bug 4355 - improve parse exception messages

1 files changed, 38 insertions, 43 deletions

diff --git a/cs/src/Ice/StringUtil.cs b/cs/src/Ice/StringUtil.cs
index dd5c1d584ca..9db9c17c697 100644
--- a/cs/src/Ice/StringUtil.cs
+++ b/cs/src/Ice/StringUtil.cs
@@ -180,7 +180,8 @@ namespace IceUtilInternal
                 {
                     if((int)special[i] < 32 || (int)special[i] > 126)
                     {
-                        throw new System.ArgumentException("special characters must be in ASCII range 32-126", "special");
+                        throw new System.ArgumentException("special characters must be in ASCII range 32-126",
+                                                           "special");
                     }
                 }
             }
@@ -197,11 +198,22 @@ namespace IceUtilInternal
             return result.ToString();
         }
         
-        private static char checkChar(char c)
+        private static char checkChar(string s, int pos)
         {
+            char c = s[pos];
             if(!(c >= 32 && c <= 126))
             {
-                throw new System.ArgumentException("illegal input character");
+                string msg;
+                if(pos > 0)
+                {
+                    msg = "character after `" + s.Substring(0, pos) + "'";
+                }
+                else
+                {
+                    msg = "first character";
+                }
+                msg += " is not a printable ASCII character (ordinal " + (int)c + ")";
+                throw new System.ArgumentException(msg);
             }
             return c;
         }
@@ -222,13 +234,13 @@ namespace IceUtilInternal
 
             if(s[start] != '\\')
             {
-                c = checkChar(s[start++]);
+                c = checkChar(s, start++);
             }
             else
             {
                 if(start + 1 == end)
                 {
-                    throw new System.ArgumentException("trailing backslash in argument");
+                    throw new System.ArgumentException("trailing backslash");
                 }
                 switch(s[++start])
                 {
@@ -278,7 +290,7 @@ namespace IceUtilInternal
                     case '6':
                     case '7':
                     {
-                        int oct = 0;
+                        int val = 0;
                         for(int j = 0; j < 3 && start < end; ++j)
                         {
                             int charVal = s[start++] - '0';
@@ -287,18 +299,20 @@ namespace IceUtilInternal
                                 --start;
                                 break;
                             }
-                            oct = oct * 8 + charVal;
+                            val = val * 8 + charVal;
                         }
-                        if(oct > 255)
+                        if(val > 255)
                         {
-                            throw new System.ArgumentException("octal value out of range", "s");
+                            string msg = "octal value \\" + System.Convert.ToString(val, 8) + " (" + val +
+                                ") is out of range";
+                            throw new System.ArgumentException(msg, "s");
                         }
-                        c = System.Convert.ToChar(oct);
+                        c = System.Convert.ToChar(val);
                         break;
                     }
                     default:
                     {
-                        c = checkChar(s[start++]);
+                        c = checkChar(s, start++);
                         break;
                     }
                 }
@@ -320,44 +334,25 @@ namespace IceUtilInternal
         }
 
         //
-        // Remove escape sequences added by escapeString.
+        // Remove escape sequences added by escapeString. Throws System.ArgumentException
+        // for an invalid input string.
         //
-        public static bool unescapeString(string s, int start, int end, out string result)
+        public static string unescapeString(string s, int start, int end)
         {
-            if(start < 0)
-            {
-                throw new System.ArgumentException("start offset must be >= 0", "start");
-            }
-            if(end > s.Length)
-            {
-                throw new System.ArgumentException("end offset must be <= s.Length", "end");
-            }
-            if(start > end)
-            {
-                throw new System.ArgumentException("start offset must be <= end offset");
-            }
-            
-            result = null;
-            try
-            {
-                StringBuilder sb = new StringBuilder();
-                decodeString(s, start, end, sb);
-                string decodedString = sb.ToString();
+            Debug.Assert(start >= 0 && start <= end && end <= s.Length);
 
-                byte[] arr = new byte[decodedString.Length];
-                for(int i = 0; i < arr.Length; ++i)
-                {
-                    arr[i] = (byte)decodedString[i];
-                }
+            StringBuilder sb = new StringBuilder();
+            decodeString(s, start, end, sb);
+            string decodedString = sb.ToString();
 
-                UTF8Encoding utf8 = new UTF8Encoding(false, true);
-                result = utf8.GetString(arr);
-                return true;
-            }
-            catch(System.Exception)
+            byte[] arr = new byte[decodedString.Length];
+            for(int i = 0; i < arr.Length; ++i)
             {
-                return false;
+                arr[i] = (byte)decodedString[i];
             }
+
+            UTF8Encoding utf8 = new UTF8Encoding(false, true);
+            return utf8.GetString(arr); // May raise ArgumentException.
         }
 
         public static int checkQuote(string s)