Encoding: encoding

All character encoding schemes supported by the HTML standard, defined as a bidirectional map between characters and binary sequences. Utf8 is strongly encouraged for new content (including all encoding purposes), but the others are retained for compatibility with existing pages.

Note that none of these are complete functions, to one degree or another, and that no guarantee is made that the mapping round-trips.

HTML: confidence

How likely the specified encoding is to be the actual stream encoding.

The spec names a third confidence level irrelevant, to be used when the stream doesn't depend on any particular encoding scheme (i.e. it is composed directly of Chars rather than parsed from a binary stream). This has not been included in the sum type, as it makes little sense to have that as a parameter of the decoding stage. Use Maybe DecoderState to represent it instead.

HTML: change the encoding

The data required to determine if a new encoding would produce an identical output to what the current one has already done, and to restart the parsing with the new one if the two are incompatible. Values may be easily initialized via emptyReparseData.

The collection of data which would indicate nothing has yet been parsed.

HTML: encoding sniffing algorithm

Given a stream and related metadata, try to determine what encoding may have been used to write it.

Will resolve and/or wait for the number of bytes requested by prescanDepth to be available in the stream (or, if it comes sooner, the end of the stream), if they have not yet been produced.

Various datapoints which may indicate a document's binary encoding, to be fed into the sniff algorithm. Values may be easily instantiated as updates to emptySnifferEnvironment.

A neutral set of parameters to pass to the sniff algorithm: no accessory data, and a prescanDepth limit of 1024 bytes.

Guess what encoding may be in use by the binary stream, and generate a collection of data based on that which results in the behaviour described by the decoding algorithm at the start of the stream.

The encoding scheme currently in use by the parser, along with how likely that scheme actually represents the binary stream.

Extract the underlying encoding scheme from the wrapping data.

HTML: algorithm for extracting a character encoding from a meta element

Find the first occurrence of an ASCII-encoded string charset in the stream, and try to parse its attribute-style value into an Encoding.

Returns Nothing if the stream does not contain charset followed by =, or if the value can not be successfully parsed as an encoding label.