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vendor/github.com/andybalholm/brotli/matchfinder/textencoder.go

@@ -0,0 +1,53 @@
+package matchfinder
+
+import "fmt"
+
+// A TextEncoder is an Encoder that produces a human-readable representation of
+// the LZ77 compression. Matches are replaced with <Length,Distance> symbols.
+type TextEncoder struct{}
+
+func (t TextEncoder) Reset() {}
+
+func (t TextEncoder) Encode(dst []byte, src []byte, matches []Match, lastBlock bool) []byte {
+	pos := 0
+	for _, m := range matches {
+		if m.Unmatched > 0 {
+			dst = append(dst, src[pos:pos+m.Unmatched]...)
+			pos += m.Unmatched
+		}
+		if m.Length > 0 {
+			dst = append(dst, []byte(fmt.Sprintf("<%d,%d>", m.Length, m.Distance))...)
+			pos += m.Length
+		}
+	}
+	if pos < len(src) {
+		dst = append(dst, src[pos:]...)
+	}
+	return dst
+}
+
+// A NoMatchFinder implements MatchFinder, but doesn't find any matches.
+// It can be used to implement the equivalent of the standard library flate package's
+// HuffmanOnly setting.
+type NoMatchFinder struct{}
+
+func (n NoMatchFinder) Reset() {}
+
+func (n NoMatchFinder) FindMatches(dst []Match, src []byte) []Match {
+	return append(dst, Match{
+		Unmatched: len(src),
+	})
+}
+
+// AutoReset wraps a MatchFinder that can return references to data in previous
+// blocks, and calls Reset before each block. It is useful for (e.g.) using a
+// snappy Encoder with a MatchFinder designed for flate. (Snappy doesn't
+// support references between blocks.)
+type AutoReset struct {
+	MatchFinder
+}
+
+func (a AutoReset) FindMatches(dst []Match, src []byte) []Match {
+	a.Reset()
+	return a.MatchFinder.FindMatches(dst, src)
+}