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import source from cmd/gofmt

Without the long tests, as the Go repository won't follow this stricter
format for now.

We also don't want the other tests, as some directly contradict the
extra changes that gofumpt will enforce. We'll check for regressions
against gofmt by running gofumpt against the Go repository as needed.
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mvdan committed Mar 30, 2019
1 parent 7b2f6c0 commit afc5dc71d3cc6136fd337a25727c1d80d1d96035
Showing with 1,148 additions and 0 deletions.
  1. +104 −0 doc.go
  2. +400 −0 gofmt.go
  3. +176 −0 internal.go
  4. +303 −0 rewrite.go
  5. +165 −0 simplify.go
104 doc.go
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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.

Gofmt formats Go programs.
It uses tabs for indentation and blanks for alignment.
Alignment assumes that an editor is using a fixed-width font.
Without an explicit path, it processes the standard input. Given a file,
it operates on that file; given a directory, it operates on all .go files in
that directory, recursively. (Files starting with a period are ignored.)
By default, gofmt prints the reformatted sources to standard output.
gofmt [flags] [path ...]
The flags are:
Do not print reformatted sources to standard output.
If a file's formatting is different than gofmt's, print diffs
to standard output.
Print all (including spurious) errors.
Do not print reformatted sources to standard output.
If a file's formatting is different from gofmt's, print its name
to standard output.
-r rule
Apply the rewrite rule to the source before reformatting.
Try to simplify code (after applying the rewrite rule, if any).
Do not print reformatted sources to standard output.
If a file's formatting is different from gofmt's, overwrite it
with gofmt's version. If an error occurred during overwriting,
the original file is restored from an automatic backup.
Debugging support:
-cpuprofile filename
Write cpu profile to the specified file.
The rewrite rule specified with the -r flag must be a string of the form:
pattern -> replacement
Both pattern and replacement must be valid Go expressions.
In the pattern, single-character lowercase identifiers serve as
wildcards matching arbitrary sub-expressions; those expressions
will be substituted for the same identifiers in the replacement.
When gofmt reads from standard input, it accepts either a full Go program
or a program fragment. A program fragment must be a syntactically
valid declaration list, statement list, or expression. When formatting
such a fragment, gofmt preserves leading indentation as well as leading
and trailing spaces, so that individual sections of a Go program can be
formatted by piping them through gofmt.
To check files for unnecessary parentheses:
gofmt -r '(a) -> a' -l *.go
To remove the parentheses:
gofmt -r '(a) -> a' -w *.go
To convert the package tree from explicit slice upper bounds to implicit ones:
gofmt -r 'α[β:len(α)] -> α[β:]' -w $GOROOT/src
The simplify command
When invoked with -s gofmt will make the following source transformations where possible.
An array, slice, or map composite literal of the form:
[]T{T{}, T{}}
will be simplified to:
[]T{{}, {}}
A slice expression of the form:
will be simplified to:
A range of the form:
for x, _ = range v {...}
will be simplified to:
for x = range v {...}
A range of the form:
for _ = range v {...}
will be simplified to:
for range v {...}
This may result in changes that are incompatible with earlier versions of Go.
package main

// BUG(rsc): The implementation of -r is a bit slow.
// BUG(gri): If -w fails, the restored original file may not have some of the
// original file attributes.

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