// Can unquote attribute detection
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// Adopted implementation of Mathias Bynens
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// https://github.com/mathiasbynens/mothereff.in/blob/master/unquoted-attributes/eff.js
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var escapesRx = /\\([0-9A-Fa-f]{1,6})(\r\n|[ \t\n\f\r])?|\\./g;
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var blockUnquoteRx = /^(-?\d|--)|[\u0000-\u002c\u002e\u002f\u003A-\u0040\u005B-\u005E\u0060\u007B-\u009f]/;
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function canUnquote(value) {
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if (value === '' || value === '-') {
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return;
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}
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// Escapes are valid, so replace them with a valid non-empty string
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value = value.replace(escapesRx, 'a');
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return !blockUnquoteRx.test(value);
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}
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module.exports = function(node) {
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var attrValue = node.value;
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if (!attrValue || attrValue.type !== 'String') {
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return;
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}
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var unquotedValue = attrValue.value.replace(/^(.)(.*)\1$/, '$2');
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if (canUnquote(unquotedValue)) {
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node.value = {
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type: 'Identifier',
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loc: attrValue.loc,
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name: unquotedValue
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};
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}
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};
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