From fb416591afdaa9cf69d331b44af705a21b64249d Mon Sep 17 00:00:00 2001
From: Charles Iliya Krempeaux <iamreiver@gmail.com>
Date: Wed, 4 Oct 2023 17:37:18 +0900
Subject: [PATCH] initial commits

---
 hexdigit.go      |  8 +++++
 hexdigit_test.go | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)
 create mode 100644 hexdigit.go
 create mode 100644 hexdigit_test.go

diff --git a/hexdigit.go b/hexdigit.go
new file mode 100644
index 0000000..78218f5
--- /dev/null
+++ b/hexdigit.go
@@ -0,0 +1,8 @@
+package rfc2234
+
+// IsHexDigit returns true if value of 'r' matches 'ALPHA' as defined in IETF RFC-2234:
+//
+//	HEXDIGIT =  %30-%39 / %41-%46 / %61-%66    ; 0-9 / A-F / a-f
+func IsHexDigit(r rune) bool {
+	return ('0' <= r && r <= '9') || ('A' <= r && r <= 'F') || ('a' <= r && r <= 'f')
+}
diff --git a/hexdigit_test.go b/hexdigit_test.go
new file mode 100644
index 0000000..5dad505
--- /dev/null
+++ b/hexdigit_test.go
@@ -0,0 +1,93 @@
+package rfc2234_test
+
+import (
+	"testing"
+
+	"sourcecode.social/reiver/go-rfc2234"
+)
+
+func TestIsHexDigit(t *testing.T) {
+
+	tests := []struct{
+		Rune rune
+		Expected bool
+	}{
+	}
+
+	for r:=rune(0); r < '0'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+	for r:='0'; r <= '9'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: true,
+		})
+	}
+	for r:='9'+1; r < 'A'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+	for r:='A'; r <= 'F'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: true,
+		})
+	}
+	for r:='F'+1; r < 'a'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+	for r:='a'; r <= 'f'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: true,
+		})
+	}
+	for r:='f'+1; r < rune(1024); r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+
+	for testNumber, test := range tests {
+		actual := rfc2234.IsHexDigit(test.Rune)
+		expected := test.Expected
+
+		if expected != actual {
+			t.Errorf("For test #%d, the actual value for rfc2234.IsHexDigit() is not what was expected.", testNumber)
+			t.Logf("EXPECTED: %t", expected)
+			t.Logf("ACTUAL:   %t", actual)
+			t.Logf("RUNE: (%U) %q", test.Rune, string(test.Rune))
+			continue
+		}
+	}
+}