Implemented #elif. #169

src/main/java/dk/camelot64/kickc/preprocessor/CPreprocessor.java

@@ -108,7 +108,11 @@ public class CPreprocessor implements TokenSource {
          return true;
       } else if(inputToken.getType() == KickCLexer.IFELSE) {
          // #else means we must skip until #endif
-         ifelse(cTokenSource);
+         skipToEndIf(cTokenSource);
+         return true;
+      } else if(inputToken.getType() == KickCLexer.ELIF) {
+         // #elif means we must skip until #endif
+         skipToEndIf(cTokenSource);
          return true;
       } else if(inputToken.getType() == KickCLexer.ENDIF) {
          // Skip #endif - they have already been handled by #if / #else
@@ -119,6 +123,25 @@ public class CPreprocessor implements TokenSource {
       return false;
    }
 
+   /**
+    * Define a macro.
+    *
+    * @param cTokenSource The token source used to get the macro name and body.
+    */
+   private void define(CTokenSource cTokenSource) {
+      // #define a new macro - find the name
+      skipWhitespace(cTokenSource);
+      String macroName = nextToken(cTokenSource, KickCLexer.NAME).getText();
+      // Examine whether the macro has parameters
+      skipWhitespace(cTokenSource);
+      if(cTokenSource.peekToken().getType() == KickCLexer.PAR_BEGIN) {
+         // Macro has parameters - find parameter name list
+         throw new CompileError("Macros with parameters not supported!");
+      }
+      final ArrayList<Token> macroBody = readBody(cTokenSource);
+      defines.put(macroName, macroBody);
+   }
+
    /**
     * Encountered an IDENTIFIER. Attempt to expand as a macro.
     *
@@ -182,7 +205,21 @@ public class CPreprocessor implements TokenSource {
       String macroName = nextToken(cTokenSource, KickCLexer.NAME).getText();
       final boolean defined = this.defines.containsKey(macroName);
       if(!defined) {
-         iffalse(cTokenSource);
+         skipIfBody(cTokenSource);
+      }
+   }
+
+   /**
+    * #ifdef checks if a macro is _NOT_ defined.
+    *
+    * @param cTokenSource The token source used to get the macro name
+    */
+   private void ifndef(CTokenSource cTokenSource) {
+      skipWhitespace(cTokenSource);
+      String macroName = nextToken(cTokenSource, KickCLexer.NAME).getText();
+      final boolean defined = this.defines.containsKey(macroName);
+      if(defined) {
+         skipIfBody(cTokenSource);
       }
    }
 
@@ -192,6 +229,19 @@ public class CPreprocessor implements TokenSource {
     * @param cTokenSource The token source used to get the condition
     */
    private void ifif(CTokenSource cTokenSource) {
+      Long conditionValue = readAndEvaluateCondition(cTokenSource);
+      if(conditionValue == null || conditionValue == 0L) {
+         skipIfBody(cTokenSource);
+      }
+   }
+
+   /**
+    * Read a condition expression ( for #if / #elif ) from a token source and evaluate it. Return the result.
+    *
+    * @param cTokenSource The token source to read from
+    * @return The value of the evaluation of the constant condition expression
+    */
+   private Long readAndEvaluateCondition(CTokenSource cTokenSource) {
       // Read the condition body
       ArrayList<Token> conditionTokens = readBody(cTokenSource);
       // Evaluate any uses of the defined operator (to prevent expansion of the named macro)
@@ -201,10 +251,7 @@ public class CPreprocessor implements TokenSource {
       // Parse the expression
       KickCParser.ExprContext conditionExpr = ExprParser.parseExpression(subPreprocessor);
       // Evaluate the expression
-      Long conditionValue = evaluateExpression(conditionExpr);
-      if(conditionValue == null || conditionValue == 0L) {
-         iffalse(cTokenSource);
-      }
+      return evaluateExpression(conditionExpr);
    }
 
    /**
@@ -269,8 +316,9 @@ public class CPreprocessor implements TokenSource {
    }
 
    /**
-    * Find and evaluate the special defined X operator which evaluates to 1 if a named macro if defined and 0 if it is undefined.
-    * Works by replacing the defined X tokens with the resulting 0/1 value in the passed token list.
+    * Find and evaluate the special "defined X" operator which evaluates to 1 if a named macro if defined and 0 if it is undefined.
+    * Works by replacing the "defined X" tokens with the resulting 0/1 value in the passed token list.
+    *
     * @param conditionTokens The token list
     */
    private void evaluateDefinedOperator(ArrayList<Token> conditionTokens) {
@@ -314,6 +362,7 @@ public class CPreprocessor implements TokenSource {
 
    /**
     * Get the next token from an iterator skipping whitespace (unless it has a newline)
+    *
     * @param tokenIt The iterator
     * @return The next non-whitespace token
     */
@@ -325,32 +374,26 @@ public class CPreprocessor implements TokenSource {
    }
 
    /**
-    * #ifdef checks if a macro is _NOT_ defined.
-    *
-    * @param cTokenSource The token source used to get the macro name
-    */
-   private void ifndef(CTokenSource cTokenSource) {
-      skipWhitespace(cTokenSource);
-      String macroName = nextToken(cTokenSource, KickCLexer.NAME).getText();
-      final boolean defined = this.defines.containsKey(macroName);
-      if(defined) {
-         iffalse(cTokenSource);
-      }
-   }
-
-   /**
-    * Skip tokens based in an #if that is false
+    * Skip tokens based in an #if that is false - look for a matching #elif, #else or the #endif
     *
     * @param cTokenSource The token source
     */
-   private void iffalse(CTokenSource cTokenSource) {
-      // Skip tokens until finding a matching #endif - respect nesting
+   private void skipIfBody(CTokenSource cTokenSource) {
+      // Skip tokens until finding a matching #endif or a matching #else - respect nesting
       int nesting = 1;
       while(true) {
          final Token token = cTokenSource.nextToken();
          final int tokenType = token.getType();
          if(tokenType == KickCLexer.IFDEF || tokenType == KickCLexer.IFNDEF || tokenType == KickCLexer.IFIF) {
             ++nesting;
+         } else if(tokenType == KickCLexer.ELIF) {
+            if(nesting == 1) {
+               // We are at the outer #if - #elif means we must evaluate the condition and maybe generate output from here!
+               final Long conditionValue = readAndEvaluateCondition(cTokenSource);
+               if(conditionValue != null && conditionValue != 0L)
+                  // #elif condition !=0 - generate output from here!
+                  return;
+            }
          } else if(tokenType == KickCLexer.IFELSE) {
             if(nesting == 1) {
                // We are at the outer #if - #else means we must generate output from here!
@@ -366,11 +409,11 @@ public class CPreprocessor implements TokenSource {
    }
 
    /**
-    * #else skips until a matching #endif
+    * Skip until a matching #endif
     *
     * @param cTokenSource The token source
     */
-   private void ifelse(CTokenSource cTokenSource) {
+   private void skipToEndIf(CTokenSource cTokenSource) {
       int nesting = 1;
       while(true) {
          final Token token = cTokenSource.nextToken();
@@ -386,24 +429,6 @@ public class CPreprocessor implements TokenSource {
       }
    }
 
-   /**
-    * Define a macro.
-    *
-    * @param cTokenSource The token source used to get the macro name and body.
-    */
-   private void define(CTokenSource cTokenSource) {
-      // #define a new macro - find the name
-      skipWhitespace(cTokenSource);
-      String macroName = nextToken(cTokenSource, KickCLexer.NAME).getText();
-      // Examine whether the macro has parameters
-      skipWhitespace(cTokenSource);
-      if(cTokenSource.peekToken().getType() == KickCLexer.PAR_BEGIN) {
-         // Macro has parameters - find parameter name list
-         throw new CompileError("Macros with parameters not supported!");
-      }
-      final ArrayList<Token> macroBody = readBody(cTokenSource);
-      defines.put(macroName, macroBody);
-   }
 
    /**
     * Read a preprocessor body (eg. a macro body) until encountering a newline

src/test/java/dk/camelot64/kickc/parsing/macros/TestPreprocessor.java

@@ -159,6 +159,8 @@ public class TestPreprocessor {
       assertEquals("name:x;name:y;", parse("#define A X\n#if defined A\nx;\n#endif\ny;"));
       // Output not generated by #if using defined operator
       assertEquals("name:y;", parse("#if defined A\nx;\n#endif\ny;"));
+      // Output generated by #elif
+      assertEquals("name:y;name:w;", parse("#if 0\nx;\n#elif 1\ny;\n#elif 1\nz;\n#else\nq;\n#endif\nw;"));
    }
 
    /**
@@ -181,12 +183,12 @@ public class TestPreprocessor {
       CParser cParser = new CParser(null);
       cParser.addSource(charStream);
       KickCParser.StmtSeqContext stmtSeqContext = cParser.getParser().stmtSeq();
-      MacrosPrinter printVisitor = new MacrosPrinter();
+      ProgramPrinter printVisitor = new ProgramPrinter();
       printVisitor.visit(stmtSeqContext);
       return printVisitor.getOut().toString();
    }
 
-   private static class MacrosPrinter extends KickCParserBaseVisitor<Object> {
+   private static class ProgramPrinter extends KickCParserBaseVisitor<Object> {
 
       StringBuilder out = new StringBuilder();