54 lines
1.8 KiB
Crystal
54 lines
1.8 KiB
Crystal
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require "./abstract_expression"
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require "./label"
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require "./wrapper"
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module Spectator
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# Represents a block from a test.
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# This is typically captured by an `expect` macro.
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# It consists of a label and parameterless block.
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# The label should be a string recognizable by the user,
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# or nil if one isn't available.
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class Block(T) < AbstractExpression
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# Cached value returned from the block.
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# Is nil if the block hasn't been called.
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@wrapper : Wrapper(T)?
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# Creates the block expression from a proc.
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# The *proc* will be called to evaluate the value of the expression.
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# The *label* is usually the Crystal code for the *proc*.
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# It can be nil if it isn't available.
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def initialize(@block : -> T, label : Label)
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super(label)
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end
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# Creates the block expression by capturing a block as a proc.
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# The block will be called to evaluate the value of the expression.
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# The *label* is usually the Crystal code for the *block*.
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# It can be nil if it isn't available.
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def initialize(label : Label, &@block : -> T)
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super(label)
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end
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# Retrieves the value of the block expression.
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# This will be the return value of the block.
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# The block is lazily evaluated and the value retrieved only once.
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# Afterwards, the value is cached and returned by successive calls to this method.
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def value
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if (wrapper = @wrapper)
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wrapper.value
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else
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call.tap do |value|
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@wrapper = Wrapper.new(value)
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end
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end
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end
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# Evaluates the block and returns the value from it.
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# This method _does not_ cache the resulting value like `#value` does.
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# Successive calls to this method may return different values.
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def call : T
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@block.call
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end
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end
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end
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