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22 lines
361 B
Go
22 lines
361 B
Go
12 years ago
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package main
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import (
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"fmt"
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)
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type UnknownSymbolError struct{ symbol }
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func (u UnknownSymbolError) Error() string {
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return fmt.Sprintf(`unknown symbol "%v"`, u.symbol)
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}
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type environment map[symbol]interface{}
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func (e environment) get(key symbol) (interface{}, error) {
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v, ok := e[key]
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if ok {
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return v, nil
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}
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return nil, UnknownSymbolError{key}
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}
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