36 lines
785 B
JavaScript
36 lines
785 B
JavaScript
'use strict'
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class Circular {
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constructor () {
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this.stack = new Map()
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}
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add (descriptor) {
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if (this.stack.has(descriptor)) throw new Error('Already in stack')
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if (descriptor.isItem !== true && descriptor.isMapEntry !== true && descriptor.isProperty !== true) {
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this.stack.set(descriptor, this.stack.size + 1)
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}
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return this
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}
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delete (descriptor) {
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if (this.stack.has(descriptor)) {
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if (this.stack.get(descriptor) !== this.stack.size) throw new Error('Not on top of stack')
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this.stack.delete(descriptor)
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}
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return this
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}
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has (descriptor) {
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return this.stack.has(descriptor)
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}
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get (descriptor) {
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return this.stack.has(descriptor)
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? this.stack.get(descriptor)
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: 0
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}
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}
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module.exports = Circular
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