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alienscience / imapsrv

An IMAP server written in Go
BSD 3-Clause "New" or "Revised" License
48 stars 9 forks source link

Convert lexer and parser to LL(k) #20

Closed alienscience closed 9 years ago

alienscience commented 9 years ago

The FETCH comand (#2) has optional tokens. One way to support optional tokens is to have a puchBack() function in the parser that retries a token.

At the moment, a pushBack() parsing function is not supported by the lexer because it uses flags to control the behaviour of the next() function. The flag may change when a token is retried.

Both the parser and lexer need to support a pushBack().

Also, the current method of passing flags to lexer.next() is a hack to support data dependence e.g a bare string is a tag or an astring depending on the position. The flag should be replaced by having different entry points e.g:

lexer.tag()
lexer.astring()
lexer.sequenceNumber()