IFの構文解析

SMILEBASIC/VM.d

@@ -51,6 +51,8 @@ enum CodeType
     Print,
     PopG,
     GotoS,
+    GotoFalse,
+    GotoTrue,
 }
 abstract class Code
 {
@@ -194,6 +196,38 @@ class GotoS : Code
         stderr.writeln("can't execute");
     }
 }
+class GotoTrue : Code
+{
+    int address;
+    this(int addr)
+    {
+        this.type = CodeType.GotoTrue;
+        address = addr;
+    }
+    override void execute(VM vm)
+    {
+        Value cond;
+        vm.pop(cond);
+        if(cond.boolValue)
+            vm.pc = address - 1;
+    }
+}
+class GotoFalse : Code
+{
+    int address;
+    this(int addr)
+    {
+        this.type = CodeType.GotoFalse;
+        address = addr;
+    }
+    override void execute(VM vm)
+    {
+        Value cond;
+        vm.pop(cond);
+        if(!cond.boolValue)
+            vm.pc = address - 1;
+    }
+}
 class Gosub : Code
 {
 

SMILEBASIC/main.d

@@ -8,7 +8,11 @@ int main(string[] argv)
         writeln(parser.calc());
     }
 
-    auto parser = new Parser("@A\nA=1+2+3+4\nPRINT 1+1,2+3;10-5,A:A=A*2:PRINT A:GOTO@A");
+    auto parser = new Parser(
+"@A\nA=1+2+3+4\nPRINT 1+1,2+3;10-5,A:A=A*2:PRINT A
+IF 1 THEN PRINT 2
+IF 3 THEN PRINT 4 ELSE PRINT 5
+");
     auto vm = parser.compile();
     vm.run();
     readln();

SMILEBASIC/node.d

@@ -20,6 +20,7 @@ enum NodeType
     Print,
     Label,
     Goto,
+    If,
 }
 abstract class Node
 {
@@ -191,3 +192,16 @@ class Goto : Statement
         this.label = name;
     }
 }
+class If : Statement
+{
+    Expression condition;
+    Statements then;
+    Statements else_;
+    this(Expression condition, Statements t, Statements e)
+    {
+        this.type = NodeType.If;
+        this.condition = condition;
+        this.then = t;
+        this.else_ = e;
+    }
+}

SMILEBASIC/parser.d

@@ -39,6 +39,10 @@ class Lexical
         reserved["NOT"] = TokenType.Not;
         reserved["PRINT"] = TokenType.Print;
         reserved["GOTO"] = TokenType.Goto;
+        reserved["IF"] = TokenType.If;
+        reserved["THEN"] = TokenType.Then;
+        reserved["ELSE"] = TokenType.Else;
+        reserved["ENDIF"] = TokenType.Endif;
         reserved.rehash();
         line = 1;
     }
@@ -289,6 +293,7 @@ class Parser
     }
     Statements parseProgram()
     {
+        lex.popFront();
         auto statements = new Statements();
         while(!lex.empty())
         {
@@ -302,19 +307,37 @@ class Parser
         }
         return statements;
     }
+    Statements ifstatements()
+    {
+        auto statements = new Statements();
+        while(!lex.empty())
+        {
+            auto type = lex.front().type;
+            if(type == TokenType.NewLine) break;
+            if(type == TokenType.Else) break;
+            if(type == TokenType.Endif) break;
+            auto statement = statement();
+            if(statement != Statement.NOP)
+            {
+                statements.addStatement(statement);
+            }
+        }
+        return statements;
+    }
     void syntaxError()
     {
-        stderr.writeln("Syntax error (", lex.getLine(), ')');
+        stderr.writeln("Syntax error (", lex.getLine(), ')', " Mysterious ", lex.front().type);
     }
     //statement
     Statement statement()
     {
-        lex.popFront();
         auto token = lex.front();
+        Statement node = null;
         switch(token.type)
         {
             case TokenType.Print:
-                return print();
+                node = print();
+                return node;
             case TokenType.Iden:
                 {
                     wstring name = token.value.stringValue;
@@ -322,7 +345,8 @@ class Parser
                     token = lex.front();
                     if(token.type == TokenType.Assign)
                     {
-                        return assign(name);
+                        node = assign(name);
+                        break;
                     }
                     //命令呼び出し
                 }
@@ -331,16 +355,69 @@ class Parser
             case TokenType.NewLine:
                 break;
             case TokenType.Label:
-                return new Label(token.value.stringValue);
+                node = new Label(token.value.stringValue);
+                break;
             case TokenType.Goto:
                 lex.popFront();
                 token = lex.front();
-                return new Goto(token.value.stringValue);
+                node = new Goto(token.value.stringValue);
+                break;
+            case TokenType.If:
+                node = if_();
+                return node;
             default:
                 syntaxError();
                 break;
         }
-        return null;
+        lex.popFront();
+        return node;
+    }
+    If if_()
+    {
+        lex.popFront();
+        auto token = lex.front();
+        auto expr = expression();
+        if(expr is null)
+        {
+            syntaxError();
+            return null;
+        }
+        token = lex.front();
+        if(token.type != TokenType.Then)
+        {
+            if(token.type != TokenType.Goto)
+            {
+                //IF expr GOSUBは不可
+                syntaxError();
+                return null;
+            }
+        }
+        if(token.type != TokenType.Goto)
+        {
+            lex.popFront();
+            token = lex.front();
+        }
+        if(token.type == TokenType.NewLine)
+        {
+            writeln("NotImpl: Multi line if");
+            syntaxError();
+            return null;
+        }
+        auto then = ifstatements();
+        token = lex.front();
+        lex.popFront();
+        Statements else_;
+        if(token.type == TokenType.Else)
+        {
+            if(lex.front().type == TokenType.NewLine)
+            {
+                //3.1現在だとエラー
+                syntaxError();
+            }
+            else_ = ifstatements();
+        }
+        auto if_ = new If(expr, then, else_);
+        return if_;
     }
     Assign assign(wstring name)
     {
@@ -379,13 +456,16 @@ class Parser
                 print.addLine();
                 break;
             }
-            if(token.type != TokenType.Colon && token.type != TokenType.NewLine && token.type != TokenType.Semicolon && token.type != TokenType.Comma)
+            if(token.type != TokenType.Colon && token.type != TokenType.NewLine && 
+               token.type != TokenType.Semicolon && token.type != TokenType.Comma &&
+               token.type != TokenType.Else && token.type != TokenType.Endif)
             {
                 syntaxError();
             }
             else
             {
-                if(token.type == TokenType.Colon || token.type == TokenType.NewLine)
+                if(token.type == TokenType.Colon || token.type == TokenType.NewLine ||
+                   token.type == TokenType.Else || token.type == TokenType.Endif)
                 {
                     print.addLine();
                     break;

SMILEBASIC/token.d

@@ -27,6 +27,9 @@ enum TokenType
     Assign,
     Label,
     Goto,
+    Then,
+    Else,
+    Endif,
 }
 
 struct Token

SMILEBASIC/type.d

@@ -45,4 +45,19 @@ struct Value
                 break;
         }
     }
+    bool boolValue()
+    {
+        switch(type)
+        {
+            case ValueType.Double:
+                return this.doubleValue != 0;
+            case ValueType.Integer:
+                return this.integerValue != 0;
+            case ValueType.String:
+                return true;//3.1現在では文字列はtrue(ただし!"A"などは動かない)
+            default:
+                //配列はtype missmatch
+                return false;
+        }
+    }
 }