from __future__ import annotations
from dataclasses import dataclass
from typing import TYPE_CHECKING, Literal
import gamspy._algebra.condition as condition
import gamspy._algebra.domain as domain
import gamspy._algebra.number as number
import gamspy._algebra.operable as operable
import gamspy._algebra.operation as operation
import gamspy._symbols as gp_syms
import gamspy._validation as validation
import gamspy.utils as utils
from gamspy._config import get_option
from gamspy._extrinsic import ExtrinsicFunction
from gamspy._symbols.implicits import ImplicitSet
from gamspy._symbols.implicits.implicit_symbol import ImplicitSymbol
from gamspy._symbols.symbol import Symbol
from gamspy.exceptions import ValidationError
from gamspy.math.misc import MathOp
if TYPE_CHECKING:
from numbers import Real
import pandas as pd
from gamspy import Alias, Set
from gamspy._symbols.implicits import ImplicitEquation
from gamspy._types import OperableType
GMS_MAX_LINE_LENGTH = 80000
LINE_LENGTH_OFFSET = 79000
@dataclass
class DomainPlaceHolder:
indices: list[tuple[str, int]]
def peek(stack):
if len(stack) > 0:
return stack[-1]
return None
# Higher number means higher precedence.
PRECEDENCE = {
"..": 0,
"=": 0,
"or": 1,
"xor": 2,
"and": 3,
"=e=": 4,
"=n=": 4,
"=b=": 4,
"eq": 4,
"ne": 4,
">=": 4,
"<=": 4,
">": 4,
"<": 4,
"=g=": 4,
"=l=": 4,
"=x=": 4,
"+": 5,
"-": 5,
"*": 6,
"/": 6,
"not": 7,
"u-": 7,
}
# Defines how operators of the same precedence are grouped.
ASSOCIATIVITY = {
"or": "left",
"xor": "left",
"and": "left",
"=e=": "left",
"=n=": "left",
"=x=": "left",
"=b=": "left",
"eq": "left",
"ne": "left",
"=": "left",
">=": "left",
"<=": "left",
">": "left",
"<": "left",
"=g=": "left",
"=l=": "left",
"..": "non",
"+": "left",
"-": "left",
"*": "left",
"/": "left",
"not": "right",
"u-": "right",
}
# Precedence for a leaf node is considered infinite.
LEAF_PRECEDENCE = float("inf")
def get_operand_gams_repr(operand) -> str:
if hasattr(operand, "gamsRepr"):
return operand.gamsRepr()
representation = str(operand)
# b[i] * -1 -> not valid
# b[i] * (-1) -> valid
if isinstance(operand, (int, float)) and operand < 0:
representation = f"({representation})"
return representation
def get_operand_latex_repr(operand) -> str:
if hasattr(operand, "latexRepr"):
return operand.latexRepr()
if isinstance(operand, float):
operand = utils._map_special_values(operand)
representation = str(operand)
return representation
def create_gams_expression(root_node: Expression) -> str:
"""
Creates GAMS representation of a binary expression tree without recursion.
It uses an iterative post-order traversal to build the expression,
adding parentheses only when necessary based on operator precedence and
associativity rules.
"""
if not isinstance(root_node, Expression):
return get_operand_gams_repr(root_node)
# 1. Get nodes in post-order (left - right - parent).
s1: list[OperableType | ImplicitEquation | str] = [root_node]
post_order_nodes = []
while s1:
node = s1.pop()
post_order_nodes.append(node)
if isinstance(node, Expression):
if node.left is not None:
s1.append(node.left)
if node.right is not None:
s1.append(node.right)
# 2. Build the GAMS expression
eval_stack: list[tuple[str, Real]] = []
for node in reversed(post_order_nodes):
if not isinstance(node, Expression):
eval_stack.append((get_operand_gams_repr(node), LEAF_PRECEDENCE))
continue
op = node.operator
op_prec = PRECEDENCE[op]
op_assoc = ASSOCIATIVITY[op]
# Handle unary ops
if op in ("u-", "not"):
operand_str, operand_prec = eval_stack.pop()
# Add parentheses if the operand's operator has lower precedence
if operand_prec < op_prec:
operand_str = f"({operand_str})"
if op == "u-":
new_str = f"(-{operand_str})"
# A parenthesized expression has the highest precedence
eval_stack.append((new_str, LEAF_PRECEDENCE))
else: # Standard handling for 'not'
new_str = f"not {operand_str}"
eval_stack.append((new_str, op_prec))
# Handle binary ops
else:
right_str, right_prec = eval_stack.pop()
left_str, left_prec = eval_stack.pop()
if left_prec < op_prec or (left_prec == op_prec and op_assoc == "right"):
left_str = f"({left_str})"
if right_prec < op_prec or (right_prec == op_prec and op_assoc == "left"):
right_str = f"({right_str})"
# get around 80000 line length limitation in GAMS
length = len(left_str) + len(op) + len(right_str)
if length >= GMS_MAX_LINE_LENGTH - LINE_LENGTH_OFFSET:
new_str = f"{left_str} {op}\n {right_str}"
else:
new_str = f"{left_str} {op} {right_str}"
eval_stack.append((new_str, op_prec))
final_string = eval_stack[0][0]
if root_node.operator in ("=", ".."):
return f"{final_string};"
return final_string
def create_latex_expression(root_node: Expression) -> str:
"""
Creates LaTeX representation of a binary expression tree without recursion.
It uses an iterative post-order traversal to build the expression,
adding parentheses only when necessary based on operator precedence and
associativity rules.
"""
if not isinstance(root_node, Expression):
return get_operand_latex_repr(root_node)
op_map = {
"=g=": "\\geq",
"=l=": "\\leq",
"=e=": "=",
"*": "\\cdot",
"and": "\\wedge",
"or": "\\vee",
"xor": "\\oplus",
"$": "|",
}
# 1. Get nodes in post-order (left - right - parent).
s1: list[OperableType | ImplicitEquation | str] = [root_node]
post_order_nodes = []
while s1:
node = s1.pop()
post_order_nodes.append(node)
if isinstance(node, Expression):
if node.left is not None:
s1.append(node.left)
if node.right is not None:
s1.append(node.right)
# 2. Build the GAMS expression
eval_stack: list[tuple[str, Real]] = []
for node in reversed(post_order_nodes):
if not isinstance(node, Expression):
eval_stack.append((get_operand_latex_repr(node), LEAF_PRECEDENCE))
continue
op = node.operator
op_prec = PRECEDENCE[op]
op_assoc = ASSOCIATIVITY[op]
# Handle unary ops
if op in ("u-", "not"):
operand_str, operand_prec = eval_stack.pop()
# Add parentheses if the operand's operator has lower precedence
if operand_prec < op_prec:
operand_str = f"({operand_str})"
if op == "u-":
new_str = f"(-{operand_str})"
# A parenthesized expression has the highest precedence
eval_stack.append((new_str, LEAF_PRECEDENCE))
else: # Standard handling for 'not'
new_str = f"not {operand_str}"
eval_stack.append((new_str, op_prec))
# Handle binary ops
else:
right_str, right_prec = eval_stack.pop()
left_str, left_prec = eval_stack.pop()
if left_prec < op_prec or (left_prec == op_prec and op_assoc == "right"):
left_str = f"({left_str})"
if right_prec < op_prec or (right_prec == op_prec and op_assoc == "left"):
right_str = f"({right_str})"
if op == "/":
eval_stack.append((f"\\frac{{{left_str}}}{{{right_str}}}", op_prec))
continue
op = op_map.get(op, op)
# get around 80000 line length limitation in GAMS
length = len(left_str) + len(op) + len(right_str)
if length >= GMS_MAX_LINE_LENGTH - LINE_LENGTH_OFFSET:
new_str = f"{left_str} {op}\n {right_str}"
else:
new_str = f"{left_str} {op} {right_str}"
eval_stack.append((new_str, op_prec))
final_string = eval_stack[0][0]
return final_string
[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: OperableType | ImplicitEquation | None,
operator: str,
right: OperableType | str | None,
):
self.left = utils._map_special_values(left) if isinstance(left, float) else left
self.operator = operator
self.right = (
utils._map_special_values(right) if isinstance(right, float) else right
)
if operator == "=" and isinstance(right, Expression):
right._fix_equalities()
self._representation: str | None = None
self.where = condition.Condition(self)
self._create_domain()
left_control = getattr(left, "controlled_domain", [])
right_control = getattr(right, "controlled_domain", [])
self.controlled_domain: list[Set | Alias] = list(
{*left_control, *right_control}
)
self.container = None
if hasattr(left, "container"):
self.container = left.container # type: ignore
elif hasattr(right, "container"):
self.container = right.container # type: ignore
@property
def representation(self) -> str:
if self._representation is None:
self._representation = create_gams_expression(self)
return self._representation
def _create_domain(self):
for loc, result in (
(self.left, "_left_domain"),
(self.right, "_right_domain"),
):
if isinstance(loc, condition.Condition):
loc = loc.conditioning_on
if loc is None or isinstance(loc, (int, float, str)):
result_domain = [] # left is a scalar
elif isinstance(loc, domain.Domain):
result_domain = loc.sets
else:
result_domain = loc.domain
setattr(self, result, result_domain)
left_domain = self._left_domain
right_domain = self._right_domain
set_to_index = {}
for domain_char, domain_ptr in (
("l", left_domain),
("r", right_domain),
):
for i, d in enumerate(domain_ptr):
if isinstance(d, str):
continue # string domains are fixed and they do not count
if d not in set_to_index:
set_to_index[d] = []
set_to_index[d].append((domain_char, i))
shadow_domain = []
result_domain = []
for d in (*left_domain, *right_domain):
if isinstance(d, str):
continue
if d not in result_domain:
result_domain.append(d)
indices = set_to_index[d]
shadow_domain.append(DomainPlaceHolder(indices=indices))
self._shadow_domain = shadow_domain
self.domain = result_domain
self.dimension = validation.get_dimension(self.domain)
def __getitem__(self, indices):
indices = validation.validate_domain(self, indices)
left_domain = [d for d in self._left_domain]
right_domain = [d for d in self._right_domain]
for i, s in enumerate(indices):
for lr, pos in self._shadow_domain[i].indices:
if lr == "l":
left_domain[pos] = s
else:
right_domain[pos] = s
left = self.left[left_domain] if left_domain else self.left
right = self.right[right_domain] if right_domain else self.right
return Expression(left, self.operator, right)
@property
def records(self) -> pd.DataFrame | None:
"""
Evaluates the expression and returns the resulting records.
Returns
-------
pd.DataFrame | None
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, records=5)
>>> b = gp.Parameter(m, records=6)
>>> (a + b).records
value
0 11.0
"""
assert self.container is not None
temp_name = "a" + utils._get_unique_name()
temp_param = gp_syms.Parameter._constructor_bypass(
self.container, temp_name, self.domain
)
temp_param[...] = self
del self.container.data[temp_name]
return temp_param.records
[docs]
def toValue(self) -> float | None:
"""
Convenience method to return expression records as a Python float. Only possible if there is a single record as a result of the expression evaluation.
Returns
-------
float | None
Raises
------
TypeError
In case the dimension of the expression is not zero.
Examples
--------
>>> import gamspy as gp
>>> m = gp.Container()
>>> a = gp.Parameter(m, records=5)
>>> b = gp.Parameter(m, records=6)
>>> (a + b).toValue()
np.float64(11.0)
"""
if self.dimension != 0:
raise TypeError(
f"Cannot extract value data for non-scalar expressions (expression dimension is {self.dimension})"
)
records = self.records
if records is not None:
return records["value"][0]
return records
[docs]
def toList(self) -> list | None:
"""
Convenience method to return the records of the expression as a list.
Returns
-------
list | None
Examples
--------
>>> import numpy as np
>>> import gamspy as gp
>>> m = gp.Container()
>>> i = gp.Set(m, records=range(3))
>>> a = gp.Parameter(m, domain=i, records=np.array([1,2,3]))
>>> b = gp.Parameter(m, domain=i, records=np.array([4,5,6]))
>>> (a + b).toList()
[['0', 5.0], ['1', 7.0], ['2', 9.0]]
"""
records = self.records
if records is not None:
return records.values.tolist()
return None
def __eq__(self, other):
return Expression(self, "=e=", other)
def __ne__(self, other):
return Expression(self, "ne", other)
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 __repr__(self) -> str:
return f"Expression(left={self.left}, data={self.operator}, right={self.right})"
def _replace_operator(self, operator: str):
self.operator = operator
[docs]
def latexRepr(self) -> str:
"""
Representation of this Expression in Latex.
Returns
-------
str
"""
return create_latex_expression(self)
[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 _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.
# Uses a stack based post-order traversal algorithm.
EQ_MAP: dict[str, str] = {"=g=": ">=", "=e=": "eq", "=l=": "<="}
stack = []
root = self
while True:
while root is not None:
if hasattr(root, "right"):
stack.append(root.right)
stack.append(root)
root = root.left if hasattr(root, "left") else None # type: ignore
if len(stack) == 0:
break
root = stack.pop()
if isinstance(root, Expression) and root.operator in EQ_MAP:
root._replace_operator(EQ_MAP[root.operator])
last_item = peek(stack)
if (
hasattr(root, "right")
and last_item is not None
and last_item is root.right
):
stack.pop()
stack.append(root)
root = root.right
else:
root = None
def _find_all_symbols(self) -> list[str]:
# Finds all symbols in an expression with a stack based inorder
# traversal algorithm (O(N)).
symbols: list[str] = []
stack = []
node = self
while True:
if node is not None:
stack.append(node)
node = getattr(node, "left", None) # type: ignore
elif stack:
node = stack.pop()
if isinstance(node, Symbol):
if node.name not in symbols:
if type(node) is gp_syms.Alias:
symbols.append(node.alias_with.name)
symbols.append(node.name)
stack += node.domain
node = None
elif isinstance(node, ImplicitSymbol):
if node.parent.name not in symbols:
symbols.append(node.parent.name)
stack += node.domain
stack += node.container[node.parent.name].domain
node = None
elif isinstance(node, operation.Operation):
stack += node.op_domain
node = node.rhs
elif isinstance(node, condition.Condition):
stack.append(node.conditioning_on)
if isinstance(node.condition, Expression):
node = node.condition
else:
stack.append(node.condition)
node = None
elif isinstance(node, (operation.Ord, operation.Card)):
stack.append(node._symbol)
node = None
elif isinstance(node, MathOp):
if isinstance(node.elements[0], Expression):
node = node.elements[0]
else:
stack += node.elements
node = None
elif isinstance(node, ExtrinsicFunction):
stack += list(node.args)
node = None
else:
node = getattr(node, "right", None)
else:
break # pragma: no cover
return symbols
def _find_symbols_in_conditions(self) -> list[str]:
symbols: list[str] = []
stack = []
node = self
while True:
if node is not None:
stack.append(node)
node = getattr(node, "left", None) # type: ignore
elif stack:
node = stack.pop()
if isinstance(node, condition.Condition):
given_condition = node.condition
if isinstance(given_condition, Expression):
symbols += given_condition._find_all_symbols()
elif isinstance(given_condition, ImplicitSymbol):
symbols.append(given_condition.parent.name)
if isinstance(node, operation.Operation):
stack += node.op_domain
node = node.rhs
else:
node = getattr(node, "right", None)
else:
break # pragma: no cover
return symbols
def _validate_definition(
self, control_stack: list[Set | Alias | ImplicitSet]
) -> None:
if not get_option("DOMAIN_VALIDATION") or not get_option("DOMAIN_VALIDATION"):
return
stack = []
node = self.right
while True:
if node is not None:
stack.append(node)
node = getattr(node, "left", None) # type: ignore
elif stack:
node = stack.pop()
if isinstance(node, operation.Operation):
node._validate_operation(control_stack.copy())
elif isinstance(node, ImplicitSymbol):
for elem in node.domain:
if hasattr(elem, "is_singleton") and elem.is_singleton:
continue
if isinstance(elem, Symbol) and elem not in control_stack:
raise ValidationError(
f"Uncontrolled set `{elem}` entered as constant!"
)
elif (
isinstance(elem, ImplicitSymbol)
and elem.parent not in control_stack
):
raise ValidationError(
f"Uncontrolled set `{elem.parent}` entered as constant!"
)
node = getattr(node, "right", None)
else:
break # pragma: no cover
class SetExpression(Expression):
def __init__(
self,
left: OperableType,
data: Literal["+", "-", "*", "not"],
right: OperableType,
):
super().__init__(left, data, right)
self._adjust_left_right()
def _adjust_left_right(self) -> None:
if isinstance(self.left, (ImplicitSet, SetExpression)):
if isinstance(self.right, (int, float)):
if self.right == 0:
self.right = "no"
elif self.right == 1:
self.right = "yes"
else:
raise ValidationError(
f"Incompatible operand `{self.right}` for the set operation `{self.operator}`."
)
elif isinstance(self.right, condition.Condition) and isinstance(
self.right.conditioning_on, number.Number
):
if self.right.conditioning_on._value == 0:
self.right.conditioning_on._value = "no"
elif self.right.conditioning_on._value == 1:
self.right.conditioning_on._value = "yes"
raise ValidationError(
f"Incompatible operand `{self.right}` for the set operation `{self.operator}`."
)
if isinstance(self.right, (ImplicitSet, SetExpression)):
if isinstance(self.left, (int, float)):
if self.left == 0:
self.left = "no"
elif self.left == 1:
self.left = "yes"
else:
raise ValidationError(
f"Incompatible operand `{self.left}` for the set operation `{self.operator}`."
)
elif isinstance(self.left, condition.Condition) and isinstance(
self.left.conditioning_on, number.Number
):
if self.left.conditioning_on._value == 0:
self.left.conditioning_on._value = "no"
elif self.left.conditioning_on._value == 1:
self.left.conditioning_on._value = "yes"
else:
raise ValidationError(
f"Incompatible operand `{self.left}` for the set operation `{self.operator}`."
)
