Support for CUE

Signed-off-by: Dave Henderson <[email protected]>

data/data.go

@@ -12,6 +12,9 @@ import (
 	"io"
 	"strings"
 
+	"cuelang.org/go/cue"
+	"cuelang.org/go/cue/cuecontext"
+	"cuelang.org/go/cue/format"
 	"github.com/Shopify/ejson"
 	ejsonJson "github.com/Shopify/ejson/json"
 	"github.com/hairyhenderson/gomplate/v4/conv"
@@ -442,3 +445,63 @@ func ToTOML(in interface{}) (string, error) {
 	}
 	return buf.String(), nil
 }
+
+// CUE - Unmarshal a CUE expression into the appropriate type
+func CUE(in string) (interface{}, error) {
+	cuectx := cuecontext.New()
+	val := cuectx.CompileString(in)
+
+	if val.Err() != nil {
+		return nil, fmt.Errorf("unable to process CUE: %w", val.Err())
+	}
+
+	switch val.Kind() {
+	case cue.StructKind:
+		out := map[string]interface{}{}
+		err := val.Decode(&out)
+		return out, err
+	case cue.ListKind:
+		out := []interface{}{}
+		err := val.Decode(&out)
+		return out, err
+	case cue.BytesKind:
+		out := []byte{}
+		err := val.Decode(&out)
+		return out, err
+	case cue.StringKind:
+		out := ""
+		err := val.Decode(&out)
+		return out, err
+	case cue.IntKind:
+		out := 0
+		err := val.Decode(&out)
+		return out, err
+	case cue.NumberKind, cue.FloatKind:
+		out := 0.0
+		err := val.Decode(&out)
+		return out, err
+	case cue.BoolKind:
+		out := false
+		err := val.Decode(&out)
+		return out, err
+	case cue.NullKind:
+		return nil, nil
+	default:
+		return nil, fmt.Errorf("unsupported CUE type %q", val.Kind())
+	}
+}
+
+func ToCUE(in interface{}) (string, error) {
+	cuectx := cuecontext.New()
+	v := cuectx.Encode(in)
+	if v.Err() != nil {
+		return "", v.Err()
+	}
+
+	bs, err := format.Node(v.Syntax())
+	if err != nil {
+		return "", err
+	}
+
+	return string(bs), nil
+}

data/data_test.go

@@ -659,3 +659,120 @@ func TestStringifyYAMLMapMapKeys(t *testing.T) {
 		assert.EqualValues(t, c.want, c.input)
 	}
 }
+
+func TestCUE(t *testing.T) {
+	in := `package foo
+import "regexp"
+matches: regexp.FindSubmatch(#"^([^:]*):(\d+)$"#, "localhost:443")
+one: 1
+two: 2
+// A field using quotes.
+"two-and-a-half": 2.5
+list: [ 1, 2, 3 ]
+`
+
+	expected := map[string]interface{}{
+		"matches": []interface{}{
+			"localhost:443",
+			"localhost",
+			"443",
+		},
+		"one":            1,
+		"two":            2,
+		"two-and-a-half": 2.5,
+		"list":           []interface{}{1, 2, 3},
+	}
+
+	out, err := CUE(in)
+	require.NoError(t, err)
+	assert.EqualValues(t, expected, out)
+
+	out, err = CUE(`[1,2,3]`)
+	require.NoError(t, err)
+	assert.EqualValues(t, []interface{}{1, 2, 3}, out)
+
+	out, err = CUE(`"hello world"`)
+	require.NoError(t, err)
+	assert.EqualValues(t, "hello world", out)
+
+	out, err = CUE(`true`)
+	require.NoError(t, err)
+	assert.EqualValues(t, true, out)
+
+	out, err = CUE(`'\x00\x01\x02\x03\x04'`)
+	require.NoError(t, err)
+	assert.EqualValues(t, []byte{0, 1, 2, 3, 4}, out)
+
+	out, err = CUE(`42`)
+	require.NoError(t, err)
+	assert.EqualValues(t, 42, out)
+
+	out, err = CUE(`42.0`)
+	require.NoError(t, err)
+	assert.EqualValues(t, 42.0, out)
+
+	out, err = CUE(`null`)
+	require.NoError(t, err)
+	assert.EqualValues(t, nil, out)
+
+	_, err = CUE(`>=0 & <=7 & >=3 & <=10`)
+	require.Error(t, err)
+}
+
+func TestToCUE(t *testing.T) {
+	in := map[string]interface{}{
+		"matches": []interface{}{
+			"localhost:443",
+			"localhost",
+			"443",
+		},
+		"one":            1,
+		"two":            2,
+		"two-and-a-half": 2.5,
+		"list":           []interface{}{1, 2, 3},
+	}
+
+	expected := `{
+	"two-and-a-half": 2.5
+	list: [1, 2, 3]
+	two: 2
+	one: 1
+	matches: ["localhost:443", "localhost", "443"]
+}`
+
+	out, err := ToCUE(in)
+	require.NoError(t, err)
+	assert.EqualValues(t, expected, out)
+
+	out, err = ToCUE([]interface{}{1, 2, 3})
+	require.NoError(t, err)
+	assert.EqualValues(t, `[1, 2, 3]`, out)
+
+	out, err = ToCUE("hello world")
+	require.NoError(t, err)
+	assert.EqualValues(t, `"hello world"`, out)
+
+	out, err = ToCUE(true)
+	require.NoError(t, err)
+	assert.EqualValues(t, `true`, out)
+
+	out, err = ToCUE([]byte{0, 1, 2, 3, 4})
+	require.NoError(t, err)
+	assert.EqualValues(t, `'\x00\x01\x02\x03\x04'`, out)
+
+	out, err = ToCUE(42)
+	require.NoError(t, err)
+	assert.EqualValues(t, `42`, out)
+
+	out, err = ToCUE(42.0)
+	require.NoError(t, err)
+	assert.EqualValues(t, `42.0`, out)
+
+	out, err = ToCUE(nil)
+	require.NoError(t, err)
+	assert.EqualValues(t, `null`, out)
+
+	out, err = ToCUE(struct{}{})
+	require.NoError(t, err)
+	assert.EqualValues(t, `{}`, out)
+}

data/datasource.go

@@ -32,6 +32,7 @@ func init() {
 	regExtension(".csv", csvMimetype)
 	regExtension(".toml", tomlMimetype)
 	regExtension(".env", envMimetype)
+	regExtension(".cue", cueMimetype)
 }
 
 // registerReaders registers the source-reader functions
@@ -348,6 +349,8 @@ func parseData(mimeType, s string) (out interface{}, err error) {
 		out, err = dotEnv(s)
 	case textMimetype:
 		out = s
+	case cueMimetype:
+		out, err = CUE(s)
 	default:
 		return nil, fmt.Errorf("datasources of type %s not yet supported", mimeType)
 	}

data/mimetypes.go

@@ -8,6 +8,7 @@ const (
 	tomlMimetype      = "application/toml"
 	yamlMimetype      = "application/yaml"
 	envMimetype       = "application/x-env"
+	cueMimetype       = "application/cue"
 )
 
 // mimeTypeAliases defines a mapping for non-canonical mime types that are

docs-src/content/functions/data.yml

@@ -369,6 +369,27 @@ funcs:
         Go
         COBOL
         ```
+  - name: data.CUE
+    alias: cue
+    description: |
+      Converts a [CUE](https://cuelang.org/) document into an object. Any type
+      of CUE document is supported. This can be used to access properties of CUE
+      documents.
+
+      Note that the `import` statement is not yet supported, and will result in
+      an error (except for importing builtin packages).
+    pipeline: true
+    arguments:
+      - name: input
+        required: true
+        description: the CUE document to parse
+    examples:
+      - |
+        $ gomplate -i '{{ $t := `data: {
+            hello: "world"
+          }` -}}
+          Hello {{ (cue $t).data.hello }}'
+        Hello world
   - name: data.ToJSON
     alias: toJSON
     description: |
@@ -492,3 +513,28 @@ funcs:
         1,2
         3,4
         ```
+  - name: data.ToCUE
+    alias: toCUE
+    description: |
+      Converts an object to a [CUE](https://cuelang.org/) document in canonical
+      format. The input object can be of any type.
+
+      This is roughly equivalent to using the `cue export --out=cue <file>`
+      command to convert from other formats to CUE.
+    pipeline: true
+    arguments:
+      - name: input
+        required: true
+        description: the object to marshal as a CUE document
+    examples:
+      - |
+        $ gomplate -i '{{ `{"foo":"bar"}` | data.JSON | data.ToCUE }}'
+        {
+        	foo: "bar"
+        }
+      - |
+        $ gomplate -i '{{ toCUE "hello world" }}'
+        "hello world"
+      - |
+        $ gomplate -i '{{ coll.Slice 1 "two" true | data.ToCUE }}'
+        [1, "two", true]

funcs/data.go

@@ -48,11 +48,13 @@ func CreateDataFuncs(ctx context.Context,
 	f["csv"] = ns.CSV
 	f["csvByRow"] = ns.CSVByRow
 	f["csvByColumn"] = ns.CSVByColumn
+	f["cue"] = ns.CUE
 	f["toJSON"] = ns.ToJSON
 	f["toJSONPretty"] = ns.ToJSONPretty
 	f["toYAML"] = ns.ToYAML
 	f["toTOML"] = ns.ToTOML
 	f["toCSV"] = ns.ToCSV
+	f["toCUE"] = ns.ToCUE
 	return f
 }
 
@@ -101,11 +103,21 @@ func (f *DataFuncs) CSVByColumn(args ...string) (cols map[string][]string, err e
 	return data.CSVByColumn(args...)
 }
 
+// CUE -
+func (f *DataFuncs) CUE(in interface{}) (interface{}, error) {
+	return data.CUE(conv.ToString(in))
+}
+
 // ToCSV -
 func (f *DataFuncs) ToCSV(args ...interface{}) (string, error) {
 	return data.ToCSV(args...)
 }
 
+// ToCUE -
+func (f *DataFuncs) ToCUE(in interface{}) (string, error) {
+	return data.ToCUE(in)
+}
+
 // ToJSON -
 func (f *DataFuncs) ToJSON(in interface{}) (string, error) {
 	return data.ToJSON(in)

go.mod

@@ -3,6 +3,7 @@ module github.com/hairyhenderson/gomplate/v4
 go 1.20
 
 require (
+	cuelang.org/go v0.6.0-alpha.2
 	github.com/Masterminds/goutils v1.1.1
 	github.com/Masterminds/semver v1.5.0
 	github.com/Shopify/ejson v1.4.0
@@ -73,6 +74,7 @@ require (
 	github.com/aws/smithy-go v1.13.5 // indirect
 	github.com/cenkalti/backoff/v3 v3.2.2 // indirect
 	github.com/cloudflare/circl v1.3.3 // indirect
+	github.com/cockroachdb/apd/v3 v3.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dustin/gojson v0.0.0-20160307161227-2e71ec9dd5ad // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
@@ -109,6 +111,7 @@ require (
 	github.com/mattn/go-isatty v0.0.19 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/mpvl/unique v0.0.0-20150818121801-cbe035fff7de // indirect
 	github.com/pjbgf/sha1cd v0.3.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/ryanuber/go-glob v1.0.0 // indirect