47 lines
1.6 KiB
Go
47 lines
1.6 KiB
Go
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package bytes
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import (
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"fmt"
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"regexp"
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"strings"
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"git.codemonkeysoftware.net/b/gigaparsec"
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"git.codemonkeysoftware.net/b/gigaparsec/cursor"
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)
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func Regexp(str string) gigaparsec.Parser[byte, []byte] {
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if !strings.HasPrefix(str, "^") {
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str = "^" + str
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}
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re := regexp.MustCompile(str)
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expected := fmt.Sprintf("match `%s`", str)
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return func(input gigaparsec.State[byte]) (consumed bool, result gigaparsec.Result[byte, []byte], err error) {
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r := cursor.NewRuneReader(input.Cursor())
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idx := re.FindReaderIndex(r)
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// TODO Check error from r; this requires an Error() method on cursor.RuneReader.
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if idx == nil {
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return false, gigaparsec.Result[byte, []byte]{}, gigaparsec.ParseError{
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Pos: input.Pos(),
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Expected: []string{expected},
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// TODO Not having a Got is unsatisfactory, but how do I extract useful information?
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// Maybe just read a fixed number of bytes or to the end, whichever comes first?
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// I could add extra methods to cursor.RuneReader to figure out how much it had read.
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}
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}
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// Alas, this is a little wasteful because a Regexp can only return indices
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// when searching a RuneReader.
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dst := make([]byte, idx[1]-idx[0])
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n, _, err := input.Cursor().Read(dst)
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if err != nil {
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// If we can't access those same bytes again, something is wrong.
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return false, gigaparsec.Result[byte, []byte]{}, fmt.Errorf("Regex: unexpected error: %w", err)
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}
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result = gigaparsec.Result[byte, []byte]{
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State: input.At(input.Pos() + n),
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Value: dst,
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Message: gigaparsec.MessageOK(input.Pos()),
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}
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return true, result, nil
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}
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}
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