Add get_as_string() and get_as_raw_ptr()

This change adds support for directly fetching resource data as std::string
as well as raw "const char *" combined with std::size_t. This allows
cleaner code in use cases where the existing file interface is
overkill.

CMakeRC.cmake

@@ -340,7 +340,7 @@ public:
         : _index(&index)
     {}
 
-    file open(const std::string& path) const {
+    const detail::file_data& _get_file_data(const std::string& path) const {
         auto entry_ptr = _get(path);
         if (!entry_ptr || !entry_ptr->is_file()) {
 #ifdef CMRC_NO_EXCEPTIONS
@@ -350,10 +350,27 @@ public:
             throw std::system_error(make_error_code(std::errc::no_such_file_or_directory), path);
 #endif
         }
-        auto& dat = entry_ptr->as_file();
+        return entry_ptr->as_file();
+    }
+
+    file open(const std::string& path) const {
+        auto& dat = _get_file_data(path);
         return file{dat.begin_ptr, dat.end_ptr};
     }
 
+    std::string get_as_string(const std::string& path) const {
+        auto& dat = _get_file_data(path);
+        auto& f = file{dat.begin_ptr, dat.end_ptr};
+        return std::string{dat.begin_ptr, f.size()};
+    }
+
+    const char *get_as_raw_ptr(const std::string& path, std::size_t& file_size) const {
+        auto& dat = _get_file_data(path);
+        auto& f = file{dat.begin_ptr, dat.end_ptr};
+        file_size = f.size();
+        return dat.begin_ptr;
+    }
+
     bool is_file(const std::string& path) const noexcept {
         auto entry_ptr = _get(path);
         return entry_ptr && entry_ptr->is_file();

README.md

@@ -136,6 +136,13 @@ statically allocated resource library data.
 - `open(const std::string& path) -> cmrc::file` - Opens and returns a
   non-directory `file` object at `path`, or throws `std::system_error()` on
   error.
+- `get_as_string(const std::string& path) -> std::string` - Returns the
+  non-directory data at `path` as a `std::string`, or throws `std::system_error()`
+  on error.
+- `get_as_raw_ptr(const std::string& path, std::size_t& file_size) -> const char *` -
+  Returns the non-directory data at `path` as a raw `const char *` pointer and updates
+  the supplied `file_size` reference with the data size, or throws
+  `std::system_error()` on error.
 - `is_file(const std::string& path) -> bool` - Returns `true` if the given
   `path` names a regular file, `false` otherwise.
 - `is_directory(const std::string& path) -> bool` - Returns `true` if the given
@@ -179,6 +186,10 @@ the library using `cmrc_add_resources` with the name of the library and the
 paths to any additional resources that you wish to compile in. This way you can
 lazily add resources to the library as your configure script runs.
 
+Resources are always stored with an extra trailing `null` byte to facilitate
+the direct use of data as C strings if needed. The `null` byte is not a part of
+the actual data and does not count towards its size.
+
 Both `cmrc_add_resource_library` and `cmrc_add_resources` take two additional
 keyword parameters:
 

tests/CMakeLists.txt

@@ -38,6 +38,20 @@ cmrc_add_test(
         subdir_a/subdir_b/file_b.txt
     )
 
+cmrc_add_test(
+    NAME simple_string
+    PASS_REGEX "^Hello, world!"
+    RESOURCES
+        hello.txt
+    )
+
+cmrc_add_test(
+    NAME simple_raw_ptr
+    PASS_REGEX "^Hello, world!"
+    RESOURCES
+        hello.txt
+    )
+
 cmrc_add_test(
     NAME flower
     RESOURCES flower.jpg

tests/simple_raw_ptr.cpp

@@ -0,0 +1,12 @@
+#include <cmrc/cmrc.hpp>
+
+#include <iostream>
+
+CMRC_DECLARE(simple_raw_ptr);
+
+int main() {
+    auto fs = cmrc::simple_raw_ptr::get_filesystem();
+    std::size_t sz;
+    const char *data = fs.get_as_raw_ptr("hello.txt", sz);
+    std::cout << std::string(data, sz) << '\n';
+}

tests/simple_string.cpp

@@ -0,0 +1,11 @@
+#include <cmrc/cmrc.hpp>
+
+#include <iostream>
+
+CMRC_DECLARE(simple_string);
+
+int main() {
+    auto fs = cmrc::simple_string::get_filesystem();
+    std::string a_string = fs.get_as_string("hello.txt");
+    std::cout << a_string << '\n';
+}