Replace Error with Assertion

Assertion violation errors currently report the location of the falsy
expression, but we'd prefer to print the actual expression (#16)

examples/raise_error.plang → examples/assertions.plang

@@ -5,7 +5,5 @@ program hibás_bemenet
   ki: "Írj be egy természetes számot!", SV
   be: x
 
-  ha x < 0 akkor
-    hiba: "nem természetes szám"
-  ha_vége
+  szerintem x > 0
 program_vége

src/main/java/ppke/itk/xplang/ast/ASTVisitor.java

@@ -19,7 +19,7 @@ public interface ASTVisitor {
     void visit(Loop loop);
     void visit(Input input);
     void visit(Output output);
-    void visit(ErrorRaising errorRaising);
+    void visit(Assertion assertion);
     void visit(FunctionCall functionCall);
     void visit(ConditionalConnective conditionalConnective);
     void visit(VarRef varRef);

src/main/java/ppke/itk/xplang/ast/ErrorRaising.java → src/main/java/ppke/itk/xplang/ast/Assertion.java

@@ -2,13 +2,13 @@
 
 import ppke.itk.xplang.common.Location;
 
-public class ErrorRaising extends Statement {
-    public ErrorRaising(Location location, RValue errorMessage) {
+public class Assertion extends Statement {
+    public Assertion(Location location, RValue condition) {
         super(location);
-        this.children.add(0, errorMessage);
+        this.children.add(0, condition);
     }
 
-    public RValue getErrorMessage() {
+    public RValue getCondition() {
         return (RValue) this.children.get(0);
     }
 

src/main/java/ppke/itk/xplang/interpreter/Interpreter.java

@@ -190,10 +190,12 @@ public void visit(Output output) throws InterpreterError {
     }
 
     @Override
-    public void visit(ErrorRaising errorRaising) throws InterpreterError {
-        errorRaising.getErrorMessage().accept(this);
-        StringValue message = valueStack.pop(StringValue.class);
-        throw new InterpreterError(ErrorCode.ASSERTION_FAILURE, message.getValue());
+    public void visit(Assertion assertion) throws InterpreterError {
+        assertion.getCondition().accept(this);
+        BooleanValue evaulated = valueStack.pop(BooleanValue.class);
+        if (evaulated.equals(BooleanValue.FALSE)) {
+            throw new InterpreterError(ErrorCode.ASSERTION_FAILURE, assertion.getCondition().location());
+        }
     }
 
     @Override public void visit(FunctionCall call) {

src/main/java/ppke/itk/xplang/lang/ErrorStatementParser.java → src/main/java/ppke/itk/xplang/lang/AssertStatementParser.java

@@ -1,29 +1,28 @@
 package ppke.itk.xplang.lang;
 
 import ppke.itk.xplang.ast.RValue;
-import ppke.itk.xplang.ast.ErrorRaising;
+import ppke.itk.xplang.ast.Assertion;
 import ppke.itk.xplang.common.Location;
 import ppke.itk.xplang.parser.*;
 import ppke.itk.xplang.type.Archetype;
 
-class ErrorStatementParser {
-    static ErrorRaising parse(Parser parser) throws ParseError {
-        Location startLoc = parser.accept(parser.symbol(PlangSymbol.ERROR)).location();
-        parser.accept(parser.symbol(PlangSymbol.COLON));
+class AssertStatementParser {
+    static Assertion parse(Parser parser) throws ParseError {
+        Location startLoc = parser.accept(parser.symbol(PlangSymbol.ASSERT)).location();
 
-        Expression messageExpression = parser.parseExpression();
-        Location endLoc = messageExpression.getLocation();
+        Expression assertion = parser.parseExpression();
+        Location endLoc = assertion.getLocation();
         RValue message = TypeChecker.in(parser.context())
-            .checking(messageExpression)
-            .expecting(Archetype.STRING_TYPE)
+            .checking(assertion)
+            .expecting(Archetype.BOOLEAN_TYPE)
             .withCustomErrorMessage(
-                node -> new ParseError(node.location(), ErrorCode.TYPE_MISMATCH_ERROR_MESSAGE, node.getType())
+                node -> new ParseError(node.location(), ErrorCode.TYPE_MISMATCH_ASSERTION, node.getType())
             )
             .build()
             .resolve();
 
         Location location = Location.between(startLoc, endLoc);
 
-        return new ErrorRaising(location, message);
+        return new Assertion(location, message);
     }
 }

src/main/java/ppke/itk/xplang/lang/PlangGrammar.java

@@ -43,7 +43,7 @@ public void setup(Context ctx) {
             makeSymbol(PlangSymbol.LOOP).register(ctx);
             makeSymbol(PlangSymbol.WHILE).register(ctx);
             makeSymbol(PlangSymbol.END_LOOP).register(ctx);
-            makeSymbol(PlangSymbol.ERROR).register(ctx);
+            makeSymbol(PlangSymbol.ASSERT).register(ctx);
             makeSymbol(PlangSymbol.ASSIGNMENT).register(ctx);
             makeSymbol(PlangSymbol.IN).register(ctx);
             makeSymbol(PlangSymbol.OUT).register(ctx);

src/main/java/ppke/itk/xplang/lang/PlangSymbol.java

@@ -18,7 +18,7 @@ enum PlangSymbol {
     LOOP,
     WHILE,
     END_LOOP,
-    ERROR,
+    ASSERT,
     ASSIGNMENT,
     IN,
     OUT,

src/main/java/ppke/itk/xplang/lang/StatementParser.java

@@ -22,7 +22,7 @@ final class StatementParser {
         statementParsers.put(PlangSymbol.OUT, OutputStatementParser::parse);
         statementParsers.put(PlangSymbol.OPEN, OpenStatementParser::parse);
         statementParsers.put(PlangSymbol.CLOSE, CloseStatementParser::parse);
-        statementParsers.put(PlangSymbol.ERROR, ErrorStatementParser::parse);
+        statementParsers.put(PlangSymbol.ASSERT, AssertStatementParser::parse);
     }
 
     private StatementParser() { /* empty private ctor */ }

src/main/java/ppke/itk/xplang/parser/ErrorCode.java

@@ -31,7 +31,7 @@ public enum ErrorCode {
     TYPE_MISMATCH_ARRAY_INDEX,
     TYPE_MISMATCH_NOT_SLICABLE,
     TYPE_MISMATCH_SLICE_INDEX,
-    TYPE_MISMATCH_ERROR_MESSAGE,
+    TYPE_MISMATCH_ASSERTION,
     TYPE_MISMATCH_NOT_READABLE,
 
     FUNCTION_AMBIGUOUS,

src/main/resources/language/plang/lexical.properties

@@ -12,7 +12,7 @@ symbol.pattern.ENDIF=ha_v[ée]ge
 symbol.pattern.LOOP=ciklus
 symbol.pattern.WHILE=am[íi]g
 symbol.pattern.END_LOOP=ciklus_v[ée]ge
-symbol.pattern.ERROR=hiba
+symbol.pattern.ASSERT=szerintem
 symbol.pattern.ASSIGNMENT=:[^\\S\\r\\n]*=
 symbol.pattern.IN=BE
 symbol.pattern.OUT=KI

src/main/resources/messages/compiler_messages.properties

@@ -25,7 +25,7 @@ TYPE_MISMATCH_NOT_ADDRESSABLE=Arrays and strings can only be indexed with intege
 TYPE_MISMATCH_ARRAY_INDEX=The [] operator is only defined for strings and array types (found %s)
 TYPE_MISMATCH_NOT_SLICABLE=Arrays and strings can only be indexed with integers (found %s)
 TYPE_MISMATCH_SLICE_INDEX=The [:] operator is only defined for strings and array tpyes (found %s)
-TYPE_MISMATCH_ERROR_MESSAGE=The error argument must be a string (found %s)
+TYPE_MISMATCH_ASSERTION=The assertion must be a boolean expression (found %s)
 TYPE_MISMATCH_NOT_READABLE=Cannot read data from variables of type %s
 FUNCTION_AMBIGUOUS=Function %1$s is ambiguous in context %3$s. Possible interpretations are: %2$s
 NO_VIABLE_FUNCTION=No function '%1$s' matches context %3$s. Candidates were: %2$s