feat: add a simple toolchain mapper

Change-Id: I4dc426204148634590eebc12b10a42df02ee058c

Blueprints

@@ -102,6 +102,18 @@ bootstrap_go_package {
 }
 
 
+bootstrap_go_package {
+    name: "bob-toolchain-mapper",
+    srcs: [
+        "core/toolchain/mapper/mapper.go",
+    ],
+    testSrcs: [
+        "core/toolchain/mapper/mapper_test.go",
+    ],
+    pkgPath: "github.com/ARM-software/bob-build/core/toolchain/mapper",
+}
+
+
 bootstrap_go_package {
     name: "bob-backend",
     deps: [

core/toolchain/mapper/BUILD.bazel

@@ -0,0 +1,15 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "mapper",
+    srcs = ["mapper.go"],
+    importpath = "github.com/ARM-software/bob-build/core/toolchain/mapper",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "mapper_test",
+    srcs = ["mapper_test.go"],
+    embed = [":mapper"],
+    deps = ["@com_github_stretchr_testify//assert"],
+)

core/toolchain/mapper/mapper.go

@@ -0,0 +1,53 @@
+package mapper
+
+import (
+	"path/filepath"
+	"sync"
+)
+
+// Map of toolchain targets by module path
+type Mapper struct {
+	modules map[string][]string
+	lock    sync.Mutex
+}
+
+func New() *Mapper {
+	return &Mapper{
+		lock:    sync.Mutex{},
+		modules: map[string][]string{},
+	}
+}
+
+func (t *Mapper) Add(path string, name string) {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+
+	if current, ok := t.modules[path]; ok {
+		t.modules[path] = append(current, name)
+	} else {
+		t.modules[path] = []string{name}
+	}
+}
+
+// Returns the toolchain module name based on the path.
+// The behavior is as follows:
+// - For given path, if a toolchain config exists return the first registered toolchain.
+// - If no config exists for current path, walk the directories upwards looking for default.
+func (t *Mapper) Get(path string) string {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+
+	for p := path; p != "."; {
+		if names, ok := t.modules[p]; ok {
+			return names[0]
+		}
+		p = filepath.Dir(p)
+	}
+
+	// Check for root
+	if names, ok := t.modules["."]; ok {
+		return names[0]
+	}
+
+	return ""
+}

core/toolchain/mapper/mapper_test.go

@@ -0,0 +1,40 @@
+package mapper
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEmptyAdd(t *testing.T) {
+	tc := New()
+	tc.Add("foo/bar/baz", "tc1")
+	tc.Add("foo/bar", "tc2")
+}
+
+func Test_UnregisteredDefault(t *testing.T) {
+	tc := New()
+	assert.Equal(t, "", tc.Get("."))
+}
+
+func TestCommon(t *testing.T) {
+	tc := New()
+	tc.Add("foo/bar/baz", "baz")
+	tc.Add("foo/bar", "bar1")
+	tc.Add("foo/bar", "bar2")
+	tc.Add(".", "root")
+
+	t.Run("DirectHit", func(t *testing.T) {
+		assert.Equal(t, "root", tc.Get("."))
+	})
+
+	t.Run("RootDefault", func(t *testing.T) {
+		assert.Equal(t, "root", tc.Get("does/not/exist"))
+	})
+
+	t.Run("OrderOfRegister", func(t *testing.T) {
+		assert.Equal(t, "bar1", tc.Get("foo/bar"))
+		assert.Equal(t, "bar1", tc.Get("foo/bar/child"))
+	})
+
+}