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