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Support IncludeCondition in ParameterRefEntry elements

Open Copilot opened this issue 2 months ago • 2 comments

Description

Implements XTCE 5.3.4 IncludeCondition support for conditional parameter parsing based on previously-parsed values.

Implementation

  • New ParameterRefEntry class wraps parameter references with optional IncludeCondition and RepeatEntry (placeholder)

    • Evaluates conditions against partially-parsed packet state using existing MatchCriteria infrastructure
    • Skips parameter parsing when condition evaluates false, leaving bit position unchanged
    • Raises NotImplementedError for RepeatEntry during parse
  • Updated SequenceContainer

    • Creates ParameterRefEntry objects only when IncludeCondition/RepeatEntry present (backward compatible)
    • Stores _parameter_lookup for runtime parameter resolution
    • Warns on unrecognized EntryList element types
    • Updated type hints: entry_list: list[Union[ParameterRefEntry, Parameter, SequenceContainer]]

Example

# XTCE with conditional parameter
<ParameterRefEntry parameterRef="CheckSum">
    <IncludeCondition>
        <Comparison parameterRef="CSFlag" value="1" comparisonOperator="=="/>
    </IncludeCondition>
</ParameterRefEntry>

# CheckSum parsed only when CSFlag == 1
packet = SpacePacket(binary_data=b"\x01\x04\xd2...")  # CSFlag=1
container.parse(packet)
assert "CheckSum" in packet

packet = SpacePacket(binary_data=b"\x00...")  # CSFlag=0
container.parse(packet)
assert "CheckSum" not in packet  # Skipped, no position advance

Limitations

ComparisonList with multiple comparisons evaluates only first element (warns user). Full AND logic requires architectural changes to support multiple MatchCriteria per condition.

Checklist

  • [x] Changes are fully implemented without dangling issues or TODO items
  • [x] Deprecated/superseded code is removed or marked with deprecation warning
  • [x] Current dependencies have been properly specified and old dependencies removed
  • [x] New code/functionality has accompanying tests and any old tests have been updated to match any new assumptions
  • [ ] The changelog.md has been updated

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Original prompt

This section details on the original issue you should resolve

<issue_title>Support IncludeCondition in ParameterRefEntry elements</issue_title> <issue_description>## Summary

Space Packet Parser supports much of the XTCE XML schema but the IncludeCondition element within ParameterRefEntry is not yet handled.

XTCE Reference: Section 5.3.4 (p. 235) of CCSDS 660.1-G-2

IncludeCondition elements allow conditional inclusion of a ParameterRefEntry in the EntryList of a SequenceContainer. The condition can only reference previously parsed parameters in the packet. During parsing, the partially-parsed packet object is available to look up these values.

XTCE Example

<xtce:SequenceContainer name="ConditionalExample">
  <xtce:EntryList>
    <xtce:ParameterRefEntry parameterRef="CSFlag"/>
    <xtce:ParameterRefEntry parameterRef="CheckSum">
      <xtce:IncludeCondition>
        <xtce:Comparison value="1" parameterRef="CSFlag"/>
      </xtce:IncludeCondition>
    </xtce:ParameterRefEntry>
  </xtce:EntryList>
</xtce:SequenceContainer>

In this example, CheckSum is only parsed if the previously-parsed CSFlag parameter equals 1.

Implementation

Current Architecture Limitation

Currently in containers.py lines 111-131, we parse SequenceContainer/EntryList elements into a simple entry_list of Parameter and SequenceContainer objects. This doesn't support:

  • Conditional inclusion (via IncludeCondition)
  • Repeated parameters (via RepeatEntry)
  • Other ParameterRefEntry attributes

Create New ParameterRefEntry Class

Create a new class in containers.py to represent the ParameterRefEntry XML element with its optional child elements.

Attributes:

  • parameter_ref: str - Name reference to the Parameter
  • repeat_entry: Optional[RepeatEntry] - Repeat information (raise NotImplementedError for now)
  • include_condition: Optional[MatchCriteria] - Condition for inclusion (use existing MatchCriteria types from comparisons.py)

Inheritance:

  • Must inherit from common.XmlObject and common.Parseable
  • Implement from_xml() to parse the XML structure
  • Implement to_xml() for serialization
  • Implement parse() to handle conditional parsing logic

Parse Logic:

  1. If include_condition exists, evaluate it using the current packet state
  2. If condition is False (or None and parameter should be skipped), return early without parsing
  3. If repeat_entry exists, raise NotImplementedError with message: "RepeatEntry is not currently supported in parsing"
  4. Otherwise, resolve the parameter reference and parse it normally

Scope Constraint (XTCE 5.8.4): The IncludeCondition can only reference parameters that have already been parsed in the current container (previous entries in the EntryList). References to "future" parameters in the same container must be rejected or produce a warning.

Update SequenceContainer.from_xml()

Modify the loop at lines 111-131 to create ParameterRefEntry objects instead of directly referencing Parameter objects:

elif entry_tag_name == "ParameterRefEntry":
    parameter_name = entry.attrib["parameterRef"]
    
    # Parse optional IncludeCondition
    include_condition = None
    if (include_cond_elem := entry.find("IncludeCondition")) is not None:
        # Use existing MatchCriteria parsing logic from comparisons module
        include_condition = cls._parse_include_condition(include_cond_elem)
    
    # Parse optional RepeatEntry
    repeat_entry = None
    if entry.find("RepeatEntry") is not None:
        repeat_entry = ...  # Parse but will raise NotImplementedError during parse()
    
    # Create ParameterRefEntry object with parameter reference and conditions
    param_ref_entry = ParameterRefEntry(
        parameter_ref=parameter_name,
        include_condition=include_condition,
        repeat_entry=repeat_entry
    )
    entry_list.append(param_ref_entry)

Add Warning for Unrecognized EntryList Elements

At the end of the if-elif chain (after line 131 in current code), add:

else:
    warnings.warn(
        f"Unrecognized entry type '{entry_tag_name}' in EntryList for container "
        f"'{element.attrib['name']}'. Supported types: ParameterRefEntry, ContainerRefEntry. "
        f"Skipping this entry.",
        category=UserWarning
    )
    continue

Change Type of entry_list

The entry_list attribute in SequenceContainer should be updated to:

entry_list: list[Union[ParameterRefEntry, SequenceContainer]]

This replaces the current list[Union[parameters.Parameter, SequenceContainer]].

Backward Compatibility: The SequenceContainer.parse() method must be updated to handle ParameterRefEntry objects, which will need to resolve their parameter references and evaluate conditions during parsing.

Test Cases

  1. Simple condition: Parameter included only when flag=1, exclud...
  • Fixes lasp/space_packet_parser#28

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Copilot avatar Nov 06 '25 02:11 Copilot

Codecov Report

:x: Patch coverage is 96.72619% with 11 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 94.11%. Comparing base (4dec594) to head (f015995).

Files with missing lines Patch % Lines
space_packet_parser/xtce/containers.py 82.81% 11 Missing :warning:
Additional details and impacted files
@@            Coverage Diff             @@
##             main     #216      +/-   ##
==========================================
+ Coverage   93.87%   94.11%   +0.23%     
==========================================
  Files          46       48       +2     
  Lines        3594     3924     +330     
==========================================
+ Hits         3374     3693     +319     
- Misses        220      231      +11     

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