Replace stringly-typed API levels.

Handling of API levels within Soong is currently fairly difficult
since it isn't always clear based on context what kind of API level a
given string represents, how much canonicalizing and error checking
the code receiving the string are expected to do, or how those errors
should be treated.

The API level struct does not export its raw data, so as to keep its
"constructor" private to the android package, and to prevent misuse of
the `number` field, which is only an implementation detail for preview
API levels. API levels can be parsed with either
`android.ApiLevelFromUser`, which returns any errors to the caller, or
`android.ApiLevelOrPanic`, which is used in the case where the input
is trusted and any errors in parsing should panic. Even within the
`android` package, these APIs should be preferred over direct
construction.

For cases where there are context specific parsing requirements, such
as handling the "minimum" alias in the cc module,
`nativeApiLevelFromUser` and `nativeApiLevelOrPanic` should be used
instead.

Test: treehugger
Bug: http://b/154667674
Change-Id: Id52921fda32cb437fb1775ac2183299dedc0cf20

1 files changed, 71 insertions, 0 deletions

diff --git a/cc/api_level.go b/cc/api_level.go
new file mode 100644
index 000000000..c93d6eda3
--- /dev/null
+++ b/cc/api_level.go
@@ -0,0 +1,71 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cc
+
+import (
+	"fmt"
+
+	"android/soong/android"
+)
+
+func minApiForArch(ctx android.BaseModuleContext,
+	arch android.ArchType) android.ApiLevel {
+
+	switch arch {
+	case android.Arm, android.X86:
+		return ctx.Config().MinSupportedSdkVersion()
+	case android.Arm64, android.X86_64:
+		return android.FirstLp64Version
+	default:
+		panic(fmt.Errorf("Unknown arch %q", arch))
+	}
+}
+
+func nativeApiLevelFromUser(ctx android.BaseModuleContext,
+	raw string) (android.ApiLevel, error) {
+
+	min := minApiForArch(ctx, ctx.Arch().ArchType)
+	if raw == "minimum" {
+		return min, nil
+	}
+
+	value, err := android.ApiLevelFromUser(ctx, raw)
+	if err != nil {
+		return android.NoneApiLevel, err
+	}
+
+	if value.LessThan(min) {
+		return min, nil
+	}
+
+	return value, nil
+}
+
+func nativeApiLevelFromUserWithDefault(ctx android.BaseModuleContext,
+	raw string, defaultValue string) (android.ApiLevel, error) {
+	if raw == "" {
+		raw = defaultValue
+	}
+	return nativeApiLevelFromUser(ctx, raw)
+}
+
+func nativeApiLevelOrPanic(ctx android.BaseModuleContext,
+	raw string) android.ApiLevel {
+	value, err := nativeApiLevelFromUser(ctx, raw)
+	if err != nil {
+		panic(err.Error())
+	}
+	return value
+}