implements: stub in the initial support for functions pulled from C

These types will be used to track what C functions are expected to be
implemented.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

contrib/implements/internal/implements/cfunctions.go

@@ -0,0 +1,32 @@
+package implements
+
+import (
+	"fmt"
+	"strings"
+)
+
+// CFunction represents a function in C code.
+type CFunction struct {
+	Name string `xml:"name,attr"`
+	Attr string `xml:"attributes,attr"`
+}
+
+// isDeprecated will return true if the C function is marked deprecated
+// via attributes.
+func (cf CFunction) isDeprecated() bool {
+	return strings.Contains(cf.Attr, "deprecated")
+}
+
+// CFunctions is a sortable slice of CFunction.
+type CFunctions []CFunction
+
+func (cfs CFunctions) Len() int           { return len(cfs) }
+func (cfs CFunctions) Swap(i, j int)      { cfs[i], cfs[j] = cfs[j], cfs[i] }
+func (cfs CFunctions) Less(i, j int) bool { return cfs[i].Name < cfs[j].Name }
+
+func (cfs CFunctions) ensure() (CFunctions, error) {
+	if len(cfs) < 1 {
+		return nil, fmt.Errorf("found %d c functions", len(cfs))
+	}
+	return cfs, nil
+}