mcfg: Parse now takes a Context, which allows for implementing WithCLITail
This commit is contained in:
parent
a596306d9e
commit
c0afa3d126
40
mcfg/cli.go
40
mcfg/cli.go
@ -13,6 +13,34 @@ import (
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"github.com/mediocregopher/mediocre-go-lib/merr"
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)
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type cliKey int
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const (
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cliKeyTailPtr cliKey = iota
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)
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// WithCLITail returns a Context which modifies the behavior of SourceCLI's
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// Parse, if SourceCLI is used with that Context at all. Normally when SourceCLI
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// encounters an unexpected Arg it will immediately return an error. This
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// function modifies the Context to indicate to Parse that the unexpected Arg,
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// and all subsequent Args (i.e. the tail) should be set to the returned
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// []string value.
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//
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// If multiple WithCLITail calls are used then only the latest returned pointer
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// will be filled.
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func WithCLITail(ctx context.Context) (context.Context, *[]string) {
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tailPtr := new([]string)
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return context.WithValue(ctx, cliKeyTailPtr, tailPtr), tailPtr
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}
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func populateCLITail(ctx context.Context, tail []string) bool {
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tailPtr, ok := ctx.Value(cliKeyTailPtr).(*[]string)
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if ok {
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*tailPtr = tail
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}
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return ok
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}
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// SourceCLI is a Source which will parse configuration from the CLI.
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//
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// Possible CLI options are generated by joining a Param's Path and Name with
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@ -37,12 +65,6 @@ type SourceCLI struct {
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Args []string // if nil then os.Args[1:] is used
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DisableHelpPage bool
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// Normally if any unexpected Arg value is encountered Parse will error out.
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// If instead TailCallback is set then it will be called whenever the first
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// unexpected Arg is encountered, and will not error out. TailCallback will
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// be given a slice of Args starting at the first unexpected element.
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TailCallback func([]string)
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}
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const (
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@ -53,7 +75,7 @@ const (
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)
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// Parse implements the method for the Source interface
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func (cli *SourceCLI) Parse(params []Param) ([]ParamValue, error) {
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func (cli *SourceCLI) Parse(ctx context.Context, params []Param) ([]ParamValue, error) {
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args := cli.Args
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if cli.Args == nil {
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args = os.Args[1:]
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@ -96,8 +118,7 @@ func (cli *SourceCLI) Parse(params []Param) ([]ParamValue, error) {
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break
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}
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if !pOk {
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if cli.TailCallback != nil {
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cli.TailCallback(args[i:])
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if ok := populateCLITail(ctx, args[i:]); ok {
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return pvs, nil
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}
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ctx := mctx.Annotate(context.Background(), "param", arg)
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@ -134,6 +155,7 @@ func (cli *SourceCLI) Parse(params []Param) ([]ParamValue, error) {
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ctx := mctx.Annotate(p.Context, "param", key)
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return nil, merr.New("param expected a value", ctx)
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}
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return pvs, nil
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}
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@ -3,6 +3,7 @@ package mcfg
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import (
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"bytes"
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"context"
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"fmt"
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"strings"
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. "testing"
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"time"
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@ -107,18 +108,11 @@ func TestSourceCLI(t *T) {
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}
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}
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func TestSourceCLITailCallback(t *T) {
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func TestWithCLITail(t *T) {
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ctx := context.Background()
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ctx, _ = WithInt(ctx, "foo", 5, "")
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ctx, _ = WithBool(ctx, "bar", "")
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var tail []string
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src := &SourceCLI{
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TailCallback: func(gotTail []string) {
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tail = gotTail
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},
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}
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type testCase struct {
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args []string
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expTail []string
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@ -127,7 +121,7 @@ func TestSourceCLITailCallback(t *T) {
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cases := []testCase{
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{
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args: []string{"--foo", "5"},
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expTail: []string{},
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expTail: nil,
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},
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{
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args: []string{"--foo", "5", "a", "b", "c"},
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@ -139,7 +133,7 @@ func TestSourceCLITailCallback(t *T) {
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},
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{
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args: []string{"--foo", "5", "--bar"},
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expTail: []string{},
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expTail: nil,
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},
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{
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args: []string{"--foo", "5", "--bar", "a", "b", "c"},
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@ -148,12 +142,25 @@ func TestSourceCLITailCallback(t *T) {
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}
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for _, tc := range cases {
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tail = []string{}
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src.Args = tc.args
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err := Populate(ctx, src)
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ctx, tail := WithCLITail(ctx)
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err := Populate(ctx, &SourceCLI{Args: tc.args})
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massert.Require(t, massert.Comment(massert.All(
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massert.Nil(err),
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massert.Equal(tc.expTail, tail),
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massert.Equal(tc.expTail, *tail),
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), "tc: %#v", tc))
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}
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}
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func ExampleWithCLITail() {
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ctx := context.Background()
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ctx, foo := WithInt(ctx, "foo", 1, "Description of foo.")
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ctx, tail := WithCLITail(ctx)
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ctx, bar := WithString(ctx, "bar", "defaultVal", "Description of bar.")
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err := Populate(ctx, &SourceCLI{
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Args: []string{"--foo=100", "BADARG", "--bar", "BAR"},
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})
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fmt.Printf("err:%v foo:%v bar:%v tail:%#v\n", err, *foo, *bar, *tail)
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// Output: err:<nil> foo:100 bar:defaultVal tail:[]string{"BADARG", "--bar", "BAR"}
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}
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@ -43,7 +43,7 @@ func (env *SourceEnv) expectedName(path []string, name string) string {
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}
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// Parse implements the method for the Source interface
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func (env *SourceEnv) Parse(params []Param) ([]ParamValue, error) {
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func (env *SourceEnv) Parse(ctx context.Context, params []Param) ([]ParamValue, error) {
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kvs := env.Env
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if kvs == nil {
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kvs = os.Environ()
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23
mcfg/mcfg.go
23
mcfg/mcfg.go
@ -72,7 +72,15 @@ func paramHash(path []string, name string) string {
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return paramFullName(path, name) + "/" + hStr
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}
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func populate(params []Param, src Source) error {
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// Populate uses the Source to populate the values of all Params which were
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// added to the given Context, and all of its children. Populate may be called
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// multiple times with the same Context, each time will only affect the values
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// of the Params which were provided by the respective Source.
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//
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// Source may be nil to indicate that no configuration is provided. Only default
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// values will be used, and if any parameters are required this will error.
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func Populate(ctx context.Context, src Source) error {
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params := collectParams(ctx)
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if src == nil {
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src = ParamValues(nil)
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}
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@ -89,7 +97,7 @@ func populate(params []Param, src Source) error {
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pM[hash] = p
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}
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pvs, err := src.Parse(params)
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pvs, err := src.Parse(ctx, params)
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if err != nil {
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return err
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}
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@ -127,14 +135,3 @@ func populate(params []Param, src Source) error {
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return nil
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}
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// Populate uses the Source to populate the values of all Params which were
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// added to the given Context, and all of its children. Populate may be called
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// multiple times with the same Context, each time will only affect the values
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// of the Params which were provided by the respective Source.
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//
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// Source may be nil to indicate that no configuration is provided. Only default
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// values will be used, and if any parameters are required this will error.
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func Populate(ctx context.Context, src Source) error {
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return populate(collectParams(ctx), src)
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}
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@ -1,6 +1,7 @@
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package mcfg
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import (
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"context"
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"encoding/json"
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)
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@ -13,7 +14,8 @@ type ParamValue struct {
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}
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// Source parses ParamValues out of a particular configuration source, given a
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// sorted set of possible Params to parse.
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// sorted set of possible Params to parse, and the Context from with the Params
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// were extracted.
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//
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// Source should not return ParamValues which were not explicitly set to a value
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// by the configuration source.
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@ -23,7 +25,7 @@ type ParamValue struct {
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// ParamValues which do not correspond to any of the passed in Params. These
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// will be ignored in Populate.
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type Source interface {
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Parse([]Param) ([]ParamValue, error)
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Parse(context.Context, []Param) ([]ParamValue, error)
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}
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// ParamValues is simply a slice of ParamValue elements, which implements Parse
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@ -31,7 +33,7 @@ type Source interface {
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type ParamValues []ParamValue
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// Parse implements the method for the Source interface.
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func (pvs ParamValues) Parse([]Param) ([]ParamValue, error) {
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func (pvs ParamValues) Parse(context.Context, []Param) ([]ParamValue, error) {
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return pvs, nil
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}
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@ -41,10 +43,10 @@ func (pvs ParamValues) Parse([]Param) ([]ParamValue, error) {
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type Sources []Source
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// Parse implements the method for the Source interface.
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func (ss Sources) Parse(params []Param) ([]ParamValue, error) {
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func (ss Sources) Parse(ctx context.Context, params []Param) ([]ParamValue, error) {
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var pvs []ParamValue
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for _, s := range ss {
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innerPVs, err := s.Parse(params)
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innerPVs, err := s.Parse(ctx, params)
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if err != nil {
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return nil, err
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}
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@ -143,7 +143,7 @@ func (scs srcCommonState) applyCtxAndPV(p srcCommonParams) srcCommonState {
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// ParamValues
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func (scs srcCommonState) assert(s Source) error {
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root := scs.mkRoot()
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gotPVs, err := s.Parse(collectParams(root))
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gotPVs, err := s.Parse(root, collectParams(root))
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if err != nil {
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return err
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}
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