[augeas-devel] Inexpressible Language

[Yclept Nemo]

> Could you provide an example of a string that does not parse with the
lens I provided, and the tree you expect the lens should produce from it?

Right, looks like I forget to reference the input case. Anyway, here it is
[2]. The tree structure is self-explanatory - identical to the previous
trees - the schema only changes what is considered a comment.

> That said, I personally prefer to map comments in the tree, if we're
going to parse them anyway.

Personally I prefer comments to be excluded, however the idea is to only
modify the comment function (del -> store) to toggle this behaviour.
Unfortunately actually handling comments is more difficult, below I have a
rough draft [1] (no comment function, no comment storing) but it produces
an error I don't understand:

    [(first two lenses) and (third lens) in entry]:exception: overlapping
lenses in tree union.put
    Example matched by both:  {  }

What does this mean? Literal braces ("{  }"), or two literal spaces ("  "),
or just a null string ?

Regards,


[1] let option              = key /[A-Z_]+/
    let value               = Sep.colon . Sep.opt_space . store /[^]
\t\n:]+/ . Sep.opt_space
    let values              = counter "value" . [ seq "value" . value ] +
    let setting             = Util.del_str "[" . option . values .
Util.del_str "]"
    let entry               =
        let not_setting     = Rx.space_in - ( lens_ctype setting . /.*/ )

            (* doesn't start with a space   - starts with setting
- doesn't match the empty string *)
        in  [ setting . del /.*/ "" . del /\n/ "\n" ] |

            (* doesn't start with a space   - doesn't start with setting
- doesn't match the empty string *)
            [ del not_setting "s" . del /[ \t]*/ "" . del /\n/ "\n" ] |

            (* starts with a space
- doesn't match the empty string *)
            [ del /[ \t]/ " " . del /.*/ "" . del /\n/ "\n" ] |

            (*
- matches the empty string *)
            [ del /\n/ "\n" ]
    let lns                 = entry *


[2] "
Change this to turn sound off.

[SOUND:YES]
[FONT:curses_640x300.png]
[RESIZABLE:YES]You may disable window resizing if you wish.

[PRINT_MODE:2D]
    Mode examples:
[SINGLE_BUFFER:NO]
[EMBARK_RECTANGLE:4:4]

Change these numbers to set the default weights for traffic designations.
If you make the last numbers too large, pathfinding might lag.
The format is (PATH_COST:<high>:<normal>:<low>:<restricted>).
[PATH_COST:1:2:5:25][A_COMMENT:4:4]

[A_COMMENT:  ]

    [ANOTHER_COMMENT:10:1:5:50]
"
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