in benchmark/old.js [626:654]
function join(left, right) {
var leftSource,
rightSource,
leftCharCode,
rightCharCode;
leftSource = toSourceNodeWhenNeeded(left).toString();
if (leftSource.length === 0) {
return [right];
}
rightSource = toSourceNodeWhenNeeded(right).toString();
if (rightSource.length === 0) {
return [left];
}
leftCharCode = leftSource.charCodeAt(leftSource.length - 1);
rightCharCode = rightSource.charCodeAt(0);
if ((leftCharCode === 0x2B /* + */ || leftCharCode === 0x2D /* - */) && leftCharCode === rightCharCode ||
esutils.code.isIdentifierPart(leftCharCode) && esutils.code.isIdentifierPart(rightCharCode) ||
leftCharCode === 0x2F /* / */ && rightCharCode === 0x69 /* i */) { // infix word operators all start with `i`
return [left, noEmptySpace(), right];
} else if (esutils.code.isWhiteSpace(leftCharCode) || esutils.code.isLineTerminator(leftCharCode) ||
esutils.code.isWhiteSpace(rightCharCode) || esutils.code.isLineTerminator(rightCharCode)) {
return [left, right];
}
return [left, space, right];
}