44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
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package parse
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// TokenKind is a number identifying a token kind. To enumerate your set of
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// tokens, use iota and start at zero.
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type TokenKind int; const (
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EOF TokenKind = -1
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)
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// Token is any token.
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type Token struct {
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Position Position
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Kind TokenKind
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Value string
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}
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// EOF returns whether or not the token is an EOF token.
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func (tok Token) EOF () bool {
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return tok.Kind == EOF
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}
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// Is returns whether or not the token kind matches any of the given kinds.
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func (tok Token) Is (kinds ...TokenKind) bool {
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for _, kind := range kinds {
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if tok.Kind == kind { return true }
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}
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return false
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}
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// Is returns whether or not the token value matches any of the given values.
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func (tok Token) ValueIs (values ...string) bool {
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for _, value := range values {
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if tok.Value == value { return true }
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}
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return false
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}
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// Lexer is an object capable of producing tokens.
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type Lexer interface {
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// Next returns the next token. If there are no more tokens, it returns
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// an EOF token. It only returns an error on EOF if the file terminated
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// unexpectedly.
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Next () (Token, error)
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}
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