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// Copyright 2019 The CUE Authors
//
// 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 yaml converts YAML encodings to and from CUE. When converting to CUE,
// comments and position information are retained.
package yaml
import (
"bytes"
"io"
"cuelang.org/go/cue"
"cuelang.org/go/cue/ast"
cueyaml "cuelang.org/go/internal/encoding/yaml"
"cuelang.org/go/internal/source"
pkgyaml "cuelang.org/go/pkg/encoding/yaml"
)
// Extract parses the YAML specified by src to a CUE expression. If
// there's more than one document, the documents will be returned as a
// list. The src argument may be a nil, string, []byte, or io.Reader. If
// src is nil, the result of reading the file specified by filename will
// be used.
func Extract(filename string, src interface{}) (*ast.File, error) {
data, err := source.ReadAll(filename, src)
if err != nil {
return nil, err
}
a := []ast.Expr{}
d := cueyaml.NewDecoder(filename, data)
for {
expr, err := d.Decode()
if err != nil {
if err != io.EOF {
return nil, err
}
if expr != nil {
a = append(a, expr)
}
break
}
a = append(a, expr)
}
f := &ast.File{Filename: filename}
switch len(a) {
case 0:
case 1:
switch x := a[0].(type) {
case *ast.StructLit:
f.Decls = x.Elts
default:
f.Decls = []ast.Decl{&ast.EmbedDecl{Expr: x}}
}
default:
f.Decls = []ast.Decl{&ast.EmbedDecl{Expr: &ast.ListLit{Elts: a}}}
}
return f, nil
}
// Encode returns the YAML encoding of v.
func Encode(v cue.Value) ([]byte, error) {
n := v.Syntax(cue.Final())
b, err := cueyaml.Encode(n)
return b, err
}
// EncodeStream returns the YAML encoding of iter, where consecutive values
// of iter are separated with a `---`.
func EncodeStream(iter cue.Iterator) ([]byte, error) {
// TODO: return an io.Reader and allow asynchronous processing.
buf := &bytes.Buffer{}
for i := 0; iter.Next(); i++ {
if i > 0 {
buf.WriteString("---\n")
}
n := iter.Value().Syntax(cue.Final())
b, err := cueyaml.Encode(n)
if err != nil {
return nil, err
}
buf.Write(b)
}
return buf.Bytes(), nil
}
// Validate validates the YAML and confirms it matches the constraints
// specified by v. For YAML streams, all values must match v.
func Validate(b []byte, v cue.Value) error {
// TODO(mvdan): encoding/yaml should not import pkg/encoding/yaml.
_, err := pkgyaml.Validate(b, v)
return err
}
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