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[toc] / antlr4-cpp-runtime-4.9.2-source / runtime / src / BailErrorStrategy.h

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+/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+
+#pragma once
+
+#include "DefaultErrorStrategy.h"
+
+namespace antlr4 {
+
+  /**
+   * This implementation of {@link ANTLRErrorStrategy} responds to syntax errors
+   * by immediately canceling the parse operation with a
+   * {@link ParseCancellationException}. The implementation ensures that the
+   * {@link ParserRuleContext#exception} field is set for all parse tree nodes
+   * that were not completed prior to encountering the error.
+   *
+   * <p>
+   * This error strategy is useful in the following scenarios.</p>
+   *
+   * <ul>
+   * <li><strong>Two-stage parsing:</strong> This error strategy allows the first
+   * stage of two-stage parsing to immediately terminate if an error is
+   * encountered, and immediately fall back to the second stage. In addition to
+   * avoiding wasted work by attempting to recover from errors here, the empty
+   * implementation of {@link BailErrorStrategy#sync} improves the performance of
+   * the first stage.</li>
+   * <li><strong>Silent validation:</strong> When syntax errors are not being
+   * reported or logged, and the parse result is simply ignored if errors occur,
+   * the {@link BailErrorStrategy} avoids wasting work on recovering from errors
+   * when the result will be ignored either way.</li>
+   * </ul>
+   *
+   * <p>
+   * {@code myparser.setErrorHandler(new BailErrorStrategy());}</p>
+   *
+   * @see Parser#setErrorHandler(ANTLRErrorStrategy)
+   */
+  class ANTLR4CPP_PUBLIC BailErrorStrategy : public DefaultErrorStrategy {
+    /// <summary>
+    /// Instead of recovering from exception {@code e}, re-throw it wrapped
+    ///  in a <seealso cref="ParseCancellationException"/> so it is not caught by the
+    ///  rule function catches.  Use <seealso cref="Exception#getCause()"/> to get the
+    ///  original <seealso cref="RecognitionException"/>.
+    /// </summary>
+  public:
+    virtual void recover(Parser *recognizer, std::exception_ptr e) override;
+
+    /// Make sure we don't attempt to recover inline; if the parser
+    ///  successfully recovers, it won't throw an exception.
+    virtual Token* recoverInline(Parser *recognizer) override;
+
+    /// <summary>
+    /// Make sure we don't attempt to recover from problems in subrules. </summary>
+    virtual void sync(Parser *recognizer) override;
+  };
+
+} // namespace antlr4