1 files changed, 332 insertions, 0 deletions
diff --git a/javaparser-core/src/main/java/com/github/javaparser/printer/lexicalpreservation/LexicalDifferenceCalculator.java b/javaparser-core/src/main/java/com/github/javaparser/printer/lexicalpreservation/LexicalDifferenceCalculator.java
new file mode 100644
index 000000000..9263dfd8a
--- /dev/null
+++ b/javaparser-core/src/main/java/com/github/javaparser/printer/lexicalpreservation/LexicalDifferenceCalculator.java
@@ -0,0 +1,332 @@
+package com.github.javaparser.printer.lexicalpreservation;
+
+import com.github.javaparser.GeneratedJavaParserConstants;
+import com.github.javaparser.ast.Modifier;
+import com.github.javaparser.ast.Node;
+import com.github.javaparser.ast.NodeList;
+import com.github.javaparser.ast.expr.StringLiteralExpr;
+import com.github.javaparser.ast.observer.ObservableProperty;
+import com.github.javaparser.printer.ConcreteSyntaxModel;
+import com.github.javaparser.printer.Printable;
+import com.github.javaparser.printer.SourcePrinter;
+import com.github.javaparser.printer.concretesyntaxmodel.*;
+import com.github.javaparser.printer.lexicalpreservation.changes.*;
+
+import java.util.*;
+
+class LexicalDifferenceCalculator {
+
+    /**
+     * The ConcreteSyntaxModel represents the general format. This model is a calculated version of the ConcreteSyntaxModel,
+     * with no condition, no lists, just tokens and node children.
+     */
+    static class CalculatedSyntaxModel {
+        final List<CsmElement> elements;
+
+        CalculatedSyntaxModel(List<CsmElement> elements) {
+            this.elements = elements;
+        }
+
+        public CalculatedSyntaxModel from(int index) {
+            List<CsmElement> newList = new LinkedList<>();
+            newList.addAll(elements.subList(index, elements.size()));
+            return new CalculatedSyntaxModel(newList);
+        }
+
+        @Override
+        public String toString() {
+            return "CalculatedSyntaxModel{" +
+                    "elements=" + elements +
+                    '}';
+        }
+
+        CalculatedSyntaxModel sub(int start, int end) {
+            return new CalculatedSyntaxModel(elements.subList(start, end));
+        }
+
+        void removeIndentationElements() {
+            elements.removeIf(el -> el instanceof CsmIndent || el instanceof CsmUnindent);
+        }
+    }
+
+    static class CsmChild implements CsmElement {
+        private final Node child;
+
+        public Node getChild() {
+            return child;
+        }
+
+        CsmChild(Node child) {
+            this.child = child;
+        }
+
+        @Override
+        public void prettyPrint(Node node, SourcePrinter printer) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public String toString() {
+            return "child(" + child.getClass().getSimpleName()+")";
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+
+            CsmChild csmChild = (CsmChild) o;
+
+            return child.equals(csmChild.child);
+        }
+
+        @Override
+        public int hashCode() {
+            return child.hashCode();
+        }
+    }
+
+    Difference calculateListRemovalDifference(ObservableProperty observableProperty, NodeList nodeList, int index) {
+        Node container = nodeList.getParentNodeForChildren();
+        CsmElement element = ConcreteSyntaxModel.forClass(container.getClass());
+        CalculatedSyntaxModel original = calculatedSyntaxModelForNode(element, container);
+        CalculatedSyntaxModel after = calculatedSyntaxModelAfterListRemoval(element, observableProperty, nodeList, index);
+        return Difference.calculate(original, after);
+    }
+
+    Difference calculateListAdditionDifference(ObservableProperty observableProperty, NodeList nodeList, int index, Node nodeAdded) {
+        Node container = nodeList.getParentNodeForChildren();
+        CsmElement element = ConcreteSyntaxModel.forClass(container.getClass());
+        CalculatedSyntaxModel original = calculatedSyntaxModelForNode(element, container);
+        CalculatedSyntaxModel after = calculatedSyntaxModelAfterListAddition(element, observableProperty, nodeList, index, nodeAdded);
+        return Difference.calculate(original, after);
+    }
+
+    Difference calculateListReplacementDifference(ObservableProperty observableProperty, NodeList nodeList, int index, Node newValue) {
+        Node container = nodeList.getParentNodeForChildren();
+        CsmElement element = ConcreteSyntaxModel.forClass(container.getClass());
+        CalculatedSyntaxModel original = calculatedSyntaxModelForNode(element, container);
+        CalculatedSyntaxModel after = calculatedSyntaxModelAfterListReplacement(element, observableProperty, nodeList, index, newValue);
+        return Difference.calculate(original, after);
+    }
+
+    public void calculatePropertyChange(NodeText nodeText, Node observedNode, ObservableProperty property, Object oldValue, Object newValue) {
+        if (nodeText == null) {
+            throw new NullPointerException();
+        }
+        CsmElement element = ConcreteSyntaxModel.forClass(observedNode.getClass());
+        CalculatedSyntaxModel original = calculatedSyntaxModelForNode(element, observedNode);
+        CalculatedSyntaxModel after = calculatedSyntaxModelAfterPropertyChange(element, observedNode, property, oldValue, newValue);
+        Difference difference = Difference.calculate(original, after);
+        difference.apply(nodeText, observedNode);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelForNode(CsmElement csm, Node node) {
+        List<CsmElement> elements = new LinkedList<>();
+        calculatedSyntaxModelForNode(csm, node, elements, new NoChange());
+        return new CalculatedSyntaxModel(elements);
+    }
+
+    CalculatedSyntaxModel calculatedSyntaxModelForNode(Node node) {
+        return calculatedSyntaxModelForNode(ConcreteSyntaxModel.forClass(node.getClass()), node);
+    }
+
+    private void calculatedSyntaxModelForNode(CsmElement csm, Node node, List<CsmElement> elements, Change change) {
+        if (csm instanceof CsmSequence) {
+            CsmSequence csmSequence = (CsmSequence) csm;
+            csmSequence.getElements().forEach(e -> calculatedSyntaxModelForNode(e, node, elements, change));
+        } else if (csm instanceof CsmComment) {
+            // nothing to do
+        } else if (csm instanceof CsmSingleReference) {
+            CsmSingleReference csmSingleReference = (CsmSingleReference)csm;
+            Node child;
+            if (change instanceof PropertyChange && ((PropertyChange)change).getProperty() == csmSingleReference.getProperty()) {
+                child = (Node)((PropertyChange)change).getNewValue();
+            } else {
+                child = csmSingleReference.getProperty().getValueAsSingleReference(node);
+            }
+            if (child != null) {
+                elements.add(new CsmChild(child));
+            }
+        } else if (csm instanceof CsmNone) {
+            // nothing to do
+        } else if (csm instanceof CsmToken) {
+            elements.add(csm);
+        } else if (csm instanceof CsmOrphanCommentsEnding) {
+            // nothing to do
+        } else if (csm instanceof CsmList) {
+            CsmList csmList = (CsmList) csm;
+            if (csmList.getProperty().isAboutNodes()) {
+                Object rawValue = change.getValue(csmList.getProperty(), node);
+                NodeList nodeList;
+                if (rawValue instanceof Optional) {
+                    Optional optional = (Optional)rawValue;
+                    if (optional.isPresent()) {
+                        if (!(optional.get() instanceof NodeList)) {
+                            throw new IllegalStateException("Expected NodeList, found " + optional.get().getClass().getCanonicalName());
+                        }
+                        nodeList = (NodeList) optional.get();
+                    } else {
+                        nodeList = new NodeList();
+                    }
+                } else {
+                    if (!(rawValue instanceof NodeList)) {
+                        throw new IllegalStateException("Expected NodeList, found " + rawValue.getClass().getCanonicalName());
+                    }
+                    nodeList = (NodeList) rawValue;
+                }
+                if (!nodeList.isEmpty()) {
+                    calculatedSyntaxModelForNode(csmList.getPreceeding(), node, elements, change);
+                    for (int i = 0; i < nodeList.size(); i++) {
+                        if (i != 0) {
+                            calculatedSyntaxModelForNode(csmList.getSeparatorPre(), node, elements, change);
+                        }
+                        elements.add(new CsmChild(nodeList.get(i)));
+                        if (i != (nodeList.size() - 1)) {
+                            calculatedSyntaxModelForNode(csmList.getSeparatorPost(), node, elements, change);
+                        }
+
+                    }
+                    calculatedSyntaxModelForNode(csmList.getFollowing(), node, elements, change);
+                }
+            } else {
+                Collection collection = (Collection) change.getValue(csmList.getProperty(), node);
+                if (!collection.isEmpty()) {
+                    calculatedSyntaxModelForNode(csmList.getPreceeding(), node, elements, change);
+
+                    boolean first = true;
+                    for (Iterator it = collection.iterator(); it.hasNext(); ) {
+                        if (!first) {
+                            calculatedSyntaxModelForNode(csmList.getSeparatorPre(), node, elements, change);
+                        }
+                        Object value = it.next();
+                        if (value instanceof Modifier) {
+                            Modifier modifier = (Modifier)value;
+                            elements.add(new CsmToken(toToken(modifier)));
+                        } else {
+                            throw new UnsupportedOperationException(it.next().getClass().getSimpleName());
+                        }
+                        if (it.hasNext()) {
+                            calculatedSyntaxModelForNode(csmList.getSeparatorPost(), node, elements, change);
+                        }
+                        first = false;
+                    }
+                    calculatedSyntaxModelForNode(csmList.getFollowing(), node, elements, change);
+                }
+            }
+        } else if (csm instanceof CsmConditional) {
+            CsmConditional csmConditional = (CsmConditional) csm;
+            boolean satisfied = change.evaluate(csmConditional, node);
+            if (satisfied) {
+                calculatedSyntaxModelForNode(csmConditional.getThenElement(), node, elements, change);
+            } else {
+                calculatedSyntaxModelForNode(csmConditional.getElseElement(), node, elements, change);
+            }
+        } else if (csm instanceof CsmIndent) {
+            elements.add(csm);
+        } else if (csm instanceof CsmUnindent) {
+            elements.add(csm);
+        } else if (csm instanceof CsmAttribute) {
+            CsmAttribute csmAttribute = (CsmAttribute) csm;
+            Object value = change.getValue(csmAttribute.getProperty(), node);
+            String text = value.toString();
+            if (value instanceof Printable) {
+                text = ((Printable) value).asString();
+            }
+            elements.add(new CsmToken(csmAttribute.getTokenType(node, value.toString()), text));
+        } else if ((csm instanceof CsmString) && (node instanceof StringLiteralExpr)) {
+            elements.add(new CsmToken(GeneratedJavaParserConstants.STRING_LITERAL,
+                    "\"" + ((StringLiteralExpr) node).getValue() + "\""));
+        } else if (csm instanceof CsmMix) {
+            CsmMix csmMix = (CsmMix)csm;
+            List<CsmElement> mixElements = new LinkedList<>();
+            csmMix.getElements().forEach(e -> calculatedSyntaxModelForNode(e, node, mixElements, change));
+            elements.add(new CsmMix(mixElements));
+        } else {
+            throw new UnsupportedOperationException(csm.getClass().getSimpleName()+ " " + csm);
+        }
+    }
+
+    private int toToken(Modifier modifier) {
+        switch (modifier) {
+            case PUBLIC:
+                return GeneratedJavaParserConstants.PUBLIC;
+            case PRIVATE:
+                return GeneratedJavaParserConstants.PRIVATE;
+            case PROTECTED:
+                return GeneratedJavaParserConstants.PROTECTED;
+            case STATIC:
+                return GeneratedJavaParserConstants.STATIC;
+            case FINAL:
+                return GeneratedJavaParserConstants.FINAL;
+            case ABSTRACT:
+                return GeneratedJavaParserConstants.ABSTRACT;
+            default:
+                throw new UnsupportedOperationException(modifier.name());
+        }
+    }
+
+    ///
+    /// Methods that calculate CalculatedSyntaxModel
+    ///
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterPropertyChange(Node node, ObservableProperty property, Object oldValue, Object newValue) {
+        return calculatedSyntaxModelAfterPropertyChange(ConcreteSyntaxModel.forClass(node.getClass()), node, property, oldValue, newValue);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterPropertyChange(CsmElement csm, Node node, ObservableProperty property, Object oldValue, Object newValue) {
+        List<CsmElement> elements = new LinkedList<>();
+        calculatedSyntaxModelForNode(csm, node, elements, new PropertyChange(property, oldValue, newValue));
+        return new CalculatedSyntaxModel(elements);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterListRemoval(CsmElement csm, ObservableProperty observableProperty, NodeList nodeList, int index) {
+        List<CsmElement> elements = new LinkedList<>();
+        Node container = nodeList.getParentNodeForChildren();
+        calculatedSyntaxModelForNode(csm, container, elements, new ListRemovalChange(observableProperty, index));
+        return new CalculatedSyntaxModel(elements);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterListAddition(CsmElement csm, ObservableProperty observableProperty, NodeList nodeList, int index, Node nodeAdded) {
+        List<CsmElement> elements = new LinkedList<>();
+        Node container = nodeList.getParentNodeForChildren();
+        calculatedSyntaxModelForNode(csm, container, elements, new ListAdditionChange(observableProperty, index, nodeAdded));
+        return new CalculatedSyntaxModel(elements);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterListAddition(Node container, ObservableProperty observableProperty, int index, Node nodeAdded) {
+        CsmElement csm = ConcreteSyntaxModel.forClass(container.getClass());
+        Object rawValue = observableProperty.getRawValue(container);
+        if (!(rawValue instanceof NodeList)) {
+            throw new IllegalStateException("Expected NodeList, found " + rawValue.getClass().getCanonicalName());
+        }
+        NodeList nodeList = (NodeList)rawValue;
+        return calculatedSyntaxModelAfterListAddition(csm, observableProperty, nodeList, index, nodeAdded);
+    }
+
+    // Visible for testing
+    CalculatedSyntaxModel calculatedSyntaxModelAfterListRemoval(Node container, ObservableProperty observableProperty, int index) {
+        CsmElement csm = ConcreteSyntaxModel.forClass(container.getClass());
+        Object rawValue = observableProperty.getRawValue(container);
+        if (!(rawValue instanceof NodeList)) {
+            throw new IllegalStateException("Expected NodeList, found " + rawValue.getClass().getCanonicalName());
+        }
+        NodeList nodeList = (NodeList)rawValue;
+        return calculatedSyntaxModelAfterListRemoval(csm, observableProperty, nodeList, index);
+    }
+
+    // Visible for testing
+    private CalculatedSyntaxModel calculatedSyntaxModelAfterListReplacement(CsmElement csm, ObservableProperty observableProperty, NodeList nodeList, int index, Node newValue) {
+        List<CsmElement> elements = new LinkedList<>();
+        Node container = nodeList.getParentNodeForChildren();
+        calculatedSyntaxModelForNode(csm, container, elements, new ListReplacementChange(observableProperty, index, newValue));
+        return new CalculatedSyntaxModel(elements);
+    }
+
+}