refactor Bazel variable export
Most of the variable export code for cc modules can be re-used for exporting variables for java modules. Refactor this code into a more composable structure for reuse. Test: build/bazel/bp2build.sh Test: manual comparison of out/soong/soong_injection/cc_toolchain/constants.bzl with previous output Change-Id: Ie5a6fee08cc888b7dc69c3e324e5c3f8aa269a8f
This commit is contained in:
Sam Delmerico
435
android/config_bp2build.go
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435
android/config_bp2build.go
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@@ -0,0 +1,435 @@
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// Copyright 2021 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package android
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import (
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"fmt"
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"reflect"
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"regexp"
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"sort"
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"strings"
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"android/soong/bazel"
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"android/soong/starlark_fmt"
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"github.com/google/blueprint"
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)
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// BazelVarExporter is a collection of configuration variables that can be exported for use in Bazel rules
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type BazelVarExporter interface {
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// asBazel expands strings of configuration variables into their concrete values
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asBazel(Config, ExportedStringVariables, ExportedStringListVariables, ExportedConfigDependingVariables) []bazelConstant
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}
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// ExportedVariables is a collection of interdependent configuration variables
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type ExportedVariables struct {
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// Maps containing toolchain variables that are independent of the
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// environment variables of the build.
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exportedStringVars ExportedStringVariables
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exportedStringListVars ExportedStringListVariables
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exportedStringListDictVars ExportedStringListDictVariables
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exportedVariableReferenceDictVars ExportedVariableReferenceDictVariables
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/// Maps containing variables that are dependent on the build config.
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exportedConfigDependingVars ExportedConfigDependingVariables
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pctx PackageContext
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}
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// NewExportedVariables creats an empty ExportedVariables struct with non-nil maps
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func NewExportedVariables(pctx PackageContext) ExportedVariables {
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return ExportedVariables{
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exportedStringVars: ExportedStringVariables{},
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exportedStringListVars: ExportedStringListVariables{},
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exportedStringListDictVars: ExportedStringListDictVariables{},
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exportedVariableReferenceDictVars: ExportedVariableReferenceDictVariables{},
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exportedConfigDependingVars: ExportedConfigDependingVariables{},
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pctx: pctx,
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}
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}
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func (ev ExportedVariables) asBazel(config Config,
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stringVars ExportedStringVariables, stringListVars ExportedStringListVariables, cfgDepVars ExportedConfigDependingVariables) []bazelConstant {
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ret := []bazelConstant{}
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ret = append(ret, ev.exportedStringVars.asBazel(config, stringVars, stringListVars, cfgDepVars)...)
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ret = append(ret, ev.exportedStringListVars.asBazel(config, stringVars, stringListVars, cfgDepVars)...)
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ret = append(ret, ev.exportedStringListDictVars.asBazel(config, stringVars, stringListVars, cfgDepVars)...)
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// Note: ExportedVariableReferenceDictVars collections can only contain references to other variables and must be printed last
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ret = append(ret, ev.exportedVariableReferenceDictVars.asBazel(config, stringVars, stringListVars, cfgDepVars)...)
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return ret
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}
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// ExportStringStaticVariable declares a static string variable and exports it to
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// Bazel's toolchain.
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func (ev ExportedVariables) ExportStringStaticVariable(name string, value string) {
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ev.pctx.StaticVariable(name, value)
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ev.exportedStringVars.set(name, value)
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}
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// ExportStringListStaticVariable declares a static variable and exports it to
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// Bazel's toolchain.
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func (ev ExportedVariables) ExportStringListStaticVariable(name string, value []string) {
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ev.pctx.StaticVariable(name, strings.Join(value, " "))
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ev.exportedStringListVars.set(name, value)
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}
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// ExportVariableConfigMethod declares a variable whose value is evaluated at
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// runtime via a function with access to the Config and exports it to Bazel's
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// toolchain.
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func (ev ExportedVariables) ExportVariableConfigMethod(name string, method interface{}) blueprint.Variable {
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ev.exportedConfigDependingVars.set(name, method)
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return ev.pctx.VariableConfigMethod(name, method)
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}
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// ExportSourcePathVariable declares a static "source path" variable and exports
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// it to Bazel's toolchain.
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func (ev ExportedVariables) ExportSourcePathVariable(name string, value string) {
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ev.pctx.SourcePathVariable(name, value)
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ev.exportedStringVars.set(name, value)
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}
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// ExportString only exports a variable to Bazel, but does not declare it in Soong
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func (ev ExportedVariables) ExportString(name string, value string) {
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ev.exportedStringVars.set(name, value)
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}
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// ExportStringList only exports a variable to Bazel, but does not declare it in Soong
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func (ev ExportedVariables) ExportStringList(name string, value []string) {
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ev.exportedStringListVars.set(name, value)
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}
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// ExportStringListDict only exports a variable to Bazel, but does not declare it in Soong
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func (ev ExportedVariables) ExportStringListDict(name string, value map[string][]string) {
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ev.exportedStringListDictVars.set(name, value)
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}
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// ExportVariableReferenceDict only exports a variable to Bazel, but does not declare it in Soong
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func (ev ExportedVariables) ExportVariableReferenceDict(name string, value map[string]string) {
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ev.exportedVariableReferenceDictVars.set(name, value)
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}
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// ExportedConfigDependingVariables is a mapping of variable names to functions
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// of type func(config Config) string which return the runtime-evaluated string
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// value of a particular variable
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type ExportedConfigDependingVariables map[string]interface{}
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func (m ExportedConfigDependingVariables) set(k string, v interface{}) {
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m[k] = v
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}
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// Ensure that string s has no invalid characters to be generated into the bzl file.
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func validateCharacters(s string) string {
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for _, c := range []string{`\n`, `"`, `\`} {
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if strings.Contains(s, c) {
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panic(fmt.Errorf("%s contains illegal character %s", s, c))
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}
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}
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return s
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}
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type bazelConstant struct {
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variableName string
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internalDefinition string
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sortLast bool
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}
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// ExportedStringVariables is a mapping of variable names to string values
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type ExportedStringVariables map[string]string
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func (m ExportedStringVariables) set(k string, v string) {
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m[k] = v
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}
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func (m ExportedStringVariables) asBazel(config Config,
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stringVars ExportedStringVariables, stringListVars ExportedStringListVariables, cfgDepVars ExportedConfigDependingVariables) []bazelConstant {
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ret := make([]bazelConstant, 0, len(m))
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for k, variableValue := range m {
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expandedVar, err := expandVar(config, variableValue, stringVars, stringListVars, cfgDepVars)
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if err != nil {
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panic(fmt.Errorf("error expanding config variable %s: %s", k, err))
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}
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if len(expandedVar) > 1 {
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panic(fmt.Errorf("%s expands to more than one string value: %s", variableValue, expandedVar))
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}
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ret = append(ret, bazelConstant{
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variableName: k,
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internalDefinition: fmt.Sprintf(`"%s"`, validateCharacters(expandedVar[0])),
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})
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}
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return ret
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}
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// ExportedStringListVariables is a mapping of variable names to a list of strings
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type ExportedStringListVariables map[string][]string
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func (m ExportedStringListVariables) set(k string, v []string) {
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m[k] = v
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}
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func (m ExportedStringListVariables) asBazel(config Config,
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stringScope ExportedStringVariables, stringListScope ExportedStringListVariables,
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exportedVars ExportedConfigDependingVariables) []bazelConstant {
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ret := make([]bazelConstant, 0, len(m))
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// For each exported variable, recursively expand elements in the variableValue
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// list to ensure that interpolated variables are expanded according to their values
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// in the variable scope.
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for k, variableValue := range m {
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var expandedVars []string
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for _, v := range variableValue {
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expandedVar, err := expandVar(config, v, stringScope, stringListScope, exportedVars)
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if err != nil {
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panic(fmt.Errorf("Error expanding config variable %s=%s: %s", k, v, err))
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}
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expandedVars = append(expandedVars, expandedVar...)
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}
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// Assign the list as a bzl-private variable; this variable will be exported
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// out through a constants struct later.
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ret = append(ret, bazelConstant{
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variableName: k,
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internalDefinition: starlark_fmt.PrintStringList(expandedVars, 0),
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})
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}
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return ret
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}
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// ExportedStringListDictVariables is a mapping from variable names to a
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// dictionary which maps keys to lists of strings
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type ExportedStringListDictVariables map[string]map[string][]string
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func (m ExportedStringListDictVariables) set(k string, v map[string][]string) {
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m[k] = v
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}
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// Since dictionaries are not supported in Ninja, we do not expand variables for dictionaries
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func (m ExportedStringListDictVariables) asBazel(_ Config, _ ExportedStringVariables,
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_ ExportedStringListVariables, _ ExportedConfigDependingVariables) []bazelConstant {
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ret := make([]bazelConstant, 0, len(m))
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for k, dict := range m {
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ret = append(ret, bazelConstant{
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variableName: k,
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internalDefinition: starlark_fmt.PrintStringListDict(dict, 0),
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})
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}
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return ret
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}
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// ExportedVariableReferenceDictVariables is a mapping from variable names to a
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// dictionary which references previously defined variables. This is used to
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// create a Starlark output such as:
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// string_var1 = "string1
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// var_ref_dict_var1 = {
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// "key1": string_var1
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// }
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// This type of variable collection must be expanded last so that it recognizes
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// previously defined variables.
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type ExportedVariableReferenceDictVariables map[string]map[string]string
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func (m ExportedVariableReferenceDictVariables) set(k string, v map[string]string) {
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m[k] = v
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}
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func (m ExportedVariableReferenceDictVariables) asBazel(_ Config, _ ExportedStringVariables,
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_ ExportedStringListVariables, _ ExportedConfigDependingVariables) []bazelConstant {
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ret := make([]bazelConstant, 0, len(m))
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for n, dict := range m {
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for k, v := range dict {
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matches, err := variableReference(v)
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if err != nil {
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panic(err)
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} else if !matches.matches {
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panic(fmt.Errorf("Expected a variable reference, got %q", v))
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} else if len(matches.fullVariableReference) != len(v) {
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panic(fmt.Errorf("Expected only a variable reference, got %q", v))
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}
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dict[k] = "_" + matches.variable
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}
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ret = append(ret, bazelConstant{
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variableName: n,
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internalDefinition: starlark_fmt.PrintDict(dict, 0),
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sortLast: true,
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})
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}
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return ret
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}
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// BazelToolchainVars expands an ExportedVariables collection and returns a string
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// of formatted Starlark variable definitions
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func BazelToolchainVars(config Config, exportedVars ExportedVariables) string {
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results := exportedVars.asBazel(
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config,
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exportedVars.exportedStringVars,
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exportedVars.exportedStringListVars,
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exportedVars.exportedConfigDependingVars,
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)
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sort.Slice(results, func(i, j int) bool {
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if results[i].sortLast != results[j].sortLast {
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return !results[i].sortLast
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}
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return results[i].variableName < results[j].variableName
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})
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definitions := make([]string, 0, len(results))
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constants := make([]string, 0, len(results))
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for _, b := range results {
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definitions = append(definitions,
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fmt.Sprintf("_%s = %s", b.variableName, b.internalDefinition))
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constants = append(constants,
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fmt.Sprintf("%[1]s%[2]s = _%[2]s,", starlark_fmt.Indention(1), b.variableName))
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}
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// Build the exported constants struct.
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ret := bazel.GeneratedBazelFileWarning
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ret += "\n\n"
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ret += strings.Join(definitions, "\n\n")
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ret += "\n\n"
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ret += "constants = struct(\n"
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ret += strings.Join(constants, "\n")
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ret += "\n)"
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return ret
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}
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type match struct {
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matches bool
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fullVariableReference string
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variable string
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}
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func variableReference(input string) (match, error) {
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// e.g. "${ExternalCflags}"
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r := regexp.MustCompile(`\${(?:config\.)?([a-zA-Z0-9_]+)}`)
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matches := r.FindStringSubmatch(input)
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if len(matches) == 0 {
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return match{}, nil
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}
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if len(matches) != 2 {
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return match{}, fmt.Errorf("Expected to only match 1 subexpression in %s, got %d", input, len(matches)-1)
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}
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return match{
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matches: true,
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fullVariableReference: matches[0],
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// Index 1 of FindStringSubmatch contains the subexpression match
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// (variable name) of the capture group.
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variable: matches[1],
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}, nil
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}
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// expandVar recursively expand interpolated variables in the exportedVars scope.
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//
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// We're using a string slice to track the seen variables to avoid
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// stackoverflow errors with infinite recursion. it's simpler to use a
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// string slice than to handle a pass-by-referenced map, which would make it
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// quite complex to track depth-first interpolations. It's also unlikely the
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// interpolation stacks are deep (n > 1).
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func expandVar(config Config, toExpand string, stringScope ExportedStringVariables,
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stringListScope ExportedStringListVariables, exportedVars ExportedConfigDependingVariables) ([]string, error) {
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// Internal recursive function.
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var expandVarInternal func(string, map[string]bool) (string, error)
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expandVarInternal = func(toExpand string, seenVars map[string]bool) (string, error) {
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var ret string
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remainingString := toExpand
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for len(remainingString) > 0 {
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matches, err := variableReference(remainingString)
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if err != nil {
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panic(err)
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}
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if !matches.matches {
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return ret + remainingString, nil
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}
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matchIndex := strings.Index(remainingString, matches.fullVariableReference)
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ret += remainingString[:matchIndex]
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remainingString = remainingString[matchIndex+len(matches.fullVariableReference):]
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variable := matches.variable
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// toExpand contains a variable.
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if _, ok := seenVars[variable]; ok {
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return ret, fmt.Errorf(
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"Unbounded recursive interpolation of variable: %s", variable)
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}
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// A map is passed-by-reference. Create a new map for
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// this scope to prevent variables seen in one depth-first expansion
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// to be also treated as "seen" in other depth-first traversals.
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newSeenVars := map[string]bool{}
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for k := range seenVars {
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newSeenVars[k] = true
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}
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newSeenVars[variable] = true
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if unexpandedVars, ok := stringListScope[variable]; ok {
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expandedVars := []string{}
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for _, unexpandedVar := range unexpandedVars {
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expandedVar, err := expandVarInternal(unexpandedVar, newSeenVars)
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if err != nil {
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return ret, err
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}
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expandedVars = append(expandedVars, expandedVar)
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}
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ret += strings.Join(expandedVars, " ")
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} else if unexpandedVar, ok := stringScope[variable]; ok {
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expandedVar, err := expandVarInternal(unexpandedVar, newSeenVars)
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if err != nil {
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return ret, err
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}
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ret += expandedVar
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} else if unevaluatedVar, ok := exportedVars[variable]; ok {
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evalFunc := reflect.ValueOf(unevaluatedVar)
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validateVariableMethod(variable, evalFunc)
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evaluatedResult := evalFunc.Call([]reflect.Value{reflect.ValueOf(config)})
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evaluatedValue := evaluatedResult[0].Interface().(string)
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expandedVar, err := expandVarInternal(evaluatedValue, newSeenVars)
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if err != nil {
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return ret, err
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}
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ret += expandedVar
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} else {
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return "", fmt.Errorf("Unbound config variable %s", variable)
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}
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}
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return ret, nil
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}
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var ret []string
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for _, v := range strings.Split(toExpand, " ") {
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val, err := expandVarInternal(v, map[string]bool{})
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if err != nil {
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return ret, err
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}
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ret = append(ret, val)
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}
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return ret, nil
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}
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func validateVariableMethod(name string, methodValue reflect.Value) {
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methodType := methodValue.Type()
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if methodType.Kind() != reflect.Func {
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panic(fmt.Errorf("method given for variable %s is not a function",
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name))
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}
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if n := methodType.NumIn(); n != 1 {
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panic(fmt.Errorf("method for variable %s has %d inputs (should be 1)",
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name, n))
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}
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if n := methodType.NumOut(); n != 1 {
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panic(fmt.Errorf("method for variable %s has %d outputs (should be 1)",
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name, n))
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}
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if kind := methodType.Out(0).Kind(); kind != reflect.String {
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panic(fmt.Errorf("method for variable %s does not return a string",
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name))
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}
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}
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