[apps/escher] Rename EditableExpressionView -> ExpressionField

Change-Id: Iadfb220ee94e68762305060215f1ead0cac951fb

apps/calculation/expression_field.cpp

@@ -0,0 +1,31 @@
+#include "expression_field.h"
+
+namespace Calculation {
+
+ExpressionField::ExpressionField(Responder * parentResponder, TextFieldDelegate * textFieldDelegate, ExpressionLayoutFieldDelegate * expressionLayoutFieldDelegate) :
+  ::ExpressionField(parentResponder, textFieldDelegate, expressionLayoutFieldDelegate)
+{
+  setEditing(true);
+}
+
+bool ExpressionField::handleEvent(Ion::Events::Event event) {
+  if (event == Ion::Events::Back) {
+    return false;
+  }
+  if (event == Ion::Events::Ans) {
+    insertText("ans");
+    return true;
+  }
+  if (isEditing() && isEmpty() &&
+      (event == Ion::Events::Multiplication ||
+       event == Ion::Events::Plus ||
+       event == Ion::Events::Power ||
+       event == Ion::Events::Square ||
+       event == Ion::Events::Division ||
+       event == Ion::Events::Sto)) {
+    insertText("ans");
+  }
+  return(::ExpressionField::handleEvent(event));
+}
+
+}