Solving the conflict

Examples > E-mail address > Solving the conflict

To solve the conflict, word must be factored out.

For phrase this is easy. The rule will be redefined as:

phrase = word*

and at all positions, where phrase is used in the grammar, phrase is replaced by:

word phrase

The mailbox production just is the only occurrence of phrase; so it becomes to:

mailbox ::= addr_spez | word phrase route_addr

Analogously is dealt with local_part. The production is redefined to

local_part ::= ("." word)*

and all places, where local_part exists in the grammar are replaced by:

word local_part

So addr_spez becomes to:

addr_spez ::= word local_part "@" domain

Finally word is extracted from addr_spez too, whereby this production regains it's old form (but with a new defined local_part):

addr_spez ::= local_part "@" domain

Here you must pay attention, because addr_spez is also used in route_addr.

route_addr ::= "<" (route)? word addr_spez ">"

And finally

mailbox ::= word addr_spez | word phrase route_addr

Now the factoring out of word can be completed:

mailbox ::= word ( addr_spez | phrase route_addr )

If you compile this rule now, there is no conflict any more.

The corrected project is:

\TextTransformer\Examples\Mailbox\mailbox2.ttp

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