Add support for switch/case/default statements.

include/chaiscript/language/chaiscript_common.hpp

@@ -23,7 +23,7 @@ namespace chaiscript
                 Comparison, Addition, Subtraction, Multiplication, Division, Modulus, 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, Catch, Finally, Method, Attr_Decl, Shift, Equality, Bitwise_And, Bitwise_Xor, Bitwise_Or, 
-                Logical_And, Logical_Or
+                Logical_And, Logical_Or, Switch, Case, Default
     };
   };
 
@@ -37,7 +37,7 @@ namespace chaiscript
                                     "Comparison", "Addition", "Subtraction", "Multiplication", "Division", "Modulus", "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", "Catch", "Finally", "Method", "Attr_Decl", "Shift", "Equality", "Bitwise_And", "Bitwise_Xor", "Bitwise_Or", 
-                                    "Logical_And", "Logical_Or"};
+                                    "Logical_And", "Logical_Or", "Switch", "Case", "Default"};
 
       return ast_node_types[ast_node_type];
     }

include/chaiscript/language/chaiscript_eval.hpp

@@ -780,6 +780,79 @@ namespace chaiscript
 
     };
 
+    struct Switch_AST_Node : public AST_Node {
+      public:
+        Switch_AST_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Switch, const boost::shared_ptr<std::string> &t_fname=boost::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :
+          AST_Node(t_ast_node_text, t_id, t_fname, t_start_line, t_start_col, t_end_line, t_end_col) { }
+        virtual ~Switch_AST_Node() {}
+        virtual Boxed_Value eval_internal(chaiscript::detail::Dispatch_Engine &t_ss) {
+          Boxed_Value match_value;
+          bool breaking = false;
+          int currentCase = 1;
+          bool hasMatched = false;
+
+          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
+
+          match_value = this->children[0]->eval(t_ss);
+
+          while (!breaking) {
+            try {
+              if (this->children[currentCase]->identifier == AST_Node_Type::Case) {
+                //This is a little odd, but because want to see both the switch and the case simultaneously, I do a downcast here.
+                try {
+                  if (hasMatched || boxed_cast<bool>(t_ss.call_function("==", match_value, this->children[currentCase]->children[0]->eval(t_ss)))) {
+                    this->children[currentCase]->eval(t_ss);
+                    hasMatched = true;
+                  }
+                }
+                catch (const exception::bad_boxed_cast &) {
+                  throw exception::eval_error("Internal error: case guard evaluation not boolean");
+                }
+              }
+              else if (this->children[currentCase]->identifier == AST_Node_Type::Default) {
+                this->children[currentCase]->eval(t_ss);
+                breaking = true;
+              }
+            }
+            catch (detail::Break_Loop &) {
+              breaking = true;
+            }
+            ++currentCase;
+            if (currentCase == this->children.size())
+              breaking = true;
+          }
+          return Boxed_Value();
+        }
+    };
+
+    struct Case_AST_Node : public AST_Node {
+      public:
+        Case_AST_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Case, const boost::shared_ptr<std::string> &t_fname=boost::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :
+          AST_Node(t_ast_node_text, t_id, t_fname, t_start_line, t_start_col, t_end_line, t_end_col) { }
+        virtual ~Case_AST_Node() {}
+        virtual Boxed_Value eval_internal(chaiscript::detail::Dispatch_Engine &t_ss) {
+          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
+
+          this->children[1]->eval(t_ss);
+          
+          return Boxed_Value();
+        }
+    };
+   
+    struct Default_AST_Node : public AST_Node {
+      public:
+        Default_AST_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Default, const boost::shared_ptr<std::string> &t_fname=boost::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :
+          AST_Node(t_ast_node_text, t_id, t_fname, t_start_line, t_start_col, t_end_line, t_end_col) { }
+        virtual ~Default_AST_Node() {}
+        virtual Boxed_Value eval_internal(chaiscript::detail::Dispatch_Engine &t_ss) {
+          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
+
+          this->children[0]->eval(t_ss);
+
+          return Boxed_Value();
+        }
+    };
+       
     struct Inline_Array_AST_Node : public AST_Node {
       public:
         Inline_Array_AST_Node(const std::string &t_ast_node_text = "", int t_id = AST_Node_Type::Inline_Array, const boost::shared_ptr<std::string> &t_fname=boost::shared_ptr<std::string>(), int t_start_line = 0, int t_start_col = 0, int t_end_line = 0, int t_end_col = 0) :

include/chaiscript/language/chaiscript_parser.hpp

@@ -1415,6 +1415,92 @@ namespace chaiscript
           return retval;
         }
 
+        /**
+         * Reads a case block from input
+         */
+        bool Case() {
+          bool retval = false;
+
+          size_t prev_stack_top = m_match_stack.size();
+
+          if (Keyword("case")) {
+            retval = true;
+            
+            if (!Char('(')) {
+              throw exception::eval_error("Incomplete 'case' expression", File_Position(m_line, m_col), *m_filename);
+            }
+
+            if (!(Operator() && Char(')'))) {
+              throw exception::eval_error("Incomplete 'case' expression", File_Position(m_line, m_col), *m_filename);
+            }
+
+            while (Eol()) {}
+
+            if (!Block()) {
+              throw exception::eval_error("Incomplete 'case' block", File_Position(m_line, m_col), *m_filename);
+            }
+            
+            build_match(AST_NodePtr(new eval::Case_AST_Node()), prev_stack_top);
+          }
+          else if (Keyword("default")) {
+            while (Eol()) {}
+
+            if (!Block()) {
+              throw exception::eval_error("Incomplete 'default' block", File_Position(m_line, m_col), *m_filename);
+            }
+            
+            build_match(AST_NodePtr(new eval::Default_AST_Node()), prev_stack_top);
+          }            
+          
+          return retval;
+        }
+      
+        /**
+         * Reads a switch statement from input
+         */
+        bool Switch() {
+          bool retval = false;
+
+          size_t prev_stack_top = m_match_stack.size();
+
+          if (Keyword("switch")) {
+            retval = true;
+
+            if (!Char('(')) {
+              throw exception::eval_error("Incomplete 'switch' expression", File_Position(m_line, m_col), *m_filename);
+            }
+
+            if (!(Operator() && Char(')'))) {
+              throw exception::eval_error("Incomplete 'switch' expression", File_Position(m_line, m_col), *m_filename);
+            }
+
+            while (Eol()) {}
+
+            if (Char('{')) {
+              retval = true;
+            
+              while (Eol()) {}
+              
+              while (Case()) {
+                while (Eol());
+              }
+
+              while (Eol());
+
+              if (!Char('}')) {
+                throw exception::eval_error("Incomplete block", File_Position(m_line, m_col), *m_filename);
+              }
+            }
+            else {
+              throw exception::eval_error("Incomplete block", File_Position(m_line, m_col), *m_filename);
+            }
+            
+            build_match(AST_NodePtr(new eval::Switch_AST_Node()), prev_stack_top);
+          }
+
+          return retval;
+        }
+      
         /**
          * Reads a curly-brace C-style block from input
          */
@@ -1928,6 +2014,14 @@ namespace chaiscript
               retval = true;
               saw_eol = true;
             }
+            else if (Switch()) {
+              if (!saw_eol) {
+                throw exception::eval_error("Two function definitions missing line separator", File_Position(prev_line, prev_col), *m_filename);
+              }
+              has_more = true;
+              retval = true;
+              saw_eol = true;
+            }
             else if (Return()) {
               if (!saw_eol) {
                 throw exception::eval_error("Two expressions missing line separator", File_Position(prev_line, prev_col), *m_filename);

unittests/switch_break.chai

@@ -0,0 +1,22 @@
+var total = 0;
+
+switch(2) { 
+  case (1) { 
+    total += 1; 
+    break;
+  } 
+  case (2) { 
+    total += 2; 
+    break;
+  } 
+  case (3) { 
+    total += 4;
+    break;
+  } 
+  case (4) { 
+    total += 8; 
+    break;
+  } 
+}
+
+assert_equal(total, 2)

unittests/switch_default.chai

@@ -0,0 +1,18 @@
+var total = 0;
+
+switch(2) { 
+  case (1) { 
+    total += 1; 
+  } 
+  case (3) { 
+    total += 4;
+  } 
+  case (4) { 
+    total += 8; 
+  } 
+  default {
+    total += 16;
+  }
+}
+
+assert_equal(total, 16)

unittests/switch_fallthru.chai

@@ -0,0 +1,18 @@
+var total = 0;
+
+switch(2) { 
+  case (1) { 
+    total += 1; 
+  } 
+  case (2) { 
+    total += 2; 
+  } 
+  case (3) { 
+    total += 4;
+  } 
+  case (4) { 
+    total += 8; 
+  } 
+}
+
+assert_equal(total, 14); 

unittests/switch_fallthru_and_break.chai

@@ -0,0 +1,19 @@
+var total = 0;
+
+switch(2) { 
+  case (1) { 
+    total += 1; 
+  } 
+  case (2) { 
+    total += 2; 
+  } 
+  case (3) { 
+    total += 4;
+    break;
+  } 
+  case (4) { 
+    total += 8; 
+  } 
+}
+
+assert_equal(total, 6)