From d261105a863e7eec365c3f84d5bbcbbf328e1e26 Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt.pharr@intel.com>
Date: Fri, 23 Sep 2011 15:51:23 -0700
Subject: [PATCH] Error/warning reporting improvements.

- Don't suggest matches when given an empty string or a single, non-alpha
  character.
- Also fixed the parser to be a bit less confusing when it encounters an
  unexpected EOF.
---
 parse.yy | 30 +++++++++++++++++++++---------
 util.cpp |  4 ++++
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/parse.yy b/parse.yy
index 2ee40e7e..69869989 100644
--- a/parse.yy
+++ b/parse.yy
@@ -928,9 +928,13 @@ parameter_list
             builtinTokens.push_back(*token);
             ++token;
         }
-        std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
-        std::string alts = lGetAlternates(alternates);
-        Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        if (strlen(yytext) == 0)
+            Error(@1, "Syntax error--premature end of file.");
+        else {
+            std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
+            std::string alts = lGetAlternates(alternates);
+            Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        }
         $$ = NULL;
     }
     ;
@@ -1027,9 +1031,13 @@ statement
             builtinTokens.push_back(*token);
             ++token;
         }
-        std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
-        std::string alts = lGetAlternates(alternates);
-        Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        if (strlen(yytext) == 0)
+            Error(@1, "Syntax error--premature end of file.");
+        else {
+            std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
+            std::string alts = lGetAlternates(alternates);
+            Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        }
         $$ = NULL;
     }
     ;
@@ -1177,9 +1185,13 @@ translation_unit
             builtinTokens.push_back(*token);
             ++token;
         }
-        std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
-        std::string alts = lGetAlternates(alternates);
-        Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        if (strlen(yytext) == 0)
+            Error(@1, "Syntax error--premature end of file.");
+        else {
+            std::vector<std::string> alternates = MatchStrings(yytext, builtinTokens);
+            std::string alts = lGetAlternates(alternates);
+            Error(@1, "Syntax error--token \"%s\" unknown.%s", yytext, alts.c_str());
+        }
     }
     ;
 
diff --git a/util.cpp b/util.cpp
index 24b730ca..599c2157 100644
--- a/util.cpp
+++ b/util.cpp
@@ -344,6 +344,10 @@ StringEditDistance(const std::string &str1, const std::string &str2, int maxDist
 
 std::vector<std::string> 
 MatchStrings(const std::string &str, const std::vector<std::string> &options) {
+    if (str.size() == 0 || (str.size() == 1 && !isalpha(str[0])))
+        // don't even try...
+        return std::vector<std::string>();
+
     const int maxDelta = 2;
     std::vector<std::string> matches[maxDelta+1];