89 lines
2.7 KiB
Ruby
89 lines
2.7 KiB
Ruby
require_relative "block"
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module Vm
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# Functions are similar to Blocks. Where Blocks can be jumped to, Functions can be called.
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# Functions also have arguments and a return. These are Value subclass instances, ie specify
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# type (by class type) and register by instance
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# Functions have a exactly three blocks, entry, exit and body, which are created for you
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# with straight branches between them.
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# Also remember that if your body exists of several blocks, they must be wrapped in a
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# block as the function really only has the one, and blocks only assemble their codes,
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# not their next links
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# This comes at zero runtime cost though, as the wrapper is just the sum of it's codes
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# If you change the body block to point elsewhere, remember to end up at exit
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class Function < Code
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def initialize(name , args = [] , return_type = nil)
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super()
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@name = name
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@args = Array.new(args.length)
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args.each_with_index do |arg , i|
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if arg.is_a?(Value)
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@args[i] = arg
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raise "arg in non std register #{arg.inspect}" unless i == arg.register
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else
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@args[i] = arg.new(i)
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end
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end
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@return_type = return_type || Vm::Integer
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if @return_type.is_a?(Value)
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raise "return in non std register #{@return_type.inspect}" unless 0 == @return_type.register
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else
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@return_type = @return_type.new(0)
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end
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@entry = Core::Kernel::function_entry( Vm::Block.new("#{name}_entry" , self) ,name )
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@exit = Core::Kernel::function_exit( Vm::Block.new("#{name}_exit", self) , name )
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@body = Block.new("#{name}_body", self)
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@locals = []
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branch_body
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end
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attr_reader :args , :entry , :exit , :body , :name
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attr_accessor :return_type
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def arity
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@args.length
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end
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def new_local type = Vm::Integer
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register = args.length + @locals.length
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l = type.new(register)
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@locals << l
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l
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end
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def link_at address , context
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raise "undefined code #{inspect}" if @body.nil?
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super #just sets the position
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@entry.link_at address , context
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address += @entry.length
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@body.link_at(address , context)
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address += @body.length
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@exit.link_at(address,context)
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end
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def position
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@entry.position
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end
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def length
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@entry.length + @exit.length + @body.length
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end
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def assemble io
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@entry.assemble(io)
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@body.assemble(io)
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@exit.assemble(io)
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end
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private
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# set up the braches from entry to body and body to exit (unless that exists, see set_body)
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def branch_body
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@entry.set_next(@body)
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@body.set_next(@exit) if @body and !@body.next
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end
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end
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end |