Allow non standard option names like -option (#1078)

This has been bounced around for a couple years now 

#474 and a few others have expressed desire to work with non-standard
option names. We have been somewhat resistant to that but I think it can
be done now. This PR adds a modifier `allow_non_standard_option_names()`
It is purposely long, it is purposely off by default. But what it does
is allow option names with a single `-` to act like a short option name.
With this modifier enabled no single letter short option names are
allowed to start with the same letter as a non-standard names. For
example `-s` and `-single` would not be allowed.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <[email protected]>

Author: 3 people

CPPLINT.cfg

@@ -3,6 +3,7 @@ linelength=120  # As in .clang-format
 
 # Unused filters
 filter=-build/c++11  # Reports e.g. chrono and thread, which overlap with Chromium's API. Not applicable to general C++ projects.
+filter=-build/c++17  # google only restrictions not relevant
 filter=-build/include_order  # Requires unusual include order that encourages creating not self-contained headers
 filter=-build/include_subdir  # Prevents including files in current directory for whatever reason
 filter=-readability/nolint  # Conflicts with clang-tidy
@@ -13,3 +14,4 @@ filter=-runtime/string  # Requires not using static const strings which makes th
 filter=-whitespace/blank_line  # Unnecessarily strict with blank lines that otherwise help with readability
 filter=-whitespace/indent  # Requires strange 3-space indent of private/protected/public markers
 filter=-whitespace/parens,-whitespace/braces  # Conflict with clang-format
+filter=-whitespace/newline # handled by clang-format

README.md

@@ -158,8 +158,6 @@ installation fuss.
 There are some other possible "features" that are intentionally not supported by
 this library:
 
-- Non-standard variations on syntax, like `-long` options. This is non-standard
-  and should be avoided, so that is enforced by this library.
 - Completion of partial options, such as Python's `argparse` supplies for
   incomplete arguments. It's better not to guess. Most third party command line
   parsers for python actually reimplement command line parsing rather than using
@@ -904,6 +902,14 @@ option_groups. These are:
   the form of `/s /long /file:file_name.ext` This option does not change how
   options are specified in the `add_option` calls or the ability to process
   options in the form of `-s --long --file=file_name.ext`.
+- `.allow_non_standard_option_names()`:🚧 Allow specification of single `-` long
+  form option names. This is not recommended but is available to enable
+  reworking of existing interfaces. If this modifier is enabled on an app or
+  subcommand, options or flags can be specified like normal but instead of
+  throwing an exception, long form single dash option names will be allowed. It
+  is not allowed to have a single character short option starting with the same
+  character as a single dash long form name; for example, `-s` and `-single` are
+  not allowed in the same application.
 - `.fallthrough()`: Allow extra unmatched options and positionals to "fall
   through" and be matched on a parent option. Subcommands by default are allowed
   to "fall through" as in they will first attempt to match on the current

azure-pipelines.yml

@@ -22,7 +22,7 @@ jobs:
   - job: CppLint
     pool:
       vmImage: "ubuntu-latest"
-    container: sharaku/cpplint:latest
+    container: helics/buildenv:cpplint
     steps:
       - bash: cpplint --counting=detailed --recursive examples include/CLI tests
         displayName: Checking against google style guide

examples/custom_parse.cpp

@@ -9,6 +9,7 @@
 #include <CLI/CLI.hpp>
 #include <iostream>
 #include <sstream>
+#include <string>
 
 // example file to demonstrate a custom lexical cast function
 

examples/formatter.cpp

@@ -7,6 +7,7 @@
 #include <CLI/CLI.hpp>
 #include <iostream>
 #include <memory>
+#include <string>
 
 class MyFormatter : public CLI::Formatter {
   public:

examples/inter_argument_order.cpp

@@ -7,6 +7,7 @@
 #include <CLI/CLI.hpp>
 #include <algorithm>
 #include <iostream>
+#include <string>
 #include <tuple>
 #include <vector>
 

include/CLI/App.hpp

@@ -260,6 +260,9 @@ class App {
     /// This is potentially useful as a modifier subcommand
     bool silent_{false};
 
+    /// indicator that the subcommand should allow non-standard option arguments, such as -single_dash_flag
+    bool allow_non_standard_options_{false};
+
     /// Counts the number of times this command/subcommand was parsed
     std::uint32_t parsed_{0U};
 
@@ -392,6 +395,12 @@ class App {
         return this;
     }
 
+    /// allow non standard option names
+    App *allow_non_standard_option_names(bool allowed = true) {
+        allow_non_standard_options_ = allowed;
+        return this;
+    }
+
     /// Set the subcommand to be disabled by default, so on clear(), at the start of each parse it is disabled
     App *disabled_by_default(bool disable = true) {
         if(disable) {
@@ -1146,6 +1155,9 @@ class App {
     /// Get the status of silence
     CLI11_NODISCARD bool get_silent() const { return silent_; }
 
+    /// Get the status of silence
+    CLI11_NODISCARD bool get_allow_non_standard_option_names() const { return allow_non_standard_options_; }
+
     /// Get the status of disabled
     CLI11_NODISCARD bool get_immediate_callback() const { return immediate_callback_; }
 

include/CLI/Option.hpp

@@ -341,9 +341,13 @@ class Option : public OptionBase<Option> {
     ///@}
 
     /// Making an option by hand is not defined, it must be made by the App class
-    Option(std::string option_name, std::string option_description, callback_t callback, App *parent)
+    Option(std::string option_name,
+           std::string option_description,
+           callback_t callback,
+           App *parent,
+           bool allow_non_standard = false)
         : description_(std::move(option_description)), parent_(parent), callback_(std::move(callback)) {
-        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(option_name));
+        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(option_name), allow_non_standard);
     }
 
   public:

include/CLI/Split.hpp

@@ -39,7 +39,7 @@ CLI11_INLINE std::vector<std::pair<std::string, std::string>> get_default_flag_v
 
 /// Get a vector of short names, one of long names, and a single name
 CLI11_INLINE std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>
-get_names(const std::vector<std::string> &input);
+get_names(const std::vector<std::string> &input, bool allow_non_standard = false);
 
 }  // namespace detail
 // [CLI11:split_hpp:end]

include/CLI/Timer.hpp

@@ -18,6 +18,7 @@
 
 #include <array>
 #include <chrono>
+#include <cstdio>
 #include <functional>
 #include <iostream>
 #include <string>