def mf2_from_json()

in python/moz/l10n/formats/mf2/from_json.py [0:0]

• 33 lines of code
• 13 McCabe index (conditional complexity)

def mf2_from_json(json: dict[str, Any]) -> Message:
    """
    Marshal a MessageFormat 2 data model [JSON Schema](https://github.com/unicode-org/message-format-wg/blob/main/spec/data-model/message.json)
    object into a parsed `moz.l10n.message.data.Message`.

    May raise `MF2ValidationError`.
    """
    try:
        msg_type = json["type"]
        if msg_type not in {"message", "select"}:
            raise MF2ValidationError(f"Invalid JSON message: {json}")

        declarations: dict[str, Expression] = {}
        for decl in json["declarations"]:
            decl_type = decl["type"]
            if decl_type not in {"input", "local"}:
                raise MF2ValidationError(f"Invalid JSON declaration type: {decl}")
            decl_name = _string(decl, "name")
            decl_expr = _expression(decl["value"])
            if decl_type == "input":
                if (
                    not isinstance(decl_expr.arg, VariableRef)
                    or decl_expr.arg.name != decl_name
                ):
                    raise MF2ValidationError(f"Invalid JSON .input declaration: {decl}")
            if decl_name in declarations:
                raise MF2ValidationError(f"Duplicate JSON declaration for ${decl_name}")
            declarations[decl_name] = decl_expr

        if msg_type == "message":
            pattern = _pattern(json["pattern"])
            return PatternMessage(pattern, declarations)

        assert msg_type == "select"
        selectors = tuple(_variable(sel) for sel in json["selectors"])
        variants = {
            tuple(_key(key) for key in vari["keys"]): _pattern(vari["value"])
            for vari in json["variants"]
        }
        return SelectMessage(declarations, selectors, variants)
    except (IndexError, KeyError, TypeError) as err:
        raise MF2ValidationError(f"Invalid JSON: {err!r}")