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diff --git a/src/base/date_time_scanner.hh b/src/base/date_time_scanner.hh
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+/**
+ * Copyright (c) 2020, Timothy Stack
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ * * 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.
+ * * Neither the name of Timothy Stack 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 REGENTS 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 REGENTS 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.
+ *
+ * @file date_time_scanner.hh
+ */
+
+#ifndef lnav_date_time_scanner_hh
+#define lnav_date_time_scanner_hh
+
+#include <ctime>
+#include <string>
+
+#include <sys/types.h>
+
+#include "time_util.hh"
+
+/**
+ * Scans a timestamp string to discover the date-time format using the custom
+ * ptimec parser.  Once a format is found, it is locked in so that the next
+ * time a timestamp needs to be scanned, the format does not have to be
+ * rediscovered.  The discovered date-time format can also be used to convert
+ * an exttm struct to a string using the ftime() method.
+ */
+struct date_time_scanner {
+    date_time_scanner() { this->clear(); }
+
+    void clear()
+    {
+        this->dts_base_time = 0;
+        this->dts_base_tm = exttm{};
+        this->dts_fmt_lock = -1;
+        this->dts_fmt_len = -1;
+        this->dts_last_tv = timeval{};
+        this->dts_last_tm = exttm{};
+    }
+
+    /**
+     * Unlock this scanner so that the format is rediscovered.
+     */
+    void unlock()
+    {
+        this->dts_fmt_lock = -1;
+        this->dts_fmt_len = -1;
+    }
+
+    void set_base_time(time_t base_time, const tm& local_tm);
+
+    /**
+     * Convert a timestamp to local time.
+     *
+     * Calling localtime_r is slow since it wants to lookup the timezone on
+     * every call, so we cache the result and only call it again if the
+     * requested time falls outside of a fifteen minute range.
+     */
+    void to_localtime(time_t t, struct exttm& tm_out);
+
+    bool dts_keep_base_tz{false};
+    bool dts_local_time{false};
+    time_t dts_base_time{0};
+    struct exttm dts_base_tm;
+    int dts_fmt_lock{-1};
+    int dts_fmt_len{-1};
+    struct exttm dts_last_tm {};
+    struct timeval dts_last_tv {};
+    time_t dts_local_offset_cache{0};
+    time_t dts_local_offset_valid{0};
+    time_t dts_local_offset_expiry{0};
+
+    static const int EXPIRE_TIME = 15 * 60;
+
+    const char* scan(const char* time_src,
+                     size_t time_len,
+                     const char* const time_fmt[],
+                     struct exttm* tm_out,
+                     struct timeval& tv_out,
+                     bool convert_local = true);
+
+    size_t ftime(char* dst,
+                 size_t len,
+                 const char* const time_fmt[],
+                 const struct exttm& tm) const;
+
+    bool convert_to_timeval(const char* time_src,
+                            ssize_t time_len,
+                            const char* const time_fmt[],
+                            struct timeval& tv_out)
+    {
+        struct exttm tm;
+
+        if (time_len == -1) {
+            time_len = strlen(time_src);
+        }
+        if (this->scan(time_src, time_len, time_fmt, &tm, tv_out) != nullptr) {
+            return true;
+        }
+        return false;
+    }
+
+    bool convert_to_timeval(const std::string& time_src, struct timeval& tv_out)
+    {
+        struct exttm tm;
+
+        if (this->scan(time_src.c_str(), time_src.size(), nullptr, &tm, tv_out)
+            != nullptr)
+        {
+            return true;
+        }
+        return false;
+    }
+};
+
+#endif