Function emit_view_structs

Scripts/codegen/generate_ue_components.py:2552–2642

For each view in `rules['views']`, return (fields_block, bind_block).

(rules: Dict[str, Any], mjxmacro: Dict[str, Any])

# ---------------------------------------------------------------------------

_VIEW_FIELD_TYPE_MAP = {
    "int": "int*", "mjtByte": "mjtByte*", "mjtBool": "mjtBool*",
    "mjtNum": "mjtNum*", "float": "float*", "char": "char*",
}


def _view_field_type_cpp(c_type: str, field_name: str = "") -> str:
    mapped = _VIEW_FIELD_TYPE_MAP.get(c_type)
    if mapped is None:
        # Don't silently default a new MuJoCo scalar type to mjtNum* — that
        # ships a wrong (often 8-byte-over-1-byte) pointer with no warning.
        # A bump that introduces a new type should surface here loudly.
        _diag_add(
            f"[diagnostic] view field '{field_name or '?'}' has unmapped C "
            f"type '{c_type}'; defaulting to 'mjtNum*'. A MuJoCo bump likely "
            f"introduced a new scalar type; add it to _VIEW_FIELD_TYPE_MAP.",
            source="view_field_type",
        )
        return "mjtNum*"
    return mapped


_MJ_M_MACRO_RE = re.compile(r"MJ_M\(\s*(\w+)\s*\)")
# Any MJ_*( ... ) macro that survives _expand_stride is an unhandled
# stride shape — emit invalid C++ in MjBind.h. The guard fires a
# diagnostic so a MuJoCo bump that introduces new stride macros (e.g.
# MJ_D(...) for mjData, MJ_V(...) for variable-size views) surfaces
# loudly rather than landing as a compile error far downstream.
_RESIDUAL_MJ_MACRO_RE = re.compile(r"\bMJ_[A-Z]\(\s*\w+\s*\)")


def _expand_stride(stride: str) -> str:
    """Convert mjxmacro stride expressions to plain C++ expressions usable
    in MjBind.h. ``MJ_M(nuser_jnt)`` -> ``m->nuser_jnt``.

    Fires a diagnostic if any ``MJ_*(...)`` macro survives the
    substitution — that's an unhandled stride shape we'd otherwise
    silently emit into MjBind.h verbatim."""
    expanded = _MJ_M_MACRO_RE.sub(r"m->\1", stride)
    residual = _RESIDUAL_MJ_MACRO_RE.findall(expanded)
    if residual:
        _diag_add(
            f"[diagnostic] _expand_stride saw stride '{stride}' with "
            f"unhandled MuJoCo macro(s) {residual}. Result '{expanded}' "
            f"will land in MjBind.h verbatim and likely fail to compile. "
            f"Teach _expand_stride about the new macro shape.",
            source="expand_stride",
        )
    return expanded


def emit_view_structs(rules: Dict[str, Any], mjxmacro: Dict[str, Any]) -> Dict[str, Tuple[str, str]]:
    """For each view in `rules['views']`, return (fields_block, bind_block)."""
    out: Dict[str, Tuple[str, str]] = {}
    views: Dict[str, Any] = rules.get("views", {})

    for view_name, view_def in views.items():
        renames: Dict[str, str] = view_def.get("field_renames", {})