95 lines
3.5 KiB
Ruby
95 lines
3.5 KiB
Ruby
module Parslet
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module ErrorReporter
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# Instead of reporting the latest error that happens like {Tree} does,
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# this class reports the deepest error. Depth is defined here as how
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# advanced into the input an error happens. The errors close to the
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# greatest depth tend to be more relevant to the end user, since they
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# specify what could be done to make them go away.
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#
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# More specifically, errors produced by this reporter won't be related to
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# the structure of the grammar at all. The positions of the errors will
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# be advanced and convey at every grammar level what the deepest rule
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# was to fail.
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#
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class Deepest
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def initialize
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@deepest_cause = nil
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end
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# Produces an error cause that combines the message at the current level
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# with the errors that happened at a level below (children).
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#
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# @param atom [Parslet::Atoms::Base] parslet that failed
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# @param source [Source] Source that we're using for this parse. (line
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# number information...)
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# @param message [String, Array] Error message at this level.
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# @param children [Array] A list of errors from a deeper level (or nil).
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# @return [Cause] An error tree combining children with message.
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#
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def err(atom, source, message, children=nil)
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position = source.pos
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cause = Cause.format(source, position, message, children)
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return deepest(cause)
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end
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# Produces an error cause that combines the message at the current level
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# with the errors that happened at a level below (children).
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#
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# @param atom [Parslet::Atoms::Base] parslet that failed
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# @param source [Source] Source that we're using for this parse. (line
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# number information...)
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# @param message [String, Array] Error message at this level.
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# @param pos [Fixnum] The real position of the error.
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# @param children [Array] A list of errors from a deeper level (or nil).
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# @return [Cause] An error tree combining children with message.
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#
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def err_at(atom, source, message, pos, children=nil)
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position = pos
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cause = Cause.format(source, position, message, children)
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return deepest(cause)
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end
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# Returns the cause that is currently deepest. Mainly for specs.
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#
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attr_reader :deepest_cause
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# Checks to see if the lineage of the cause given includes a cause with
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# an error position deeper than the current deepest cause stored. If
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# yes, it passes the cause through to the caller. If no, it returns the
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# current deepest error that was saved as a reference.
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#
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def deepest(cause)
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rank, leaf = deepest_child(cause)
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if !deepest_cause || leaf.pos >= deepest_cause.pos
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# This error reaches deeper into the input, save it as reference.
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@deepest_cause = leaf
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return cause
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end
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return deepest_cause
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end
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private
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# Returns the leaf from a given error tree with the biggest rank.
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#
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def deepest_child(cause, rank=0)
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max_child = cause
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max_rank = rank
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if cause.children && !cause.children.empty?
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cause.children.each do |child|
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c_rank, c_cause = deepest_child(child, rank+1)
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if c_rank > max_rank
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max_rank = c_rank
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max_child = c_cause
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end
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end
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end
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return max_rank, max_child
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end
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end
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end
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end |