core_read's ParseScript(): minor cleanups

- use .empty() rather than .size() == 0
- use a const_iterator rather than BOOST_FOREACH
- validate iterators before creating a string from them

src/core_read.cpp

@@ -21,7 +21,7 @@ CScript ParseScript(std::string s)
 
     static map<string, opcodetype> mapOpNames;
 
-    if (mapOpNames.size() == 0)
+    if (mapOpNames.empty())
     {
         for (int op = 0; op <= OP_NOP10; op++)
         {
@@ -43,36 +43,36 @@ CScript ParseScript(std::string s)
     vector<string> words;
     split(words, s, is_any_of(" \t\n"), token_compress_on);
 
-    BOOST_FOREACH(string w, words)
+    for (std::vector<std::string>::const_iterator w = words.begin(); w != words.end(); ++w)
     {
-        if (w.size() == 0)
+        if (w->empty())
         {
             // Empty string, ignore. (boost::split given '' will return one word)
         }
-        else if (all(w, is_digit()) ||
-            (starts_with(w, "-") && all(string(w.begin()+1, w.end()), is_digit())))
+        else if (all(*w, is_digit()) ||
+            (starts_with(*w, "-") && all(string(w->begin()+1, w->end()), is_digit())))
         {
             // Number
-            int64_t n = atoi64(w);
+            int64_t n = atoi64(*w);
             result << n;
         }
-        else if (starts_with(w, "0x") && IsHex(string(w.begin()+2, w.end())))
+        else if (starts_with(*w, "0x") && (w->begin()+2 != w->end()) && IsHex(string(w->begin()+2, w->end())))
         {
             // Raw hex data, inserted NOT pushed onto stack:
-            std::vector<unsigned char> raw = ParseHex(string(w.begin()+2, w.end()));
+            std::vector<unsigned char> raw = ParseHex(string(w->begin()+2, w->end()));
             result.insert(result.end(), raw.begin(), raw.end());
         }
-        else if (w.size() >= 2 && starts_with(w, "'") && ends_with(w, "'"))
+        else if (w->size() >= 2 && starts_with(*w, "'") && ends_with(*w, "'"))
         {
             // Single-quoted string, pushed as data. NOTE: this is poor-man's
             // parsing, spaces/tabs/newlines in single-quoted strings won't work.
-            std::vector<unsigned char> value(w.begin()+1, w.end()-1);
+            std::vector<unsigned char> value(w->begin()+1, w->end()-1);
             result << value;
         }
-        else if (mapOpNames.count(w))
+        else if (mapOpNames.count(*w))
         {
             // opcode, e.g. OP_ADD or ADD:
-            result << mapOpNames[w];
+            result << mapOpNames[*w];
         }
         else
         {