def step
case
when scan(/\s+/)
start_group :normal, matched
when match = scan(/#\s*(\w*)/)
match << scan_until(/\n/)
start_group :preprocessor, match
when scan(/ L?' (?: [^\'\n\\] | \\ #{ANSIC_ESCAPE} )? '? /ox)
start_group :char, matched
when scan(/0[xX][0-9A-Fa-f]+/)
start_group :hex, matched
when scan(/(?:0[0-7]+)(?![89.eEfF])/)
start_group :oct, matched
when scan(/(?:\d+)(?![.eEfF])/)
start_group :integer, matched
when scan(/\d[fF]?|\d*\.\d+(?:[eE][+-]?\d+)?[fF]?|\d+[eE][+-]?\d+[fF]?/)
start_group :float, matched
when scan(/"(?:[^"\\]|\\.)*"/)
start_group :string, matched
when scan( %r{ ('(?: . | [\t\b\n] )') }x )
start_group :char, matched
when scan(/[a-z_][a-z_\d]+/)
if ANSIC_KEYWORDS.include?( matched )
start_group :keyword, matched
elsif ANSIC_PREDEFINED_TYPES.include?( matched )
start_group :predefined_types, matched
else
start_group :ident, matched
end
when scan(%r! // [^\n\\]* (?: \\. [^\n\\]* )* | /\* (?: .*? \*/ | .* ) !mx)
start_group :comment, matched
else
start_group :other, scan(/./x)
end
end