[Qt] RPC-Console: support nested commands and simple value queries

Commands can be executed with bracket syntax, example: `getwalletinfo()`.
Commands can be nested, example: `sendtoaddress(getnewaddress(), 10)`.
Simple queries are possible: `listunspent()[0][txid]`
Object values are accessed with a non-quoted string, example: [txid].

Fully backward compatible.
`generate 101` is identical to `generate(101)`
Result value queries indicated with `[]` require the new brackets syntax.
Comma as argument separator is now also possible: `sendtoaddress,<address>,<amount>`
Space as argument separator works also with the bracket syntax, example: `sendtoaddress(getnewaddress() 10)

No dept limitation, complex commands are possible:
`decoderawtransaction(getrawtransaction(getblock(getbestblockhash())[tx][0]))[vout][0][value]`

1 files changed, 160 insertions, 69 deletions

diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
index bcaa9164c9..0456b89da2 100644
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -113,9 +113,11 @@ public:
 #include "rpcconsole.moc"
 
 /**
- * Split shell command line into a list of arguments. Aims to emulate \c bash and friends.
+ * Split shell command line into a list of arguments and execute the command(s).
+ * Aims to emulate \c bash and friends.
  *
- * - Arguments are delimited with whitespace
+ * - Command nesting is possible with brackets [example: validateaddress(getnewaddress())]
+ * - Arguments are delimited with whitespace or comma
  * - Extra whitespace at the beginning and end and between arguments will be ignored
  * - Text can be "double" or 'single' quoted
  * - The backslash \c \ is used as escape character
@@ -123,11 +125,15 @@ public:
  *   - Within double quotes, only escape \c " and backslashes before a \c " or another backslash
  *   - Within single quotes, no escaping is possible and no special interpretation takes place
  *
- * @param[out]   args        Parsed arguments will be appended to this list
+ * @param[out]   result      stringified Result from the executed command(chain)
  * @param[in]    strCommand  Command line to split
  */
-bool parseCommandLine(std::vector<std::string> &args, const std::string &strCommand)
+
+bool RPCConsole::RPCExecuteCommandLine(std::string &strResult, const std::string &strCommand)
 {
+    std::vector< std::vector<std::string> > stack;
+    stack.push_back(std::vector<std::string>());
+
     enum CmdParseState
     {
         STATE_EATING_SPACES,
@@ -135,95 +141,180 @@ bool parseCommandLine(std::vector<std::string> &args, const std::string &strComm
         STATE_SINGLEQUOTED,
         STATE_DOUBLEQUOTED,
         STATE_ESCAPE_OUTER,
-        STATE_ESCAPE_DOUBLEQUOTED
+        STATE_ESCAPE_DOUBLEQUOTED,
+        STATE_COMMAND_EXECUTED,
+        STATE_COMMAND_EXECUTED_INNER
     } state = STATE_EATING_SPACES;
     std::string curarg;
-    Q_FOREACH(char ch, strCommand)
+    UniValue lastResult;
+
+    std::string strCommandTerminated = strCommand;
+    if (strCommandTerminated.back() != '\n')
+        strCommandTerminated += "\n";
+    for(char ch: strCommandTerminated)
     {
         switch(state)
         {
-        case STATE_ARGUMENT: // In or after argument
-        case STATE_EATING_SPACES: // Handle runs of whitespace
-            switch(ch)
+            case STATE_COMMAND_EXECUTED_INNER:
+            case STATE_COMMAND_EXECUTED:
             {
-            case '"': state = STATE_DOUBLEQUOTED; break;
-            case '\'': state = STATE_SINGLEQUOTED; break;
-            case '\\': state = STATE_ESCAPE_OUTER; break;
-            case ' ': case '\n': case '\t':
-                if(state == STATE_ARGUMENT) // Space ends argument
+                bool breakParsing = true;
+                switch(ch)
                 {
-                    args.push_back(curarg);
-                    curarg.clear();
+                    case '[': curarg.clear(); state = STATE_COMMAND_EXECUTED_INNER; break;
+                    default:
+                        if (state == STATE_COMMAND_EXECUTED_INNER)
+                        {
+                            if (ch != ']')
+                            {
+                                // append char to the current argument (which is also used for the query command)
+                                curarg += ch;
+                                break;
+                            }
+                            if (curarg.size())
+                            {
+                                // if we have a value query, query arrays with index and objects with a string key
+                                UniValue subelement;
+                                if (lastResult.isArray())
+                                {
+                                    for(char argch: curarg)
+                                        if (!std::isdigit(argch))
+                                            throw std::runtime_error("Invalid result query");
+                                    subelement = lastResult[atoi(curarg.c_str())];
+                                }
+                                else if (lastResult.isObject())
+                                    subelement = find_value(lastResult, curarg);
+                                else
+                                    throw std::runtime_error("Invalid result query"); //no array or object: abort
+                                lastResult = subelement;
+                            }
+
+                            state = STATE_COMMAND_EXECUTED;
+                            break;
+                        }
+                        // don't break parsing when the char is required for the next argument
+                        breakParsing = false;
+
+                        // pop the stack and return the result to the current command arguments
+                        stack.pop_back();
+
+                        // don't stringify the json in case of a string to avoid doublequotes
+                        if (lastResult.isStr())
+                            curarg = lastResult.get_str();
+                        else
+                            curarg = lastResult.write(2);
+
+                        // if we have a non empty result, use it as stack argument otherwise as general result
+                        if (curarg.size())
+                        {
+                            if (stack.size())
+                                stack.back().push_back(curarg);
+                            else
+                                strResult = curarg;
+                        }
+                        curarg.clear();
+                        // assume eating space state
+                        state = STATE_EATING_SPACES;
                 }
-                state = STATE_EATING_SPACES;
-                break;
-            default: curarg += ch; state = STATE_ARGUMENT;
+                if (breakParsing)
+                    break;
             }
-            break;
-        case STATE_SINGLEQUOTED: // Single-quoted string
-            switch(ch)
+            case STATE_ARGUMENT: // In or after argument
+            case STATE_EATING_SPACES: // Handle runs of whitespace
+                switch(ch)
             {
-            case '\'': state = STATE_ARGUMENT; break;
-            default: curarg += ch;
+                case '"': state = STATE_DOUBLEQUOTED; break;
+                case '\'': state = STATE_SINGLEQUOTED; break;
+                case '\\': state = STATE_ESCAPE_OUTER; break;
+                case '(': case ')': case '\n':
+                    if (state == STATE_ARGUMENT)
+                    {
+                        if (ch == '(' && stack.size() && stack.back().size() > 0)
+                            stack.push_back(std::vector<std::string>());
+                        if (curarg.size())
+                        {
+                            // don't allow commands after executed commands on baselevel
+                            if (!stack.size())
+                                throw std::runtime_error("Invalid Syntax");
+                            stack.back().push_back(curarg);
+                        }
+                        curarg.clear();
+                        state = STATE_EATING_SPACES;
+                    }
+                    if ((ch == ')' || ch == '\n') && stack.size() > 0)
+                    {
+                        std::string strPrint;
+                        // Convert argument list to JSON objects in method-dependent way,
+                        // and pass it along with the method name to the dispatcher.
+                        lastResult = tableRPC.execute(stack.back()[0], RPCConvertValues(stack.back()[0], std::vector<std::string>(stack.back().begin() + 1, stack.back().end())));
+
+                        state = STATE_COMMAND_EXECUTED;
+                        curarg.clear();
+                    }
+                    break;
+                case ' ': case ',': case '\t':
+                    if(state == STATE_ARGUMENT) // Space ends argument
+                    {
+                        if (curarg.size())
+                            stack.back().push_back(curarg);
+                        curarg.clear();
+                    }
+                    state = STATE_EATING_SPACES;
+                    break;
+                default: curarg += ch; state = STATE_ARGUMENT;
             }
-            break;
-        case STATE_DOUBLEQUOTED: // Double-quoted string
-            switch(ch)
+                break;
+            case STATE_SINGLEQUOTED: // Single-quoted string
+                switch(ch)
             {
-            case '"': state = STATE_ARGUMENT; break;
-            case '\\': state = STATE_ESCAPE_DOUBLEQUOTED; break;
-            default: curarg += ch;
+                case '\'': state = STATE_ARGUMENT; break;
+                default: curarg += ch;
             }
-            break;
-        case STATE_ESCAPE_OUTER: // '\' outside quotes
-            curarg += ch; state = STATE_ARGUMENT;
-            break;
-        case STATE_ESCAPE_DOUBLEQUOTED: // '\' in double-quoted text
-            if(ch != '"' && ch != '\\') curarg += '\\'; // keep '\' for everything but the quote and '\' itself
-            curarg += ch; state = STATE_DOUBLEQUOTED;
-            break;
+                break;
+            case STATE_DOUBLEQUOTED: // Double-quoted string
+                switch(ch)
+            {
+                case '"': state = STATE_ARGUMENT; break;
+                case '\\': state = STATE_ESCAPE_DOUBLEQUOTED; break;
+                default: curarg += ch;
+            }
+                break;
+            case STATE_ESCAPE_OUTER: // '\' outside quotes
+                curarg += ch; state = STATE_ARGUMENT;
+                break;
+            case STATE_ESCAPE_DOUBLEQUOTED: // '\' in double-quoted text
+                if(ch != '"' && ch != '\\') curarg += '\\'; // keep '\' for everything but the quote and '\' itself
+                curarg += ch; state = STATE_DOUBLEQUOTED;
+                break;
         }
     }
     switch(state) // final state
     {
-    case STATE_EATING_SPACES:
-        return true;
-    case STATE_ARGUMENT:
-        args.push_back(curarg);
-        return true;
-    default: // ERROR to end in one of the other states
-        return false;
+        case STATE_COMMAND_EXECUTED:
+            if (lastResult.isStr())
+                strResult = lastResult.get_str();
+            else
+                strResult = lastResult.write(2);
+        case STATE_ARGUMENT:
+        case STATE_EATING_SPACES:
+            return true;
+        default: // ERROR to end in one of the other states
+            return false;
     }
 }
 
 void RPCExecutor::request(const QString &command)
 {
-    std::vector<std::string> args;
-    if(!parseCommandLine(args, command.toStdString()))
-    {
-        Q_EMIT reply(RPCConsole::CMD_ERROR, QString("Parse error: unbalanced ' or \""));
-        return;
-    }
-    if(args.empty())
-        return; // Nothing to do
     try
     {
-        std::string strPrint;
-        // Convert argument list to JSON objects in method-dependent way,
-        // and pass it along with the method name to the dispatcher.
-        UniValue result = tableRPC.execute(
-            args[0],
-            RPCConvertValues(args[0], std::vector<std::string>(args.begin() + 1, args.end())));
-
-        // Format result reply
-        if (result.isNull())
-            strPrint = "";
-        else if (result.isStr())
-            strPrint = result.get_str();
-        else
-            strPrint = result.write(2);
-
-        Q_EMIT reply(RPCConsole::CMD_REPLY, QString::fromStdString(strPrint));
+        std::string result;
+        std::string executableCommand = command.toStdString() + "\n";
+        if(!RPCConsole::RPCExecuteCommandLine(result, executableCommand))
+        {
+            Q_EMIT reply(RPCConsole::CMD_ERROR, QString("Parse error: unbalanced ' or \""));
+            return;
+        }
+        Q_EMIT reply(RPCConsole::CMD_REPLY, QString::fromStdString(result));
     }
     catch (UniValue& objError)
     {