91 lines
2.7 KiB
Ruby
91 lines
2.7 KiB
Ruby
module CoffeeScript
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# Scope objects form a tree corresponding to the shape of the function
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# definitions present in the script. They provide lexical scope, to determine
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# whether a variable has been seen before or if it needs to be declared.
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class Scope
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attr_reader :parent, :expressions, :function, :variables, :temp_variable
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# Initialize a scope with its parent, for lookups up the chain,
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# as well as the Expressions body where it should declare its variables,
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# and the function that it wraps.
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def initialize(parent, expressions, function)
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@parent, @expressions, @function = parent, expressions, function
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@variables = {}
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@temp_variable = @parent ? @parent.temp_variable.dup : '__a'
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end
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# Look up a variable in lexical scope, or declare it if not found.
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def find(name, remote=false)
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found = check(name)
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return found if found || remote
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@variables[name.to_sym] = :var
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found
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end
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# Define a local variable as originating from a parameter in current scope
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# -- no var required.
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def parameter(name)
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@variables[name.to_sym] = :param
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end
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# Just check to see if a variable has already been declared.
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def check(name)
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return true if @variables[name.to_sym]
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!!(@parent && @parent.check(name))
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end
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# You can reset a found variable on the immediate scope.
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def reset(name)
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@variables[name.to_sym] = false
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end
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# Find an available, short, name for a compiler-generated variable.
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def free_variable
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@temp_variable.succ! while check(@temp_variable)
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@variables[@temp_variable.to_sym] = :var
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Value.new(@temp_variable.dup)
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end
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# Ensure that an assignment is made at the top of scope (or top-level
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# scope, if requested).
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def assign(name, value, top=false)
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return @parent.assign(name, value, top) if top && @parent
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@variables[name.to_sym] = Value.new(value)
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end
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def declarations?(body)
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!declared_variables.empty? && body == @expressions
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end
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def assignments?(body)
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!assigned_variables.empty? && body == @expressions
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end
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# Return the list of variables first declared in current scope.
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def declared_variables
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@variables.select {|k, v| v == :var }.map {|pair| pair[0].to_s }.sort
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end
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# Return the list of variables that are supposed to be assigned at the top
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# of scope.
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def assigned_variables
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@variables.select {|k, v| v.is_a?(Value) }.sort_by {|pair| pair[0].to_s }
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end
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def compiled_declarations
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declared_variables.join(', ')
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end
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def compiled_assignments
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assigned_variables.map {|name, val| "#{name} = #{val}"}.join(', ')
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end
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def inspect
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"<Scope:#{__id__} #{@variables.inspect}>"
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end
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end
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end |