Add MaskToRegex helper

utils.go

@@ -0,0 +1,64 @@
+package irc
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// MaskToRegex converts an irc mask to a go Regexp for more convenient
+// use. This should never return an error, but we have this here just
+// in case.
+func MaskToRegex(rawMask string) (*regexp.Regexp, error) {
+	backslashed := false
+	unprocessed := rawMask
+	buf := &bytes.Buffer{}
+	buf.WriteByte('^')
+
+	for len(unprocessed) > 0 {
+		i := strings.IndexAny(unprocessed, "\\?*")
+		if i < 0 {
+			if backslashed {
+				buf.WriteString(regexp.QuoteMeta("\\"))
+				backslashed = false
+			}
+
+			buf.WriteString(regexp.QuoteMeta(unprocessed))
+			unprocessed = ""
+			break
+		}
+
+		if backslashed && i > 0 {
+			buf.WriteString(regexp.QuoteMeta("\\"))
+			backslashed = false
+		} else if backslashed && i == 0 {
+			buf.WriteString(regexp.QuoteMeta(string(unprocessed[0])))
+			unprocessed = unprocessed[1:]
+			backslashed = false
+			continue
+		}
+
+		buf.WriteString(regexp.QuoteMeta(unprocessed[:i]))
+
+		switch unprocessed[i] {
+		case '\\':
+			backslashed = true
+		case '?':
+			buf.WriteString(".")
+		case '*':
+			buf.WriteString(".*")
+		}
+
+		unprocessed = unprocessed[i+1:]
+		fmt.Println(unprocessed)
+	}
+
+	if backslashed {
+		buf.WriteString(regexp.QuoteMeta("\\"))
+	}
+
+	buf.WriteByte('$')
+
+	return regexp.Compile(buf.String())
+}

utils_test.go

@@ -0,0 +1,61 @@
+package irc
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMaskToRegex(t *testing.T) {
+	var testCases = []struct {
+		Input  string
+		Expect string
+	}{
+		{ // Empty should be fine
+			Input:  "",
+			Expect: "^$",
+		},
+		{ // EVERYONE!
+			Input:  "*!*@*",
+			Expect: "^.*!.*@.*$",
+		},
+		{
+			Input:  "",
+			Expect: "^$",
+		},
+		{
+			Input:  "",
+			Expect: "^$",
+		},
+		{ // Escape the slash
+			Input:  "a\\\\b",
+			Expect: "^a\\\\b$",
+		},
+		{ // Escape a *
+			Input:  "a\\*b",
+			Expect: "^a\\*b$",
+		},
+		{ // Escape a ?
+			Input:  "a\\?b",
+			Expect: "^a\\?b$",
+		},
+		{ // Single slash in the middle of a string should be a slash
+			Input:  "a\\b",
+			Expect: "^a\\\\b$",
+		},
+		{ // Single slash should just match a single slash
+			Input:  "\\",
+			Expect: "^\\\\$",
+		},
+		{
+			Input:  "\\a?",
+			Expect: "^\\\\a.$",
+		},
+	}
+
+	for _, testCase := range testCases {
+		ret, err := MaskToRegex(testCase.Input)
+		assert.NoError(t, err)
+		assert.Equal(t, testCase.Expect, ret.String())
+	}
+}