prepared expression parser for implementation of more complex expressions

components/compiler/exprparser.cpp

@@ -4,34 +4,51 @@
 #include <stdexcept>
 
 #include "generator.hpp"
+#include "scanner.hpp"
+#include "errorhandler.hpp"
 
 namespace Compiler
 {
     ExprParser::ExprParser (ErrorHandler& errorHandler, Context& context, Locals& locals,
         Literals& literals)
-    : Parser (errorHandler, context), mLocals (locals), mLiterals (literals)
+    : Parser (errorHandler, context), mLocals (locals), mLiterals (literals),
+      mNextOperand (true)
     {}
 
     bool ExprParser::parseInt (int value, const TokenLoc& loc, Scanner& scanner)
     {
-        Operand operand;
-        operand.mType = 'l';
-        operand.mInteger = value;
+        if (mNextOperand)
+        {
+            Operand operand;
+            operand.mType = 'l';
+            operand.mInteger = value;
         
-        mOperands.push_back (operand);
+            mOperands.push_back (operand);
+            
+            mNextOperand = false;
+            mTokenLoc = loc;
+            return true;
+        }
         
-        return false;
+        return Parser::parseInt (value, loc, scanner);
     }
 
     bool ExprParser::parseFloat (float value, const TokenLoc& loc, Scanner& scanner)
     {
-        Operand operand;
-        operand.mType = 'f';
-        operand.mFloat = value;
+        if (mNextOperand)
+        {    
+            Operand operand;
+            operand.mType = 'f';
+            operand.mFloat = value;
         
-        mOperands.push_back (operand);
+            mOperands.push_back (operand);
+            
+            mNextOperand = false;
+            mTokenLoc = loc;
+            return true;
+        }            
             
-        return false;
+        return Parser::parseFloat (value, loc, scanner);
     }
 
     bool ExprParser::parseName (const std::string& name, const TokenLoc& loc,
@@ -47,19 +64,39 @@ namespace Compiler
 
     bool ExprParser::parseSpecial (int code, const TokenLoc& loc, Scanner& scanner)
     {
+        if (code==Scanner::S_comma)
+        {
+            // end marker
+            mTokenLoc = loc;
+            return false;
+        }
+        
+        if (code==Scanner::S_newline)
+        {
+            // end marker
+            mTokenLoc = loc;
+            scanner.putbackNewline (loc);
+            return false;
+        }
+        
         return Parser::parseSpecial (code, loc, scanner);
     }
     
     void ExprParser::reset()
     {
         mOperands.clear();
+        mOperators.clear();
+        mNextOperand = true;
     }
     
     char ExprParser::write (std::vector<Interpreter::Type_Code>& code)
     {
-        if (mOperands.empty())
-            throw std::logic_error ("empty expression");
+        if (mOperands.empty() && mOperators.empty())
+            getErrorHandler().error ("missing expression", mTokenLoc);
             
+        if (mNextOperand)
+            getErrorHandler().error ("syntax error in expression", mTokenLoc);
+
         Operand operand = mOperands[mOperands.size()-1];
         mOperands.clear();
         

components/compiler/exprparser.hpp

@@ -6,6 +6,7 @@
 #include <components/interpreter/types.hpp>
 
 #include "parser.hpp"
+#include "tokenloc.hpp"
 
 namespace Compiler
 {
@@ -24,6 +25,9 @@ namespace Compiler
             Locals& mLocals;  
             Literals& mLiterals;
             std::vector<Operand> mOperands;
+            std::vector<char> mOperators;
+            bool mNextOperand;
+            TokenLoc mTokenLoc;
             
         public:
     

components/compiler/scanner.cpp

@@ -43,6 +43,12 @@ namespace Compiler
 
     bool Scanner::scanToken (Parser& parser)
     {
+        if (mNewline)
+        {
+            mNewline = false;
+            return parser.parseSpecial (S_newline, mPutbackLoc, *this);
+        }
+    
         char c;
 
         if (!get (c))
@@ -412,13 +418,20 @@ namespace Compiler
     // constructor
 
     Scanner::Scanner (ErrorHandler& errorHandler, std::istream& inputStream)
-    : mErrorHandler (errorHandler), mStream (inputStream)
+    : mErrorHandler (errorHandler), mStream (inputStream), mNewline (false)
     {
     }
 
     void Scanner::scan (Parser& parser)
     {
+        mNewline = false;
         while (scanToken (parser));
     }
+    
+    void Scanner::putbackNewline (const TokenLoc& loc)
+    {
+        mNewline = true;
+        mPutbackLoc = loc;
+    }
 }
 

components/compiler/scanner.hpp

@@ -22,6 +22,8 @@ namespace Compiler
             TokenLoc mLoc;
             TokenLoc mPrevLoc;
             std::istream& mStream;
+            bool mNewline;
+            TokenLoc mPutbackLoc;
 
         public:
 
@@ -78,6 +80,9 @@ namespace Compiler
 
             void scan (Parser& parser);
             ///< Scan a token and deliver it to the parser.
+            
+            void putbackNewline (const TokenLoc& loc);
+            ///< put back a newline token
     };
 }