Space character and related stuff

Blocks of literal

Most of times, the text inside blocks of literal should be kept in one piece. A blatant example is a numeric value and its unit.

Compact several spaces into one for the same reason as above.Trim leading and trailing spaces. Otherwise they offer a suspicious mean to override text layout.Replace spaces by non-break spaces.

With the low line character _ figuring the no-break space we’d like to obtain such transformation:

` 20   m  ` -> `20_m`

This means a long block of literal with several spaces (transformed into no-break spaces) could become very cumbersome and mess the layout. So we need a hint to allow line breaks at some places. This can be done by splitting the big block of literal into several small ones, which are not separated by spaces.

With the vertical bar character | figuring the zero-width space we have such transformation:

   `Y.O.U.``A.R.E.``B.E.A.U.T.I.F.U.L` 
-> `Y.O.U.|A.R.E.|B.E.A.U.T.I.F.U.L`

See more about the zero-width space here. A quick test shows that FOP supports it.

Implementation will be done at tree-mangling level. A whitespace between two consecutive blocks of literal will be replaced by a special node meaning that a break is allowed here. The special node will be replaced by a no-width space at rendering time.

Apostrophe

This technique could be useful to keep apostrophe character stuck to a word when in last position. By now, Novelang does not take care of the whitespace after or before the apostrophe.

he's here     -> he’s here
houses' roofs -> houses’roofs
during '60    -> during’60

This is because whitespaces are used as separators, but don’t cary “real” information (except in a few cases, like indentation for embedded lists). Before discarding WHITESPACE nodes, the ones immediately preceding or following an apostrophe could become an EXPLICIT_WHITESPACE to be rendered as, yes, a space character.