cuelang.org/go@v0.10.1/internal/filetypes/types.go (about)

     1  // Copyright 2020 CUE Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package filetypes
    16  
    17  import (
    18  	_ "embed"
    19  	"fmt"
    20  	"sync"
    21  
    22  	"cuelang.org/go/cue"
    23  	"cuelang.org/go/cue/build"
    24  	"cuelang.org/go/cue/cuecontext"
    25  )
    26  
    27  //go:embed types.cue
    28  var typesCUE string
    29  
    30  var (
    31  	typesValue cue.Value
    32  	fileForExt map[string]*build.File
    33  	fileForCUE *build.File
    34  )
    35  
    36  var typesInit = sync.OnceFunc(func() {
    37  	ctx := cuecontext.New()
    38  	typesValue = ctx.CompileString(typesCUE, cue.Filename("types.cue"))
    39  	if err := typesValue.Err(); err != nil {
    40  		panic(err)
    41  	}
    42  	// Reading a file in input mode with a non-explicit scope is a very
    43  	// common operation, so cache the build.File value for all
    44  	// the known file extensions.
    45  	if err := typesValue.LookupPath(cue.MakePath(cue.Str("fileForExtVanilla"))).Decode(&fileForExt); err != nil {
    46  		panic(err)
    47  	}
    48  	fileForCUE = fileForExt[".cue"]
    49  	// Check invariants assumed by FromFile
    50  	if fileForCUE.Form != "" || fileForCUE.Interpretation != "" || fileForCUE.Encoding != build.CUE {
    51  		panic(fmt.Errorf("unexpected value for CUE file type: %#v", fileForCUE))
    52  	}
    53  })