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'use strict';
// Expose to the world
module.exports.parseHeader = parseHeader;
module.exports.generateHeader = generateHeader;
module.exports.formatCharset = formatCharset;
module.exports.foldLine = foldLine;
/**
* Parses a header string into an object of key-value pairs
*
* @param {String} str Header string
* @return {Object} An object of key-value pairs
*/
function parseHeader(str) {
var lines = (str || '').split('\n'),
headers = {};
lines.forEach(function(line) {
var parts = line.trim().split(':'),
key = (parts.shift() || '').trim().toLowerCase(),
value = parts.join(':').trim();
if (!key) {
return;
}
headers[key] = value;
});
return headers;
}
/**
* Convert first letters after - to uppercase, other lowercase
*
* @param {String} str String to be updated
* @return {String} A string with uppercase words
*/
function upperCaseWords(str) {
return (str || '').toLowerCase().trim().replace(/^(MIME|POT?(?=\-)|[a-z])|\-[a-z]/gi, function(str) {
return str.toUpperCase();
});
}
/**
* Joins a header object of key value pairs into a header string
*
* @param {Object} header Object of key value pairs
* @return {String} Header string
*/
function generateHeader(header) {
var lines = [];
Object.keys(header || {}).forEach(function(key) {
if (key) {
lines.push(upperCaseWords(key) + ': ' + (header[key] || '').trim());
}
});
return lines.join('\n') + (lines.length ? '\n' : '');
}
/**
* Normalizes charset name. Converts utf8 to utf-8, WIN1257 to windows-1257 etc.
*
* @param {String} charset Charset name
* @return {String} Normalized charset name
*/
function formatCharset(charset, defaultCharset) {
return (charset || 'iso-8859-1').toString().toLowerCase().
replace(/^utf[\-_]?(\d+)$/, 'utf-$1').
replace(/^win(?:dows)?[\-_]?(\d+)$/, 'windows-$1').
replace(/^latin[\-_]?(\d+)$/, 'iso-8859-$1').
replace(/^(us[\-_]?)?ascii$/, 'ascii').
replace(/^charset$/, defaultCharset || 'iso-8859-1').
trim();
}
/**
* Folds long lines according to PO format
*
* @param {String} str PO formatted string to be folded
* @param {Number} [maxLen=76] Maximum allowed length for folded lines
* @return {Array} An array of lines
*/
function foldLine(str, maxLen) {
maxLen = maxLen || 76;
var lines = [],
curLine = '',
pos = 0,
len = str.length,
match;
while (pos < len) {
curLine = str.substr(pos, maxLen);
// ensure that the line never ends with a partial escaping
// make longer lines if needed
while (curLine.substr(-1) === '\\' && pos + curLine.length < len) {
curLine += str.charAt(pos + curLine.length);
}
// ensure that if possible, line breaks are done at reasonable places
if ((match = curLine.match(/\\n/))) {
curLine = curLine.substr(0, match.index + 2);
} else if (pos + curLine.length < len) {
if ((match = curLine.match(/(\s+)[^\s]*$/)) && match.index > 0) {
curLine = curLine.substr(0, match.index + match[1].length);
} else if ((match = curLine.match(/([\x21-\x40\x5b-\x60\x7b-\x7e]+)[^\x21-\x40\x5b-\x60\x7b-\x7e]*$/)) && match.index > 0) {
curLine = curLine.substr(0, match.index + match[1].length);
}
}
lines.push(curLine);
pos += curLine.length;
}
return lines;
}
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