def _nt_parsing_expression
start_index = index
if node_cache[:parsing_expression].has_key?(index)
cached = node_cache[:parsing_expression][index]
if cached
node_cache[:parsing_expression][index] = cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
@index = cached.interval.end
end
return cached
end
i0 = index
r1 = _nt_choice
if r1
r1 = SyntaxNode.new(input, (index-1)...index) if r1 == true
r0 = r1
else
r2 = _nt_sequence
if r2
r2 = SyntaxNode.new(input, (index-1)...index) if r2 == true
r0 = r2
else
r3 = _nt_primary
if r3
r3 = SyntaxNode.new(input, (index-1)...index) if r3 == true
r0 = r3
else
@index = i0
r0 = nil
end
end
end
node_cache[:parsing_expression][start_index] = r0
r0
end