Supported python build in host side.

The base module handles all the common functionalites, such as version
compatibilty check, version variations split, source file format check,
source/data file duplicate check.

The library/binary module focuses on how to generate binary build actions,
such as setting up stub script, zipping, filling in __init__.py in
runfiles dir tree.

Bug: b/31676493
Test: go test under python package

Change-Id: I06608369f350f7195873d459e1c8d1bdb811e77e
diff --git a/python/builder.go b/python/builder.go
new file mode 100644
index 0000000..6223448
--- /dev/null
+++ b/python/builder.go
@@ -0,0 +1,146 @@
+// Copyright 2017 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 python
+
+// This file contains Ninja build actions for building Python program.
+
+import (
+	"strings"
+
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+	_ "github.com/google/blueprint/bootstrap"
+)
+
+var (
+	pctx = android.NewPackageContext("android/soong/python")
+
+	par = pctx.AndroidStaticRule("par",
+		blueprint.RuleParams{
+			Command: `touch $initFile && ` +
+				`sed -e 's/%interpreter%/$interp/g' -e 's/%main%/$main/g' $template > $stub && ` +
+				`$parCmd -o $parFile $parArgs && echo '#!/usr/bin/env python' | cat - $parFile > $out && ` +
+				`chmod +x $out && (rm -f $initFile; rm -f $stub; rm -f $parFile)`,
+			CommandDeps: []string{"$parCmd", "$template"},
+			Description: "build par $out",
+		},
+		"initFile", "interp", "main", "template", "stub", "parCmd", "parFile", "parArgs")
+)
+
+func init() {
+	pctx.Import("github.com/google/blueprint/bootstrap")
+	pctx.Import("android/soong/common")
+
+	pctx.HostBinToolVariable("parCmd", "soong_zip")
+}
+
+type fileListSpec struct {
+	fileList     android.Path
+	relativeRoot string
+}
+
+type parSpec struct {
+	rootPrefix string
+
+	fileListSpecs []fileListSpec
+}
+
+func (p parSpec) soongParArgs() string {
+	ret := "-P " + p.rootPrefix
+
+	for _, spec := range p.fileListSpecs {
+		ret += " -C " + spec.relativeRoot + " -l " + spec.fileList.String()
+	}
+
+	return ret
+}
+
+func registerBuildActionForModuleFileList(ctx android.ModuleContext,
+	name string, files android.Paths) android.Path {
+	fileList := android.PathForModuleOut(ctx, name+".list")
+
+	content := []string{}
+	for _, file := range files {
+		content = append(content, file.String())
+	}
+
+	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
+		Rule:      android.WriteFile,
+		Output:    fileList,
+		Implicits: files,
+		Args: map[string]string{
+			"content": strings.Join(content, "\n"),
+		},
+	})
+
+	return fileList
+}
+
+func registerBuildActionForParFile(ctx android.ModuleContext,
+	interpreter, main, binName string, newPyPkgs []string, parSpecs []parSpec) android.Path {
+
+	// intermediate output path for __init__.py
+	initFile := android.PathForModuleOut(ctx, initFileName).String()
+
+	// the path of stub_template_host.txt from source tree.
+	template := android.PathForSource(ctx, stubTemplateHost)
+
+	// intermediate output path for __main__.py
+	stub := android.PathForModuleOut(ctx, mainFileName).String()
+
+	// intermediate output path for par file.
+	parFile := android.PathForModuleOut(ctx, binName+parFileExt)
+
+	// intermediate output path for bin executable.
+	binFile := android.PathForModuleOut(ctx, binName)
+
+	// implicit dependency for parFile build action.
+	implicits := android.Paths{}
+	for _, p := range parSpecs {
+		for _, f := range p.fileListSpecs {
+			implicits = append(implicits, f.fileList)
+		}
+	}
+
+	parArgs := []string{}
+	parArgs = append(parArgs, "-C "+strings.TrimSuffix(stub, mainFileName)+" -f "+stub)
+	parArgs = append(parArgs, "-C "+strings.TrimSuffix(initFile, initFileName)+" -f "+initFile)
+	for _, pkg := range newPyPkgs {
+		parArgs = append(parArgs, "-P "+pkg+" -f "+initFile)
+	}
+	for _, p := range parSpecs {
+		parArgs = append(parArgs, p.soongParArgs())
+	}
+
+	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
+		Rule:      par,
+		Output:    binFile,
+		Implicits: implicits,
+		Args: map[string]string{
+			"initFile": initFile,
+			// the "\" isn't being interpreted by regex parser, it's being
+			// interpreted in the string literal.
+			"interp":   strings.Replace(interpreter, "/", `\/`, -1),
+			"main":     strings.Replace(main, "/", `\/`, -1),
+			"template": template.String(),
+			"stub":     stub,
+			"parFile":  parFile.String(),
+			"parArgs":  strings.Join(parArgs, " "),
+		},
+	})
+
+	return binFile
+}