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/**
* @fileoverview Rule to forbid or enforce dangling commas.
* @author Ian Christian Myers
* @copyright 2015 Mathias Schreck
* @copyright 2013 Ian Christian Myers
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function (context) {
var allowDangle = context.options[0];
var forbidDangle = allowDangle !== "always-multiline" && allowDangle !== "always";
var UNEXPECTED_MESSAGE = "Unexpected trailing comma.";
var MISSING_MESSAGE = "Missing trailing comma.";
/**
* Checks the given node for trailing comma and reports violations.
* @param {ASTNode} node The node of an ObjectExpression or ArrayExpression
* @returns {void}
*/
function checkForTrailingComma(node) {
var items = node.properties || node.elements,
length = items.length,
nodeIsMultiLine = node.loc.start.line !== node.loc.end.line,
lastItem,
penultimateToken,
hasDanglingComma;
if (length) {
lastItem = items[length - 1];
if (lastItem) {
penultimateToken = context.getLastToken(node, 1);
hasDanglingComma = penultimateToken.value === ",";
if (forbidDangle && hasDanglingComma) {
context.report(lastItem, penultimateToken.loc.start, UNEXPECTED_MESSAGE);
} else if (allowDangle === "always-multiline") {
if (hasDanglingComma && !nodeIsMultiLine) {
context.report(lastItem, penultimateToken.loc.start, UNEXPECTED_MESSAGE);
} else if (!hasDanglingComma && nodeIsMultiLine) {
context.report(lastItem, penultimateToken.loc.end, MISSING_MESSAGE);
}
} else if (allowDangle === "always" && !hasDanglingComma) {
context.report(lastItem, lastItem.loc.end, MISSING_MESSAGE);
}
}
}
}
return {
"ObjectExpression": checkForTrailingComma,
"ArrayExpression": checkForTrailingComma
};
};
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