Class: Ruckus::Vector

Inherits:
Parsel show all
Defined in:
lib/ruckus/vector.rb

Overview

A vector of count elements of the same class, as in

elt0
elt1

… [eltN]

Constant Summary

Constants inherited from Parsel

Parsel::VERBOTEN

Instance Attribute Summary

Attributes inherited from Parsel

#name, #parent, #rendered_offset, #rendering, #tag, #value

Instance Method Summary collapse

Methods inherited from Parsel

bytes_for_bits, coerce, #each_matching_selector, endian?, factory?, #find_containing, #find_tag, #find_tag_struct, #fixup, #in, #incomplete!, #index_for_selectors, #inspect, #matches_selector?, #method_missing, #native?, native?, #next, #out, #parent_structure, #permute, #prev, #resolve, #respond_to?, #root, #size, #visit, #where_am_i?

Constructor Details

#initialize(opts = {}) ⇒ Vector

Options include:

  • :class the class of each element

  • :e_opts opts to pass when creating each element (:name is always deleted)

  • :count the number of elements of class :class in the vector. Can be a reference to another field

via :from_field



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# File 'lib/ruckus/vector.rb', line 12

def initialize(opts={})
    opts[:count] = 0x1fffffff if opts[:count] == :unlimited # grotesque hack XXX
    opts[:e_opts] ||= {}

    raise "need a class" if not opts[:class] and not opts[:classes_from]

    if opts[:classes_from]
        if not opts[:keys_from]
            raise "need a module to pull keys from (protocol numbers, command IDs, whatever) as :keys_from"
        end

        begin
            @keys = (m = opts[:keys_from]).constants.
                select {|x| m.const_get(x).kind_of? Numeric}.
                map {|x| [m.const_get(x), x]}.
                to_hash
        rescue => e
            raise "can't look up keys:\n #{ e }"
        end

        begin
            @classes = (m = opts[:classes_from]).constants.
                select {|x| m.const_get(x).kind_of? Class}.
                map do |x|
                    name = (klass = m.const_get(x)).
                             to_s.
                             underscore.
                             upcase
                    name = name[name.rindex(":")+1..-1]
                    [ name, klass ]
                end.to_hash
        rescue => e
            raise "can't generate class dictionary:\n #{ e }"
        end

        raise "need a :key_field or :key_finder" if not opts[:key_field] and not opts[:key_finder]
    end

    super(opts)
    @value = Blob.new
    @value.parent = self
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Ruckus::Parsel

Instance Method Details

#capture(str) ⇒ Object 



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# File 'lib/ruckus/vector.rb', line 55

def capture(str)
    count = resolve(@count)
    if not count
        raise "You need to provide a :count value to parse a vector; did you give it :size by mistake?"
    end

    count.downto(1) do |i|
        break if not str or str.empty?

        if @class
            o = @class.new(@e_opts.merge(:parent => self))
            str = o.capture(str)
            @value << o
        else
            if @key_field
                key = parent_struct.send(@key_field)
            end

            if @key_finder
                key = @key_finder.call(str)
            end

            begin
                o = @classes[@keys[key]].new(@e_opts.merge(:parent => self))
                str = o.capture(str)
                @value << o
            rescue => e
                raise "couldn't create an object from key:\n#{ e }"
            end
        end
    end
    @count = @value.count
    str
end

#to_s(off = nil) ⇒ Object 



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# File 'lib/ruckus/vector.rb', line 90

def to_s(off=nil)
    @rendered_offset = off || 0
    (@value)? @value.to_s(off) : ""
end