Add self-contained gometalinter build tooling.

tools/vendor/github.com/mvdan/interfacer/cache.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2015, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package interfacer
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+type pkgTypes struct {
+	ifaces    map[string]string
+	funcSigns map[string]bool
+}
+
+func (p *pkgTypes) getTypes(pkg *types.Package) {
+	p.ifaces = make(map[string]string)
+	p.funcSigns = make(map[string]bool)
+	done := make(map[*types.Package]bool)
+	addTypes := func(pkg *types.Package, top bool) {
+		if done[pkg] {
+			return
+		}
+		done[pkg] = true
+		ifs, funs := fromScope(pkg.Scope())
+		fullName := func(name string) string {
+			if !top {
+				return pkg.Path() + "." + name
+			}
+			return name
+		}
+		for iftype, name := range ifs {
+			// only suggest exported interfaces
+			if ast.IsExported(name) {
+				p.ifaces[iftype] = fullName(name)
+			}
+		}
+		for ftype := range funs {
+			// ignore non-exported func signatures too
+			p.funcSigns[ftype] = true
+		}
+	}
+	for _, imp := range pkg.Imports() {
+		addTypes(imp, false)
+		for _, imp2 := range imp.Imports() {
+			addTypes(imp2, false)
+		}
+	}
+	addTypes(pkg, true)
+}