61 lines
1.8 KiB
Crystal
61 lines
1.8 KiB
Crystal
module Ameba::AST
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# A class that utilizes a logic to traverse AST nodes and
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# fire a source test callback if a redundant `Crystal::ControlExpression`
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# is reached.
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class RedundantControlExpressionVisitor
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# A corresponding rule that uses this visitor.
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getter rule : Rule::Base
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# A source that needs to be traversed.
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getter source : Source
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# A node to run traversal on.
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getter node : Crystal::ASTNode
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def initialize(@rule, @source, @node)
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traverse_node node
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end
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private def traverse_control_expression(node)
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@rule.test(@source, node, self)
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end
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private def traverse_node(node)
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case node
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when Crystal::ControlExpression then traverse_control_expression node
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when Crystal::Expressions then traverse_expressions node
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when Crystal::If, Crystal::Unless then traverse_condition node
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when Crystal::Case then traverse_case node
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when Crystal::BinaryOp then traverse_binary_op node
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when Crystal::ExceptionHandler then traverse_exception_handler node
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end
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end
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private def traverse_expressions(node)
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traverse_node node.expressions.last?
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end
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private def traverse_condition(node)
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return if node.else.nil? || node.else.nop?
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traverse_node(node.then)
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traverse_node(node.else)
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end
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private def traverse_case(node)
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node.whens.each { |when_node| traverse_node when_node.body }
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traverse_node(node.else)
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end
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private def traverse_binary_op(node)
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traverse_node(node.right)
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end
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private def traverse_exception_handler(node)
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traverse_node node.body
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traverse_node node.else
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node.rescues.try &.each { |rescue_node| traverse_node rescue_node.body }
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end
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end
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end
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