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- // Copyright 2021 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 config
- import (
- "fmt"
- "reflect"
- "regexp"
- "sort"
- "strings"
- "android/soong/android"
- "android/soong/starlark_fmt"
- "github.com/google/blueprint"
- )
- type bazelVarExporter interface {
- asBazel(android.Config, exportedStringVariables, exportedStringListVariables, exportedConfigDependingVariables) []bazelConstant
- }
- // Helpers for exporting cc configuration information to Bazel.
- var (
- // Maps containing toolchain variables that are independent of the
- // environment variables of the build.
- exportedStringListVars = exportedStringListVariables{}
- exportedStringVars = exportedStringVariables{}
- exportedStringListDictVars = exportedStringListDictVariables{}
- /// Maps containing variables that are dependent on the build config.
- exportedConfigDependingVars = exportedConfigDependingVariables{}
- )
- type exportedConfigDependingVariables map[string]interface{}
- func (m exportedConfigDependingVariables) Set(k string, v interface{}) {
- m[k] = v
- }
- // Ensure that string s has no invalid characters to be generated into the bzl file.
- func validateCharacters(s string) string {
- for _, c := range []string{`\n`, `"`, `\`} {
- if strings.Contains(s, c) {
- panic(fmt.Errorf("%s contains illegal character %s", s, c))
- }
- }
- return s
- }
- type bazelConstant struct {
- variableName string
- internalDefinition string
- }
- type exportedStringVariables map[string]string
- func (m exportedStringVariables) Set(k string, v string) {
- m[k] = v
- }
- func (m exportedStringVariables) asBazel(config android.Config,
- stringVars exportedStringVariables, stringListVars exportedStringListVariables, cfgDepVars exportedConfigDependingVariables) []bazelConstant {
- ret := make([]bazelConstant, 0, len(m))
- for k, variableValue := range m {
- expandedVar, err := expandVar(config, variableValue, stringVars, stringListVars, cfgDepVars)
- if err != nil {
- panic(fmt.Errorf("error expanding config variable %s: %s", k, err))
- }
- if len(expandedVar) > 1 {
- panic(fmt.Errorf("%s expands to more than one string value: %s", variableValue, expandedVar))
- }
- ret = append(ret, bazelConstant{
- variableName: k,
- internalDefinition: fmt.Sprintf(`"%s"`, validateCharacters(expandedVar[0])),
- })
- }
- return ret
- }
- // Convenience function to declare a static variable and export it to Bazel's cc_toolchain.
- func exportStringStaticVariable(name string, value string) {
- pctx.StaticVariable(name, value)
- exportedStringVars.Set(name, value)
- }
- type exportedStringListVariables map[string][]string
- func (m exportedStringListVariables) Set(k string, v []string) {
- m[k] = v
- }
- func (m exportedStringListVariables) asBazel(config android.Config,
- stringScope exportedStringVariables, stringListScope exportedStringListVariables,
- exportedVars exportedConfigDependingVariables) []bazelConstant {
- ret := make([]bazelConstant, 0, len(m))
- // For each exported variable, recursively expand elements in the variableValue
- // list to ensure that interpolated variables are expanded according to their values
- // in the variable scope.
- for k, variableValue := range m {
- var expandedVars []string
- for _, v := range variableValue {
- expandedVar, err := expandVar(config, v, stringScope, stringListScope, exportedVars)
- if err != nil {
- panic(fmt.Errorf("Error expanding config variable %s=%s: %s", k, v, err))
- }
- expandedVars = append(expandedVars, expandedVar...)
- }
- // Assign the list as a bzl-private variable; this variable will be exported
- // out through a constants struct later.
- ret = append(ret, bazelConstant{
- variableName: k,
- internalDefinition: starlark_fmt.PrintStringList(expandedVars, 0),
- })
- }
- return ret
- }
- // Convenience function to declare a static "source path" variable and export it to Bazel's cc_toolchain.
- func exportVariableConfigMethod(name string, method interface{}) blueprint.Variable {
- exportedConfigDependingVars.Set(name, method)
- return pctx.VariableConfigMethod(name, method)
- }
- // Convenience function to declare a static "source path" variable and export it to Bazel's cc_toolchain.
- func exportSourcePathVariable(name string, value string) {
- pctx.SourcePathVariable(name, value)
- exportedStringVars.Set(name, value)
- }
- // Convenience function to declare a static variable and export it to Bazel's cc_toolchain.
- func exportStringListStaticVariable(name string, value []string) {
- pctx.StaticVariable(name, strings.Join(value, " "))
- exportedStringListVars.Set(name, value)
- }
- func ExportStringList(name string, value []string) {
- exportedStringListVars.Set(name, value)
- }
- type exportedStringListDictVariables map[string]map[string][]string
- func (m exportedStringListDictVariables) Set(k string, v map[string][]string) {
- m[k] = v
- }
- // Since dictionaries are not supported in Ninja, we do not expand variables for dictionaries
- func (m exportedStringListDictVariables) asBazel(_ android.Config, _ exportedStringVariables,
- _ exportedStringListVariables, _ exportedConfigDependingVariables) []bazelConstant {
- ret := make([]bazelConstant, 0, len(m))
- for k, dict := range m {
- ret = append(ret, bazelConstant{
- variableName: k,
- internalDefinition: starlark_fmt.PrintStringListDict(dict, 0),
- })
- }
- return ret
- }
- // BazelCcToolchainVars generates bzl file content containing variables for
- // Bazel's cc_toolchain configuration.
- func BazelCcToolchainVars(config android.Config) string {
- return bazelToolchainVars(
- config,
- exportedStringListDictVars,
- exportedStringListVars,
- exportedStringVars)
- }
- func bazelToolchainVars(config android.Config, vars ...bazelVarExporter) string {
- ret := "# GENERATED FOR BAZEL FROM SOONG. DO NOT EDIT.\n\n"
- results := []bazelConstant{}
- for _, v := range vars {
- results = append(results, v.asBazel(config, exportedStringVars, exportedStringListVars, exportedConfigDependingVars)...)
- }
- sort.Slice(results, func(i, j int) bool { return results[i].variableName < results[j].variableName })
- definitions := make([]string, 0, len(results))
- constants := make([]string, 0, len(results))
- for _, b := range results {
- definitions = append(definitions,
- fmt.Sprintf("_%s = %s", b.variableName, b.internalDefinition))
- constants = append(constants,
- fmt.Sprintf("%[1]s%[2]s = _%[2]s,", starlark_fmt.Indention(1), b.variableName))
- }
- // Build the exported constants struct.
- ret += strings.Join(definitions, "\n\n")
- ret += "\n\n"
- ret += "constants = struct(\n"
- ret += strings.Join(constants, "\n")
- ret += "\n)"
- return ret
- }
- // expandVar recursively expand interpolated variables in the exportedVars scope.
- //
- // We're using a string slice to track the seen variables to avoid
- // stackoverflow errors with infinite recursion. it's simpler to use a
- // string slice than to handle a pass-by-referenced map, which would make it
- // quite complex to track depth-first interpolations. It's also unlikely the
- // interpolation stacks are deep (n > 1).
- func expandVar(config android.Config, toExpand string, stringScope exportedStringVariables,
- stringListScope exportedStringListVariables, exportedVars exportedConfigDependingVariables) ([]string, error) {
- // e.g. "${ExternalCflags}"
- r := regexp.MustCompile(`\${([a-zA-Z0-9_]+)}`)
- // Internal recursive function.
- var expandVarInternal func(string, map[string]bool) (string, error)
- expandVarInternal = func(toExpand string, seenVars map[string]bool) (string, error) {
- var ret string
- remainingString := toExpand
- for len(remainingString) > 0 {
- matches := r.FindStringSubmatch(remainingString)
- if len(matches) == 0 {
- return ret + remainingString, nil
- }
- if len(matches) != 2 {
- panic(fmt.Errorf("Expected to only match 1 subexpression in %s, got %d", remainingString, len(matches)-1))
- }
- matchIndex := strings.Index(remainingString, matches[0])
- ret += remainingString[:matchIndex]
- remainingString = remainingString[matchIndex+len(matches[0]):]
- // Index 1 of FindStringSubmatch contains the subexpression match
- // (variable name) of the capture group.
- variable := matches[1]
- // toExpand contains a variable.
- if _, ok := seenVars[variable]; ok {
- return ret, fmt.Errorf(
- "Unbounded recursive interpolation of variable: %s", variable)
- }
- // A map is passed-by-reference. Create a new map for
- // this scope to prevent variables seen in one depth-first expansion
- // to be also treated as "seen" in other depth-first traversals.
- newSeenVars := map[string]bool{}
- for k := range seenVars {
- newSeenVars[k] = true
- }
- newSeenVars[variable] = true
- if unexpandedVars, ok := stringListScope[variable]; ok {
- expandedVars := []string{}
- for _, unexpandedVar := range unexpandedVars {
- expandedVar, err := expandVarInternal(unexpandedVar, newSeenVars)
- if err != nil {
- return ret, err
- }
- expandedVars = append(expandedVars, expandedVar)
- }
- ret += strings.Join(expandedVars, " ")
- } else if unexpandedVar, ok := stringScope[variable]; ok {
- expandedVar, err := expandVarInternal(unexpandedVar, newSeenVars)
- if err != nil {
- return ret, err
- }
- ret += expandedVar
- } else if unevaluatedVar, ok := exportedVars[variable]; ok {
- evalFunc := reflect.ValueOf(unevaluatedVar)
- validateVariableMethod(variable, evalFunc)
- evaluatedResult := evalFunc.Call([]reflect.Value{reflect.ValueOf(config)})
- evaluatedValue := evaluatedResult[0].Interface().(string)
- expandedVar, err := expandVarInternal(evaluatedValue, newSeenVars)
- if err != nil {
- return ret, err
- }
- ret += expandedVar
- } else {
- return "", fmt.Errorf("Unbound config variable %s", variable)
- }
- }
- return ret, nil
- }
- var ret []string
- for _, v := range strings.Split(toExpand, " ") {
- val, err := expandVarInternal(v, map[string]bool{})
- if err != nil {
- return ret, err
- }
- ret = append(ret, val)
- }
- return ret, nil
- }
- func validateVariableMethod(name string, methodValue reflect.Value) {
- methodType := methodValue.Type()
- if methodType.Kind() != reflect.Func {
- panic(fmt.Errorf("method given for variable %s is not a function",
- name))
- }
- if n := methodType.NumIn(); n != 1 {
- panic(fmt.Errorf("method for variable %s has %d inputs (should be 1)",
- name, n))
- }
- if n := methodType.NumOut(); n != 1 {
- panic(fmt.Errorf("method for variable %s has %d outputs (should be 1)",
- name, n))
- }
- if kind := methodType.Out(0).Kind(); kind != reflect.String {
- panic(fmt.Errorf("method for variable %s does not return a string",
- name))
- }
- }
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