feat: add backend

pkg/wildcard/match.go

@@ -0,0 +1,51 @@
+package wildcard
+
+// MatchSimple - finds whether the text matches/satisfies the pattern string.
+// supports only '*' wildcard in the pattern.
+// considers a file system path as a flat name space.
+func MatchSimple(pattern, name string) bool {
+	if pattern == "" {
+		return name == pattern
+	}
+	if pattern == "*" {
+		return true
+	}
+	// Does only wildcard '*' match.
+	return deepMatchRune([]rune(name), []rune(pattern), true)
+}
+
+// Match -  finds whether the text matches/satisfies the pattern string.
+// supports  '*' and '?' wildcards in the pattern string.
+// unlike path.Match(), considers a path as a flat name space while matching the pattern.
+// The difference is illustrated in the example here https://play.golang.org/p/Ega9qgD4Qz .
+func Match(pattern, name string) (matched bool) {
+	if pattern == "" {
+		return name == pattern
+	}
+	if pattern == "*" {
+		return true
+	}
+	// Does extended wildcard '*' and '?' match.
+	return deepMatchRune([]rune(name), []rune(pattern), false)
+}
+
+func deepMatchRune(str, pattern []rune, simple bool) bool {
+	for len(pattern) > 0 {
+		switch pattern[0] {
+		default:
+			if len(str) == 0 || str[0] != pattern[0] {
+				return false
+			}
+		case '?':
+			if len(str) == 0 && !simple {
+				return false
+			}
+		case '*':
+			return deepMatchRune(str, pattern[1:], simple) ||
+				(len(str) > 0 && deepMatchRune(str[1:], pattern, simple))
+		}
+		str = str[1:]
+		pattern = pattern[1:]
+	}
+	return len(str) == 0 && len(pattern) == 0
+}

pkg/wildcard/match_test.go

@@ -0,0 +1,37 @@
+package wildcard
+
+import "testing"
+
+// TestMatch - Tests validate the logic of wild card matching.
+// `Match` supports '*' and '?' wildcards.
+// Sample usage: In resource matching for bucket policy validation.
+func TestMatch(t *testing.T) {
+	testCases := []struct {
+		pattern string
+		text    string
+		matched bool
+	}{
+		{
+			pattern: "The?Simpsons*",
+			text:    "The Simpsons S12",
+			matched: true,
+		},
+		{
+			pattern: "The?Simpsons*",
+			text:    "The.Simpsons.S12",
+			matched: true,
+		},
+		{
+			pattern: "The?Simpsons*",
+			text:    "The.Simps.S12",
+			matched: false,
+		},
+	}
+	// Iterating over the test cases, call the function under test and asert the output.
+	for i, testCase := range testCases {
+		actualResult := Match(testCase.pattern, testCase.text)
+		if testCase.matched != actualResult {
+			t.Errorf("Test %d: Expected the result to be `%v`, but instead found it to be `%v`", i+1, testCase.matched, actualResult)
+		}
+	}
+}