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A StreamStack subclass that parses headers until an emtpy line is found.

This module can be used to parse "headers" from a ReadableStream until an empty line is found. "headers" is a somewhat broad term that has a lot of edge-cases, but this parser can be used to parse HTTP headers, MIME e-mail headers, CGI script headers, multipart headers, and I'm sure much more.

The parser by default only emits a single 'headers' event when the end of the headers have been reached. It can optionally emit a 'firstLine' event after the first line has been parsed (useful for HTTP, off by default). See below for the other parsing options available.


new Parser([readableStream] [, options]) -> parser

Creates a new Parser instance that will parse headers. If a readableStream is passed in (optional), then 'data' events from it will be used to parse the header. An optional options argument may also be provided. Recognized options are:

  • emitFirstLine - (Default false) - If set to true, then the first line that gets parsed by the Parser won't be treated like a header line, but instead will be given back to the user in a 'firstLine' event.

  • strictCRLF - (Default false) - If set to true, then ONLY CRLF values will be allowed for the line delimiter. If false, then both CRLF and lone LF will be valid delimiters.

  • strictSpaceAfterColon - (Default false) - If set to true, an error will be emitted if a header is found without a space after the delimiter colon. If false then a space after the colon will be optional.

  • allowFoldedHeaders - (Default false) - If set to true then folded headers will be allowed. Folded headers are headers lines that start with whitespace, and are intended to be concatenated with the previous header. If false, then the parse will throw an error if a folded header is encountered.

parser.parse(b) -> undefined

If no readableStream instance was passed into the Parser constructor, then you have to option to manually call parse(buffer) to do the parsing.

parser event 'headers' -> function(headers, leftover)

Emitted when the end of the headers has been parsed. headers is a Headers instance, which is a special Array subclass with other helper functions. leftover may be a Buffer with any leftover data the Parser received before finishing, it will be the beginning of anything after the headers, and should be fed into whatever is parsing the Stream next.

parser event 'error' -> function(err)

Emitted if a malformed header line is encountered. i.e. a header line without a valid delimiter. If this is emitted, then a 'headers' event will NOT be emitted.

new Headers() -> headers

The Headers class is an Array subclass that has some additional helper functions to use and mutate the headers easily.

headers.addHeader(key, value) -> undefined

Adds a new header to the end of the list of headers with the given key and value.

headers.toString([ options ]) -> undefined

The toString function of the Headers class can be used to turn a headers instance back into it's sendable form. The default options are for the most common use cases, but you may specify:

  • firstLine - (Default false) - If set to a String instance, then the given string will be used as the first line of the output string (useful for HTTP).

  • delimiter - (Default '\r\n') - The delimiter that should be used in between each header and to signify the end of the headers.

  • emptyLastLine - (Default true) - If true then the returned String will contain another "delimiter" at the end, to signify the end of the headers.