAMS language.
Returns
-------
str
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, name="a")
>>> b = gp.Parameter(m, name="b")
>>> expression = a * b
>>> expression.gamsRepr()
'(a * b)'
"""
return self.representation
[docs]
def getDeclaration(self) -> str:
"""
Declaration of the Expression in GAMS
Returns
-------
str
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, name="a")
>>> b = gp.Parameter(m, name="b")
>>> expression = a * b
>>> expression.getDeclaration()
'(a * b)'
"""
return self.gamsRepr()
def _find_variables(self) -> list[Variable]:
stack = []
variables: list[Variable] = []
node: OperandType = self
while True:
if node is not None:
stack.append(node)
node = getattr(node, "left", None)
elif stack:
node = stack.pop()
if hasattr(node, "data") and isinstance(
node.data, (MathOp, ExtrinsicFunction)
):
variables += node.data._find_variables()
if isinstance(node, symbols.Variable):
variables.append(node.name)
elif isinstance(node, implicits.ImplicitVariable):
variables.append(node.parent.name)
elif isinstance(node, operation.Operation):
operation_variables = node._extract_variables()
variables += operation_variables
node = getattr(node, "right", None)
else:
break # pragma: no cover
return list(set(variables))
def _fix_equalities(self) -> None:
# Equality operations on Parameter and Variable objects generate
# GAMS equality signs: =g=, =e=, =l=. If these signs appear on
# assignments, replace them with regular equality ops.
EQ_MAP: dict[Any, str] = {"=g=": ">=", "=e=": "eq", "=l=": "<="}
stack = []
node: Expression | None = self
while True:
if node is not None:
stack.append(node)
node = getattr(node, "left", None)
elif stack:
node = stack.pop()
if isinstance(node, Expression) and node.data in EQ_MAP:
node._replace_operator(EQ_MAP[node.data])
if isinstance(node, operation.Operation) and isinstance(
node.expression, Expression
):
node.expression._fix_equalities()
node = getattr(node, "right", None)
else:
break # pragma: no cover
self.representation = self._create_representation()
