lang: core, funcs, types: Add ctx to simple func

Plumb through the standard context.Context so that a function can be
cancelled if someone requests this. It makes it less awkward to write
simple functions that might depend on io or network access.

lang/core/strings/split_func.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"strings"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -45,7 +46,7 @@ func init() {
 
 // Split splits the input string using the separator and returns the segments as
 // a list.
-func Split(input []types.Value) (types.Value, error) {
+func Split(ctx context.Context, input []types.Value) (types.Value, error) {
 	str, sep := input[0].Str(), input[1].Str()
 
 	segments := strings.Split(str, sep)

lang/core/strings/split_func_test.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"fmt"
 	"testing"
 
@@ -40,7 +41,7 @@ import (
 func testSplit(input, sep string, output []string) error {
 	inputVal, sepVal := &types.StrValue{V: input}, &types.StrValue{V: sep}
 
-	val, err := Split([]types.Value{inputVal, sepVal})
+	val, err := Split(context.Background(), []types.Value{inputVal, sepVal})
 	if err != nil {
 		return err
 	}

lang/core/strings/to_lower_func.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"strings"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -44,7 +45,7 @@ func init() {
 }
 
 // ToLower turns a string to lowercase.
-func ToLower(input []types.Value) (types.Value, error) {
+func ToLower(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: strings.ToLower(input[0].Str()),
 	}, nil

lang/core/strings/to_lower_func_test.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -37,7 +38,7 @@ import (
 
 func testToLower(t *testing.T, input, expected string) {
 	inputStr := &types.StrValue{V: input}
-	value, err := ToLower([]types.Value{inputStr})
+	value, err := ToLower(context.Background(), []types.Value{inputStr})
 	if err != nil {
 		t.Error(err)
 		return