43b980368a
The `ActiveSupport::DeepMergeable` module allows a class to provide `deep_merge` and `deep_merge!` methods simply by implementing a `merge!(other, &block)` method. Values will be deep merged only when they are compatible, according to `deep_merge?`. By default, that only includes instances of the same class or its subclasses. A class may override `deep_merge?` to further restrict or expand the domain of deep mergeable values. This does introduce a small change in behavior. Previously, `Hash#deep_merge` would only deep merge `Hash` instances. Now, `deep_merge` will deep merge any `DeepMergeable` instances that are compatible with each other.
54 lines
1.7 KiB
Ruby
54 lines
1.7 KiB
Ruby
# frozen_string_literal: true
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module ActiveSupport
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# Provides +deep_merge+ and +deep_merge!+ methods. Expects the including class
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# to provide a <tt>merge!(other, &block)</tt> method.
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module DeepMergeable # :nodoc:
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# Returns a new instance with the values from +other+ merged recursively.
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#
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# class Hash
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# include ActiveSupport::DeepMergeable
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# end
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#
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# hash_1 = { a: true, b: { c: [1, 2, 3] } }
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# hash_2 = { a: false, b: { x: [3, 4, 5] } }
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#
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# hash_1.deep_merge(hash_2)
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# # => { a: false, b: { c: [1, 2, 3], x: [3, 4, 5] } }
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#
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# A block can be provided to merge non-<tt>DeepMergeable</tt> values:
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#
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# hash_1 = { a: 100, b: 200, c: { c1: 100 } }
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# hash_2 = { b: 250, c: { c1: 200 } }
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#
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# hash_1.deep_merge(hash_2) do |key, this_val, other_val|
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# this_val + other_val
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# end
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# # => { a: 100, b: 450, c: { c1: 300 } }
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#
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def deep_merge(other, &block)
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dup.deep_merge!(other, &block)
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end
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# Same as #deep_merge, but modifies +self+.
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def deep_merge!(other, &block)
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merge!(other) do |key, this_val, other_val|
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if this_val.is_a?(DeepMergeable) && this_val.deep_merge?(other_val)
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this_val.deep_merge(other_val, &block)
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elsif block_given?
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block.call(key, this_val, other_val)
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else
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other_val
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end
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end
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end
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# Returns true if +other+ can be deep merged into +self+. Classes may
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# override this method to restrict or expand the domain of deep mergeable
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# values. Defaults to checking that +other+ is of type +self.class+.
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def deep_merge?(other)
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other.is_a?(self.class)
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end
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end
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end
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