Import convert util templates

Import an external dependency: a template-based conversion toolkit.

Signed-off-by: David Wagner <david.wagner@intel.com>

1 files changed, 176 insertions, 0 deletions

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+/*
+ * Copyright (c) 2011-2014, Intel Corporation
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <limits>
+#include <sstream>
+#include <string>
+#include <stdint.h>
+
+/* details namespace is here to hide implementation details to header end user. It
+ * is NOT intended to be used outside. */
+namespace details
+{
+
+/** Helper class to limit instantiation of templates */
+template<typename T>
+struct ConvertionAllowed;
+
+/* List of allowed types for conversion */
+template<> struct ConvertionAllowed<bool> {};
+template<> struct ConvertionAllowed<uint64_t> {};
+template<> struct ConvertionAllowed<int64_t> {};
+template<> struct ConvertionAllowed<uint32_t> {};
+template<> struct ConvertionAllowed<int32_t> {};
+template<> struct ConvertionAllowed<uint16_t> {};
+template<> struct ConvertionAllowed<int16_t> {};
+template<> struct ConvertionAllowed<float> {};
+
+} // namespace details
+
+/**
+ * Convert a string to a given type.
+ *
+ * This template function read the value of the type T in the given string.
+ * The function does not allow to have white spaces around the value to parse
+ * and tries to parse the whole string, which means that if some bytes were not
+ * read in the string, the function fails.
+ * Hexadecimal representation (ie numbers starting with 0x) is supported only
+ * for integral types conversions.
+ * Result may be modified, even in case of failure.
+ *
+ * @param[in]  str    the string to parse.
+ * @param[out] result reference to object where to store the result.
+ *
+ * @return true if conversion was successful, false otherwise.
+ */
+template<typename T>
+static inline bool convertTo(const std::string &str, T &result)
+{
+    /* Check that conversion to that type is allowed.
+     * If this fails, this means that this template was not intended to be used
+     * with this type, thus that the result is undefined. */
+    details::ConvertionAllowed<T>();
+
+    if (str.find_first_of(std::string("\r\n\t\v ")) != std::string::npos) {
+        return false;
+    }
+
+    /* Check for a '-' in string. If type is unsigned and a - is found, the
+     * parsing fails. This is made necessary because "-1" is read as 65535 for
+     * uint16_t, for example */
+    if (str.find("-") != std::string::npos
+        && !std::numeric_limits<T>::is_signed) {
+        return false;
+    }
+
+    std::stringstream ss(str);
+
+    /* Sadly, the stream conversion does not handle hexadecimal format, thus
+     * check is done manually */
+    if (str.substr(0, 2) == "0x") {
+        if (std::numeric_limits<T>::is_integer) {
+            ss >> std::hex >> result;
+        }
+        else {
+            /* Conversion undefined for non integers */
+            return false;
+        }
+    } else {
+        ss >> result;
+    }
+
+    return ss.eof() && !ss.fail() && !ss.bad();
+}
+
+/**
+ * Specialization for int16_t of convertTo template function.
+ *
+ * This function follows the same paradigm than it's generic version.
+ *
+ * The specific implementation is made necessary because the stlport version of
+ * string streams is bugged and does not fail when giving overflowed values.
+ * This specialisation can be safely removed when stlport behaviour is fixed.
+ *
+ * @param[in]  str    the string to parse.
+ * @param[out] result reference to object where to store the result.
+ *
+ * @return true if conversion was successful, false otherwise.
+ */
+template<>
+inline bool convertTo<int16_t>(const std::string &str, int16_t &result)
+{
+    int64_t res;
+
+    if (!convertTo<int64_t>(str, res)) {
+        return false;
+    }
+
+    if (res > std::numeric_limits<int16_t>::max() || res < std::numeric_limits<int16_t>::min()) {
+        return false;
+    }
+
+    result = static_cast<int16_t>(res);
+    return true;
+}
+
+/**
+ * Specialization for boolean of convertTo template function.
+ *
+ * This function follows the same paradigm than it's generic version.
+ * This function accepts to parse boolean as "0/1" or "false/true" or
+ * "FALSE/TRUE".
+ * The specific implementation is made necessary because the behaviour of
+ * string streams when parsing boolean values is not sufficient to fit our
+ * requirements. Indeed, parsing "true" will correctly parse the value, but the
+ * end of stream is not reached which makes the ss.eof() fails in the generic
+ * implementation.
+ *
+ * @param[in]  str    the string to parse.
+ * @param[out] result reference to object where to store the result.
+ *
+ * @return true if conversion was successful, false otherwise.
+ */
+template<>
+inline bool convertTo<bool>(const std::string &str, bool &result)
+{
+    if (str == "0" || str == "FALSE" || str == "false") {
+        result = false;
+        return true;
+    }
+
+    if (str == "1" || str == "TRUE" || str == "true") {
+        result = true;
+        return true;
+    }
+
+    return false;
+}