1 files changed, 381 insertions, 0 deletions
diff --git a/src/core/parser/utils/Tokenizer.cpp b/src/core/parser/utils/Tokenizer.cpp
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+++ b/src/core/parser/utils/Tokenizer.cpp
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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/>.
+*/
+
+#include <memory>
+#include <vector>
+
+#include <core/common/CharReader.hpp>
+#include <core/common/Exceptions.hpp>
+#include <core/common/Utils.hpp>
+#include <core/common/WhitespaceHandler.hpp>
+
+#include "Tokenizer.hpp"
+
+namespace ousia {
+
+namespace {
+
+/* Internal class TokenMatch */
+
+/**
+ * Contains information about a matching token.
+ */
+struct TokenMatch {
+	/**
+	 * Token that was matched.
+	 */
+	Token token;
+
+	/**
+	 * Current length of the data within the text handler. The text buffer needs
+	 * to be trimmed to this length if this token matches.
+	 */
+	size_t textLength;
+
+	/**
+	 * End location of the current text handler. This location needs to be used
+	 * for the text token that is emitted before the actual token.
+	 */
+	size_t textEnd;
+
+	/**
+	 * Constructor of the TokenMatch class.
+	 */
+	TokenMatch() : textLength(0), textEnd(0) {}
+
+	/**
+	 * Returns true if this TokenMatch instance actually represents a match.
+	 */
+	bool hasMatch() { return token.type != EmptyToken; }
+};
+
+/* Internal class TokenLookup */
+
+/**
+ * The TokenLookup class is used to represent a thread in a running token
+ * lookup.
+ */
+class TokenLookup {
+private:
+	/**
+	 * Current node within the token trie.
+	 */
+	TokenTrie::Node const *node;
+
+	/**
+	 * Start offset within the source file.
+	 */
+	size_t start;
+
+	/**
+	 * Current length of the data within the text handler. The text buffer needs
+	 * to be trimmed to this length if this token matches.
+	 */
+	size_t textLength;
+
+	/**
+	 * End location of the current text handler. This location needs to be used
+	 * for the text token that is emitted before the actual token.
+	 */
+	size_t textEnd;
+
+public:
+	/**
+	 * Constructor of the TokenLookup class.
+	 *
+	 * @param node is the current node.
+	 * @param start is the start position.
+	 * @param textLength is the text buffer length of the previous text token.
+	 * @param textEnd is the current end location of the previous text token.
+	 */
+	TokenLookup(const TokenTrie::Node *node, size_t start, size_t textLength,
+	            size_t textEnd)
+	    : node(node), start(start), textLength(textLength), textEnd(textEnd)
+	{
+	}
+
+	/**
+	 * Tries to extend the current path in the token trie with the given
+	 * character. If a complete token is matched, stores this match in the
+	 * tokens list (in case it is longer than any previous token).
+	 *
+	 * @param c is the character that should be appended to the current prefix.
+	 * @param lookups is a list to which new TokeLookup instances are added --
+	 * which could potentially be expanded in the next iteration.
+	 * @param match is the Token instance to which the matching token
+	 * should be written.
+	 * @param tokens is a reference at the internal token list of the
+	 * Tokenizer.
+	 * @param end is the end byte offset of the current character.
+	 * @param sourceId is the source if of this file.
+	 */
+	void advance(char c, std::vector<TokenLookup> &lookups, TokenMatch &match,
+	             const std::vector<std::string> &tokens, SourceOffset end,
+	             SourceId sourceId)
+	{
+		// Check whether we can continue the current token path with the given
+		// character without visiting an already visited node
+		auto it = node->children.find(c);
+		if (it == node->children.end()) {
+			return;
+		}
+
+		// Check whether the new node represents a complete token a whether it
+		// is longer than the current token. If yes, replace the current token.
+		node = it->second.get();
+		if (node->type != EmptyToken) {
+			const std::string &str = tokens[node->type];
+			size_t len = str.size();
+			if (len > match.token.content.size()) {
+				match.token =
+				    Token{node->type, str, {sourceId, start, end}};
+				match.textLength = textLength;
+				match.textEnd = textEnd;
+			}
+		}
+
+		// If this state can possibly be advanced, store it in the states list.
+		if (!node->children.empty()) {
+			lookups.emplace_back(*this);
+		}
+	}
+};
+
+/**
+ * Transforms the given token into a text token containing the extracted
+ * text.
+ *
+ * @param handler is the WhitespaceHandler containing the collected data.
+ * @param token is the output token to which the text should be written.
+ * @param sourceId is the source id of the underlying file.
+ */
+static void buildTextToken(const WhitespaceHandler &handler, TokenMatch &match,
+                           SourceId sourceId)
+{
+	if (match.hasMatch()) {
+		match.token.content =
+		    std::string{handler.textBuf.data(), match.textLength};
+		match.token.location =
+		    SourceLocation{sourceId, handler.textStart, match.textEnd};
+	} else {
+		match.token.content = handler.toString();
+		match.token.location =
+		    SourceLocation{sourceId, handler.textStart, handler.textEnd};
+	}
+	match.token.type = TextToken;
+}
+}
+
+/* Class Tokenizer */
+
+Tokenizer::Tokenizer(WhitespaceMode whitespaceMode)
+    : whitespaceMode(whitespaceMode), nextTokenTypeId(0)
+{
+}
+
+template <typename TextHandler, bool read>
+bool Tokenizer::next(CharReader &reader, Token &token)
+{
+	// If we're in the read mode, reset the char reader peek position to the
+	// current read position
+	if (read) {
+		reader.resetPeek();
+	}
+
+	// Prepare the lookups in the token trie
+	const TokenTrie::Node *root = trie.getRoot();
+	TokenMatch match;
+	std::vector<TokenLookup> lookups;
+	std::vector<TokenLookup> nextLookups;
+
+	// Instantiate the text handler
+	TextHandler textHandler;
+
+	// Peek characters from the reader and try to advance the current token tree
+	// cursor
+	char c;
+	size_t charStart = reader.getPeekOffset();
+	const SourceId sourceId = reader.getSourceId();
+	while (reader.peek(c)) {
+		const size_t charEnd = reader.getPeekOffset();
+		const size_t textLength = textHandler.textBuf.size();
+		const size_t textEnd = textHandler.textEnd;
+
+		// If we do not have a match yet, start a new lookup from the root
+		if (!match.hasMatch()) {
+			TokenLookup{root, charStart, textLength, textEnd}.advance(
+			    c, nextLookups, match, tokens, charEnd, sourceId);
+		}
+
+		// Try to advance all other lookups with the new character
+		for (TokenLookup &lookup : lookups) {
+			lookup.advance(c, nextLookups, match, tokens, charEnd, sourceId);
+		}
+
+		// We have found a token and there are no more states to advance or the
+		// text handler has found something -- abort to return the new token
+		if (match.hasMatch()) {
+			if ((nextLookups.empty() || textHandler.hasText())) {
+				break;
+			}
+		} else {
+			// Record all incomming characters
+			textHandler.append(c, charStart, charEnd);
+		}
+
+		// Swap the lookups and the nextLookups list
+		lookups = std::move(nextLookups);
+		nextLookups.clear();
+
+		// Advance the offset
+		charStart = charEnd;
+	}
+
+	// If we found text, emit that text
+	if (textHandler.hasText() && (!match.hasMatch() || match.textLength > 0)) {
+		buildTextToken(textHandler, match, sourceId);
+	}
+
+	// Move the read/peek cursor to the end of the token, abort if an error
+	// happens while doing so
+	if (match.hasMatch()) {
+		// Make sure we have a valid location
+		if (match.token.location.getEnd() == InvalidSourceOffset) {
+			throw OusiaException{"Token end position offset out of range"};
+		}
+
+		// Seek to the end of the current token
+		const size_t end = match.token.location.getEnd();
+		if (read) {
+			reader.seek(end);
+		} else {
+			reader.seekPeekCursor(end);
+		}
+		token = match.token;
+	} else {
+		token = Token{};
+	}
+	return match.hasMatch();
+}
+
+bool Tokenizer::read(CharReader &reader, Token &token)
+{
+	switch (whitespaceMode) {
+		case WhitespaceMode::PRESERVE:
+			return next<PreservingWhitespaceHandler, true>(reader, token);
+		case WhitespaceMode::TRIM:
+			return next<TrimmingWhitespaceHandler, true>(reader, token);
+		case WhitespaceMode::COLLAPSE:
+			return next<CollapsingWhitespaceHandler, true>(reader, token);
+	}
+	return false;
+}
+
+bool Tokenizer::peek(CharReader &reader, Token &token)
+{
+	switch (whitespaceMode) {
+		case WhitespaceMode::PRESERVE:
+			return next<PreservingWhitespaceHandler, false>(reader, token);
+		case WhitespaceMode::TRIM:
+			return next<TrimmingWhitespaceHandler, false>(reader, token);
+		case WhitespaceMode::COLLAPSE:
+			return next<CollapsingWhitespaceHandler, false>(reader, token);
+	}
+	return false;
+}
+
+TokenTypeId Tokenizer::registerToken(const std::string &token)
+{
+	// Abort if an empty token should be registered
+	if (token.empty()) {
+		return EmptyToken;
+	}
+
+	// Search for a new slot in the tokens list
+	TokenTypeId type = EmptyToken;
+	for (size_t i = nextTokenTypeId; i < tokens.size(); i++) {
+		if (tokens[i].empty()) {
+			tokens[i] = token;
+			type = i;
+			break;
+		}
+	}
+
+	// No existing slot was found, add a new one -- make sure we do not
+	// override the special token type handles
+	if (type == EmptyToken) {
+		type = tokens.size();
+		if (type == TextToken || type == EmptyToken) {
+			throw OusiaException{"Token type ids depleted!"};
+		}
+		tokens.emplace_back(token);
+	}
+	nextTokenTypeId = type + 1;
+
+	// Try to register the token in the trie -- if this fails, remove it
+	// from the tokens list
+	if (!trie.registerToken(token, type)) {
+		tokens[type] = std::string{};
+		nextTokenTypeId = type;
+		return EmptyToken;
+	}
+	return type;
+}
+
+bool Tokenizer::unregisterToken(TokenTypeId type)
+{
+	// Unregister the token from the trie, abort if an invalid type is given
+	if (type < tokens.size() && trie.unregisterToken(tokens[type])) {
+		tokens[type] = std::string{};
+		nextTokenTypeId = type;
+		return true;
+	}
+	return false;
+}
+
+std::string Tokenizer::getTokenString(TokenTypeId type)
+{
+	if (type < tokens.size()) {
+		return tokens[type];
+	}
+	return std::string{};
+}
+
+void Tokenizer::setWhitespaceMode(WhitespaceMode mode)
+{
+	whitespaceMode = mode;
+}
+
+WhitespaceMode Tokenizer::getWhitespaceMode() { return whitespaceMode; }
+
+/* Explicitly instantiate all possible instantiations of the "next" member
+   function */
+template bool Tokenizer::next<PreservingWhitespaceHandler, false>(
+    CharReader &reader, Token &token);
+template bool Tokenizer::next<TrimmingWhitespaceHandler, false>(
+    CharReader &reader, Token &token);
+template bool Tokenizer::next<CollapsingWhitespaceHandler, false>(
+    CharReader &reader, Token &token);
+template bool Tokenizer::next<PreservingWhitespaceHandler, true>(
+    CharReader &reader, Token &token);
+template bool Tokenizer::next<TrimmingWhitespaceHandler, true>(
+    CharReader &reader, Token &token);
+template bool Tokenizer::next<CollapsingWhitespaceHandler, true>(
+    CharReader &reader, Token &token);
+}
+