88 lines
2.2 KiB
Ruby
88 lines
2.2 KiB
Ruby
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require 'stringio'
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require 'strscan'
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require 'parslet/source/line_cache'
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module Parslet
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# Wraps the input string for parslet.
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#
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class Source
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def initialize(str)
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raise(
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ArgumentError,
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"Must construct Source with a string like object."
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) unless str.respond_to?(:to_str)
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@str = StringScanner.new(str)
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# maps 1 => /./m, 2 => /../m, etc...
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@re_cache = Hash.new { |h,k|
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h[k] = /(.|$){#{k}}/m }
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@line_cache = LineCache.new
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@line_cache.scan_for_line_endings(0, str)
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end
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# Checks if the given pattern matches at the current input position.
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#
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# @param pattern [Regexp] pattern to check for
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# @return [Boolean] true if the pattern matches at #pos
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#
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def matches?(pattern)
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@str.match?(pattern)
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end
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alias match matches?
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# Consumes n characters from the input, returning them as a slice of the
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# input.
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#
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def consume(n)
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original_pos = @str.pos
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slice_str = @str.scan(@re_cache[n])
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slice = Parslet::Slice.new(
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slice_str,
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original_pos,
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@line_cache)
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return slice
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end
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# Returns how many chars remain in the input.
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#
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def chars_left
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@str.rest_size
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end
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# Returns how many chars there are between current position and the
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# string given. If the string given doesn't occur in the source, then
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# the remaining chars (#chars_left) are returned.
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#
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# @return [Fixnum] count of chars until str or #chars_left
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#
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def chars_until str
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slice_str = @str.check_until(Regexp.new(Regexp.escape(str)))
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return chars_left unless slice_str
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return slice_str.size - str.size
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end
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# Position of the parse as a character offset into the original string.
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# @note: Encodings...
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def pos
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@str.pos
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end
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def pos=(n)
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@str.pos = n
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rescue RangeError
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end
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# Returns a <line, column> tuple for the given position. If no position is
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# given, line/column information is returned for the current position
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# given by #pos.
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#
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def line_and_column(position=nil)
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@line_cache.line_and_column(position || self.pos)
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end
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end
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end
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