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# frozen_string_literal: true
require "graphql/execution/lazy/lazy_method_map"
require "graphql/execution/lazy/resolve"
module GraphQL
module Execution
# This wraps a value which is available, but not yet calculated, like a promise or future.
#
# Calling `#value` will trigger calculation & return the "lazy" value.
#
# This is an itty-bitty promise-like object, with key differences:
# - It has only two states, not-resolved and resolved
# - It has no error-catching functionality
# @api private
class Lazy
# Traverse `val`, lazily resolving any values along the way
# @param val [Object] A data structure containing mixed plain values and `Lazy` instances
# @return void
def self.resolve(val)
Resolve.resolve(val)
end
# Create a {Lazy} which will get its inner value by calling the block
# @param get_value_func [Proc] a block to get the inner value (later)
def initialize(&get_value_func)
@get_value_func = get_value_func
@resolved = false
end
# @return [Object] The wrapped value, calling the lazy block if necessary
def value
if !@resolved
@resolved = true
@value = begin
@get_value_func.call
rescue GraphQL::ExecutionError => err
err
end
end
@value
end
# @return [Lazy] A {Lazy} whose value depends on another {Lazy}, plus any transformations in `block`
def then
self.class.new {
yield(value)
}
end
# This can be used for fields which _had no_ lazy results
# @api private
NullResult = Lazy.new(){}
NullResult.value
end
end
end
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36 entries across 36 versions & 1 rubygems