fn validate()

in tokenizers/src/processors/template.rs [468:524]
53 lines of code
7 McCabe index (conditional complexity)

    fn validate(&self) -> std::result::Result<(), String> {
        let pair_has_both = self.pair.as_ref().is_none_or(|pair| {
            let mut has_a = false;
            let mut has_b = false;
            for piece in &pair.0 {
                if let Piece::Sequence {
                    id: Sequence::A, ..
                } = piece
                {
                    has_a = true;
                }
                if let Piece::Sequence {
                    id: Sequence::B, ..
                } = piece
                {
                    has_b = true;
                }
            }
            has_a && has_b
        });
        if !pair_has_both {
            return Err("Template for `pair` must use both sequences".into());
        }

        let check = |sp| {
            let exist = self
                .special_tokens
                .as_ref()
                .is_some_and(|map| map.0.contains_key(sp));

            match exist {
                false => Some(sp),
                true => None,
            }
        };

        let empty = [];
        let missing: AHashSet<&str> = self
            .single
            .as_ref()
            .map_or(empty.iter(), |s| s.0.iter())
            .chain(self.pair.as_ref().map_or(empty.iter(), |s| s.0.iter()))
            .filter_map(|piece| match piece {
                Piece::Sequence { .. } => None,
                Piece::SpecialToken { id, .. } => check(id.as_ref()),
            })
            .collect::<AHashSet<_>>();

        if missing.is_empty() {
            Ok(())
        } else {
            Err(format!(
                "Missing SpecialToken(s) with id(s) `{}`",
                missing.iter().join(", ")
            ))
        }
    }