From 9e0ea1cb4a2155eb07fbd731d9fab5ce27554fed Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Sat, 27 Sep 2014 17:08:26 -0400
Subject: [PATCH] Eval

- Better error message for malformed expressions, ie when a binary operator
  expects two values, and sees less then two or when a unary operator sees
  less than one.
---
 src/Eval.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Eval.cpp b/src/Eval.cpp
index 985fe1199..a98972985 100644
--- a/src/Eval.cpp
+++ b/src/Eval.cpp
@@ -243,6 +243,9 @@ void Eval::evaluatePostfixStack (
     if (token->second == Lexer::typeOperator &&
         token->first == "!")
     {
+      if (values.size () < 1)
+        throw std::string (STRING_EVAL_NO_EVAL);
+
       Variant right = values.back ();
       values.pop_back ();
       if (_debug)
@@ -256,6 +259,9 @@ void Eval::evaluatePostfixStack (
     else if (token->second == Lexer::typeOperator &&
              token->first == "_neg_")
     {
+      if (values.size () < 1)
+        throw std::string (STRING_EVAL_NO_EVAL);
+
       Variant right = values.back ();
       values.pop_back ();
       if (_debug)
@@ -279,6 +285,9 @@ void Eval::evaluatePostfixStack (
     // Binary operators.
     else if (token->second == Lexer::typeOperator)
     {
+      if (values.size () < 2)
+        throw std::string (STRING_EVAL_NO_EVAL);
+
       Variant right = values.back ();
       values.pop_back ();