Upgrade mapfile parser

[mholthausen]

With this PR

• the DATA block of a mapfile is removed, because it is irrelevant for the style and the content could lead to misinterpretation of the whole document,
• a check of color values to hexadecimal format is added. Previously, values were converted that were already given as hex values,
• implements various minor code improvements,
• no more style symbolizers are created due to empty mapfile STYLE blocks,
• the MAXSCALEDENOM/MINSCALEDENOM value at the particular class will always be used, even if a different value is present at the layer,
• no visibility property set if OUTLINECOLOR is present
• sets haloColor and haloWidth from OUTLINECOLOR and OUTLINEWIDTH for LABEL
• replaces the name of SYMBOLS with the linked filename if SYMBOLS are defined within the Mapfile and not framed by a SYMBOLSET
• prevents counting single numbers of a lineObject as a block which led to a wrong amount of blocks related to END keys
• integrates support for geostyler-style version 4.0.1 and updates dependencies
• adds node version 14 to TRAVIS CI pipeline

I request a final review of the changes made here by this PR

[jansule]

Never mind. I just noticed the DRAFT flag

[mholthausen]

Thanks @jansule! Even though it is still DRAFT, any advice is greatly appreciated!

[geographika]

Sorry for gatecrashing this ticket, but it might be something of interest.
There are JSON schemas for all Mapfile elements at https://github.com/geographika/mappyfile/tree/master/mappyfile/schemas might be useful for validation.
This schema will (at some point) be proposed as an official schema via an RFC for MapServer.

[jansule]

Nice work @mholthausen! Just some minor nitpicks you might want to address.
I would also love to get some feedback from @b4l, @ger-benjamin or @faselm.

[b4l]

Sorry for gatecrashing this ticket, but it might be something of interest.
There are JSON schemas for all Mapfile elements at https://github.com/geographika/mappyfile/tree/master/mappyfile/schemas might be useful for validation.
This schema will (at some point) be proposed as an official schema via an RFC for MapServer.

Also might want to switch to a more advanced parsing step leveraging a proper grammar/schema than the current mediocre line based one.

[mholthausen]

Thanks for the reviews! When all uncertainties are solved, the changes can be merged.

[mholthausen]

Sorry for gatecrashing this ticket, but it might be something of interest.
There are JSON schemas for all Mapfile elements at https://github.com/geographika/mappyfile/tree/master/mappyfile/schemas might be useful for validation.
This schema will (at some point) be proposed as an official schema via an RFC for MapServer.

Also might want to switch to a more advanced parsing step leveraging a proper grammar/schema than the current mediocre line based one.

Sorry for gatecrashing this ticket, but it might be something of interest.
There are JSON schemas for all Mapfile elements at https://github.com/geographika/mappyfile/tree/master/mappyfile/schemas might be useful for validation.
This schema will (at some point) be proposed as an official schema via an RFC for MapServer.

Also might want to switch to a more advanced parsing step leveraging a proper grammar/schema than the current mediocre line based one.

That's a good consideration! A discussion should be continued on this in the Issues or GitHub Discussions. These changes exceed the requirements of this PR.

[marcjansen]

I am +1 on merging, and we should probably make dedicated issues out of:

• A future use of the JSON schemas mentioned in this comment
• a replacement for the current line based parser, as mentioned in this comment

[marcjansen]

Hey @mholthausen, @geographika & @b4l maybe you want to join the monthly meeting today? Than we can have a chat about this. Drop us an email at reports@geostyler.org, then you'll get invited

[jansule]

Very nice!