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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package patch
import "os"
// An Op is a single operation to execute to apply a patch.
type Op struct {
Verb Verb; // action
Src string; // source file
Dst string; // destination file
Mode int; // mode for destination (if non-zero)
Data []byte; // data for destination (if non-nil)
}
// Apply applies the patch set to the files named in the patch set,
// constructing an in-memory copy of the new file state.
// It is the client's job to write the changes to the file system
// if desired.
//
// The function readFile should return the contents of the named file.
// Typically this function will be io.ReadFile.
//
func (set *Set) Apply(readFile func(string) ([]byte, os.Error)) ([]Op, os.Error) {
op := make([]Op, len(set.File));
for i, f := range set.File {
o := &op[i];
o.Verb = f.Verb;
o.Src = f.Src;
o.Dst = f.Dst;
o.Mode = f.NewMode;
if f.Diff != NoDiff || o.Verb != Edit {
// Clients assume o.Data == nil means no data diff.
// Start with a non-nil data.
var old []byte = make([]byte, 0); // not nil
var err os.Error;
if f.Src != "" {
old, err = readFile(f.Src);
if err != nil {
return nil, &os.PathError{string(f.Verb), f.Src, err};
}
}
o.Data, err = f.Diff.Apply(old);
if err != nil {
return nil, &os.PathError{string(f.Verb), f.Src, err};
}
}
}
return op, nil;
}
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