54 lines
1.6 KiB
Ruby
54 lines
1.6 KiB
Ruby
module Imbecile
|
|
class Grammar
|
|
|
|
# @return [String, nil] Module name.
|
|
attr_reader :modulename
|
|
|
|
# @return [String, nil] Class name.
|
|
attr_reader :classname
|
|
|
|
def initialize(input_file)
|
|
@tokens = {}
|
|
@rules = {}
|
|
File.read(input_file).each_line.each_with_index do |line, line_index|
|
|
line = line.chomp
|
|
line_number = line_index + 1
|
|
if line =~ /^\s*#/
|
|
# Skip comment lines.
|
|
elsif line =~ /^\s*$/
|
|
# Skip blank lines.
|
|
elsif line =~ /^\s*module\s+(\S+)$/
|
|
@modulename = $1
|
|
elsif line =~ /^\s*class\s+(\S+)$/
|
|
@classname = $1
|
|
elsif line =~ /^\s*token\s+(\S+)(?:\s+(\S+))?$/
|
|
name, pattern = $1, $2
|
|
if pattern.to_s == ""
|
|
pattern = name
|
|
end
|
|
unless name =~ /^[a-zA-Z_][a-zA-Z_0-9]*$/
|
|
raise Error.new("Invalid token name #{name} on line #{line_number}")
|
|
end
|
|
if @tokens[name]
|
|
raise Error.new("Duplicate token name #{name} on line #{line_number}")
|
|
end
|
|
@tokens[name] = {pattern: pattern}
|
|
else
|
|
raise Error.new("Unexpected input on line #{line_number}: #{line}")
|
|
end
|
|
end
|
|
|
|
# Build NFA from each token expression.
|
|
i = 0
|
|
@tokens.each do |token_name, token_def|
|
|
token_def[:regex] = Regex.new(token_def[:pattern])
|
|
token_def[:regex].nfa.end_state.accepts = "#{i}:#{token_name}"
|
|
i += 1
|
|
end
|
|
dfa = Regex::DFA.new(@tokens.map {|token_name, token_def| token_def[:regex].nfa})
|
|
puts dfa
|
|
end
|
|
|
|
end
|
|
end
|