129 lines
3.6 KiB
Ruby
129 lines
3.6 KiB
Ruby
module Rscons
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# This class represents a collection of variables which can be accessed
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# as certain types.
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# Only nil, strings, arrays, and hashes should be stored in a VarSet.
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class VarSet
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# Create a VarSet.
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# @param vars [Hash] Optional initial variables.
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def initialize(vars = {})
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@my_vars = {}
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@coa_vars = []
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append(vars)
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end
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# Access the value of variable as a particular type
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# @param key [String, Symbol] The variable name.
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# @return [Object] The variable's value.
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def [](key)
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if @my_vars.include?(key)
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@my_vars[key]
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else
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@coa_vars.each do |coa_vars|
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if coa_vars.include?(key)
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@my_vars[key] = deep_dup(coa_vars[key])
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return @my_vars[key]
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end
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end
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nil
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end
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end
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# Assign a value to a variable.
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# @param key [String, Symbol] The variable name.
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# @param val [Object] The value to set.
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def []=(key, val)
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@my_vars[key] = val
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end
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# Check if the VarSet contains a variable.
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# @param key [String, Symbol] The variable name.
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# @return [true, false] Whether the VarSet contains a variable.
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def include?(key)
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if @my_vars.include?(key)
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true
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else
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@coa_vars.find do |coa_vars|
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coa_vars.include?(key)
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end
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end
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end
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# Add or overwrite a set of variables
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# @param values [VarSet, Hash] New set of variables.
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def append(values)
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coa!
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if values.is_a?(VarSet)
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values.send(:coa!)
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@coa_vars = values.instance_variable_get(:@coa_vars) + @coa_vars
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else
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@my_vars = deep_dup(values)
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end
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self
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end
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# Create a new VarSet object based on the first merged with other.
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# @param other [VarSet, Hash] Other variables to add or overwrite.
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def merge(other = {})
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coa!
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varset = self.class.new
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varset.instance_variable_set(:@coa_vars, @coa_vars.dup)
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varset.append(other)
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end
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alias_method :clone, :merge
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# Replace "$" variable references in varref with the variables values,
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# recursively.
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# @param varref [String, Array] Value containing references to variables.
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def expand_varref(varref)
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if varref.is_a?(Array)
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varref.map do |ent|
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expand_varref(ent)
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end.flatten
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else
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if varref =~ /^(.*)\$\{([^}]+)\}(.*)$/
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prefix, varname, suffix = $1, $2, $3
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varval = expand_varref(self[varname])
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if varval.is_a?(String)
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expand_varref("#{prefix}#{varval}#{suffix}")
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elsif varval.is_a?(Array)
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varval.map {|vv| expand_varref("#{prefix}#{vv}#{suffix}")}.flatten
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else
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raise "I do not know how to expand a variable reference to a #{varval.class.name} (from #{varname.inspect} => #{self[varname].inspect})"
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end
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else
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varref
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end
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end
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end
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private
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# Move all VarSet variables into the copy-on-access list.
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def coa!
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unless @my_vars.empty?
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@coa_vars.unshift(@my_vars)
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@my_vars = {}
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end
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end
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# Create a deep copy of an object.
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# @param obj [nil, String, Array, Hash] Object to deep copy.
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# @return [nil, String, Array, Hash] Deep copied value.
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def deep_dup(obj)
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obj_class = obj.class
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if obj_class == Hash
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obj.reduce({}) do |result, (k, v)|
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result[k] = deep_dup(v)
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result
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end
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elsif obj_class == Array
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obj.map { |v| deep_dup(v) }
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elsif obj_class == String
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obj.dup
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else
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obj
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end
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end
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end
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end
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