Continue writing parser for plain document format

1 files changed, 190 insertions, 0 deletions

diff --git a/src/plugins/plain/DynamicTokenizer.hpp b/src/plugins/plain/DynamicTokenizer.hpp
new file mode 100644
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+++ b/src/plugins/plain/DynamicTokenizer.hpp
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+/*
+    Ousía
+    Copyright (C) 2014  Benjamin Paaßen, Andreas Stöckel
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program 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 for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file DynamicTokenizer.hpp
+ *
+ * Tokenizer that can be reconfigured at runtime used for parsing the plain
+ * text format.
+ *
+ * @author Andreas Stöckel (astoecke@techfak.uni-bielefeld.de)
+ */
+
+#ifndef _OUSIA_DYNAMIC_TOKENIZER_HPP_
+#define _OUSIA_DYNAMIC_TOKENIZER_HPP_
+
+#include <core/common/Location.hpp>
+
+namespace ousia {
+
+// Forward declarations
+class CharReader;
+class TokenDescriptor;
+
+/**
+ * The DynamicToken structure describes a token discovered by the Tokenizer.
+ */
+struct DynamicToken {
+	/**
+	 * Pointer pointing at the TokenDescriptor instance this token corresponds
+	 * to. May be one of the special TokenDescriptors defined as static members
+	 * of the DynamicTokenizer class.
+	 */
+	TokenDescriptor const *descriptor;
+
+	/**
+	 * String that was matched.
+	 */
+	std::string str;
+
+	/**
+	 * Location from which the string was extracted.
+	 */
+	SourceLocation location;
+};
+
+/**
+ * Enum specifying the whitespace handling of the DynamicTokenizer class when
+ * reading non-token text.
+ */
+enum class WhitespaceMode {
+	/**
+	 * Preserves all whitespaces as they are found in the source file.
+	 */
+	PRESERVE,
+
+	/**
+	 * Trims whitespace at the beginning and the end of the found text.
+	 */
+	TRIM,
+
+	/**
+	 * Whitespaces are trimmed and collapsed, multiple whitespace characters
+	 * are replaced by a single space character.
+	 */
+	COLLAPSE
+};
+
+/**
+ * The DynamicTokenizer is used to extract tokens and chunks of text from a
+ * CharReader. It allows to register and unregister tokens while parsing and
+ * to modify the handling of whitespace characters.
+ */
+class DynamicTokenizer {
+private:
+	/**
+	 * Reference at the char reader.
+	 */
+	CharReader &reader;
+
+	/**
+	 * Flag defining whether whitespaces should be preserved or not.
+	 */
+	WhitespaceMode whitespaceMode;
+
+	/**
+	 * Vector containing all registered token descriptors.
+	 */
+	std::vector<std::unique_ptr<TokenDescriptor>> descriptors;
+
+public:
+	/**
+	 * Constructor of the DynamicTokenizer class.
+	 *
+	 * @param reader is the CharReader that should be used for reading the
+	 * tokens.
+	 * @param preserveWhitespaces should be set to true if all whitespaces
+	 * should be preserved (for preformated environments).
+	 */
+	DynamicTokenizer(CharReader &reader)
+	    : reader(reader),
+	      preserveWhitespaces(preserveWhitespaces),
+	      location(reader.getSourceId()),
+	      empty(true),
+	      hasWhitespace(false)
+	{
+	}
+
+	/**
+	 * Destructor of the DynamicTokenizer class.
+	 */
+	~DynamicTokenizer();
+
+	/**
+	 * Registers the given string as a token. Returns a const pointer at a
+	 * TokenDescriptor that will be used to reference the newly created token.
+	 *
+	 * @param token is the token string that should be registered.
+	 * @return a pointer at a TokenDescriptor which is representative for the
+	 * newly registered token. Returns nullptr if a token with this string
+	 * was already registered.
+	 */
+	const TokenDescriptor* registerToken(const std::string &token);
+
+	/**
+	 * Unregisters the token belonging to the given TokenDescriptor.
+	 *
+	 * @param descr is a TokenDescriptor that was previously returned by
+	 * registerToken.
+	 * @return true if the operation was successful, false otherwise (e.g.
+	 * because the given TokenDescriptor was already unregistered).
+	 */
+	bool unregisterToken(const TokenDescriptor *descr);
+
+	/**
+	 * Sets the whitespace mode.
+	 *
+	 * @param whitespaceMode defines how whitespace should be treated in text
+	 * tokens.
+	 */
+	void setWhitespaceMode(WhitespaceMode mode);
+
+	/**
+	 * Returns the current value of the whitespace mode.
+	 *
+	 * @return the whitespace mode.
+	 */
+	WhitespaceMode getWhitespaceMode();
+
+	/**
+	 * Reads a new token from the CharReader and stores it in the given
+	 * DynamicToken instance.
+	 *
+	 * @param token is a reference at the token instance into which the Token
+	 * information should be written.
+	 * @return true if a token could be read, false if the end of the stream
+	 * has been reached.
+	 */
+	bool read(DynamicToken &token);
+
+	/**
+	 * TokenDescriptor representing an empty token.
+	 */
+	static const *TokenDescriptor Empty;
+
+	/**
+	 * TokenDescriptor representing generic text.
+	 */
+	static const *TokenDescriptor Text;
+
+};
+
+}
+
+#endif /* _OUSIA_DYNAMIC_TOKENIZER_HPP_ */
+