feat: ffdhall

Signed-off-by: jolheiser <john.olheiser@gmail.com>

ff_map.go

@@ -0,0 +1,64 @@
+// This is taken from https://github.com/peterbourgon/ff/blob/e267c41b1d149b5151fb637d65f53b6e833448fd/internal/traverse_map.go
+package ffdhall
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+)
+
+// traverseMap recursively walks the given map, calling set for each value. If the
+// value is a slice, set is called for each element of the slice. The keys of
+// nested maps are joined with the given delimiter.
+func traverseMap(m map[string]any, delimiter string, set func(name, value string) error) error {
+	return traverse("", m, delimiter, set)
+}
+
+func traverse(key string, val any, delimiter string, set func(name, value string) error) error {
+	switch v := val.(type) {
+	case string:
+		return set(key, v)
+	case json.Number:
+		return set(key, v.String())
+	case uint64:
+		return set(key, strconv.FormatUint(v, 10))
+	case int:
+		return set(key, strconv.Itoa(v))
+	case int64:
+		return set(key, strconv.FormatInt(v, 10))
+	case float64:
+		return set(key, strconv.FormatFloat(v, 'g', -1, 64))
+	case bool:
+		return set(key, strconv.FormatBool(v))
+	case nil:
+		return set(key, "")
+	case []any:
+		for _, v := range v {
+			if err := traverse(key, v, delimiter, set); err != nil {
+				return err
+			}
+		}
+	case map[string]any:
+		for k, v := range v {
+			if key != "" {
+				k = key + delimiter + k
+			}
+			if err := traverse(k, v, delimiter, set); err != nil {
+				return err
+			}
+		}
+	case map[any]any:
+		for k, v := range v {
+			ks := fmt.Sprint(k)
+			if key != "" {
+				ks = key + delimiter + ks
+			}
+			if err := traverse(ks, v, delimiter, set); err != nil {
+				return err
+			}
+		}
+	default:
+		return fmt.Errorf("couldn't convert %q (type %T) to string", val, val)
+	}
+	return nil
+}

ffdhall.go

@@ -0,0 +1,72 @@
+package ffdhall
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/philandstuff/dhall-golang/v6"
+)
+
+// DhallParser is a helper function that uses a default DhallParseConfig.
+func DhallParser(r io.Reader, set func(name, value string) error) error {
+	return (&DhallParseConfig{}).Parse(r, set)
+}
+
+// DhallParseConfig collects parameters for the Dhall config file parser.
+type DhallParseConfig struct {
+	// Delimiter is used when concatenating nested node keys into a flag name.
+	// The default delimiter is ".".
+	Delimiter string
+}
+
+// Parse a Dhall document from the provided io.Reader, using the provided set
+// function to set flag values. Flag names are derived from the node names and
+// their key/value pairs.
+func (pc *DhallParseConfig) Parse(r io.Reader, set func(name, value string) error) error {
+	if pc.Delimiter == "" {
+		pc.Delimiter = "."
+	}
+
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return err
+	}
+
+	// Compatibility with other parsers
+	if strings.TrimSpace(string(data)) == "" {
+		return nil
+	}
+
+	var m interface{}
+	if err := dhall.Unmarshal(data, &m); err != nil {
+		return DhallParseError{Inner: err}
+	}
+	mm, ok := m.(map[string]interface{})
+	if !ok {
+		return errors.New("could not unmarshal to map[string]interface{}")
+	}
+
+	if err := traverseMap(mm, pc.Delimiter, set); err != nil {
+		return DhallParseError{Inner: err}
+	}
+
+	return nil
+}
+
+// DhallParseError wraps all errors originating from the DhallParser.
+type DhallParseError struct {
+	Inner error
+}
+
+// Error implenents the error interface.
+func (e DhallParseError) Error() string {
+	return fmt.Sprintf("could not parse Dhall config: %v", e.Inner)
+}
+
+// Unwrap implements the errors.Wrapper interface, allowing errors.Is and
+// errors.As to work with DhallParseErrors.
+func (e DhallParseError) Unwrap() error {
+	return e.Inner
+}

ffdhall_test.go

@@ -0,0 +1,56 @@
+package ffdhall
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/peterbourgon/ff/v3"
+	"github.com/peterbourgon/ff/v3/fftest"
+)
+
+func TestDhallParser(t *testing.T) {
+	t.Parallel()
+
+	for _, testcase := range []struct {
+		name string
+		args []string
+		file string
+		want fftest.Vars
+	}{
+		{
+			name: "empty input",
+			args: []string{},
+			file: "testdata/empty.dhall",
+			want: fftest.Vars{},
+		},
+		{
+			name: "basic KV pairs",
+			args: []string{},
+			file: "testdata/basic.dhall",
+			want: fftest.Vars{S: "s", I: 10, B: true, D: 5 * time.Second},
+		},
+		{
+			name: "value arrays",
+			args: []string{},
+			file: "testdata/value_arrays.dhall",
+			want: fftest.Vars{S: "bb", I: 12, B: true, D: 5 * time.Second, X: []string{"a", "B", "👍"}},
+		},
+		{
+			name: "bad Dhall file",
+			args: []string{},
+			file: "testdata/bad.dhall",
+			want: fftest.Vars{WantParseErrorString: "no match found"},
+		},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			fs, vars := fftest.Pair()
+			vars.ParseError = ff.Parse(fs, testcase.args,
+				ff.WithConfigFile(testcase.file),
+				ff.WithConfigFileParser(DhallParser),
+			)
+			fmt.Println(vars.ParseError)
+			fftest.Compare(t, &testcase.want, vars)
+		})
+	}
+}

go.mod

@@ -0,0 +1,13 @@
+module go.jolheiser.com/ffdhall
+
+go 1.22.3
+
+require (
+	github.com/peterbourgon/ff/v3 v3.4.0
+	github.com/philandstuff/dhall-golang/v6 v6.0.2
+)
+
+require (
+	github.com/fxamacker/cbor/v2 v2.2.1-0.20200511212021-28e39be4a84f // indirect
+	github.com/x448/float16 v0.8.4 // indirect
+)

go.sum

@@ -0,0 +1,53 @@
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testdata/bad.dhall

@@ -0,0 +1 @@
+{

testdata/basic.dhall

@@ -0,0 +1 @@
+{ s = "s", i = 10, b = True, d = "5s" }

testdata/empty.dhall

@@ -0,0 +1 @@
+

testdata/value_arrays.dhall

@@ -0,0 +1,6 @@
+{ s = [ "a", "bb" ]
+, i = [ "10", "11", "12" ]
+, b = [ False, True ]
+, d = [ "10m", "5s" ]
+, x = [ "a", "B", "👍" ]
+}