72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
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* Use of this file is governed by the BSD 3-clause license that
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* can be found in the LICENSE.txt file in the project root.
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*/
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#include "support/CPPUtils.h"
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#include "tree/ParseTreeListener.h"
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#include "tree/ParseTree.h"
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#include "tree/ErrorNode.h"
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#include "IterativeParseTreeWalker.h"
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using namespace antlr4::tree;
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void IterativeParseTreeWalker::walk(ParseTreeListener *listener, ParseTree *t) const {
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std::vector<ParseTree *> nodeStack;
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std::vector<size_t> indexStack;
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ParseTree *currentNode = t;
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size_t currentIndex = 0;
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while (currentNode != nullptr) {
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// pre-order visit
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if (antlrcpp::is<ErrorNode *>(currentNode)) {
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listener->visitErrorNode(dynamic_cast<ErrorNode *>(currentNode));
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} else if (antlrcpp::is<TerminalNode *>(currentNode)) {
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listener->visitTerminal((TerminalNode *)currentNode);
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} else {
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enterRule(listener, currentNode);
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}
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// Move down to first child, if it exists.
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if (!currentNode->children.empty()) {
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nodeStack.push_back(currentNode);
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indexStack.push_back(currentIndex);
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currentIndex = 0;
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currentNode = currentNode->children[0];
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continue;
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}
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// No child nodes, so walk tree.
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do {
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// post-order visit
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if (!antlrcpp::is<TerminalNode *>(currentNode)) {
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exitRule(listener, currentNode);
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}
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// No parent, so no siblings.
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if (nodeStack.empty()) {
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currentNode = nullptr;
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currentIndex = 0;
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break;
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}
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// Move to next sibling if possible.
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if (nodeStack.back()->children.size() > ++currentIndex) {
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currentNode = nodeStack.back()->children[currentIndex];
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break;
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}
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// No next sibling, so move up.
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currentNode = nodeStack.back();
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nodeStack.pop_back();
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currentIndex = indexStack.back();
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indexStack.pop_back();
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} while (currentNode != nullptr);
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}
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}
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