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expand.go
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expand.go
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package main
// Modified copy of os/env.go. The Go LICENSE file is included below:
// Copyright (c) 2009 The Go Authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Copyright 2010 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.
func expand(s, escape string, mapping func(string) string) string {
buf := make([]byte, 0, 2*len(s))
i := 0
shouldEscape := len(escape) > 0
escaped := escape + "$"
for j := 0; j < len(s); j++ {
if shouldEscape {
if j+len(escaped) < len(s) && s[j:j+len(escaped)] == escaped {
buf = append(buf, s[i:j]...)
buf = append(buf, s[j+len(escape):j+len(escaped)]...)
i = j + len(escaped)
j = i
continue
}
}
if s[j] == '$' && j+1 < len(s) {
buf = append(buf, s[i:j]...)
name, w := variableName(s[j+1:])
value := mapping(name)
buf = append(buf, value...)
j += w
i = j + 1
}
}
return string(buf) + s[i:]
}
func isAlphaNum(c uint8) bool {
return c == '_' || '0' <= c && c <= '9' || 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z'
}
func variableName(s string) (string, int) {
if s[0] == '{' {
for i := 1; i < len(s); i++ {
if s[i] == '}' {
return s[1:i], i + 1
}
}
return "", 1
}
var i int
for i = 0; i < len(s) && isAlphaNum(s[i]); i++ {
}
return s[:i], i
}