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@ -195,6 +195,39 @@ module Lox
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"#{type} #{lexeme} #{literal}"
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end
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end
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module Expr
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Binary = Struct.new(:left, :op, :right) do
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def accept(visitor) = visitor.visit_binary(self)
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end
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Grouping = Struct.new(:expr) do
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def accept(visitor) = visitor.visit_grouping(self)
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end
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Literal = Struct.new(:value) do
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def accept(visitor) = visitor.visit_literal(self)
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end
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Unary = Struct.new(:op, :right) do
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def accept(visitor) = visitor.visit_unary(self)
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end
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end
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class AstPrinter
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def print(expr) = expr.accept(self)
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def visit_binary(expr) = parenthesize(expr.op.lexeme, expr.left, expr.right)
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def visit_grouping(expr) = parenthesize("group", expr.expr)
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def visit_literal(expr) = expr.value&.to_s || "nil"
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def visit_unary(expr) = parenthesize(expr.op.lexeme, expr.right)
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private
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def parenthesize(name, *exprs)
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"(#{name} #{exprs.map {|expr| expr.accept(self) }.join(" ")})"
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end
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end
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end
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if __FILE__ == $0
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