55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
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package participle
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import (
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"github.com/alecthomas/participle/v2/lexer"
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)
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// An Option to modify the behaviour of the Parser.
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type Option func(p *Parser) error
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// Lexer is an Option that sets the lexer to use with the given grammar.
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func Lexer(def lexer.Definition) Option {
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return func(p *Parser) error {
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p.lex = def
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return nil
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}
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}
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// UseLookahead allows branch lookahead up to "n" tokens.
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//
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// If parsing cannot be disambiguated before "n" tokens of lookahead, parsing will fail.
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//
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// Note that increasing lookahead has a minor performance impact, but also
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// reduces the accuracy of error reporting.
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func UseLookahead(n int) Option {
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return func(p *Parser) error {
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p.useLookahead = n
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return nil
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}
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}
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// CaseInsensitive allows the specified token types to be matched case-insensitively.
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//
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// Note that the lexer itself will also have to be case-insensitive; this option
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// just controls whether literals in the grammar are matched case insensitively.
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func CaseInsensitive(tokens ...string) Option {
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return func(p *Parser) error {
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for _, token := range tokens {
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p.caseInsensitive[token] = true
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}
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return nil
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}
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}
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// ParseOption modifies how an individual parse is applied.
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type ParseOption func(p *parseContext)
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// AllowTrailing tokens without erroring.
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//
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// That is, do not error if a full parse completes but additional tokens remain.
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func AllowTrailing(ok bool) ParseOption {
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return func(p *parseContext) {
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p.allowTrailing = ok
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}
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}
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