33 lines
708 B
Ruby
33 lines
708 B
Ruby
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# Evaluates a block at parse time. The result from the block must be a parser
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# (something which implements #apply). In the first case, the parser will then
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# be applied to the input, creating the result.
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#
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# Dynamic parses are never cached.
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#
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# Example:
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# dynamic { rand < 0.5 ? str('a') : str('b') }
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#
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class Parslet::Atoms::Dynamic < Parslet::Atoms::Base
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attr_reader :block
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def initialize(block)
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@block = block
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end
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def cached?
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false
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end
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def try(source, context, consume_all)
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result = block.call(source, context)
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# Result is a parslet atom.
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return result.apply(source, context, consume_all)
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end
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def to_s_inner(prec)
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"dynamic { ... }"
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end
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end
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