Class: Duby::AST::If

Inherits:
Node show all
Defined in:
lib/duby/ast/flow.rb,
lib/duby/compiler.rb,
lib/duby/jvm/source_generator/precompile.rb

Instance Attribute Summary collapse

Attributes inherited from Node

#children, #inferred_type, #newline, #parent, #position

Instance Method Summary collapse

Methods inherited from Node

#[], #each, #inspect, #line_number, #log, #precompile, #resolve_if, #resolved!, #resolved?, #simple_name, #temp, #to_s

Constructor Details

#initialize(parent, line_number, &block) ⇒ If

Returns a new instance of If.



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# File 'lib/duby/ast/flow.rb', line 33

def initialize(parent, line_number, &block)
  super(parent, line_number, &block)
  @condition, @body, @else = children
end

Instance Attribute Details

#body ⇒ Object

Returns the value of attribute body.



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# File 'lib/duby/ast/flow.rb', line 31

def body
  @body
end

#condition ⇒ Object

Returns the value of attribute condition.



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# File 'lib/duby/ast/flow.rb', line 31

def condition
  @condition
end

#else ⇒ Object

Returns the value of attribute else.



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# File 'lib/duby/ast/flow.rb', line 31

def else
  @else
end

Instance Method Details

#compile(compiler, expression) ⇒ Object 



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# File 'lib/duby/compiler.rb', line 124

def compile(compiler, expression)
  compiler.line(line_number)
  compiler.branch(self, expression)
end

#expr?(compiler) ⇒ Boolean

Returns:



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# File 'lib/duby/jvm/source_generator/precompile.rb', line 50

def expr?(compiler)
  return false unless condition.predicate.expr?(compiler)
  return false unless body.nil? || body.expr?(compiler)
  return false unless self.else.nil? || self.else.expr?(compiler)
  true
end

#infer(typer) ⇒ Object 



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# File 'lib/duby/ast/flow.rb', line 38

def infer(typer)
  unless resolved?
    condition_type = typer.infer(condition)
    unless condition_type
      typer.defer(condition)
    end

    # condition type is unrelated to body types, so we proceed with bodies
    then_type = typer.infer(body) if body

    if !then_type
      # attempt to determine else branch
      if self.else
        else_type = typer.infer(self.else)

        if !else_type
          # we have neither type, defer until later
          typer.defer(self)
        else
          # we have else but not then, defer only then and use else type for now
          @inferred_type = else_type
          typer.defer(self)
        end
      else
        # no then type could be inferred and no else body, defer for now
        typer.defer(self)
      end
    else
      if self.else
        else_type = typer.infer(self.else)

        if !else_type
          # we determined a then type, so we use that and defer the else body
          @inferred_type = then_type
          typer.defer(self)
        else
          # both then and else inferred, ensure they're compatible
          if then_type.compatible?(else_type)
            # types are compatible...if condition is resolved, we're done
            @inferred_type = then_type.narrow(else_type)
            resolved! if condition_type
          else
            raise Typer::InferenceError.new("if statement with incompatible result types")
          end
        end
      else
        # only then and type inferred, we're 100% resolved
        @inferred_type = then_type
        resolved! if condition_type
      end
    end
  end

  @inferred_type
end