Add nice skylark wrappers to abstract changing based on compiler etc
Change-Id: I1210ee698e13cab273a9d68d7669f1b0e5c9b7f7
diff --git a/tools/build_rules/select.bzl b/tools/build_rules/select.bzl
new file mode 100644
index 0000000..18701ef
--- /dev/null
+++ b/tools/build_rules/select.bzl
@@ -0,0 +1,63 @@
+# This file contains replacements for select where the keys have more abstract
+# meanings so we can map multiple conditions to the same value easily and
+# quickly find issues where something new isn't handled.
+# It will also make adding ORs when it makes sense easy to do nicely.
+
+all_cpus = ['amd64', 'roborio']
+'''All of the CPUs we know about.'''
+
+'''A select wrapper for CPU architectures.
+
+Args:
+ values: A mapping from architecture names (as strings) to other things.
+ Currently amd64 and roborio are recognized.
+ 'else' is also allowed as a default.
+Returns a select which evaluates to the correct element of values.
+'''
+def cpu_select(values):
+ for cpu in all_cpus:
+ if cpu not in values:
+ if 'else' in values:
+ values[cpu] = values['else']
+ else:
+ fail('Need to handle %s CPUs!' % cpu, 'values')
+ for key in values:
+ if key not in all_cpus and key != 'else':
+ fail('Not sure what a %s CPU is!' % key, 'values')
+ return select({
+ '//tools:cpu_k8': values['amd64'],
+ '//tools:cpu_roborio': values['roborio'],
+ })
+
+'''A select wrapper for address space sizes.
+
+Args:
+ values: A mapping from address space sizes (as strings) to other things.
+Returns a select which evaluates to the correct element of values.
+'''
+def address_size_select(values):
+ if '32' not in values:
+ fail('Need to handle 32 bit addresses!', 'values')
+ if '64' not in values:
+ fail('Need to handle 64 bit addresses!', 'values')
+ return select({
+ '//tools:cpu_k8': values['64'],
+ '//tools:cpu_roborio': values['32'],
+ })
+
+'''A select wrapper for compilers.
+
+Args:
+ values: A mapping from compiler names (as strings) to other things.
+ Currently 'gcc' and 'clang' are recognized.
+Returns a select which evaluates to the correct element of values.
+'''
+def compiler_select(values):
+ if 'gcc' not in values:
+ fail('Need to handle gcc!', 'values')
+ if 'clang' not in values:
+ fail('Need to handle clang!', 'values')
+ return select({
+ '//tools:compiler_gcc': values['gcc'],
+ '//tools:compiler_clang': values['clang'],
+ })