Suppress shift-selection when handling a binding that requires shift

Context in pull req #281

Author: marijnh

lib/codemirror.js

@@ -432,14 +432,31 @@ var CodeMirror = (function() {
       e.dataTransfer.setData("Text", txt);
     }
     function handleKeyBinding(e) {
-      if (e.altGraphKey) return false;
-      var bound = lookupKey(e, options.extraKeys, options.keyMap);
-      var next = keyMap[options.keyMap].auto;
-      if (next && !isModifierKey(e)) options.keyMap = next;
+      var name = keyNames[event.keyCode], next = keyMap[options.keyMap].auto, bound, dropShift;
+      if (name == null || e.altGraphKey) {
+        if (next) options.keyMap = next;
+        return null;
+      }
+      if (event.altKey) name = "Alt-" + name;
+      if (event.ctrlKey) name = "Ctrl-" + name;
+      if (event.metaKey) name = "Cmd-" + name;
+      if (event.shiftKey && (bound = lookupKey("Shift-" + name, options.extraKeys, options.keyMap))) {
+        dropShift = true;
+      } else {
+        bound = lookupKey(name, options.extraKeys, options.keyMap);
+      }
+      if (typeof bound == "string") {
+        if (commands.propertyIsEnumerable(bound)) bound = commands[bound];
+        else bound = null;
+      }
+      if (next && (bound || !isModifierKey(e))) options.keyMap = next;
       if (!bound) return false;
-      if (typeof bound != "string") bound(instance);
-      else if (commands.propertyIsEnumerable(bound)) commands[bound](instance);
-      else if (!next) return false;
+      if (dropShift) {
+        var prevShift = shiftSelecting;
+        shiftSelecting = null;
+        bound(instance);
+        shiftSelecting = prevShift;
+      } else bound(instance);
       e_preventDefault(e);
       return true;
     }
@@ -1835,12 +1852,7 @@ var CodeMirror = (function() {
     "Alt-D": "delWordRight", "Alt-Backspace": "delWordLeft", "Ctrl-K": "killLine", "Ctrl-T": "transposeChars"
   };
 
-  function lookupKey(event, extraMap, map) {
-    var name = keyNames[event.keyCode];
-    if (name == null) return null;
-    if (event.altKey) name = "Alt-" + name;
-    if (event.ctrlKey) name = "Ctrl-" + name;
-    if (event.metaKey) name = "Cmd-" + name;
+  function lookupKey(name, extraMap, map) {
     function lookup(name, map, ft) {
       var found = map[name];
       if (found != null) return found;
@@ -1853,14 +1865,7 @@ var CodeMirror = (function() {
       }
       return null;
     }
-    function lookup0(name) {
-      return extraMap ? lookup(name, extraMap, map) : lookup(name, keyMap[map]);
-    }
-    if (event.shiftKey) {
-      var found = lookup0("Shift-" + name);
-      if (found != null) return found;
-    }
-    return lookup0(name);
+    return extraMap ? lookup(name, extraMap, map) : lookup(name, keyMap[map]);
   }
   function isModifierKey(event) {
     var name = keyNames[event.keyCode];