From 2b6b62c52c0994a424415e8fe7f665cbee2a5fa7 Mon Sep 17 00:00:00 2001
From: Henry Fredrick Schreiner <henry.fredrick.schreiner@cern.ch>
Date: Thu, 3 May 2018 15:52:55 +0200
Subject: [PATCH] Adding smart validators

---
 include/CLI/Option.hpp     |   8 ++
 include/CLI/Validators.hpp | 205 +++++++++++++++++++++++++++----------
 tests/HelpTest.cpp         |  78 ++++++++++++++
 tests/HelpersTest.cpp      |  57 +++++++++++
 4 files changed, 294 insertions(+), 54 deletions(-)

diff --git a/include/CLI/Option.hpp b/include/CLI/Option.hpp
index c74caf81..62524ba2 100644
--- a/include/CLI/Option.hpp
+++ b/include/CLI/Option.hpp
@@ -272,6 +272,14 @@ class Option : public OptionBase<Option> {
         return this;
     }
 
+    /// Adds a validator with a built in type name
+    Option *check(const Validator &validator) {
+        validators_.emplace_back(validator.func);
+        if(!validator.tname.empty())
+            set_type_name(validator.tname);
+        return this;
+    }
+
     /// Adds a validator
     Option *check(std::function<std::string(const std::string &)> validator) {
         validators_.emplace_back(validator);
diff --git a/include/CLI/Validators.hpp b/include/CLI/Validators.hpp
index f158f927..e8efde3d 100644
--- a/include/CLI/Validators.hpp
+++ b/include/CLI/Validators.hpp
@@ -18,74 +18,171 @@
 namespace CLI {
 
 /// @defgroup validator_group Validators
+
 /// @brief Some validators that are provided
 ///
-/// These are simple `void(std::string&)` validators that are useful. They throw
-/// a ValidationError if they fail (or the normally expected error if the cast fails)
+/// These are simple `std::string(const std::string&)` validators that are useful. They return
+/// a string if the validation fails. A custom struct is provided, as well, with the same user
+/// semantics, but with the ability to provide a new type name.
 /// @{
 
-/// Check for an existing file
-inline std::string ExistingFile(const std::string &filename) {
-    struct stat buffer;
-    bool exist = stat(filename.c_str(), &buffer) == 0;
-    bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
-    if(!exist) {
-        return "File does not exist: " + filename;
-    } else if(is_dir) {
-        return "File is actually a directory: " + filename;
-    }
-    return std::string();
-}
+///
+struct Validator {
+    /// This is the type name, if emtpy the type name will not be changed
+    std::string tname;
+    std::function<std::string(const std::string &filename)> func;
 
-/// Check for an existing directory
-inline std::string ExistingDirectory(const std::string &filename) {
-    struct stat buffer;
-    bool exist = stat(filename.c_str(), &buffer) == 0;
-    bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
-    if(!exist) {
-        return "Directory does not exist: " + filename;
-    } else if(!is_dir) {
-        return "Directory is actually a file: " + filename;
+    /// This is the required operator for a validator - provided to help
+    /// users (CLI11 uses the func directly)
+    std::string operator()(const std::string &filename) const { return func(filename); };
+
+    /// Combining validators is a new validator
+    Validator operator&(const Validator &other) const {
+        Validator newval;
+        newval.tname = (tname == other.tname ? tname : "");
+
+        // Give references (will make a copy in lambda function)
+        const std::function<std::string(const std::string &filename)> &f1 = func;
+        const std::function<std::string(const std::string &filename)> &f2 = other.func;
+
+        newval.func = [f1, f2](const std::string &filename) {
+            std::string s1 = f1(filename);
+            std::string s2 = f2(filename);
+            if(!s1.empty() && !s2.empty())
+                return s1 + " & " + s2;
+            else
+                return s1 + s2;
+        };
+        return newval;
     }
-    return std::string();
-}
+
+    /// Combining validators is a new validator
+    Validator operator|(const Validator &other) const {
+        Validator newval;
+        newval.tname = (tname == other.tname ? tname : "");
+
+        // Give references (will make a copy in lambda function)
+        const std::function<std::string(const std::string &filename)> &f1 = func;
+        const std::function<std::string(const std::string &filename)> &f2 = other.func;
+
+        newval.func = [f1, f2](const std::string &filename) {
+            std::string s1 = f1(filename);
+            std::string s2 = f2(filename);
+            if(s1.empty() || s2.empty())
+                return std::string();
+            else
+                return s1 + " & " + s2;
+        };
+        return newval;
+    }
+};
+
+// The implemntation of the built in validators is using the Validator class;
+// the user is only expected to use the const static versions (since there's no setup).
+// Therefore, this is in detail.
+namespace detail {
+
+/// Check for an existing file (returns error message if check fails)
+struct ExistingFileValidator : public Validator {
+    ExistingFileValidator() {
+        tname = "FILE";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
+            if(!exist) {
+                return "File does not exist: " + filename;
+            } else if(is_dir) {
+                return "File is actually a directory: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
+
+/// Check for an existing directory (returns error message if check fails)
+struct ExistingDirectoryValidator : public Validator {
+    ExistingDirectoryValidator() {
+        tname = "DIR";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
+            if(!exist) {
+                return "Directory does not exist: " + filename;
+            } else if(!is_dir) {
+                return "Directory is actually a file: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
 
 /// Check for an existing path
-inline std::string ExistingPath(const std::string &filename) {
-    struct stat buffer;
-    bool const exist = stat(filename.c_str(), &buffer) == 0;
-    if(!exist) {
-        return "Path does not exist: " + filename;
+struct ExistingPathValidator : public Validator {
+    ExistingPathValidator() {
+        tname = "PATH";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool const exist = stat(filename.c_str(), &buffer) == 0;
+            if(!exist) {
+                return "Path does not exist: " + filename;
+            }
+            return std::string();
+        };
     }
-    return std::string();
-}
+};
 
-/// Check for a non-existing path
-inline std::string NonexistentPath(const std::string &filename) {
-    struct stat buffer;
-    bool exist = stat(filename.c_str(), &buffer) == 0;
-    if(exist) {
-        return "Path already exists: " + filename;
+/// Check for an non-existing path
+struct NonexistentPathValidator : public Validator {
+    NonexistentPathValidator() {
+        tname = "PATH";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            if(exist) {
+                return "Path already exists: " + filename;
+            }
+            return std::string();
+        };
     }
-    return std::string();
-}
+};
+} // namespace detail
 
-/// Produce a range validator function
-template <typename T> std::function<std::string(const std::string &)> Range(T min, T max) {
-    return [min, max](std::string input) {
-        T val;
-        detail::lexical_cast(input, val);
-        if(val < min || val > max)
-            return "Value " + input + " not in range " + std::to_string(min) + " to " + std::to_string(max);
+// Static is not needed here, because global const implies static.
 
-        return std::string();
-    };
-}
+/// Check for existing file (returns error message if check fails)
+const static detail::ExistingFileValidator ExistingFile;
 
-/// Range of one value is 0 to value
-template <typename T> std::function<std::string(const std::string &)> Range(T max) {
-    return Range(static_cast<T>(0), max);
-}
+/// Check for an existing directory (returns error message if check fails)
+const static detail::ExistingDirectoryValidator ExistingDirectory;
+
+/// Check for an existing path
+const static detail::ExistingPathValidator ExistingPath;
+
+/// Check for an non-existing path
+const static detail::NonexistentPathValidator NonexistentPath;
+
+///  Produce a range (factory). Min and max are inclusive.
+struct Range : public Validator {
+    template <typename T> Range(T min, T max) {
+        std::stringstream out;
+        out << detail::type_name<T>() << " in [" << min << " - " << max << "]";
+
+        tname = out.str();
+        func = [min, max](std::string input) {
+            T val;
+            detail::lexical_cast(input, val);
+            if(val < min || val > max)
+                return "Value " + input + " not in range " + std::to_string(min) + " to " + std::to_string(max);
+
+            return std::string();
+        };
+    }
+
+    /// Range of one value is 0 to value
+    template <typename T> explicit Range(T max) : Range(static_cast<T>(0), max) {}
+};
 
 /// @}
 
diff --git a/tests/HelpTest.cpp b/tests/HelpTest.cpp
index e742a1df..e70901bc 100644
--- a/tests/HelpTest.cpp
+++ b/tests/HelpTest.cpp
@@ -588,3 +588,81 @@ TEST(THelp, GroupOrder) {
     EXPECT_NE(aee_loc, std::string::npos);
     EXPECT_LT(zee_loc, aee_loc);
 }
+
+TEST(THelp, ValidatorsText) {
+    CLI::App app;
+
+    std::string filename;
+    int x;
+    unsigned int y;
+    app.add_option("--f1", filename)->check(CLI::ExistingFile);
+    app.add_option("--f3", x)->check(CLI::Range(1, 4));
+    app.add_option("--f4", y)->check(CLI::Range(12));
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("FILE"));
+    EXPECT_THAT(help, HasSubstr("INT in [1 - 4]"));
+    EXPECT_THAT(help, HasSubstr("INT in [0 - 12]")); // Loses UINT
+    EXPECT_THAT(help, Not(HasSubstr("TEXT")));
+}
+
+TEST(THelp, ValidatorsNonPathText) {
+    CLI::App app;
+
+    std::string filename;
+    app.add_option("--f2", filename)->check(CLI::NonexistentPath);
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("PATH"));
+    EXPECT_THAT(help, Not(HasSubstr("TEXT")));
+}
+
+TEST(THelp, ValidatorsDirText) {
+    CLI::App app;
+
+    std::string filename;
+    app.add_option("--f2", filename)->check(CLI::ExistingDirectory);
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("DIR"));
+    EXPECT_THAT(help, Not(HasSubstr("TEXT")));
+}
+
+TEST(THelp, ValidatorsPathText) {
+    CLI::App app;
+
+    std::string filename;
+    app.add_option("--f2", filename)->check(CLI::ExistingPath);
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("PATH"));
+    EXPECT_THAT(help, Not(HasSubstr("TEXT")));
+}
+
+TEST(THelp, CombinedValidatorsText) {
+    CLI::App app;
+
+    std::string filename;
+    app.add_option("--f1", filename)->check(CLI::ExistingFile | CLI::ExistingDirectory);
+
+    // This would be nice if it put something other than string, but would it be path or file?
+    // Can't programatically tell!
+    // (Users can use ExistingPath, by the way)
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("TEXT"));
+    EXPECT_THAT(help, Not(HasSubstr("PATH")));
+    EXPECT_THAT(help, Not(HasSubstr("FILE")));
+}
+
+// Don't do this in real life, please
+TEST(THelp, CombinedValidatorsPathyText) {
+    CLI::App app;
+
+    std::string filename;
+    app.add_option("--f1", filename)->check(CLI::ExistingPath | CLI::NonexistentPath);
+
+    // Combining validators with the same type string is OK
+    std::string help = app.help();
+    EXPECT_THAT(help, Not(HasSubstr("TEXT")));
+    EXPECT_THAT(help, HasSubstr("PATH"));
+}
diff --git a/tests/HelpersTest.cpp b/tests/HelpersTest.cpp
index 281b8f6d..4c8249f9 100644
--- a/tests/HelpersTest.cpp
+++ b/tests/HelpersTest.cpp
@@ -155,6 +155,63 @@ TEST(Validators, PathNotExistsDir) {
     EXPECT_NE(CLI::ExistingPath(mydir), "");
 }
 
+TEST(Validators, CombinedAndRange) {
+    auto crange = CLI::Range(0, 12) & CLI::Range(4, 16);
+    EXPECT_TRUE(crange("4").empty());
+    EXPECT_TRUE(crange("12").empty());
+    EXPECT_TRUE(crange("7").empty());
+
+    EXPECT_FALSE(crange("-2").empty());
+    EXPECT_FALSE(crange("2").empty());
+    EXPECT_FALSE(crange("15").empty());
+    EXPECT_FALSE(crange("16").empty());
+    EXPECT_FALSE(crange("18").empty());
+}
+
+TEST(Validators, CombinedOrRange) {
+    auto crange = CLI::Range(0, 4) | CLI::Range(8, 12);
+
+    EXPECT_FALSE(crange("-2").empty());
+    EXPECT_TRUE(crange("2").empty());
+    EXPECT_FALSE(crange("5").empty());
+    EXPECT_TRUE(crange("8").empty());
+    EXPECT_TRUE(crange("12").empty());
+    EXPECT_FALSE(crange("16").empty());
+}
+
+TEST(Validators, CombinedPaths) {
+    std::string myfile{"TestFileNotUsed.txt"};
+    EXPECT_FALSE(CLI::ExistingFile(myfile).empty());
+    bool ok = static_cast<bool>(std::ofstream(myfile.c_str()).put('a')); // create file
+    EXPECT_TRUE(ok);
+
+    std::string dir{"../tests"};
+    std::string notpath{"nondirectory"};
+
+    auto path_or_dir = CLI::ExistingPath | CLI::ExistingDirectory;
+    EXPECT_TRUE(path_or_dir(dir).empty());
+    EXPECT_TRUE(path_or_dir(myfile).empty());
+    EXPECT_FALSE(path_or_dir(notpath).empty());
+
+    auto file_or_dir = CLI::ExistingFile | CLI::ExistingDirectory;
+    EXPECT_TRUE(file_or_dir(dir).empty());
+    EXPECT_TRUE(file_or_dir(myfile).empty());
+    EXPECT_FALSE(file_or_dir(notpath).empty());
+
+    auto path_and_dir = CLI::ExistingPath & CLI::ExistingDirectory;
+    EXPECT_TRUE(path_and_dir(dir).empty());
+    EXPECT_FALSE(path_and_dir(myfile).empty());
+    EXPECT_FALSE(path_and_dir(notpath).empty());
+
+    auto path_and_file = CLI::ExistingFile & CLI::ExistingDirectory;
+    EXPECT_FALSE(path_and_file(dir).empty());
+    EXPECT_FALSE(path_and_file(myfile).empty());
+    EXPECT_FALSE(path_and_file(notpath).empty());
+
+    std::remove(myfile.c_str());
+    EXPECT_FALSE(CLI::ExistingFile(myfile).empty());
+}
+
 // Yes, this is testing an app_helper :)
 TEST(AppHelper, TempfileCreated) {
     std::string name = "TestFileNotUsed.txt";