| // Copyright 2019 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 source contains utility functions that standardize reading source |
| // bytes across cue packages. |
| package source |
| |
| import ( |
| "bytes" |
| "fmt" |
| "io" |
| "io/ioutil" |
| ) |
| |
| // Read loads the source bytes for the given arguments. If src != nil, |
| // Read converts src to a []byte if possible; otherwise it returns an |
| // error. If src == nil, readSource returns the result of reading the file |
| // specified by filename. |
| // |
| func Read(filename string, src interface{}) ([]byte, error) { |
| if src != nil { |
| switch s := src.(type) { |
| case string: |
| return []byte(s), nil |
| case []byte: |
| return s, nil |
| case *bytes.Buffer: |
| // is io.Reader, but src is already available in []byte form |
| if s != nil { |
| return s.Bytes(), nil |
| } |
| case io.Reader: |
| var buf bytes.Buffer |
| if _, err := io.Copy(&buf, s); err != nil { |
| return nil, err |
| } |
| return buf.Bytes(), nil |
| } |
| return nil, fmt.Errorf("invalid source type %T", src) |
| } |
| return ioutil.ReadFile(filename) |
| } |