--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.dsl.processor/src/com/oracle/truffle/dsl/processor/parser/MethodSpecParser.java	Mon Aug 18 18:41:16 2014 +0200
@@ -0,0 +1,288 @@
+/*
+ * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.dsl.processor.parser;
+
+import static com.oracle.truffle.dsl.processor.java.ElementUtils.*;
+
+import java.util.*;
+
+import javax.lang.model.element.*;
+import javax.lang.model.type.*;
+
+import com.oracle.truffle.dsl.processor.java.*;
+import com.oracle.truffle.dsl.processor.model.*;
+
+public final class MethodSpecParser {
+
+    private boolean emitErrors = true;
+    private boolean useVarArgs = false;
+
+    private final Template template;
+
+    public MethodSpecParser(Template template) {
+        this.template = template;
+    }
+
+    public Template getTemplate() {
+        return template;
+    }
+
+    public TypeSystemData getTypeSystem() {
+        return template.getTypeSystem();
+    }
+
+    public boolean isEmitErrors() {
+        return emitErrors;
+    }
+
+    public boolean isUseVarArgs() {
+        return useVarArgs;
+    }
+
+    public void setEmitErrors(boolean emitErrors) {
+        this.emitErrors = emitErrors;
+    }
+
+    public void setUseVarArgs(boolean useVarArgs) {
+        this.useVarArgs = useVarArgs;
+    }
+
+    public TemplateMethod parse(MethodSpec methodSpecification, ExecutableElement method, AnnotationMirror annotation, int naturalOrder) {
+        if (methodSpecification == null) {
+            return null;
+        }
+
+        methodSpecification.applyTypeDefinitions("types");
+
+        String id = method.getSimpleName().toString();
+        TypeMirror returnType = method.getReturnType();
+        List<TypeMirror> parameterTypes = new ArrayList<>();
+        for (VariableElement var : method.getParameters()) {
+            parameterTypes.add(var.asType());
+        }
+
+        return parseImpl(methodSpecification, naturalOrder, id, method, annotation, returnType, parameterTypes);
+    }
+
+    public TemplateMethod parseImpl(MethodSpec methodSpecification, int naturalOrder, String id, ExecutableElement method, AnnotationMirror annotation, TypeMirror returnType,
+                    List<TypeMirror> parameterTypes) {
+        ParameterSpec returnTypeSpec = methodSpecification.getReturnType();
+        Parameter returnTypeMirror = matchParameter(returnTypeSpec, returnType, -1, -1);
+        if (returnTypeMirror == null) {
+            if (emitErrors) {
+                TemplateMethod invalidMethod = new TemplateMethod(id, naturalOrder, template, methodSpecification, method, annotation, returnTypeMirror, Collections.<Parameter> emptyList());
+                String expectedReturnType = returnTypeSpec.toSignatureString(true);
+                String actualReturnType = ElementUtils.getSimpleName(returnType);
+
+                String message = String.format("The provided return type \"%s\" does not match expected return type \"%s\".\nExpected signature: \n %s", actualReturnType, expectedReturnType,
+                                methodSpecification.toSignatureString(method.getSimpleName().toString()));
+                invalidMethod.addError(message);
+                return invalidMethod;
+            } else {
+                return null;
+            }
+        }
+
+        List<Parameter> parameters = parseParameters(methodSpecification, parameterTypes, isUseVarArgs() && method != null ? method.isVarArgs() : false);
+        if (parameters == null) {
+            if (isEmitErrors() && method != null) {
+                TemplateMethod invalidMethod = new TemplateMethod(id, naturalOrder, template, methodSpecification, method, annotation, returnTypeMirror, Collections.<Parameter> emptyList());
+                String message = String.format("Method signature %s does not match to the expected signature: \n%s", createActualSignature(method),
+                                methodSpecification.toSignatureString(method.getSimpleName().toString()));
+                invalidMethod.addError(message);
+                return invalidMethod;
+            } else {
+                return null;
+            }
+        }
+
+        return new TemplateMethod(id, naturalOrder, template, methodSpecification, method, annotation, returnTypeMirror, parameters);
+    }
+
+    private static String createActualSignature(ExecutableElement method) {
+        StringBuilder b = new StringBuilder("(");
+        String sep = "";
+        if (method != null) {
+            for (VariableElement var : method.getParameters()) {
+                b.append(sep);
+                b.append(ElementUtils.getSimpleName(var.asType()));
+                sep = ", ";
+            }
+        }
+        b.append(")");
+        return b.toString();
+    }
+
+    /*
+     * Parameter parsing tries to parse required arguments starting from offset 0 with increasing
+     * offset until it finds a signature end that matches the required specification. If there is no
+     * end matching the required arguments, parsing fails. Parameters prior to the parsed required
+     * ones are cut and used to parse the optional parameters.
+     */
+    private List<Parameter> parseParameters(MethodSpec spec, List<TypeMirror> parameterTypes, boolean varArgs) {
+        List<Parameter> parsedRequired = null;
+        int offset = 0;
+        for (; offset <= parameterTypes.size(); offset++) {
+            List<TypeMirror> parameters = new ArrayList<>();
+            parameters.addAll(parameterTypes.subList(offset, parameterTypes.size()));
+            parsedRequired = parseParametersRequired(spec, parameters, varArgs);
+            if (parsedRequired != null) {
+                break;
+            }
+        }
+
+        if (parsedRequired == null) {
+            return null;
+        }
+
+        if (parsedRequired.isEmpty() && offset == 0) {
+            offset = parameterTypes.size();
+        }
+        List<TypeMirror> potentialOptionals = parameterTypes.subList(0, offset);
+        List<Parameter> parsedOptionals = parseParametersOptional(spec, potentialOptionals);
+        if (parsedOptionals == null) {
+            return null;
+        }
+
+        List<Parameter> finalParameters = new ArrayList<>();
+        finalParameters.addAll(parsedOptionals);
+        finalParameters.addAll(parsedRequired);
+        return finalParameters;
+    }
+
+    private List<Parameter> parseParametersOptional(MethodSpec spec, List<TypeMirror> types) {
+        List<Parameter> parsedParams = new ArrayList<>();
+
+        int typeStartIndex = 0;
+        List<ParameterSpec> specifications = spec.getOptional();
+        outer: for (int specIndex = 0; specIndex < specifications.size(); specIndex++) {
+            ParameterSpec specification = specifications.get(specIndex);
+            for (int typeIndex = typeStartIndex; typeIndex < types.size(); typeIndex++) {
+                TypeMirror actualType = types.get(typeIndex);
+                Parameter optionalParam = matchParameter(specification, actualType, -1, -1);
+                if (optionalParam != null) {
+                    parsedParams.add(optionalParam);
+                    typeStartIndex = typeIndex + 1;
+                    continue outer;
+                }
+            }
+        }
+
+        if (typeStartIndex < types.size()) {
+            // not enough types found
+            return null;
+        }
+        return parsedParams;
+    }
+
+    private List<Parameter> parseParametersRequired(MethodSpec spec, List<TypeMirror> types, boolean typeVarArgs) {
+        List<Parameter> parsedParams = new ArrayList<>();
+        List<ParameterSpec> specifications = spec.getRequired();
+        boolean specVarArgs = spec.isVariableRequiredParameters();
+        int typeIndex = 0;
+        int specificationIndex = 0;
+
+        ParameterSpec specification;
+        while ((specification = nextSpecification(specifications, specificationIndex, specVarArgs)) != null) {
+            TypeMirror actualType = nextActualType(types, typeIndex, typeVarArgs);
+            if (actualType == null) {
+                if (spec.isIgnoreAdditionalSpecifications()) {
+                    break;
+                }
+                return null;
+            }
+
+            int typeVarArgsIndex = typeVarArgs ? typeIndex - types.size() + 1 : -1;
+            int specVarArgsIndex = specVarArgs ? specificationIndex - specifications.size() + 1 : -1;
+
+            if (typeVarArgsIndex >= 0 && specVarArgsIndex >= 0) {
+                // both specifications and types have a variable number of arguments
+                // we would get into an endless loop if we would continue
+                break;
+            }
+
+            Parameter resolvedParameter = matchParameter(specification, actualType, specVarArgsIndex, typeVarArgsIndex);
+            if (resolvedParameter == null) {
+                return null;
+            }
+            parsedParams.add(resolvedParameter);
+            typeIndex++;
+            specificationIndex++;
+        }
+
+        if (typeIndex < types.size()) {
+            // additional types available
+            if (spec.isIgnoreAdditionalParameters()) {
+                return parsedParams;
+            } else {
+                return null;
+            }
+        }
+
+        return parsedParams;
+    }
+
+    private static ParameterSpec nextSpecification(List<ParameterSpec> specifications, int specIndex, boolean varArgs) {
+        if (varArgs && specIndex >= specifications.size() - 1 && !specifications.isEmpty()) {
+            return specifications.get(specifications.size() - 1);
+        } else if (specIndex < specifications.size()) {
+            return specifications.get(specIndex);
+        } else {
+            return null;
+        }
+    }
+
+    private static TypeMirror nextActualType(List<TypeMirror> types, int typeIndex, boolean varArgs) {
+        if (varArgs && typeIndex >= types.size() - 1 && !types.isEmpty()) {
+            // unpack varargs array argument
+            TypeMirror actualType = types.get(types.size() - 1);
+            if (actualType.getKind() == TypeKind.ARRAY) {
+                actualType = ((ArrayType) actualType).getComponentType();
+            }
+            return actualType;
+        } else if (typeIndex < types.size()) {
+            return types.get(typeIndex);
+        } else {
+            return null;
+        }
+    }
+
+    private Parameter matchParameter(ParameterSpec specification, TypeMirror mirror, int specificationIndex, int varArgsIndex) {
+        TypeMirror resolvedType = mirror;
+        if (hasError(resolvedType)) {
+            return null;
+        }
+
+        if (!specification.matches(resolvedType)) {
+            return null;
+        }
+
+        TypeData resolvedTypeData = getTypeSystem().findTypeData(resolvedType);
+        if (resolvedTypeData != null) {
+            return new Parameter(specification, resolvedTypeData, specificationIndex, varArgsIndex);
+        } else {
+            return new Parameter(specification, resolvedType, specificationIndex, varArgsIndex);
+        }
+    }
+
+}