[WIP] Add formatting for json output

Use one space indent per-level, and one line per node rather
than one big, unformatted line for whole tree.

TODO: Cleanup and fix output of redundant newlines (resulting in
empty lines)

src/V3Ast.h

@@ -2220,7 +2220,7 @@ class AstNode VL_NOT_FINAL {
     void dumpTreeDot(std::ostream& os = std::cout) const;
     void dumpTreeDotFile(const string& filename, bool doDump = true);
     virtual void dumpExtraJson(std::ostream& os) const {};  // node specific fields
-    void dumpTreeJson(std::ostream& os) const;
+    void dumpTreeJson(std::ostream& os, const string& indent = "") const;
     void dumpTreeJsonFile(const string& filename, bool doDump = true);
 
     // METHODS - static advancement

src/V3AstNodes.cpp

@@ -1441,15 +1441,29 @@ void AstNode::dump(std::ostream& str) const {
     }
 }
 
-static void dumpNodeListJson(std::ostream& os, const AstNode* nodep, const std::string& listName) {
-    os << "," << SQUOT(listName) << ": [";
-    bool comma = false;
+
+static void dumpNodeListJson(std::ostream& os, const AstNode* nodep, const std::string& listName, const string& indent) {
+    // yeah, it is a bit dirty, TODO: cleanup
+    bool empty = (nodep == NULL); // TODO: Consider not dumping empty lists at all
+
+    if(listName == "op1") {
+        os << ",";
+    }
+
+    if(!empty) os << "\n " << indent;
+
+    os << SQUOT(listName) << ": [";
+    if(!empty) os << "\n";
     for (; nodep; nodep = nodep->nextp()) {
-        if (comma) os << ", ";
-        comma = true;
-        nodep->dumpTreeJson(os);
+        nodep->dumpTreeJson(os, indent + "  ");
+        if (nodep->nextp()) os << ",\n";
     }
     os << "]";
+
+    if(listName != "op4") { // dirty trick to check if it is not last field
+        os << ",";
+        if(!empty) os << "\n" << indent;
+    }
 }
 
 static void dumpFileInfo(std::ostream& os, const FileLine* fileinfop) {
@@ -1460,20 +1474,20 @@ static void dumpFileInfo(std::ostream& os, const FileLine* fileinfop) {
     os << "}";
 }
 
-void AstNode::dumpTreeJson(std::ostream& os) const {
+void AstNode::dumpTreeJson(std::ostream& os, const string& indent) const {
     // TODO: dump dtype
-    os << "{" << SQUOT("type") << ":" << SQUOT(typeName());
+    os << indent << "{" << SQUOT("type") << ":" << SQUOT(typeName());
     dumpJsonStr(os, "name", V3OutFormatter::quoteNameControls(name()));
     dumpJsonPtr(os, "addr", this);
     dumpFileInfo(os, fileline());
 #ifdef VL_DEBUG
     dumpJsonNum(os, "editNum", editCount());
 #endif
     dumpExtraJson(os);
-    dumpNodeListJson(os, op1p(), "op1");
-    dumpNodeListJson(os, op2p(), "op2");
-    dumpNodeListJson(os, op3p(), "op3");
-    dumpNodeListJson(os, op4p(), "op4");
+    dumpNodeListJson(os, op1p(), "op1", indent);
+    dumpNodeListJson(os, op2p(), "op2", indent);
+    dumpNodeListJson(os, op3p(), "op3", indent);
+    dumpNodeListJson(os, op4p(), "op4", indent);
     os << "}";
 }