Feature: [#978]. Update preprocessor defines upon encountering an #undef directive.

From Alpha.

2 files changed, 20 insertions, 3 deletions

diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 8ffba3dac..fb3e71478 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -418,6 +418,7 @@
       </tr><tr>
 	<td>G. Hu</td>
 	<td>Byron Hawkins</td>
+	<td>Alpha</td>
     </tr>
     </table>
     <p>
diff --git a/lexers/LexCPP.cxx b/lexers/LexCPP.cxx
index f30cdfbdd..a064328c8 100644
--- a/lexers/LexCPP.cxx
+++ b/lexers/LexCPP.cxx
@@ -132,8 +132,9 @@ struct PPDefinition {
 	int line;
 	std::string key;
 	std::string value;
-	PPDefinition(int line_, const std::string &key_, const std::string &value_) :
-		line(line_), key(key_), value(value_) {
+	bool isUndef;
+	PPDefinition(int line_, const std::string &key_, const std::string &value_, bool isUndef_ = false) :
+		line(line_), key(key_), value(value_), isUndef(isUndef_) {
 	}
 };
 
@@ -547,7 +548,10 @@ void SCI_METHOD LexerCPP::Lex(unsigned int startPos, int length, int initStyle,
 
 	std::map<std::string, std::string> preprocessorDefinitions = preprocessorDefinitionsStart;
 	for (std::vector<PPDefinition>::iterator itDef = ppDefineHistory.begin(); itDef != ppDefineHistory.end(); ++itDef) {
-		preprocessorDefinitions[itDef->key] = itDef->value;
+		if (itDef->isUndef)
+			preprocessorDefinitions.erase(itDef->key);
+		else
+			preprocessorDefinitions[itDef->key] = itDef->value;
 	}
 
 	std::string rawStringTerminator = rawStringTerminators.ValueAt(lineCurrent-1);
@@ -991,6 +995,18 @@ void SCI_METHOD LexerCPP::Lex(unsigned int startPos, int length, int initStyle,
 									}
 								}
 							}
+						} else if (sc.Match("undef")) {
+							if (options.updatePreprocessor && !preproc.IsInactive()) {
+								std::string restOfLine = GetRestOfLine(styler, sc.currentPos + 5, true);
+								std::vector<std::string> tokens = Tokenize(restOfLine);
+								std::string key;
+								if (tokens.size() >= 1) {
+									key = tokens[0];
+									preprocessorDefinitions.erase(key);
+									ppDefineHistory.push_back(PPDefinition(lineCurrent, key, "", true));
+									definitionsChanged = true;
+								}
+							}
 						}
 					}
 				}