import re


def c_name(name: str, protect: bool = True) -> str:
    """
    Map ``name`` to a valid C identifier.

    Used for converting 'name' from a 'name':'type' qapi definition
    into a generated struct member, as well as converting type names
    into substrings of a generated C function name.

    '__a.b_c' -> '__a_b_c', 'x-foo' -> 'x_foo'
    protect=True: 'int' -> 'q_int'; protect=False: 'int' -> 'int'

    :param name: The name to map.
    :param protect: If true, avoid returning certain ticklish identifiers
                    (like C keywords) by prepending ``q_``.
    """
    # ANSI X3J11/88-090, 3.1.1
    c89_words = set(['auto', 'break', 'case', 'char', 'const', 'continue',
                     'default', 'do', 'double', 'else', 'enum', 'extern',
                     'float', 'for', 'goto', 'if', 'int', 'long', 'register',
                     'return', 'short', 'signed', 'sizeof', 'static',
                     'struct', 'switch', 'typedef', 'union', 'unsigned',
                     'void', 'volatile', 'while'])
    # ISO/IEC 9899:1999, 6.4.1
    c99_words = set(['inline', 'restrict', '_Bool', '_Complex', '_Imaginary'])
    # ISO/IEC 9899:2011, 6.4.1
    c11_words = set(['_Alignas', '_Alignof', '_Atomic', '_Generic',
                     '_Noreturn', '_Static_assert', '_Thread_local'])
    # GCC http://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/C-Extensions.html
    # excluding _.*
    gcc_words = set(['asm', 'typeof'])
    # C++ ISO/IEC 14882:2003 2.11
    cpp_words = set(['bool', 'catch', 'class', 'const_cast', 'delete',
                     'dynamic_cast', 'explicit', 'false', 'friend', 'mutable',
                     'namespace', 'new', 'operator', 'private', 'protected',
                     'public', 'reinterpret_cast', 'static_cast', 'template',
                     'this', 'throw', 'true', 'try', 'typeid', 'typename',
                     'using', 'virtual', 'wchar_t',
                     # alternative representations
                     'and', 'and_eq', 'bitand', 'bitor', 'compl', 'not',
                     'not_eq', 'or', 'or_eq', 'xor', 'xor_eq'])
    # namespace pollution:
    polluted_words = set(['unix', 'errno', 'mips', 'sparc', 'i386'])
    name = re.sub(r'[^A-Za-z0-9_]', '_', name)
    if protect and (name in (c89_words | c99_words | c11_words | gcc_words
                             | cpp_words | polluted_words)
                    or name[0].isdigit()):
        return 'q_' + name
    return name