Class ASTRewrite


  • public class ASTRewrite
    extends Object
    Infrastructure for modifying code by describing changes to AST nodes. The AST rewriter collects descriptions of modifications to nodes and translates these descriptions into text edits that can then be applied to the original source. The key thing is that this is all done without actually modifying the original AST, which has the virtue of allowing one to entertain several alternate sets of changes on the same AST (e.g., for calculating multiple quick fix proposals). The rewrite infrastructure tries to generate minimal text changes, preserve existing comments and indentation, and follow code formatter settings.

    The following code snippet illustrated usage of this class:

     Document document = new Document("import java.util.List;\nclass X {}\n");
     ASTParser parser = ASTParser.newParser(AST.JLS3);
     parser.setSource(document.get().toCharArray());
     CompilationUnit cu = (CompilationUnit) parser.createAST(null);
     AST ast = cu.getAST();
     ImportDeclaration id = ast.newImportDeclaration();
     id.setName(ast.newName(new String[] {"java", "util", "Set"}));
     ASTRewrite rewriter = ASTRewrite.create(ast);
     TypeDeclaration td = (TypeDeclaration) cu.types().get(0);
     ITrackedNodePosition tdLocation = rewriter.track(td);
     ListRewrite lrw = rewriter.getListRewrite(cu, CompilationUnit.IMPORTS_PROPERTY);
     lrw.insertLast(id, null);
     TextEdit edits = rewriter.rewriteAST(document, null);
     UndoEdit undo = null;
     try {
         undo = edits.apply(document);
     } catch(MalformedTreeException e) {
         e.printStackTrace();
     } catch(BadLocationException e) {
         e.printStackTrace();
     }
     assert "import java.util.List;\nimport java.util.Set;\nclass X {}\n".equals(document.get());
     // tdLocation.getStartPosition() and tdLocation.getLength()
     // are new source range for "class X {}" in document.get()
     

    If you are sure you never have to explore multiple alternate changes and you never need to create copies or string placeholders, then you can also try CompilationUnit.recordModifications() instead.

    ASTRewrite cannot rewrite (non-Javadoc) comments from CompilationUnit.getCommentList(), since those comment nodes are not part of the normal node hierarchy.

    This class is not intended to be subclassed.

    Since:
    3.0
    Restriction:
    This class is not intended to be subclassed by clients.
    Restriction:
    This class is not intended to be instantiated by clients.
    • Constructor Detail

      • ASTRewrite

        protected ASTRewrite​(AST ast)
        Internal constructor. Creates a new instance for the given AST. Clients should use create(AST) to create instances.
        Parameters:
        ast - the AST being rewritten
    • Method Detail

      • create

        public static ASTRewrite create​(AST ast)
        Creates a new instance for describing manipulations of the given AST.
        Parameters:
        ast - the AST whose nodes will be rewritten
        Returns:
        the new rewriter instance
      • getAST

        public final AST getAST()
        Returns the AST the rewrite was set up on.
        Returns:
        the AST the rewrite was set up on
      • getRewriteEventStore

        protected final org.eclipse.jdt.internal.core.dom.rewrite.RewriteEventStore getRewriteEventStore()
        Internal method. Returns the internal event store. Clients should not use.
        Returns:
        Returns the internal event store. Clients should not use.
      • getNodeStore

        protected final org.eclipse.jdt.internal.core.dom.rewrite.NodeInfoStore getNodeStore()
        Internal method. Returns the internal node info store. Clients should not use.
        Returns:
        Returns the internal info store. Clients should not use.
      • rewriteAST

        public TextEdit rewriteAST​(IDocument document,
                                   Map options)
                            throws IllegalArgumentException
        Converts all modifications recorded by this rewriter into an object representing the corresponding text edits to the given document containing the original source code. The document itself is not modified.

        For nodes in the original that are being replaced or deleted, this rewriter computes the adjusted source ranges by calling getExtendedSourceRangeComputer().computeSourceRange(node).

        Calling this methods does not discard the modifications on record. Subsequence modifications are added to the ones already on record. If this method is called again later, the resulting text edit object will accurately reflect the net cumulative effect of all those changes.

        Parameters:
        document - original document containing source code
        options - the table of formatter options (key type: String; value type: String); or null to use the standard global options JavaCore.getOptions()
        Returns:
        text edit object describing the changes to the document corresponding to the changes recorded by this rewriter
        Throws:
        IllegalArgumentException - An IllegalArgumentException is thrown if the document passed does not correspond to the AST that is rewritten.
      • remove

        public final void remove​(ASTNode node,
                                 TextEditGroup editGroup)
        Removes the given node from its parent in this rewriter. The AST itself is not actually modified in any way; rather, the rewriter just records a note that this node should not be there.
        Parameters:
        node - the node being removed. The node can either be an original node in the AST or (since 3.4) a new node already inserted or used as replacement in this AST rewriter.
        editGroup - the edit group in which to collect the corresponding text edits, or null if ungrouped
        Throws:
        IllegalArgumentException - if the node is null, or if the node is not part of this rewriter's AST, or if the described modification is invalid (such as removing a required node)
      • replace

        public final void replace​(ASTNode node,
                                  ASTNode replacement,
                                  TextEditGroup editGroup)
        Replaces the given node in this rewriter. The replacement node must either be brand new (not part of the original AST) or a placeholder node (for example, one created by createCopyTarget(ASTNode) or createStringPlaceholder(String, int)). The AST itself is not actually modified in any way; rather, the rewriter just records a note that this node has been replaced.
        Parameters:
        node - the node being replaced. The node can either be an original node in the AST or (since 3.4) a new node already inserted or used as replacement in this AST rewriter.
        replacement - the replacement node, or null if no replacement
        editGroup - the edit group in which to collect the corresponding text edits, or null if ungrouped
        Throws:
        IllegalArgumentException - if the node is null, or if the node is not part of this rewriter's AST, or if the replacement node is not a new node (or placeholder), or if the described modification is otherwise invalid
      • set

        public final void set​(ASTNode node,
                              StructuralPropertyDescriptor property,
                              Object value,
                              TextEditGroup editGroup)
        Sets the given property of the given node. If the given property is a child property, the value must be a replacement node that is either be brand new (not part of the original AST) or a placeholder node (for example, one created by createCopyTarget(ASTNode) or createStringPlaceholder(String, int)); or it must be null, indicating that the child should be deleted. If the given property is a simple property, the value must be the new value (primitive types must be boxed) or null. The AST itself is not actually modified in any way; rather, the rewriter just records a note that this node has been changed in the specified way.
        Parameters:
        node - the node
        property - the node's property; either a simple property or a child property
        value - the replacement child or new value, or null if none
        editGroup - the edit group in which to collect the corresponding text edits, or null if ungrouped
        Throws:
        IllegalArgumentException - if the node or property is null, or if the node is not part of this rewriter's AST, or if the property is not a node property, or if the described modification is invalid
      • get

        public Object get​(ASTNode node,
                          StructuralPropertyDescriptor property)
        Returns the value of the given property as managed by this rewriter. If the property has been removed, null is returned. If it has been replaced, the replacing value is returned. If the property has not been changed yet, the original value is returned.

        For child list properties use ListRewrite.getRewrittenList() to get access to the rewritten nodes in a list.

        Parameters:
        node - the node
        property - the node's property
        Returns:
        the value of the given property as managed by this rewriter
        Since:
        3.2
      • getListRewrite

        public final ListRewrite getListRewrite​(ASTNode node,
                                                ChildListPropertyDescriptor property)
        Creates and returns a new rewriter for describing modifications to the given list property of the given node.
        Parameters:
        node - the node
        property - the node's property; the child list property
        Returns:
        a new list rewriter object
        Throws:
        IllegalArgumentException - if the node or property is null, or if the node is not part of this rewriter's AST, or if the property is not a node property, or if the described modification is invalid
      • getProperty

        public final Object getProperty​(String propertyName)
        Returns the value of the named property of this rewrite, or null if none.
        Parameters:
        propertyName - the property name
        Returns:
        the property value, or null if none
        Throws:
        IllegalArgumentException - if the given property name is null
        Since:
        3.7
        See Also:
        setProperty(String,Object)
      • track

        public final ITrackedNodePosition track​(ASTNode node)
        Returns an object that tracks the source range of the given node across the rewrite to its AST. Upon return, the result object reflects the given node's current source range in the AST. After rewrite is called, the result object is updated to reflect the given node's source range in the rewritten AST.
        Parameters:
        node - the node to track
        Returns:
        an object that tracks the source range of node
        Throws:
        IllegalArgumentException - if the node is null, or if the node is not part of this rewriter's AST, or if the node is already being tracked
      • createStringPlaceholder

        public final ASTNode createStringPlaceholder​(String code,
                                                     int nodeType)
        Creates and returns a placeholder node for a source string that is to be inserted into the output document at the position corresponding to the placeholder. The string will be inserted without being reformatted beyond correcting the indentation level. The placeholder node can either be inserted as new or used to replace an existing node.
        Parameters:
        code - the string to be inserted; lines should should not have extra indentation
        nodeType - the ASTNode type that corresponds to the passed code.
        Returns:
        the new placeholder node
        Throws:
        IllegalArgumentException - if the code is null, or if the node type is invalid
      • createGroupNode

        public final ASTNode createGroupNode​(ASTNode[] targetNodes)
        Creates and returns a node that represents a sequence of nodes. Each of the given nodes must be either be brand new (not part of the original AST), or a placeholder node (for example, one created by createCopyTarget(ASTNode) or createStringPlaceholder(String, int)), or another group node. The type of the returned node is unspecified. The returned node can be used to replace an existing node (or as an element of another group node). When the document is rewritten, the source code for each of the given nodes is inserted, in order, into the output document at the position corresponding to the group (indentation is adjusted).
        Parameters:
        targetNodes - the nodes to go in the group
        Returns:
        the new group node
        Throws:
        IllegalArgumentException - if the targetNodes is null or empty
        Since:
        3.1
      • createCopyTarget

        public final ASTNode createCopyTarget​(ASTNode node)
        Creates and returns a placeholder node for a true copy of the given node. The placeholder node can either be inserted as new or used to replace an existing node. When the document is rewritten, a copy of the source code for the given node is inserted into the output document at the position corresponding to the placeholder (indentation is adjusted).
        Parameters:
        node - the node to create a copy placeholder for
        Returns:
        the new placeholder node
        Throws:
        IllegalArgumentException - if the node is null, or if the node is not part of this rewriter's AST
      • createMoveTarget

        public final ASTNode createMoveTarget​(ASTNode node)
        Creates and returns a placeholder node for the new locations of the given node. After obtaining a placeholder, the node must be removed or replaced. The placeholder node can either be inserted as new or used to replace an existing node. The placeholder must be used somewhere in the AST and must not be dropped by subsequent modifications. When the document is rewritten, the source code for the given node is inserted into the output document at the position corresponding to the placeholder (indentation is adjusted).
        Parameters:
        node - the node to create a move placeholder for
        Returns:
        the new placeholder node
        Throws:
        IllegalArgumentException - if the node is null, or if the node is not part of this rewriter's AST
      • setProperty

        public final void setProperty​(String propertyName,
                                      Object data)
        Sets the named property of this rewrite to the given value, or to null to clear it.

        Clients should employ property names that are sufficiently unique to avoid inadvertent conflicts with other clients that might also be setting properties on the same rewrite.

        Note that modifying a property is not considered a modification to the AST itself. This is to allow clients to decorate existing rewrites with their own properties without jeopardizing certain things (like the validity of bindings), which rely on the underlying tree remaining static.

        Parameters:
        propertyName - the property name
        data - the new property value, or null if none
        Throws:
        IllegalArgumentException - if the given property name is null
        Since:
        3.7
        See Also:
        getProperty(String)
      • setTargetSourceRangeComputer

        public final void setTargetSourceRangeComputer​(TargetSourceRangeComputer computer)
        Sets a custom target source range computer for this AST rewriter. This is advanced feature to modify how comments are associated with nodes, which should be done only in special cases.
        Parameters:
        computer - a target source range computer, or null to restore the default value of new TargetSourceRangeComputer()
        Since:
        3.1
        See Also:
        getExtendedSourceRangeComputer()
      • toString

        public String toString()
        Returns a string suitable for debugging purposes (only).
        Overrides:
        toString in class Object
        Returns:
        a debug string