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