1 files changed, 115 insertions, 0 deletions
diff --git a/tvloader/parser2v3/util.go b/tvloader/parser2v3/util.go
new file mode 100644
index 0000000..743b3f6
--- /dev/null
+++ b/tvloader/parser2v3/util.go
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+
+package parser2v3
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/spdx/tools-golang/spdx/common"
+)
+
+// used to extract key / value from embedded substrings
+// returns subkey, subvalue, nil if no error, or "", "", error otherwise
+func extractSubs(value string) (string, string, error) {
+	// parse the value to see if it's a valid subvalue format
+	sp := strings.SplitN(value, ":", 2)
+	if len(sp) == 1 {
+		return "", "", fmt.Errorf("invalid subvalue format for %s (no colon found)", value)
+	}
+
+	subkey := strings.TrimSpace(sp[0])
+	subvalue := strings.TrimSpace(sp[1])
+
+	return subkey, subvalue, nil
+}
+
+// used to extract DocumentRef and SPDXRef values from an SPDX Identifier
+// which can point either to this document or to a different one
+func extractDocElementID(value string) (common.DocElementID, error) {
+	docRefID := ""
+	idStr := value
+
+	// check prefix to see if it's a DocumentRef ID
+	if strings.HasPrefix(idStr, "DocumentRef-") {
+		// extract the part that comes between "DocumentRef-" and ":"
+		strs := strings.Split(idStr, ":")
+		// should be exactly two, part before and part after
+		if len(strs) < 2 {
+			return common.DocElementID{}, fmt.Errorf("no colon found although DocumentRef- prefix present")
+		}
+		if len(strs) > 2 {
+			return common.DocElementID{}, fmt.Errorf("more than one colon found")
+		}
+
+		// trim the prefix and confirm non-empty
+		docRefID = strings.TrimPrefix(strs[0], "DocumentRef-")
+		if docRefID == "" {
+			return common.DocElementID{}, fmt.Errorf("document identifier has nothing after prefix")
+		}
+		// and use remainder for element ID parsing
+		idStr = strs[1]
+	}
+
+	// check prefix to confirm it's got the right prefix for element IDs
+	if !strings.HasPrefix(idStr, "SPDXRef-") {
+		return common.DocElementID{}, fmt.Errorf("missing SPDXRef- prefix for element identifier")
+	}
+
+	// make sure no colons are present
+	if strings.Contains(idStr, ":") {
+		// we know this means there was no DocumentRef- prefix, because
+		// we would have handled multiple colons above if it was
+		return common.DocElementID{}, fmt.Errorf("invalid colon in element identifier")
+	}
+
+	// trim the prefix and confirm non-empty
+	eltRefID := strings.TrimPrefix(idStr, "SPDXRef-")
+	if eltRefID == "" {
+		return common.DocElementID{}, fmt.Errorf("element identifier has nothing after prefix")
+	}
+
+	// we're good
+	return common.DocElementID{DocumentRefID: docRefID, ElementRefID: common.ElementID(eltRefID)}, nil
+}
+
+// used to extract SPDXRef values from an SPDX Identifier, OR "special" strings
+// from a specified set of permitted values. The primary use case for this is
+// the right-hand side of Relationships, where beginning in SPDX 2.3 the values
+// "NONE" and "NOASSERTION" are permitted. If the value does not match one of
+// the specified permitted values, it will fall back to the ordinary
+// DocElementID extractor.
+func extractDocElementSpecial(value string, permittedSpecial []string) (common.DocElementID, error) {
+	// check value against special set first
+	for _, sp := range permittedSpecial {
+		if sp == value {
+			return common.DocElementID{SpecialID: sp}, nil
+		}
+	}
+	// not found, fall back to regular search
+	return extractDocElementID(value)
+}
+
+// used to extract SPDXRef values only from an SPDX Identifier which can point
+// to this document only. Use extractDocElementID for parsing IDs that can
+// refer either to this document or a different one.
+func extractElementID(value string) (common.ElementID, error) {
+	// check prefix to confirm it's got the right prefix for element IDs
+	if !strings.HasPrefix(value, "SPDXRef-") {
+		return common.ElementID(""), fmt.Errorf("missing SPDXRef- prefix for element identifier")
+	}
+
+	// make sure no colons are present
+	if strings.Contains(value, ":") {
+		return common.ElementID(""), fmt.Errorf("invalid colon in element identifier")
+	}
+
+	// trim the prefix and confirm non-empty
+	eltRefID := strings.TrimPrefix(value, "SPDXRef-")
+	if eltRefID == "" {
+		return common.ElementID(""), fmt.Errorf("element identifier has nothing after prefix")
+	}
+
+	// we're good
+	return common.ElementID(eltRefID), nil
+}