Unit parser

include/tscpp/util/Makefile.am

@@ -27,4 +27,6 @@ library_include_HEADERS = \
 	Strerror.h \
 	TextView.h \
 	TsSharedMutex.h \
+	ts_unit_parser.h \
+	ts_time_parser.h \
         YamlCfg.h

include/tscpp/util/ts_time_parser.h

@@ -0,0 +1,43 @@
+/** @file
+
+  Parse strings with units.
+
+  @section license License
+
+  Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.
+  See the NOTICE file distributed with this work for additional information regarding copyright
+  ownership.  The ASF licenses this file to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance with the License.  You may obtain a
+  copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software distributed under the License
+  is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+  or implied. See the License for the specific language governing permissions and limitations under
+  the License.
+*/
+
+#pragma once
+
+#include "tscpp/util/ts_unit_parser.h"
+
+namespace ts
+{
+
+namespace detail
+{
+  extern UnitParser const time_parser_ns;
+}
+/** Parse duration string.
+ *
+ * @param text Input text to parse.
+ * @return A return value containing the time in nanoseconds or parsing errors.
+ */
+inline swoc::Rv<std::chrono::nanoseconds>
+time_parser(swoc::TextView text)
+{
+  auto &&[duration, errata] = detail::time_parser_ns(text);
+  return {std::chrono::nanoseconds(duration), std::move(errata)};
+}
+} // namespace ts

include/tscpp/util/ts_unit_parser.h

@@ -0,0 +1,103 @@
+/** @file
+
+  Parse strings with units.
+
+  @section license License
+
+  Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.
+  See the NOTICE file distributed with this work for additional information regarding copyright
+  ownership.  The ASF licenses this file to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance with the License.  You may obtain a
+  copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software distributed under the License
+  is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+  or implied. See the License for the specific language governing permissions and limitations under
+  the License.
+*/
+
+#pragma once
+
+#include <cstdint>
+
+#include "swoc/Lexicon.h"
+#include "swoc/Errata.h"
+
+namespace ts
+{
+
+using swoc::TextView;
+using swoc::Lexicon;
+using swoc::Errata;
+using swoc::Rv;
+
+/** Parse a string that consists of counts and units.
+ *
+ * Give a set of units, each of which is a list of names and a multiplier, parse a string. The
+ * string contents must consist of (optional whitespace) with alternating counts and units,
+ * starting with a count. Each count is multiplied by the value of the subsequent unit. Optionally
+ * the parser can be set to allow counts without units, which are not multiplied.
+ *
+ * For example, if the units were [ "X", 10 ] , [ "L", 50 ] , [ "C", 100 ] , [ "M", 1000 ]
+ * then the following strings would be parsed as
+ *
+ * - "1X" : 10
+ * - "1L3X" : 80
+ * - "2C" : 200
+ * - "1M 4C 4X" : 1,440
+ * - "3M 5 C3 X" : 3,530
+ */
+class UnitParser
+{
+  using self_type = UnitParser; ///< Self reference type.
+public:
+  using value_type = uintmax_t;                 ///< Integral type returned.
+  using Units      = swoc::Lexicon<value_type>; ///< Unit definition type.
+
+  /// Symbolic name for setting whether units are required.
+  static constexpr bool UNITS_REQUIRED = true;
+  /// Symbolic name for setting whether units are required.
+  static constexpr bool UNITS_NOT_REQUIRED = false;
+
+  /** Constructor.
+   *
+   * @param units A @c Lexicon of unit definitions.
+   * @param unit_required_p Whether valid input requires units on all values.
+   */
+  UnitParser(Units &&units, bool unit_required_p = true) noexcept;
+
+  /** Set whether a unit is required.
+   *
+   * @param flag @c true if a unit is required, @c false if not.
+   * @return @a this.
+   */
+  self_type &unit_required(bool flag);
+
+  /** Parse a string.
+   *
+   * @param src Input string.
+   * @return The computed value if the input is valid, or an error report.
+   */
+  Rv<value_type> operator()(swoc::TextView const &src) const noexcept;
+
+protected:
+  bool _unit_required_p = true; ///< Whether unitless values are allowed.
+  Units _units;                 ///< Unit definitions.
+};
+
+inline UnitParser::UnitParser(UnitParser::Units &&units, bool unit_required_p) noexcept
+  : _unit_required_p(unit_required_p), _units(std::move(units))
+{
+  _units.set_default(value_type{0}); // Used to check for bad unit names.
+}
+
+inline UnitParser::self_type &
+UnitParser::unit_required(bool flag)
+{
+  _unit_required_p = false;
+  return *this;
+}
+
+} // namespace ts

src/tscpp/util/CMakeLists.txt

@@ -19,7 +19,7 @@
 add_library(tscpputil SHARED
         TextView.cc
         YamlCfg.cc
-        )
+        ts_unit_parser.cc)
 target_link_libraries(tscpputil PRIVATE yaml-cpp libswoc)
 
 add_executable(test_tscpputil
@@ -28,6 +28,7 @@ add_executable(test_tscpputil
         unit_tests/test_TextView.cc
         unit_tests/test_Strerror.cc
         unit_tests/test_ts_meta.cc
+	unit_tests/test_time_parser.cc
         unit_tests/unit_test_main.cc
         )
 target_link_libraries(test_tscpputil PRIVATE tscpputil libswoc)

src/tscpp/util/Makefile.am

@@ -30,7 +30,7 @@ libtscpputil_la_LDFLAGS = @AM_LDFLAGS@ -no-undefined -version-info @TS_LIBTOOL_V
 libtscpputil_la_LIBADD = @SWOC_LIBS@ @YAMLCPP_LIBS@
 
 libtscpputil_la_SOURCES = \
-	ts_diags.cc ts_ip.cc TextView.cc YamlCfg.cc
+	ts_diags.cc ts_ip.cc TextView.cc YamlCfg.cc ts_unit_parser.cc
 
 test_tscpputil_CPPFLAGS = $(AM_CPPFLAGS)\
 	-I$(abs_top_srcdir)/tests/include @SWOC_INCLUDES@
@@ -43,7 +43,9 @@ test_tscpputil_SOURCES = \
 	unit_tests/test_PostScript.cc \
 	unit_tests/test_Strerror.cc \
 	unit_tests/test_TextView.cc \
-	unit_tests/test_ts_meta.cc
+	unit_tests/test_ts_meta.cc \
+	unit_tests/test_time_parser.cc
+
 
 clean-local:
 	rm -f ParseRulesCType ParseRulesCTypeToLower ParseRulesCTypeToUpper

src/tscpp/util/ts_unit_parser.cc

@@ -0,0 +1,91 @@
+/** @file Support for common diagnostics between core, plugins, and libswoc.
+
+  This enables specifying the set of methods usable by a user agent based on the remove IP address
+  for a user agent connection.
+
+  @section license License
+
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <chrono>
+
+#include "tscpp/util/ts_unit_parser.h"
+#include "tscpp/util/ts_time_parser.h"
+
+namespace ts
+{
+
+auto
+UnitParser::operator()(swoc::TextView const &src) const noexcept -> Rv<value_type>
+{
+  value_type zret = 0;
+  TextView text   = src; // Keep @a src around to report error offsets.
+
+  while (text.ltrim_if(&isspace)) {
+    TextView parsed;
+    auto n = swoc::svtou(text, &parsed);
+    if (parsed.empty()) {
+      return Errata("Required count not found at offset {}", text.data() - src.data());
+    } else if (n == std::numeric_limits<decltype(n)>::max()) {
+      return Errata("Count at offset {} was out of bounds", text.data() - src.data());
+    }
+    text.remove_prefix(parsed.size());
+    auto ptr = text.ltrim_if(&isspace).data(); // save for error reporting.
+    // Everything up to the next digit or whitespace.
+    auto unit = text.clip_prefix_of([](char c) { return !(isspace(c) || isdigit(c)); });
+    if (unit.empty()) {
+      if (_unit_required_p) {
+        return Errata("Required unit not found at offset {}", ptr - src.data());
+      }
+    } else {
+      auto mult = _units[unit]; // What's the multiplier?
+      if (mult == 0) {
+        return Errata("Unknown unit \"{}\" at offset {}", unit, ptr - src.data());
+      }
+      n *= mult;
+    }
+    zret += n;
+  }
+  return zret;
+}
+
+// Concrete unit parsers.
+
+using namespace std::chrono;
+
+namespace detail
+{
+  /** Functor to parse duration strings.
+   * @c time_parser is a functor and is used like a function.
+   * @code
+   *   TextView text = "12 hours 30 minutes";
+   *   auto duration = std::chrono::nanoseconds(ts::time_parser_ns(text));
+   * @endcode
+   */
+  UnitParser const time_parser_ns{UnitParser::Units{{{nanoseconds{1}.count(), {"ns", "nanosec", "nanoseconds"}},
+                                                     {nanoseconds{microseconds{1}}.count(), {"us", "microsec", "microseconds"}},
+                                                     {nanoseconds{milliseconds{1}}.count(), {"ms", "millisec", "milliseconds"}},
+                                                     {nanoseconds{seconds{1}}.count(), {"s", "sec", "seconds"}},
+                                                     {nanoseconds{minutes{1}}.count(), {"m", "min", "minutes"}},
+                                                     {nanoseconds{hours{1}}.count(), {"h", "hour", "hours"}},
+                                                     {nanoseconds{hours{24}}.count(), {"d", "day", "days"}},
+                                                     {nanoseconds{hours{168}}.count(), {"w", "week", "weeks"}}}}};
+
+} // namespace detail
+
+} // namespace ts

src/tscpp/util/unit_tests/test_time_parser.cc

@@ -0,0 +1,43 @@
+/** @file
+
+    Unit tests for time parsing.
+
+    @section license License
+
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+ */
+
+#include <chrono>
+
+#include "catch.hpp"
+#include "tscpp/util/ts_time_parser.h"
+
+using namespace std::chrono;
+
+TEST_CASE("Time Parsing", "[libts][time_parser]")
+{
+  SECTION("1")
+  {
+    auto [dt, errata] = ts::time_parser("11 hours 30m");
+    REQUIRE(dt == minutes(690));
+  }
+  SECTION("2")
+  {
+    auto [dt, errata] = ts::time_parser("30 minutes 11h");
+    REQUIRE(dt == minutes(690));
+  }
+}