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27 lines
620 B
27 lines
620 B
// Package grammar is used for parsing a stream of runes according to a set of
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// grammatical rules. This package only supports context-free grammars.
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package grammar
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import "fmt"
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// Stringer is a convenience tool for working with fmt.Stringer. Exactly one of
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// the fields must be set, and will be used to implement the fmt.Stringer
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// interface.
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type Stringer struct {
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I fmt.Stringer
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F func() string
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S string
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}
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func (s Stringer) String() string {
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switch {
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case s.I != nil:
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return s.I.String()
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case s.F != nil:
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return s.F()
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case s.S != "":
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return s.S
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default:
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panic("no fields set on Stringer")
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}
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}
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