mirror of
https://github.com/gdamore/tcell.git
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76 lines
2.8 KiB
Go
76 lines
2.8 KiB
Go
// Copyright 2015 The TCell Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use file except in compliance with the License.
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// You may obtain a copy of the license at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tcell
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import (
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"sync"
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"golang.org/x/text/encoding"
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)
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var encodings map[string]encoding.Encoding
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var encodingLk sync.Mutex
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// RegisterEncoding may be called by the application to register an encoding. The
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// presence of additional encodings will facilitate application usage with terminal
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// environments where the I/O subsystem does not support Unicode. Please see the
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// Go documentation for encodings -- most of the common ones exist already as stock
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// variables. For example, ISO8859-15 can be registered using the following code:
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//
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// import "golang.org/x/text/encoding/charmap"
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//
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// ...
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// RegisterEncoding("ISO8859-15", charmap.ISO8859_15)
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//
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// Aliases can be registered as well, for example "8859-15" could be an alias for
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// "ISO8859-15".
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//
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// For POSIX systems, the tcell pacakge will check the environment variables LC_ALL, LC_CTYPE,
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// and LANG (in that order) to determine the character set. These are expected to have the
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// following pattern: $language[.$codeset[@$variant] We extract only the $codeset part,
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// which will usually be something like UTF-8 or ISO8859-15 or KOI8-R. Note that if the
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// locale is either "POSIX" or "C", then we assume US-ASCII (the POSIX 'portable character set'
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// and assume all other characters are somehow invalid.)
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//
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// On Windows systems, the Console is assumed to be UTF-16LE. As we communicate with the
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// console subsystem using UTF-16LE, no conversions are necessary. So none of this is required
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// for Windows systems.
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//
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// Modern POSIX systems and terminal emulators may use UTF-8, and for those systems, this
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// API is also unnecessary. For example, Darwin (MacOS X) and modern Linux running modern
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// xterm generally will out of the box without any of this.
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//
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// Note that some encodings are quite large (for example GB18030 which is a superset of
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// Unicode) and so the application size can be expected ot increase quite a bit as each
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// encoding is added.
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//
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func RegisterEncoding(name string, enc encoding.Encoding) {
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encodingLk.Lock()
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if encodings == nil {
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encodings = make(map[string]encoding.Encoding)
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}
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encodings[name] = enc
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encodingLk.Unlock()
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}
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func GetEncoding(name string) encoding.Encoding {
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encodingLk.Lock()
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defer encodingLk.Unlock()
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if enc, ok := encodings[name]; ok {
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return enc
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}
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return nil
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}
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