node: convert comments to /* */ format, to fix non-statement contexts

node.go

@@ -53,6 +53,47 @@ type conversionState struct {
 
 //
 
+func normaliseCommentStrFragment(s string) string {
+	if len(s) == 0 {
+		return s
+	}
+
+	lines := strings.Split(s, "\n")
+	for i, _ := range lines {
+		lines[i] = strings.TrimLeft(lines[i], "\t\r\n ")
+		if strings.HasPrefix(lines[i], `//`) {
+			lines[i] = lines[i][2:]
+		}
+	}
+	return `/* ` + strings.TrimRight(strings.Join(lines, "\n"), "\n") + `*/`
+}
+
+func normaliseCommentStr(s string) string {
+
+	// A comment may be injected at any point in the source tree
+	// It's not necessarily valid to use line comments (`//`) mid-AST
+	// Avoid the problem by unconditionally transforming to range comments (`/**/`)
+
+	extents := strings.Split(s, `/*`)
+	ret := make([]string, 0, len(extents)*2)
+	for _, extent := range extents {
+		parts := strings.SplitN(extent, `*/`, 2) // any further */ after this has no effect
+		if len(parts) == 1 {
+			// No range comment, only line comment/whitespace
+			// Transform single range only
+			ret = append(ret, normaliseCommentStrFragment(parts[0]))
+
+		} else { // len(parts) == 2
+			// Range comment part is OK
+			// Only second middle part needs normalising
+			ret = append(ret, parts[0], normaliseCommentStrFragment(parts[1]))
+
+		}
+	}
+
+	return strings.Join(ret, "")
+}
+
 func (this *conversionState) convert(n node.Node) (string, error) {
 
 	// Get any whitespace/comments attached to this node
@@ -93,9 +134,12 @@ func (this *conversionState) convert(n node.Node) (string, error) {
 		return "", err
 	}
 
-	if len(freePrefix) > 0 && !(strings.HasSuffix(freePrefix, "\n") || strings.HasSuffix(freePrefix, `*/`)) {
-		freePrefix += "\n"
-	}
+	//if len(freePrefix) > 0 && !(strings.HasSuffix(freePrefix, "\n") || strings.HasSuffix(freePrefix, `*/`)) {
+	//	freePrefix += "\n"
+	//}
+
+	freePrefix = normaliseCommentStr(freePrefix)
+	freeSuffix = normaliseCommentStr(freeSuffix)
 
 	return freePrefix + ret + freeSuffix, nil
 }