33 lines
791 B
JavaScript
33 lines
791 B
JavaScript
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'use strict'
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var convert = require('./convert')
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module.exports = is
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is.convert = convert
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// Assert if `test` passes for `node`.
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// When a `parent` node is known the `index` of node should also be given.
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function is(node, test, index, parent, context) {
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var check = convert(test)
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if (
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index != null &&
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(typeof index !== 'number' || index < 0 || index === Infinity)
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) {
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throw new Error('Expected positive finite index')
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}
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if (parent != null && (!is(parent) || !parent.children)) {
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throw new Error('Expected parent node')
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}
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if ((parent == null) !== (index == null)) {
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throw new Error('Expected both parent and index')
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}
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return node && node.type && typeof node.type === 'string'
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? Boolean(check.call(context, node, index, parent))
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: false
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}
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