| // 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 ( |
| "fmt" |
| "io/ioutil" |
| "os" |
| |
| "cuelang.org/go/cue/format" |
| "cuelang.org/go/internal" |
| "cuelang.org/go/tools/trim" |
| "github.com/spf13/cobra" |
| ) |
| |
| // 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 maching 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), |
| } |
| |
| flagOut.Add(cmd) |
| return cmd |
| } |
| |
| func runTrim(cmd *Command, args []string) error { |
| // TODO: Do something more fine-grained. Optional fields are mostly not |
| // useful to consider as an optional field will almost never subsume |
| // another value. However, an optional field may subsume and therefore |
| // trigger the removal of another optional field. |
| // For now this is the better approach: trimming is not 100% accurate, |
| // and optional fields are just more likely to cause edge cases that may |
| // block a removal. |
| internal.DropOptional = true |
| defer func() { internal.DropOptional = false }() |
| |
| binst := loadFromArgs(cmd, args, defaultConfig) |
| if binst == nil { |
| return nil |
| } |
| instances := buildInstances(cmd, binst) |
| |
| // dst := flagName("o").String(cmd) |
| dst := flagOut.String(cmd) |
| if dst != "" && dst != "-" { |
| switch _, err := os.Stat(dst); { |
| case os.IsNotExist(err): |
| case err == nil: |
| default: |
| return fmt.Errorf("error creating file: %v", err) |
| } |
| } |
| |
| 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 |
| } |
| |
| if flagDryrun.Bool(cmd) { |
| continue |
| } |
| |
| 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 |
| } |