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// Copyright 2011 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 main
import (
"go/ast"
)
var oserrorstringFix = fix{
"oserrorstring",
oserrorstring,
`Replace os.ErrorString() conversions with calls to os.NewError().
http://codereview.appspot.com/4607052
`,
}
func init() {
register(oserrorstringFix)
}
func oserrorstring(f *ast.File) bool {
if !imports(f, "os") {
return false
}
fixed := false
walk(f, func(n interface{}) {
// The conversion os.ErrorString(x) looks like a call
// of os.ErrorString with one argument.
if call := callExpr(n, "os", "ErrorString"); call != nil {
// os.ErrorString(args) -> os.NewError(args)
call.Fun.(*ast.SelectorExpr).Sel.Name = "NewError"
// os.ErrorString(args) -> os.NewError(args)
call.Fun.(*ast.SelectorExpr).Sel.Name = "NewError"
fixed = true
return
}
// Remove os.Error type from variable declarations initialized
// with an os.NewError.
// (An *ast.ValueSpec may also be used in a const declaration
// but those won't be initialized with a call to os.NewError.)
if spec, ok := n.(*ast.ValueSpec); ok &&
len(spec.Names) == 1 &&
isPkgDot(spec.Type, "os", "Error") &&
len(spec.Values) == 1 &&
callExpr(spec.Values[0], "os", "NewError") != nil {
// var name os.Error = os.NewError(x) ->
// var name = os.NewError(x)
spec.Type = nil
fixed = true
return
}
// Other occurrences of os.ErrorString are not fixed
// but they are rare.
})
return fixed
}
// callExpr returns the call expression if x is a call to pkg.name with one argument;
// otherwise it returns nil.
func callExpr(x interface{}, pkg, name string) *ast.CallExpr {
if call, ok := x.(*ast.CallExpr); ok &&
len(call.Args) == 1 &&
isPkgDot(call.Fun, pkg, name) {
return call
}
return nil
}
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