PreferFirstLastRule class

Rule that prefers .first/.last over index access.

Using .first and .last is more expressive and idiomatic Dart compared to accessing 0 or length - 1.

Known Limitations

This rule operates on syntactic patterns without resolved type information. As a result, it may produce false positives in the following cases:

• String indexing: String supports [0] but does not have .first or .last properties. The rule cannot distinguish String from List.

  String s = "hello";
  print(s[0]);  // Will trigger, but s.first doesn't exist
  

• Custom indexable types: Any type with operator[] but without .first/.last getters will trigger false positives.

Recommended Mitigation

Exclude files with heavy string manipulation:

anteater:
  rules:
    - prefer-first-last:
        exclude:
          - '**/string_utils.dart'
          - '**/text_*.dart'