/*
filename syntax: addr_filename[_colon:separated:tags].ext[.ext]
addr: sequence of one or more a-p. String.
filename: anything except underscore or period. String.
tags: colon-separated list of tags. Array of Strings.
ext: period, then a-z0-9. Multiple allowed. String, including periods.
*/
line = addr:addr name:name tags:tags? ext:ext {return {
	addr: addr.value,
    name: name.value,
    tags: tags?.tags,
    ext: ext.value
}}
ext = value:$(("." [a-z0-9]+))+ {return {type: "extension", value}}

//tags are separated by colon to allow dashes in values for e.g. dates.
tags = _ tags:tag|..,":"| {return {type: "tags", tags}}
tag = $[^:.]+
addr = value:$[a-p]+ {return {type: "address", value}}

//a limitation: filenames may not contain periods.
//Otherwise it gets more complicated to handle extensions.
name = _ value:$[^_.]i+ {return {type: "name", value}}
_ = "_"