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Diffstat (limited to 'couchjs/js/mimeparse.js')
| -rw-r--r-- | couchjs/js/mimeparse.js | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/couchjs/js/mimeparse.js b/couchjs/js/mimeparse.js new file mode 100644 index 00000000..3642a194 --- /dev/null +++ b/couchjs/js/mimeparse.js @@ -0,0 +1,158 @@ +// mimeparse.js +// +// This module provides basic functions for handling mime-types. It can +// handle matching mime-types against a list of media-ranges. See section +// 14.1 of the HTTP specification [RFC 2616] for a complete explanation. +// +// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1 +// +// A port to JavaScript of Joe Gregorio's MIME-Type Parser: +// +// http://code.google.com/p/mimeparse/ +// +// Ported by J. Chris Anderson <jchris@apache.org>, targeting the Spidermonkey runtime. +// +// To run the tests, open mimeparse-js-test.html in a browser. +// Ported from version 0.1.2 +// Comments are mostly excerpted from the original. + +var Mimeparse = (function() { + // private helpers + function strip(string) { + return string.replace(/^\s+/, '').replace(/\s+$/, '') + }; + + function parseRanges(ranges) { + var parsedRanges = [], rangeParts = ranges.split(","); + for (var i=0; i < rangeParts.length; i++) { + parsedRanges.push(publicMethods.parseMediaRange(rangeParts[i])) + }; + return parsedRanges; + }; + + var publicMethods = { + // Carves up a mime-type and returns an Array of the + // [type, subtype, params] where "params" is a Hash of all + // the parameters for the media range. + // + // For example, the media range "application/xhtml;q=0.5" would + // get parsed into: + // + // ["application", "xhtml", { "q" : "0.5" }] + parseMimeType : function(mimeType) { + var fullType, typeParts, params = {}, parts = mimeType.split(';'); + for (var i=0; i < parts.length; i++) { + var p = parts[i].split('='); + if (p.length == 2) { + params[strip(p[0])] = strip(p[1]); + } + }; + fullType = parts[0].replace(/^\s+/, '').replace(/\s+$/, ''); + if (fullType == '*') fullType = '*/*'; + typeParts = fullType.split('/'); + return [typeParts[0], typeParts[1], params]; + }, + + // Carves up a media range and returns an Array of the + // [type, subtype, params] where "params" is a Object with + // all the parameters for the media range. + // + // For example, the media range "application/*;q=0.5" would + // get parsed into: + // + // ["application", "*", { "q" : "0.5" }] + // + // In addition this function also guarantees that there + // is a value for "q" in the params dictionary, filling it + // in with a proper default if necessary. + parseMediaRange : function(range) { + var q, parsedType = this.parseMimeType(range); + if (!parsedType[2]['q']) { + parsedType[2]['q'] = '1'; + } else { + q = parseFloat(parsedType[2]['q']); + if (isNaN(q)) { + parsedType[2]['q'] = '1'; + } else if (q > 1 || q < 0) { + parsedType[2]['q'] = '1'; + } + } + return parsedType; + }, + + // Find the best match for a given mime-type against + // a list of media_ranges that have already been + // parsed by parseMediaRange(). Returns an array of + // the fitness value and the value of the 'q' quality + // parameter of the best match, or (-1, 0) if no match + // was found. Just as for qualityParsed(), 'parsed_ranges' + // must be a list of parsed media ranges. + fitnessAndQualityParsed : function(mimeType, parsedRanges) { + var bestFitness = -1, bestFitQ = 0, target = this.parseMediaRange(mimeType); + var targetType = target[0], targetSubtype = target[1], targetParams = target[2]; + + for (var i=0; i < parsedRanges.length; i++) { + var parsed = parsedRanges[i]; + var type = parsed[0], subtype = parsed[1], params = parsed[2]; + if ((type == targetType || type == "*" || targetType == "*") && + (subtype == targetSubtype || subtype == "*" || targetSubtype == "*")) { + var matchCount = 0; + for (param in targetParams) { + if (param != 'q' && params[param] && params[param] == targetParams[param]) { + matchCount += 1; + } + } + + var fitness = (type == targetType) ? 100 : 0; + fitness += (subtype == targetSubtype) ? 10 : 0; + fitness += matchCount; + + if (fitness > bestFitness) { + bestFitness = fitness; + bestFitQ = params["q"]; + } + } + }; + return [bestFitness, parseFloat(bestFitQ)]; + }, + + // Find the best match for a given mime-type against + // a list of media_ranges that have already been + // parsed by parseMediaRange(). Returns the + // 'q' quality parameter of the best match, 0 if no + // match was found. This function bahaves the same as quality() + // except that 'parsedRanges' must be a list of + // parsed media ranges. + qualityParsed : function(mimeType, parsedRanges) { + return this.fitnessAndQualityParsed(mimeType, parsedRanges)[1]; + }, + + // Returns the quality 'q' of a mime-type when compared + // against the media-ranges in ranges. For example: + // + // >>> Mimeparse.quality('text/html','text/*;q=0.3, text/html;q=0.7, text/html;level=1, text/html;level=2;q=0.4, */*;q=0.5') + // 0.7 + quality : function(mimeType, ranges) { + return this.qualityParsed(mimeType, parseRanges(ranges)); + }, + + // Takes a list of supported mime-types and finds the best + // match for all the media-ranges listed in header. The value of + // header must be a string that conforms to the format of the + // HTTP Accept: header. The value of 'supported' is a list of + // mime-types. + // + // >>> bestMatch(['application/xbel+xml', 'text/xml'], 'text/*;q=0.5,*/*; q=0.1') + // 'text/xml' + bestMatch : function(supported, header) { + var parsedHeader = parseRanges(header); + var weighted = []; + for (var i=0; i < supported.length; i++) { + weighted.push([publicMethods.fitnessAndQualityParsed(supported[i], parsedHeader), i, supported[i]]) + }; + weighted.sort(); + return weighted[weighted.length-1][0][1] ? weighted[weighted.length-1][2] : ''; + } + } + return publicMethods; +})(); |