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Truffle is a multi-language framework for executing dynamic languages
that achieves high performance when combined with Graal.
/*
* Copyright (c) 2018, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
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package com.oracle.truffle.api.instrumentation;
import java.util.List;
import java.util.Set;
import com.oracle.truffle.api.instrumentation.InstrumentableNode.WrapperNode;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.NodeUtil;
import com.oracle.truffle.api.nodes.NodeVisitor;
import com.oracle.truffle.api.source.SourceSection;
/**
* Implements the default logic of searching for the nearest {@link Node node} to the given source
* character index according to the execution flow, that is tagged with the given tag.
*
* This code assumes that the Truffle Node hierarchy corresponds with the logical guest language
* AST structure.
*
* If this is not the case for a particular guest language,
* {@link InstrumentableNode#findNearestNodeAt(int, Set)} needs to be implemented, possibly with
* logic in this class applied to the language logical AST nodes.
*/
class DefaultNearestNodeSearch {
/**
* We have a source offset (the character index) and a context node given. The offset is in
* node's source. The context node is an instrumentable node, but may not have any particular
* tags. We're searching for an instrumentable node tagged with at least one of the given tags,
* which is nearest to the given offset according to the guest language execution flow. We find
* the nearest tagged {@link Node node} in following steps:
*
* - When the offset is inside the context node, we search for the first tagged parent node
* and call {@link #findChildTaggedNode(Node, int, Set, boolean)} to find a tagged child. If we
* find it, we return it, if not, we continue to search recursively for a tagged child of node's
* parent. If we encounter the first tagged parent node, return it, otherwise return tagged
* child found during the recursive process, if any.
* - When the offset is behind the context node, we return the last tagged child of the
* context node.
* - When the offset is before the context node, we return the first tagged child of the
* context node.
*
*/
static Node findNearestNodeAt(int offset, Node contextNode, Set> tags) {
Node node = (Node) ((InstrumentableNode) contextNode).materializeInstrumentableNodes(tags);
SourceSection section = node.getSourceSection();
int startIndex = section.getCharIndex();
int endIndex = getCharEndIndex(section);
if (startIndex <= offset && offset <= endIndex) {
Node parent = findParentTaggedNode(node, tags);
Node ch = findChildTaggedNode(node, offset, tags, parent != null, false);
while (ch == null) {
if (node == parent) {
return parent;
}
node = node.getParent();
if (node == null) {
break;
}
ch = findChildTaggedNode(node, offset, tags, parent != null, false);
}
return ch;
} else if (endIndex < offset) {
return findLastNode(node, tags);
} else { // offset < o1
return findFirstNode(node, tags);
}
}
/**
* Finds the nearest tagged {@link Node node}. See the algorithm description at
* {@link InstrumentableNode#findNearestNodeAt(int, Set)}.
*/
private static Node findChildTaggedNode(Node node, int offset, Set> tags, boolean haveOuterCandidate, boolean preferFirst) {
Node[] highestLowerNode = new Node[]{null};
Node[] highestLowerTaggedNode = new Node[]{null};
Node[] lowestHigherNode = new Node[]{null};
Node[] lowestHigherTaggedNode = new Node[]{null};
final Node[] foundNode = new Node[]{null};
NodeUtil.forEachChild(node, new NodeVisitor() {
int highestLowerNodeIndex = 0;
int highestLowerTaggedNodeIndex = 0;
int lowestHigherNodeIndex = 0;
int lowestHigherTaggedNodeIndex = 0;
@Override
public boolean visit(Node childNode) {
Node ch = childNode;
if (ch instanceof WrapperNode) {
ch = ((WrapperNode) ch).getDelegateNode();
}
SourceSection ss;
if (ch instanceof InstrumentableNode && ((InstrumentableNode) ch).isInstrumentable()) {
ch = (Node) ((InstrumentableNode) ch).materializeInstrumentableNodes(tags);
ss = ch.getSourceSection();
if (ss == null) {
return true;
}
} else {
// An unknown node, process its children on the same level.
NodeUtil.forEachChild(ch, this);
return foundNode[0] == null;
}
boolean isTagged = isTaggedWith((InstrumentableNode) ch, tags);
int i1 = ss.getCharIndex();
int i2 = getCharEndIndex(ss);
if (isTagged && offset == i1) {
// We're at it
foundNode[0] = ch;
return false;
}
if (i1 <= offset && offset <= i2) {
// In an encapsulating source section
Node taggedNode = findChildTaggedNode(ch, offset, tags, isTagged || haveOuterCandidate, preferFirst);
if (taggedNode != null) {
foundNode[0] = taggedNode;
return false;
}
if (isTagged) {
// If nothing in and is tagged, return it
foundNode[0] = ch;
return false;
}
}
if (offset < i1) {
// We're after the offset
if (lowestHigherNode[0] == null || lowestHigherNodeIndex > i1) {
lowestHigherNode[0] = ch;
lowestHigherNodeIndex = i1;
}
if (isTagged) {
if (lowestHigherTaggedNode[0] == null || lowestHigherTaggedNodeIndex > i1) {
lowestHigherTaggedNode[0] = ch;
lowestHigherTaggedNodeIndex = i1;
}
}
}
if (i2 < offset) {
// We're before the offset
if (highestLowerNode[0] == null || (preferFirst ? i1 < highestLowerNodeIndex : highestLowerNodeIndex < i1)) {
highestLowerNode[0] = ch;
highestLowerNodeIndex = i1;
}
if (isTagged) {
if (highestLowerTaggedNode[0] == null || (preferFirst ? i1 < highestLowerTaggedNodeIndex : highestLowerTaggedNodeIndex < i1)) {
highestLowerTaggedNode[0] = ch;
highestLowerTaggedNodeIndex = i1;
}
}
}
return true;
}
});
if (foundNode[0] != null) {
return foundNode[0];
}
Node primaryNode;
Node primaryTaggedNode;
Node secondaryNode;
Node secondaryTaggedNode;
if (preferFirst) {
// Prefer node before the offset:
primaryNode = highestLowerNode[0];
primaryTaggedNode = highestLowerTaggedNode[0];
secondaryNode = lowestHigherNode[0];
secondaryTaggedNode = lowestHigherTaggedNode[0];
} else {
// Prefer node after the offset:
primaryNode = lowestHigherNode[0];
primaryTaggedNode = lowestHigherTaggedNode[0];
secondaryNode = highestLowerNode[0];
secondaryTaggedNode = highestLowerTaggedNode[0];
}
if (isTaggedWith(primaryNode, tags)) {
return primaryNode;
}
// Try to go in the preferred node:
Node taggedNode = null;
if (!haveOuterCandidate) {
if (primaryNode != null) {
taggedNode = findChildTaggedNode(primaryNode, offset, tags, haveOuterCandidate, true);
}
}
if (taggedNode == null && primaryTaggedNode != null) {
return primaryTaggedNode;
}
if (isTaggedWith(secondaryNode, tags)) {
return secondaryNode;
}
// Try to go in a node before:
if (!haveOuterCandidate) {
if (taggedNode == null && secondaryNode != null) {
taggedNode = findChildTaggedNode(secondaryNode, offset, tags, haveOuterCandidate, true);
}
}
if (taggedNode == null && secondaryTaggedNode != null) {
return secondaryTaggedNode;
}
return taggedNode;
}
/** Get the last character index (inclusive). */
private static int getCharEndIndex(SourceSection ss) {
if (ss.getCharLength() > 0) {
return ss.getCharEndIndex() - 1;
} else {
return ss.getCharIndex();
}
}
private static Node findParentTaggedNode(Node node, Set> tags) {
if (isTaggedWith(node, tags)) {
return node;
}
Node parent = node.getParent();
if (parent == null) {
return null;
}
return findParentTaggedNode(parent, tags);
}
private static Node findFirstNode(Node contextNode, Set> tags) {
Node[] first = new Node[]{null};
contextNode.accept(new NodeVisitor() {
@Override
public boolean visit(Node node) {
if (isTaggedWith(node, tags)) {
first[0] = node;
return false;
}
return true;
}
});
return first[0];
}
private static Node findLastNode(Node contextNode, Set> tags) {
if (isTaggedWith(contextNode, tags)) {
return contextNode;
}
List children = NodeUtil.findNodeChildren(contextNode);
for (int i = children.size() - 1; i >= 0; i--) {
Node ch = children.get(i);
if (ch instanceof WrapperNode) {
ch = ((WrapperNode) ch).getDelegateNode();
}
Node last = findLastNode(ch, tags);
if (last != null) {
return last;
}
}
return null;
}
private static boolean isTaggedWith(Node node, Set> tags) {
if (node instanceof InstrumentableNode && ((InstrumentableNode) node).isInstrumentable()) {
InstrumentableNode inode = ((InstrumentableNode) node).materializeInstrumentableNodes(tags);
return isTaggedWith(inode, tags);
}
return false;
}
private static boolean isTaggedWith(InstrumentableNode inode, Set> tags) {
for (Class tag : tags) {
if (inode.hasTag(tag)) {
return true;
}
}
return false;
}
}
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