mirror of git://gcc.gnu.org/git/gcc.git
75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
// Copyright 2015 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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// This file contains the code to handle template options.
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package template
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import "strings"
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// missingKeyAction defines how to respond to indexing a map with a key that is not present.
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type missingKeyAction int
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const (
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mapInvalid missingKeyAction = iota // Return an invalid reflect.Value.
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mapZeroValue // Return the zero value for the map element.
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mapError // Error out
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)
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type option struct {
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missingKey missingKeyAction
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}
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// Option sets options for the template. Options are described by
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// strings, either a simple string or "key=value". There can be at
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// most one equals sign in an option string. If the option string
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// is unrecognized or otherwise invalid, Option panics.
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//
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// Known options:
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//
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// missingkey: Control the behavior during execution if a map is
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// indexed with a key that is not present in the map.
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// "missingkey=default" or "missingkey=invalid"
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// The default behavior: Do nothing and continue execution.
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// If printed, the result of the index operation is the string
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// "<no value>".
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// "missingkey=zero"
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// The operation returns the zero value for the map type's element.
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// "missingkey=error"
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// Execution stops immediately with an error.
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//
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func (t *Template) Option(opt ...string) *Template {
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t.init()
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for _, s := range opt {
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t.setOption(s)
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}
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return t
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}
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func (t *Template) setOption(opt string) {
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if opt == "" {
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panic("empty option string")
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}
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elems := strings.Split(opt, "=")
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switch len(elems) {
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case 2:
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// key=value
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switch elems[0] {
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case "missingkey":
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switch elems[1] {
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case "invalid", "default":
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t.option.missingKey = mapInvalid
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return
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case "zero":
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t.option.missingKey = mapZeroValue
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return
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case "error":
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t.option.missingKey = mapError
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return
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}
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}
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}
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panic("unrecognized option: " + opt)
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}
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