node_modules/prismjs/tests/languages/parser/expression_feature.test

((3-(9-2))*4)
^eval(4+2)

<div class="foo-^eval(4+2)">

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[
	["expression", [
		["punctuation", "("],
		["punctuation", "("],
		["number", "3"],
		["operator", "-"],
		["punctuation", "("],
		["number", "9"],
		["operator", "-"],
		["number", "2"],
		["punctuation", ")"],
		["punctuation", ")"],
		["operator", "*"],
		["number", "4"],
		["punctuation", ")"]
	]],
	["keyword", "^eval"],

	["expression", [
		["punctuation", "("],
		["number", "4"],
		["operator", "+"],
		["number", "2"],
		["punctuation", ")"]
	]],

	["tag", [
		["tag", [
			["punctuation", "<"],
			"div"
		]],
		["attr-name", ["class"]],
		["attr-value", [
			["punctuation", "="],
			["punctuation", "\""],
			"foo-",
			["keyword", "^eval"],
			["expression", [
				["punctuation", "("],
				["number", "4"], ["operator", "+"], ["number", "2"],
				["punctuation", ")"]
			]],
			["punctuation", "\""]
		]],
		["punctuation", ">"]
	]]
]

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Checks for expressions, up to 3 levels of depth.