Added guarded exception catches

include/chaiscript/chaiscript.hpp

@@ -41,7 +41,7 @@ namespace chaiscript
     class Token_Type { public: enum Type { Error, Int, Float, Id, Char, Str, Eol, Fun_Call, Inplace_Fun_Call, Arg_List, Variable, Equation, Var_Decl,
         Expression, Comparison, Additive, Multiplicative, Negate, Not, Array_Call, Dot_Access, Quoted_String, Single_Quoted_String,
         Lambda, Block, Def, While, If, For, Inline_Array, Inline_Map, Return, File, Prefix, Break, Map_Pair, Value_Range,
-        Inline_Range, Annotation, Try }; };
+        Inline_Range, Annotation, Try, Catch }; };
 
     /**
      * Helper lookup to get the name of each node type
@@ -50,7 +50,7 @@ namespace chaiscript
         const char *token_types[] = { "Internal Parser Error", "Int", "Float", "Id", "Char", "Str", "Eol", "Fun_Call", "Inplace_Fun_Call", "Arg_List", "Variable", "Equation", "Var_Decl",
             "Expression", "Comparison", "Additive", "Multiplicative", "Negate", "Not", "Array_Call", "Dot_Access", "Quoted_String", "Single_Quoted_String",
             "Lambda", "Block", "Def", "While", "If", "For", "Inline_Array", "Inline_Map", "Return", "File", "Prefix", "Break", "Map_Pair", "Value_Range",
-            "Inline_Range", "Annotation", "Try"};
+            "Inline_Range", "Annotation", "Try", "Catch"};
 
         return token_types[tokentype];
     }

include/chaiscript/language/chaiscript_eval.hpp

@@ -586,19 +586,25 @@ namespace chaiscript
     Boxed_Value eval_try(Eval_System &ss, const TokenPtr &node) {
         Boxed_Value retval;        
         retval = Boxed_Value();
+        Boxed_Value except;
+        bool succeeded = false;
 
         ss.new_scope();
         try {
             retval = eval_token(ss, node->children[0]);
+            succeeded = true;
         }
         catch (const Eval_Error &) {
+            ss.pop_scope();
             throw;
         }
         catch (const std::exception &e) {
+            except = Boxed_Value(boost::ref(e));
+            /*
             if (node->children.size() > 2) {
                 if (node->children[1]->text == "catch") {
                     if (node->children.size() > 3) {
-                        ss.add_object(node->children[2]->text, Boxed_Value(boost::ref(e)));
+                        ss.add_object(node->children[2]->text, );
                         retval = eval_token(ss, node->children[3]);
                     }
                     else {
@@ -606,8 +612,11 @@ namespace chaiscript
                     }
                 }
             }
+            */
         }
         catch (Boxed_Value &bv) {
+            except = bv;
+            /*
             if (node->children.size() > 2) {
                 if (node->children[1]->text == "catch") {
                     if (node->children.size() > 3) {
@@ -619,7 +628,52 @@ namespace chaiscript
                     }
                 }
             }
+            */
         }
+        catch (...) {
+            ss.pop_scope();
+            throw;
+        }
+
+        if (!succeeded) {
+
+            for (unsigned int i = 1; i < node->children.size(); ++i) {
+                TokenPtr catch_block = node->children[i];
+
+                if (catch_block->children.size() == 1) {
+                    //No variable capture, no guards
+                    retval = eval_token(ss, catch_block->children[0]);
+                    break;
+                }
+                else if (catch_block->children.size() == 2) {
+                    //Variable capture, no guards
+                    ss.add_object(catch_block->children[0]->text, except);
+                    retval = eval_token(ss, catch_block->children[1]);
+                    break;
+                }
+                else if (catch_block->children.size() == 3) {
+                    //Variable capture, no guards
+                    ss.add_object(catch_block->children[0]->text, except);
+
+                    bool guard;
+                    try {
+                        guard = boxed_cast<bool>(eval_token(ss, catch_block->children[1]));
+                    } catch (const bad_boxed_cast &) {
+                        ss.pop_scope();
+                        throw Eval_Error("Guard condition not boolean", catch_block->children[1]);
+                    }
+                    if (guard) {
+                        retval = eval_token(ss, catch_block->children[2]);
+                        break;
+                    }
+                }
+                else {
+                    ss.pop_scope();
+                    throw Eval_Error("Internal error: catch block size unrecognized", catch_block);
+                }
+            }
+        }
+
         ss.pop_scope();
 
         return retval;

include/chaiscript/language/chaiscript_parser.hpp

@@ -947,11 +947,17 @@ namespace chaiscript
                 while (has_matches) {
                     while (Eol());
                     has_matches = false;
-                    if (Keyword("catch", true)) {
+                    if (Keyword("catch", false)) {
+                        int catch_stack_top = match_stack.size();
                         if (Char('(')) {
                             if (!(Id(true) && Char(')'))) {
                                 throw Eval_Error("Incomplete 'catch' expression", File_Position(line, col), filename);
                             }
+                            if (Char(':')) {
+                                if (!Expression()) {
+                                    throw Eval_Error("Missing guard expression for catch", File_Position(line, col), filename);
+                                }
+                            }
                         }
 
                         while (Eol());
@@ -959,7 +965,7 @@ namespace chaiscript
                         if (!Block()) {
                             throw Eval_Error("Incomplete 'catch' block", File_Position(line, col), filename);
                         }
-                        
+                        build_match(Token_Type::Catch, catch_stack_top);
                         has_matches = true;
                     }
                 }

unittests/exception_guards.chai

@@ -0,0 +1,28 @@
+for (var i = 2; i < 6; ++i) {
+  try {
+    throw(i)
+  }
+  catch(e) : e < 2 {
+    print("Catch 1: " + e.to_string())
+  }
+  catch(e) : e < 4 {
+    print("Catch 2: " + e.to_string())
+  }
+  catch(e) {
+    print("Catch 3: " + e.to_string())
+  }
+  catch {
+    print("This is never called")
+  }
+}
+
+try {
+  throw(3)
+}
+catch(e) : e < 3 
+{
+  print("Caught less than 3") 
+}
+catch {
+  print("Backup catch")
+}

unittests/exception_guards.txt

@@ -0,0 +1,5 @@
+Catch 2: 2
+Catch 2: 3
+Catch 3: 4
+Catch 3: 5
+Backup catch