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module PgQuery
class ParserResult
# Walks the parse tree and calls the passed block for each contained node
#
# If you pass a block with 1 argument, you will get each node.
# If you pass a block with 4 arguments, you will get each parent_node, parent_field, node and location.
#
# Location uniquely identifies a given node within the parse tree. This is a stable identifier across
# multiple parser runs, assuming the same pg_query release and no modifications to the parse tree.
def walk!(&block)
if block.arity == 1
treewalker!(@tree) do |_, _, node, _|
yield(node)
end
else
treewalker!(@tree) do |parent_node, parent_field, node, location|
yield(parent_node, parent_field, node, location)
end
end
end
private
def treewalker!(tree) # rubocop:disable Metrics/CyclomaticComplexity
nodes = [[tree.dup, []]]
loop do
parent_node, parent_location = nodes.shift
case parent_node
when Google::Protobuf::MessageExts
parent_node.to_h.keys.each do |parent_field|
node = parent_node[parent_field.to_s]
next if node.nil?
location = parent_location + [parent_field]
yield(parent_node, parent_field, node, location) if node.is_a?(Google::Protobuf::MessageExts) || node.is_a?(Google::Protobuf::RepeatedField)
nodes << [node, location] unless node.nil?
end
when Google::Protobuf::RepeatedField
parent_node.each_with_index do |node, parent_field|
next if node.nil?
location = parent_location + [parent_field]
yield(parent_node, parent_field, node, location) if node.is_a?(Google::Protobuf::MessageExts) || node.is_a?(Google::Protobuf::RepeatedField)
nodes << [node, location] unless node.nil?
end
end
break if nodes.empty?
end
end
def find_tree_location(tree, searched_location)
treewalker! tree do |parent_node, parent_field, node, location|
next unless location == searched_location
yield(parent_node, parent_field, node)
end
end
end
end
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