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// Copyright 2018 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 cmd
import (
"errors"
"fmt"
"io/ioutil"
"os"
"github.com/spf13/cobra"
"cuelang.org/go/cue/format"
"cuelang.org/go/cue/load"
"cuelang.org/go/internal/diff"
"cuelang.org/go/tools/trim"
)
// TODO:
// - remove the limitations mentioned in the documentation
// - implement verification post-processing as extra safety
// newTrimCmd creates a trim command
func newTrimCmd(c *Command) *cobra.Command {
cmd := &cobra.Command{
Use: "trim",
Short: "remove superfluous fields",
Long: `trim removes fields from structs that can be inferred from constraints
A field, struct, or list is removed if it is implied by a constraint, such
as from an optional field matching a required field, a list type value,
a comprehension or any other implied content. It will modify the files in place.
Limitations
Removal is on a best effort basis. Some caveats:
- Fields in implied content may refer to fields within the struct in which
they are included, but are only resolved on a best-effort basis.
- Disjunctions that contain structs in implied content cannot be used to
remove fields.
- There is currently no verification step: manual verification is required.
Examples:
$ cat <<EOF > foo.cue
light: [string]: {
room: string
brightnessOff: *0.0 | >=0 & <=100.0
brightnessOn: *100.0 | >=0 & <=100.0
}
light: ceiling50: {
room: "MasterBedroom"
brightnessOff: 0.0 // this line
brightnessOn: 100.0 // and this line will be removed
}
EOF
$ cue trim foo.cue
$ cat foo.cue
light: [string]: {
room: string
brightnessOff: *0.0 | >=0 & <=100.0
brightnessOn: *100.0 | >=0 & <=100.0
}
light: ceiling50: {
room: "MasterBedroom"
}
It is guaranteed that the resulting files give the same output as before the
removal.
`,
RunE: mkRunE(c, runTrim),
}
addOutFlags(cmd.Flags(), false)
return cmd
}
func runTrim(cmd *Command, args []string) error {
binst := loadFromArgs(cmd, args, nil)
if binst == nil {
return nil
}
instances := buildInstances(cmd, binst)
dst := flagOutFile.String(cmd)
if dst != "" && dst != "-" && !flagForce.Bool(cmd) {
switch _, err := os.Stat(dst); {
case os.IsNotExist(err):
default:
return fmt.Errorf("error writing %q: file already exists", dst)
}
}
overlay := map[string]load.Source{}
for i, inst := range binst {
root := instances[i]
err := trim.Files(inst.Files, root, &trim.Config{
Trace: flagTrace.Bool(cmd),
})
if err != nil {
return err
}
for _, f := range inst.Files {
overlay[f.Filename] = load.FromFile(f)
}
}
cfg := *defaultConfig.loadCfg
cfg.Overlay = overlay
tinsts := buildInstances(cmd, load.Instances(args, &cfg))
if len(tinsts) != len(binst) {
return errors.New("unexpected number of new instances")
}
if !flagIgnore.Bool(cmd) {
for i, p := range instances {
k, script := diff.Final.Diff(p.Value(), tinsts[i].Value())
if k != diff.Identity {
diff.Print(os.Stdout, script)
fmt.Println("Aborting trim, output differs after trimming. This is a bug! Use -i to force trim.")
fmt.Println("You can file a bug here: https://github.com/cuelang/cue/issues/new?assignees=&labels=NeedsInvestigation&template=bug_report.md&title=")
os.Exit(1)
}
}
}
if flagDryrun.Bool(cmd) {
return nil
}
for _, inst := range binst {
for _, f := range inst.Files {
filename := f.Filename
opts := []format.Option{}
if flagSimplify.Bool(cmd) {
opts = append(opts, format.Simplify())
}
b, err := format.Node(f, opts...)
if err != nil {
return fmt.Errorf("error formatting file: %v", err)
}
if dst == "-" {
_, err := cmd.OutOrStdout().Write(b)
if err != nil {
return err
}
continue
} else if dst != "" {
filename = dst
}
err = ioutil.WriteFile(filename, b, 0644)
if err != nil {
return err
}
}
}
return nil
}