Preserve approved pixel tower prototype as development baseline
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Codex
@@ -0,0 +1,266 @@
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class_name StateTransaction
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extends RefCounted
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enum Status {
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OPEN,
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COMMITTED,
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ROLLED_BACK,
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FAILED,
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}
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class StagedChange:
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extends RefCounted
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var label := ""
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var validate_action := Callable()
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var apply_action := Callable()
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var rollback_action := Callable()
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func _init(
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p_label: String,
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p_validate_action: Callable,
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p_apply_action: Callable,
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p_rollback_action: Callable
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) -> void:
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label = p_label
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validate_action = p_validate_action
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apply_action = p_apply_action
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rollback_action = p_rollback_action
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var status: Status = Status.OPEN
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var _changes: Array[StagedChange] = []
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var _validators: Array[Callable] = []
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var _configuration_errors: Array[String] = []
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func stage_dictionary_set(
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target: Dictionary,
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key: Variant,
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value: Variant,
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label: String = ""
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) -> bool:
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if not _require_open("stage_dictionary_set"):
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return false
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var had_key := target.has(key)
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var original_value: Variant = target.get(key)
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var original_snapshot: Variant = _copy_value(original_value)
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var staged_value: Variant = _copy_value(value)
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var change_label := label if not label.is_empty() else "set dictionary key %s" % str(key)
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return stage_custom(
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change_label,
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func() -> Variant:
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if target.has(key) != had_key:
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return "Dictionary key presence changed before commit."
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if had_key and target[key] != original_snapshot:
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return "Dictionary value changed before commit."
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return true,
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func() -> Variant:
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target[key] = _copy_value(staged_value)
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return true,
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func() -> void:
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if had_key:
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target[key] = original_value
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else:
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target.erase(key)
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)
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func stage_dictionary_erase(
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target: Dictionary,
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key: Variant,
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label: String = ""
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) -> bool:
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if not _require_open("stage_dictionary_erase"):
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return false
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var had_key := target.has(key)
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var original_value: Variant = target.get(key)
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var original_snapshot: Variant = _copy_value(original_value)
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var change_label := label if not label.is_empty() else "erase dictionary key %s" % str(key)
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return stage_custom(
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change_label,
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func() -> Variant:
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if target.has(key) != had_key:
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return "Dictionary key presence changed before commit."
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if had_key and target[key] != original_snapshot:
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return "Dictionary value changed before commit."
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return true,
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func() -> Variant:
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target.erase(key)
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return true,
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func() -> void:
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if had_key:
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target[key] = original_value
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)
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func stage_dictionary_increment(
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target: Dictionary,
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key: Variant,
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delta: Variant,
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minimum: Variant = null,
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maximum: Variant = null,
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label: String = ""
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) -> bool:
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if not _require_open("stage_dictionary_increment"):
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return false
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if not target.has(key) or not _is_number(target[key]) or not _is_number(delta):
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_configuration_errors.append("Increment requires an existing numeric value and numeric delta.")
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return false
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var next_value: Variant = target[key] + delta
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if minimum != null and (not _is_number(minimum) or next_value < minimum):
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_configuration_errors.append("Increment result is below its minimum.")
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return false
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if maximum != null and (not _is_number(maximum) or next_value > maximum):
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_configuration_errors.append("Increment result is above its maximum.")
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return false
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return stage_dictionary_set(target, key, next_value, label)
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func add_validator(validator: Callable) -> bool:
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if not _require_open("add_validator"):
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return false
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if not validator.is_valid():
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_configuration_errors.append("Validator is not callable.")
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return false
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_validators.append(validator)
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return true
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func stage_custom(
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label: String,
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validate_action: Callable,
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apply_action: Callable,
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rollback_action: Callable
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) -> bool:
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if not _require_open("stage_custom"):
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return false
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if not apply_action.is_valid() or not rollback_action.is_valid():
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_configuration_errors.append("Custom change '%s' requires apply and rollback actions." % label)
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return false
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_changes.append(StagedChange.new(label, validate_action, apply_action, rollback_action))
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return true
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func validate() -> CommandResult:
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if status != Status.OPEN:
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return CommandResult.failed(
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CommandResult.Code.TRANSACTION_CLOSED,
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0,
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"Transaction is not open."
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)
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if not _configuration_errors.is_empty():
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return CommandResult.failed(
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CommandResult.Code.VALIDATION_FAILED,
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0,
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_configuration_errors[0],
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{"errors": _configuration_errors.duplicate()}
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)
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for index in _validators.size():
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var validator_result := _validation_result(_validators[index].call(), "validator %d" % index)
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if validator_result != null:
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return validator_result
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for change in _changes:
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if not change.validate_action.is_valid():
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continue
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var change_result := _validation_result(change.validate_action.call(), change.label)
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if change_result != null:
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return change_result
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return CommandResult.succeeded()
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func commit() -> CommandResult:
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var validation_result := validate()
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if not validation_result.is_success():
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if status == Status.OPEN:
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status = Status.FAILED
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return validation_result
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var applied: Array[StagedChange] = []
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for change in _changes:
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var returned: Variant = change.apply_action.call()
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var apply_failure := _apply_result(returned, change.label)
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if apply_failure != null:
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change.rollback_action.call()
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for index in range(applied.size() - 1, -1, -1):
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applied[index].rollback_action.call()
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status = Status.ROLLED_BACK
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apply_failure.details["rolled_back"] = true
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return apply_failure
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applied.append(change)
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status = Status.COMMITTED
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return CommandResult.succeeded(0, {"change_count": _changes.size()})
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func rollback() -> CommandResult:
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if status != Status.OPEN:
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return CommandResult.failed(
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CommandResult.Code.TRANSACTION_CLOSED,
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0,
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"Only an open transaction can be cancelled."
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)
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status = Status.ROLLED_BACK
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return CommandResult.succeeded()
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func change_count() -> int:
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return _changes.size()
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func _require_open(operation: String) -> bool:
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if status == Status.OPEN:
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return true
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_configuration_errors.append("%s cannot run on a closed transaction." % operation)
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return false
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func _validation_result(returned: Variant, label: String) -> CommandResult:
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if returned == null or (returned is bool and returned):
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return null
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if returned is CommandResult:
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var command_result: CommandResult = returned
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if command_result.is_success():
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return null
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return command_result.copy()
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var message := str(returned) if returned is String and not returned.is_empty() else "Validation failed."
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return CommandResult.failed(
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CommandResult.Code.VALIDATION_FAILED,
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0,
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"%s: %s" % [label, message],
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{"change": label}
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)
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func _apply_result(returned: Variant, label: String) -> CommandResult:
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if returned == null or (returned is bool and returned):
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return null
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if returned is CommandResult:
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var command_result: CommandResult = returned
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if command_result.is_success():
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return null
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return command_result.copy()
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var message := str(returned) if returned is String and not returned.is_empty() else "Apply action failed."
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return CommandResult.failed(
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CommandResult.Code.TRANSACTION_APPLY_FAILED,
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0,
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"%s: %s" % [label, message],
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{"change": label}
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)
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static func _copy_value(value: Variant) -> Variant:
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if value is Dictionary or value is Array:
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return value.duplicate(true)
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return value
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static func _is_number(value: Variant) -> bool:
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return value is int or value is float
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