77 lines
2.1 KiB
Java
77 lines
2.1 KiB
Java
package cd.frontend.semantic;
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import cd.frontend.semantic.SemanticFailure.Cause;
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import cd.ir.Ast.ClassDecl;
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import cd.ir.Ast.MethodDecl;
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import cd.ir.AstVisitor;
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import cd.ir.Symbol.ClassSymbol;
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import cd.ir.Symbol.MethodSymbol;
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import cd.ir.Symbol.VariableSymbol;
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import cd.util.Pair;
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import java.util.HashSet;
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import java.util.Set;
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public class InheritanceChecker extends AstVisitor<Void, Void> {
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ClassSymbol classSym;
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@Override
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public Void classDecl(ClassDecl ast, Void arg) {
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classSym = ast.sym;
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// check for cycles in the inheritance hierarchy:
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Set<ClassSymbol> supers = new HashSet<ClassSymbol>();
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ClassSymbol sc = classSym.superClass;
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supers.add(classSym);
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while (sc != null) {
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if (supers.contains(sc))
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throw new SemanticFailure(
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Cause.CIRCULAR_INHERITANCE,
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"Class %s has %s as a superclass twice",
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ast.name, sc.name);
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supers.add(sc);
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sc = sc.superClass;
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}
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this.visitChildren(ast, null);
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return null;
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}
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@Override
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public Void methodDecl(MethodDecl ast, Void arg) {
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// check that methods overridden from a parent class agree
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// on number/type of parameters
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MethodSymbol sym = ast.sym;
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MethodSymbol superSym = classSym.superClass.getMethod(ast.name);
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sym.overrides = superSym;
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if (superSym != null) {
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if (superSym.parameters.size() != sym.parameters.size())
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throw new SemanticFailure(
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Cause.INVALID_OVERRIDE,
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"Overridden method %s has %d parameters, " +
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"but original has %d",
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ast.name, sym.parameters.size(),
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superSym.parameters.size());
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for (Pair<VariableSymbol> pair : Pair.zip(sym.parameters, superSym.parameters))
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if (pair.a.type != pair.b.type)
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throw new SemanticFailure(
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Cause.INVALID_OVERRIDE,
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"Method parameter %s has type %s, but " +
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"corresponding base class parameter %s has type %s",
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pair.a.name, pair.a.type, pair.b.name, pair.b.type);
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if (superSym.returnType != sym.returnType)
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throw new SemanticFailure(
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Cause.INVALID_OVERRIDE,
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"Overridden method %s has return type %s," +
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"but its superclass has %s",
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ast.name, sym.returnType, superSym.returnType);
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}
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return null;
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}
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}
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