105 lines
3.2 KiB
Go
105 lines
3.2 KiB
Go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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Gofmt formats Go programs.
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It uses tabs for indentation and blanks for alignment.
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Alignment assumes that an editor is using a fixed-width font.
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Without an explicit path, it processes the standard input. Given a file,
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it operates on that file; given a directory, it operates on all .go files in
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that directory, recursively. (Files starting with a period are ignored.)
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By default, gofmt prints the reformatted sources to standard output.
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Usage:
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gofmt [flags] [path ...]
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The flags are:
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-d
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Do not print reformatted sources to standard output.
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If a file's formatting is different than gofmt's, print diffs
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to standard output.
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-e
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Print all (including spurious) errors.
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-l
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Do not print reformatted sources to standard output.
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If a file's formatting is different from gofmt's, print its name
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to standard output.
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-r rule
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Apply the rewrite rule to the source before reformatting.
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-s
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Try to simplify code (after applying the rewrite rule, if any).
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-w
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Do not print reformatted sources to standard output.
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If a file's formatting is different from gofmt's, overwrite it
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with gofmt's version. If an error occurred during overwriting,
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the original file is restored from an automatic backup.
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Debugging support:
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-cpuprofile filename
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Write cpu profile to the specified file.
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The rewrite rule specified with the -r flag must be a string of the form:
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pattern -> replacement
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Both pattern and replacement must be valid Go expressions.
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In the pattern, single-character lowercase identifiers serve as
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wildcards matching arbitrary sub-expressions; those expressions
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will be substituted for the same identifiers in the replacement.
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When gofmt reads from standard input, it accepts either a full Go program
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or a program fragment. A program fragment must be a syntactically
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valid declaration list, statement list, or expression. When formatting
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such a fragment, gofmt preserves leading indentation as well as leading
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and trailing spaces, so that individual sections of a Go program can be
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formatted by piping them through gofmt.
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Examples
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To check files for unnecessary parentheses:
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gofmt -r '(a) -> a' -l *.go
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To remove the parentheses:
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gofmt -r '(a) -> a' -w *.go
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To convert the package tree from explicit slice upper bounds to implicit ones:
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gofmt -r 'α[β:len(α)] -> α[β:]' -w $GOROOT/src
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The simplify command
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When invoked with -s gofmt will make the following source transformations where possible.
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An array, slice, or map composite literal of the form:
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[]T{T{}, T{}}
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will be simplified to:
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[]T{{}, {}}
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A slice expression of the form:
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s[a:len(s)]
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will be simplified to:
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s[a:]
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A range of the form:
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for x, _ = range v {...}
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will be simplified to:
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for x = range v {...}
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A range of the form:
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for _ = range v {...}
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will be simplified to:
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for range v {...}
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This may result in changes that are incompatible with earlier versions of Go.
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*/
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package main
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// BUG(rsc): The implementation of -r is a bit slow.
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// BUG(gri): If -w fails, the restored original file may not have some of the
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// original file attributes.
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