Refactored number class out of VariantReader and added documentation

1 files changed, 259 insertions, 0 deletions

diff --git a/src/core/common/Number.cpp b/src/core/common/Number.cpp
new file mode 100644
index 0000000..12f64ae
--- /dev/null
+++ b/src/core/common/Number.cpp
@@ -0,0 +1,259 @@
+/*
+    Ousía
+    Copyright (C) 2014, 2015  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 <cmath>
+#include <sstream>
+
+#include "CharReader.hpp"
+#include "Logger.hpp"
+#include "Number.hpp"
+#include "Utils.hpp"
+
+namespace ousia {
+
+// TODO: Invent common system for error messages which allows localization
+// TODO: Possibly adapt the clang error logging system
+
+static const char *ERR_UNEXPECTED_CHAR = "Unexpected character";
+static const char *ERR_UNEXPECTED_END = "Unexpected end of number literal";
+static const char *ERR_TOO_LARGE = "Value too large to represent";
+
+static std::string unexpectedMsg(const char *expected, const char got)
+{
+	std::stringstream ss;
+	ss << ERR_UNEXPECTED_CHAR << ": Expected " << expected << " but got \'"
+	   << got << "\'";
+	return ss.str();
+}
+
+/* Class Number */
+
+/**
+ * Returns the numeric value of the given ASCII character (returns 0 for
+ * '0', 1 for '1', 10 for 'A' and so on).
+ *
+ * @param c is the character for which the numeric value should be returned.
+ * @return the numeric value the character represents.
+ */
+static int charValue(char c)
+{
+	if (c >= '0' && c <= '9') {
+		return c & 0x0F;
+	}
+	if ((c >= 'A' && c <= 'O') || (c >= 'a' && c <= 'o')) {
+		return (c & 0x0F) + 9;
+	}
+	return -1;
+}
+
+double Number::doubleValue()
+{
+	return s * (a + ((double)n / (double)d)) * pow(10.0, (double)(sE * e));
+}
+
+int64_t Number::intValue() { return s * a; }
+
+bool Number::appendChar(char c, int base, Part p, CharReader &reader,
+                Logger &logger)
+{
+	// Check whether the given character is valid
+	int v = charValue(c);
+	if (v < 0 || v >= base) {
+		logger.error(unexpectedMsg("digit", c), reader);
+		return false;
+	}
+
+	// Append the number to the specified part
+	switch (p) {
+		case Part::A:
+			a = a * base + v;
+			break;
+		case Part::N:
+			n = n * base + v;
+			d = d * base;
+			break;
+		case Part::E:
+			e = e * base + v;
+			break;
+	}
+
+	// Check for any overflows
+	if (a < 0 || n < 0 || d < 0 || e < 0) {
+		logger.error(ERR_TOO_LARGE, reader);
+		return false;
+	}
+	return true;
+}
+
+bool Number::parse(CharReader &reader, Logger &logger,
+                   const std::unordered_set<char> &delims)
+{
+	State state = State::INIT;
+	char c;
+
+	// Consume the first whitespace characters
+	reader.consumeWhitespace();
+
+	// Iterate over the FSM to extract numbers
+	while (reader.peek(c)) {
+		// Abort, once a delimiter or whitespace is reached
+		if (Utils::isWhitespace(c) || delims.count(c)) {
+			reader.resetPeek();
+			break;
+		}
+
+		// The character is not a whitespace character and not a delimiter
+		switch (state) {
+			case State::INIT:
+			case State::HAS_MINUS:
+				switch (c) {
+					case '-':
+						// Do not allow multiple minus signs
+						if (state == State::HAS_MINUS) {
+							logger.error(unexpectedMsg("digit", c), reader);
+							return false;
+						}
+						state = State::HAS_MINUS;
+						s = -1;
+						break;
+					case '0':
+						// Remember a leading zero for the detection of "0x"
+						state = State::LEADING_ZERO;
+						break;
+					case '.':
+						// Remember a leading point as ".eXXX" is invalid
+						state = State::LEADING_POINT;
+						validInteger = false;
+						break;
+					default:
+						state = State::INT;
+						if (!appendChar(c, 10, Part::A, reader, logger)) {
+							return false;
+						}
+						break;
+				}
+				break;
+			case State::LEADING_ZERO:
+				if (c == 'x' || c == 'X') {
+					state = State::HEX;
+					break;
+				}
+			// fallthrough
+			case State::INT:
+				switch (c) {
+					case '.':
+						state = State::POINT;
+						validInteger = false;
+						break;
+					case 'e':
+					case 'E':
+						state = State::EXP_INIT;
+						break;
+					default:
+						state = State::INT;
+						if (!appendChar(c, 10, Part::A, reader, logger)) {
+							return false;
+						}
+						break;
+				}
+				break;
+			case State::HEX:
+				if (!appendChar(c, 16, Part::A, reader, logger)) {
+					return false;
+				}
+				break;
+			case State::LEADING_POINT:
+			case State::POINT:
+				switch (c) {
+					case 'e':
+					case 'E':
+						if (state == State::LEADING_POINT) {
+							logger.error(unexpectedMsg("digit", c), reader);
+							return false;
+						}
+						state = State::EXP_INIT;
+						break;
+					default:
+						state = State::POINT;
+						if (!appendChar(c, 10, Part::N, reader, logger)) {
+							return false;
+						}
+						break;
+				}
+				break;
+			case State::EXP_HAS_MINUS:
+			case State::EXP_INIT:
+				if (c == '-') {
+					if (state == State::EXP_HAS_MINUS) {
+						logger.error(unexpectedMsg("digit", c), reader);
+						return false;
+					}
+					state = State::EXP_HAS_MINUS;
+					sE = -1;
+				} else {
+					state = State::EXP;
+					if (!appendChar(c, 10, Part::E, reader, logger)) {
+						return false;
+					}
+				}
+				break;
+			case State::EXP:
+				if (!appendChar(c, 10, Part::E, reader, logger)) {
+					return false;
+				}
+				break;
+		}
+		reader.consumePeek();
+	}
+
+	// States in which ending is valid. Log an error in other states
+	if (state == State::LEADING_ZERO || state == State::HEX ||
+	    state == State::INT || state == State::POINT || state == State::EXP) {
+		return true;
+	}
+	logger.error(ERR_UNEXPECTED_END, reader);
+	return false;
+}
+
+bool Number::parse(const std::string &str, Logger &logger)
+{
+	// Create a char reader instance with the given string and call the actual
+	// parse function
+	CharReader reader(str);
+	return parse(reader, logger);
+}
+
+bool Number::parseFixedLenInt(CharReader &reader, int len, int base, Logger &logger)
+{
+	char c;
+	reader.consumePeek();
+	for (int i = 0; i < len; i++) {
+		if (!reader.peek(c)) {
+			logger.error("Unexpected end of escape sequence", reader);
+			return false;
+		}
+		if (!appendChar(c, base, Number::Part::A, reader, logger)) {
+			return false;
+		}
+		reader.consumePeek();
+	}
+	return true;
+}
+
+}
+