chore: upgrade coredns version (#550)

vendor/github.com/expr-lang/expr/file/source.go

@@ -0,0 +1,48 @@
+package file
+
+import (
+	"strings"
+	"unicode/utf8"
+)
+
+type Source []rune
+
+func NewSource(contents string) Source {
+	return []rune(contents)
+}
+
+func (s Source) String() string {
+	return string(s)
+}
+
+func (s Source) Snippet(line int) (string, bool) {
+	if s == nil {
+		return "", false
+	}
+	lines := strings.Split(string(s), "\n")
+	lineOffsets := make([]int, len(lines))
+	var offset int
+	for i, line := range lines {
+		offset = offset + utf8.RuneCountInString(line) + 1
+		lineOffsets[i] = offset
+	}
+	charStart, found := getLineOffset(lineOffsets, line)
+	if !found || len(s) == 0 {
+		return "", false
+	}
+	charEnd, found := getLineOffset(lineOffsets, line+1)
+	if found {
+		return string(s[charStart : charEnd-1]), true
+	}
+	return string(s[charStart:]), true
+}
+
+func getLineOffset(lineOffsets []int, line int) (int, bool) {
+	if line == 1 {
+		return 0, true
+	} else if line > 1 && line <= len(lineOffsets) {
+		offset := lineOffsets[line-2]
+		return offset, true
+	}
+	return -1, false
+}