3 files changed, 174 insertions, 0 deletions
diff --git a/internal/cpe/avstring.go b/internal/cpe/avstring.go
new file mode 100644
index 0000000..46e16cf
--- /dev/null
+++ b/internal/cpe/avstring.go
@@ -0,0 +1,54 @@
+package cpe
+
+//go:generate stringer -linecomment -type=AvStringType
+
+import (
+  "fmt"
+)
+
+// type of avstring.
+type AvStringType byte
+
+const (
+  AnyString AvStringType = iota // any
+  NaString // na
+  ValString // val
+)
+
+// String value (NISTIR 7695, CPE 2.3 spec, Figure 6-3)
+type AvString struct {
+  Type AvStringType // value type
+  Val  string // value
+}
+
+// token type to avstring type map
+var avTypes = map[tokenType]AvStringType {
+  anyToken: AnyString,
+  naToken: NaString,
+  valToken: ValString,
+}
+
+// create new AvString from token.
+func newAvString(t token) (AvString, error) {
+  if at, ok := avTypes[t.Type]; ok {
+    return AvString { at, t.Val }, nil
+  } else {
+    err := fmt.Errorf("invalid token type: 0x%02x", byte(t.Type))
+    return AvString { 0, "" }, err
+  }
+}
+
+// Serialize as string.
+func (s AvString) String() string {
+  switch s.Type {
+  case AnyString:
+    return "*"
+  case NaString:
+    return "-"
+  case ValString:
+    return s.Val
+  default:
+    // not sure what to return here
+    return ""
+  }
+}
diff --git a/internal/cpe/avstring_test.go b/internal/cpe/avstring_test.go
new file mode 100644
index 0000000..8cbb14b
--- /dev/null
+++ b/internal/cpe/avstring_test.go
@@ -0,0 +1,95 @@
+package cpe
+
+import (
+  "testing"
+)
+
+func TestNewAvString(t *testing.T) {
+  passTests := []struct {
+    name string
+    val token
+    exp AvString
+  } {
+    { "any", token { Type: anyToken }, AvString { Type: AnyString } },
+    { "na", token { Type: naToken }, AvString { Type: NaString } },
+    { "empty", token { Type: valToken }, AvString { ValString, "" } },
+    { "foo", token { valToken, "foo" }, AvString { ValString, "foo" } },
+  }
+
+  for _, test := range(passTests) {
+    t.Run(test.name, func(t *testing.T) {
+      got, err := newAvString(test.val)
+      if err != nil {
+        t.Error(err)
+      } else if got.Type != test.exp.Type {
+        t.Errorf("token: got %s, exp %s", got.Type, test.exp.Type)
+      } else if got.Type == ValString && got.Val != test.exp.Val {
+        t.Errorf("value: got \"%s\", exp \"%s\"", got.Val, test.exp.Val)
+      }
+    })
+  }
+
+  failTests := []struct {
+    name string
+    val token
+    exp string
+  } {{
+    name: "invalid token",
+    val:  token { Type: tokenType(127), Val: "foo" },
+    exp:  "invalid token type: 0x7f",
+  }}
+
+  for _, test := range(failTests) {
+    t.Run(test.name, func(t *testing.T) {
+      got, err := newAvString(test.val)
+      if err == nil {
+        t.Errorf("got %v, exp error", got)
+      } else if err.Error() != test.exp {
+        t.Errorf("got \"%s\", exp \"%s\"", err.Error(), test.exp)
+      }
+    })
+  }
+}
+
+func TestAvStringString(t *testing.T) {
+  tests := []struct {
+    name string
+    val AvString
+    exp string
+  } {
+    { "any", AvString { AnyString, "" }, "*" },
+    { "na", AvString { NaString, "" }, "-" },
+    { "foo", AvString { ValString, "foo" }, "foo" },
+    { "junk", AvString { AvStringType(255), "foo" }, "" },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.name, func(t *testing.T) {
+      got := test.val.String()
+      if got != test.exp {
+        t.Errorf("value: got \"%s\", exp \"%s\"", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestAvStringTypeString(t *testing.T) {
+  tests := []struct {
+    val AvStringType
+    exp string
+  } {
+    { AnyString, "any" },
+    { NaString, "na" },
+    { ValString, "val" },
+    { AvStringType(255), "AvStringType(255)" },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.exp, func(t *testing.T) {
+      got := test.val.String()
+      if got != test.exp {
+        t.Errorf("got \"%s\", exp \"%s\"", got, test.exp)
+      }
+    })
+  }
+}
diff --git a/internal/cpe/avstringtype_string.go b/internal/cpe/avstringtype_string.go
new file mode 100644
index 0000000..6fb88e1
--- /dev/null
+++ b/internal/cpe/avstringtype_string.go
@@ -0,0 +1,25 @@
+// Code generated by "stringer -linecomment -type=AvStringType"; DO NOT EDIT.
+
+package cpe
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[AnyString-0]
+	_ = x[NaString-1]
+	_ = x[ValString-2]
+}
+
+const _AvStringType_name = "anynaval"
+
+var _AvStringType_index = [...]uint8{0, 3, 5, 8}
+
+func (i AvStringType) String() string {
+	if i >= AvStringType(len(_AvStringType_index)-1) {
+		return "AvStringType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _AvStringType_name[_AvStringType_index[i]:_AvStringType_index[i+1]]
+}