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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 ast
import (
"datafmt";
"go/ast";
"go/token";
"io";
"os";
)
// Format is a customized datafmt.Format for printing of ASTs.
type Format datafmt.Format;
// ----------------------------------------------------------------------------
// Custom formatters
// The AST-specific formatting state is maintained by a state variable.
type state struct {
// for now we have very little state
// TODO maintain list of unassociated comments
optSemi *bool
}
func (s *state) Copy() datafmt.Environment {
optSemi := *s.optSemi;
return &state{&optSemi};
}
func isValidPos(s *datafmt.State, value interface{}, ruleName string) bool {
pos := value.(token.Position);
return pos.IsValid();
}
func isSend(s *datafmt.State, value interface{}, ruleName string) bool {
return value.(ast.ChanDir) & ast.SEND != 0;
}
func isRecv(s *datafmt.State, value interface{}, ruleName string) bool {
return value.(ast.ChanDir) & ast.RECV != 0;
}
func isMultiLineComment(s *datafmt.State, value interface{}, ruleName string) bool {
return value.([]byte)[1] == '*';
}
func clearOptSemi(s *datafmt.State, value interface{}, ruleName string) bool {
*s.Env().(*state).optSemi = false;
return true;
}
func setOptSemi(s *datafmt.State, value interface{}, ruleName string) bool {
*s.Env().(*state).optSemi = true;
return true;
}
func optSemi(s *datafmt.State, value interface{}, ruleName string) bool {
if !*s.Env().(*state).optSemi {
s.Write([]byte{';'});
}
return true;
}
var fmap = datafmt.FormatterMap {
"isValidPos": isValidPos,
"isSend": isSend,
"isRecv": isRecv,
"isMultiLineComment": isMultiLineComment,
"/": clearOptSemi,
"clearOptSemi": clearOptSemi,
"setOptSemi": setOptSemi,
"optSemi": optSemi,
}
// ----------------------------------------------------------------------------
// Printing
// NewFormat parses a datafmt format specification from a file
// and adds AST-specific custom formatter rules. The result is
// the customized format or an os.Error, if any.
//
func NewFormat(filename string) (Format, os.Error) {
src, err := io.ReadFile(filename);
if err != nil {
return nil, err;
}
f, err := datafmt.Parse(src, fmap);
return Format(f), err;
}
// Fprint formats each AST node provided as argument according to the
// format f and writes to standard output. The result is the total number
// of bytes written and an os.Error, if any.
//
func (f Format) Fprint(w io.Writer, nodes ...) (int, os.Error) {
s := state{new(bool)};
return datafmt.Format(f).Fprint(w, &s, nodes);
}
// Fprint formats each AST node provided as argument according to the
// format f and writes to w. The result is the total number of bytes
// written and an os.Error, if any.
//
func (f Format) Print(nodes ...) (int, os.Error) {
return f.Fprint(os.Stdout, nodes);
}
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