Introduce support for specifying variables from X resources. (#2286)

This patch introduces a new 'set_from_resource' config directive which
allows defining a variable by retrieving its value from the X resource
database. This avoids having to configure a color scheme in multiple
files. The directive takes an additional fallback value which is used
in case the resource cannot be found or during config validation where
no X connection is available.

Furthermore, this patch includes the following changes:
- If the same variable is defined twice, we now properly overwrite the
  value of the assignment rather than inserting two variable definitions
  with the same key.
- We now depend on xcb-util-xrm to query the resource.
- Increase the buffer size for variable / resource assignments.

fixes #2130

1 files changed, 23 insertions, 22 deletions

diff --git a/DEPENDS b/DEPENDS
index fad11da5..227aaec3 100644
--- a/DEPENDS
+++ b/DEPENDS
@@ -4,28 +4,29 @@
    "min" means minimum required version
    "lkgv" means last known good version
 
-┌──────────────┬────────┬────────┬────────────────────────────────────────┐
-│ dependency   │ min.   │ lkgv   │ URL                                    │
-├──────────────┼────────┼────────┼────────────────────────────────────────┤
-│ pkg-config   │ 0.25   │ 0.28   │ http://pkgconfig.freedesktop.org/      │
-│ libxcb       │ 1.1.93 │ 1.11   │ http://xcb.freedesktop.org/dist/       │
-│ xcb-util     │ 0.3.3  │ 0.4.1  │ http://xcb.freedesktop.org/dist/       │
-│ xkbcommon    │ 0.4.0  │ 0.5.0  │ http://xkbcommon.org/                  │
-│ xkbcommon-x11│ 0.4.0  │ 0.5.0  │ http://xkbcommon.org/                  │
-│ util-cursor³⁴│ 0.0.99 │ 0.1.2  │ http://xcb.freedesktop.org/dist/       │
-│ util-wm⁴     │ 0.3.8  │ 0.3.8  │ http://xcb.freedesktop.org/dist/       │
-│ util-keysyms⁴│ 0.3.8  │ 0.4.0  │ http://xcb.freedesktop.org/dist/       │
-│ libev        │ 4.0    │ 4.19   │ http://libev.schmorp.de/               │
-│ yajl         │ 2.0.1  │ 2.1.0  │ http://lloyd.github.com/yajl/          │
-│ asciidoc     │ 8.3.0  │ 8.6.8  │ http://www.methods.co.nz/asciidoc/     │
-│ xmlto        │ 0.0.23 │ 0.0.23 │ http://www.methods.co.nz/asciidoc/     │
-│ Pod::Simple² │ 3.22   │ 3.22   │ http://search.cpan.org/~dwheeler/Pod-Simple-3.23/
-│ docbook-xml  │ 4.5    │ 4.5    │ http://www.methods.co.nz/asciidoc/     │
-│ PCRE         │ 8.12   │ 8.35   │ http://www.pcre.org/                   │
-│ libsn¹       │ 0.10   │ 0.12   │ http://freedesktop.org/wiki/Software/startup-notification
-│ pango        │ 1.30.0 | 1.36.8 │ http://www.pango.org/                  │
-│ cairo        │ 1.14.4 │ 1.14.4 │ http://cairographics.org/              │
-└──────────────┴────────┴────────┴────────────────────────────────────────┘
+┌──────────────┬────────┬────────┬───────────────────────────────────────────────────────────┐
+│ dependency   │ min.   │ lkgv   │ URL                                                       │
+├──────────────┼────────┼────────┼───────────────────────────────────────────────────────────┤
+│ pkg-config   │ 0.25   │ 0.28   │ http://pkgconfig.freedesktop.org/                         │
+│ libxcb       │ 1.1.93 │ 1.11   │ http://xcb.freedesktop.org/dist/                          │
+│ xcb-util     │ 0.3.3  │ 0.4.1  │ http://xcb.freedesktop.org/dist/                          │
+│ xkbcommon    │ 0.4.0  │ 0.5.0  │ http://xkbcommon.org/                                     │
+│ xkbcommon-x11│ 0.4.0  │ 0.5.0  │ http://xkbcommon.org/                                     │
+│ util-cursor³⁴│ 0.0.99 │ 0.1.2  │ http://xcb.freedesktop.org/dist/                          │
+│ util-wm⁴     │ 0.3.8  │ 0.3.8  │ http://xcb.freedesktop.org/dist/                          │
+│ util-keysyms⁴│ 0.3.8  │ 0.4.0  │ http://xcb.freedesktop.org/dist/                          │
+│ util-xrm⁴    │ 1.0.0  │ 1.0.0  │ https://github.com/Airblader/xcb-util-xrm                 │
+│ libev        │ 4.0    │ 4.19   │ http://libev.schmorp.de/                                  │
+│ yajl         │ 2.0.1  │ 2.1.0  │ http://lloyd.github.com/yajl/                             │
+│ asciidoc     │ 8.3.0  │ 8.6.8  │ http://www.methods.co.nz/asciidoc/                        │
+│ xmlto        │ 0.0.23 │ 0.0.23 │ http://www.methods.co.nz/asciidoc/                        │
+│ Pod::Simple² │ 3.22   │ 3.22   │ http://search.cpan.org/~dwheeler/Pod-Simple-3.23/         │
+│ docbook-xml  │ 4.5    │ 4.5    │ http://www.methods.co.nz/asciidoc/                        │
+│ PCRE         │ 8.12   │ 8.35   │ http://www.pcre.org/                                      │
+│ libsn¹       │ 0.10   │ 0.12   │ http://freedesktop.org/wiki/Software/startup-notification │
+│ pango        │ 1.30.0 | 1.36.8 │ http://www.pango.org/                                     │
+│ cairo        │ 1.14.4 │ 1.14.4 │ http://cairographics.org/                                 │
+└──────────────┴────────┴────────┴───────────────────────────────────────────────────────────┘
  ¹ libsn = libstartup-notification
  ² Pod::Simple is a Perl module required for converting the testsuite
    documentation to HTML. See http://michael.stapelberg.de/cpan/#Pod::Simple