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// 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 task provides a registry for tasks to be used by commands.
package task
import (
"context"
"io"
"sync"
"cuelang.org/go/cue"
"cuelang.org/go/cue/errors"
"cuelang.org/go/cue/token"
"cuelang.org/go/internal/core/adt"
"cuelang.org/go/internal/value"
)
// A Context provides context for running a task.
type Context struct {
Context context.Context
Stdin io.Reader
Stdout io.Writer
Stderr io.Writer
Obj cue.Value
Err errors.Error
}
func (c *Context) Lookup(field string) cue.Value {
f := c.Obj.LookupPath(cue.MakePath(cue.Str(field)))
if !f.Exists() {
c.addErr(f, nil, "could not find field %q", field)
return cue.Value{}
}
if err := f.Err(); err != nil {
c.Err = errors.Append(c.Err, errors.Promote(err, "lookup"))
}
return f
}
func (c *Context) Int64(field string) int64 {
f := c.Obj.LookupPath(cue.MakePath(cue.Str(field)))
value, err := f.Int64()
if err != nil {
c.addErr(f, err, "invalid integer argument")
return 0
}
return value
}
func (c *Context) String(field string) string {
f := c.Obj.LookupPath(cue.MakePath(cue.Str(field)))
value, err := f.String()
if err != nil {
c.addErr(f, err, "invalid string argument")
return ""
}
return value
}
func (c *Context) Bytes(field string) []byte {
f := c.Obj.LookupPath(cue.MakePath(cue.Str(field)))
value, err := f.Bytes()
if err != nil {
c.addErr(f, err, "invalid bytes argument")
return nil
}
return value
}
func (c *Context) addErr(v cue.Value, wrap error, format string, args ...interface{}) {
err := &taskError{
task: c.Obj,
v: v,
Message: errors.NewMessagef(format, args...),
}
c.Err = errors.Append(c.Err, errors.Wrap(err, wrap))
}
// taskError wraps some error values to retain position information about the
// error.
type taskError struct {
task cue.Value
v cue.Value
errors.Message
}
var _ errors.Error = &taskError{}
func (t *taskError) Path() (a []string) {
for _, x := range t.v.Path().Selectors() {
a = append(a, x.String())
}
return a
}
func (t *taskError) Position() token.Pos {
return t.task.Pos()
}
func (t *taskError) InputPositions() (a []token.Pos) {
_, nx := value.ToInternal(t.v)
nx.VisitLeafConjuncts(func(x adt.Conjunct) bool {
if src := x.Source(); src != nil {
a = append(a, src.Pos())
}
return true
})
return a
}
// A RunnerFunc creates a Runner.
type RunnerFunc func(v cue.Value) (Runner, error)
// A Runner defines a command type.
type Runner interface {
// Init is called with the original configuration before any task is run.
// As a result, the configuration may be incomplete, but allows some
// validation before tasks are kicked off.
// Init(v cue.Value)
// Runner runs given the current value and returns a new value which is to
// be unified with the original result.
Run(ctx *Context) (results interface{}, err error)
}
// Register registers a task for cue commands.
func Register(key string, f RunnerFunc) {
runners.Store(key, f)
}
// Lookup returns the RunnerFunc for a key.
func Lookup(key string) RunnerFunc {
v, ok := runners.Load(key)
if !ok {
return nil
}
return v.(RunnerFunc)
}
var runners sync.Map
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