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Diffstat (limited to 'src/cmd/internal/quoted/quoted.go')
-rw-r--r-- | src/cmd/internal/quoted/quoted.go | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/src/cmd/internal/quoted/quoted.go b/src/cmd/internal/quoted/quoted.go new file mode 100644 index 0000000..a812275 --- /dev/null +++ b/src/cmd/internal/quoted/quoted.go @@ -0,0 +1,129 @@ +// Copyright 2017 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 quoted provides string manipulation utilities. +package quoted + +import ( + "flag" + "fmt" + "strings" + "unicode" +) + +func isSpaceByte(c byte) bool { + return c == ' ' || c == '\t' || c == '\n' || c == '\r' +} + +// Split splits s into a list of fields, +// allowing single or double quotes around elements. +// There is no unescaping or other processing within +// quoted fields. +// +// Keep in sync with cmd/dist/quoted.go +func Split(s string) ([]string, error) { + // Split fields allowing '' or "" around elements. + // Quotes further inside the string do not count. + var f []string + for len(s) > 0 { + for len(s) > 0 && isSpaceByte(s[0]) { + s = s[1:] + } + if len(s) == 0 { + break + } + // Accepted quoted string. No unescaping inside. + if s[0] == '"' || s[0] == '\'' { + quote := s[0] + s = s[1:] + i := 0 + for i < len(s) && s[i] != quote { + i++ + } + if i >= len(s) { + return nil, fmt.Errorf("unterminated %c string", quote) + } + f = append(f, s[:i]) + s = s[i+1:] + continue + } + i := 0 + for i < len(s) && !isSpaceByte(s[i]) { + i++ + } + f = append(f, s[:i]) + s = s[i:] + } + return f, nil +} + +// Join joins a list of arguments into a string that can be parsed +// with Split. Arguments are quoted only if necessary; arguments +// without spaces or quotes are kept as-is. No argument may contain both +// single and double quotes. +func Join(args []string) (string, error) { + var buf []byte + for i, arg := range args { + if i > 0 { + buf = append(buf, ' ') + } + var sawSpace, sawSingleQuote, sawDoubleQuote bool + for _, c := range arg { + switch { + case c > unicode.MaxASCII: + continue + case isSpaceByte(byte(c)): + sawSpace = true + case c == '\'': + sawSingleQuote = true + case c == '"': + sawDoubleQuote = true + } + } + switch { + case !sawSpace && !sawSingleQuote && !sawDoubleQuote: + buf = append(buf, arg...) + + case !sawSingleQuote: + buf = append(buf, '\'') + buf = append(buf, arg...) + buf = append(buf, '\'') + + case !sawDoubleQuote: + buf = append(buf, '"') + buf = append(buf, arg...) + buf = append(buf, '"') + + default: + return "", fmt.Errorf("argument %q contains both single and double quotes and cannot be quoted", arg) + } + } + return string(buf), nil +} + +// A Flag parses a list of string arguments encoded with Join. +// It is useful for flags like cmd/link's -extldflags. +type Flag []string + +var _ flag.Value = (*Flag)(nil) + +func (f *Flag) Set(v string) error { + fs, err := Split(v) + if err != nil { + return err + } + *f = fs[:len(fs):len(fs)] + return nil +} + +func (f *Flag) String() string { + if f == nil { + return "" + } + s, err := Join(*f) + if err != nil { + return strings.Join(*f, " ") + } + return s +} |