Add more options for xerces-c recipe

As specified in http://xerces.apache.org/xerces-c/build-3.html#CMake
there are a number of project specific options for configuring xerces-c.
Currently, only the `XMLCh` type could be configured through a conan
option. This commit adds corresponding conan options for all of the
other options (i.e. network accessor, transcoder, message loader and
mutex manager) that were previously hardcoded. Since not every value of
these options is valid on every platform this commit also adds proper
validation of the user input to detect invalid configurations. Setting
the default value for the conan options is a bit more complicated
because for some options this value is not the same for all platforms.
Therefore, the `default_options` have been dropped in favor of setting
the `options` manually from within `config_options()` if not set by the
user.

recipes/xerces-c/all/conanfile.py

@@ -1,6 +1,7 @@
 from conans import ConanFile, CMake, tools
 from conans.errors import ConanInvalidConfiguration
 import os
+from typing import Union, Tuple
 
 
 class XercesCConan(ConanFile):
@@ -18,9 +19,13 @@ class XercesCConan(ConanFile):
     options = {
         "shared": [True, False],
         "fPIC": [True, False],
+        # https://xerces.apache.org/xerces-c/build-3.html
         "char_type": ["uint16_t", "char16_t", "wchar_t"],
+        "network_accessor": ["curl", "socket", "cfurl", "winsock"],
+        "transcoder": ["gnuiconv", "iconv", "icu", "macosunicodeconverter", "windows"],
+        "message_loader": ["inmemory", "icu", "iconv"],
+        "mutex_manager": ["standard", "posix", "windows"],
     }
-    default_options = {"shared": False, "fPIC": True, "char_type": "uint16_t"}
 
     _cmake = None
 
@@ -32,15 +37,57 @@ def _source_subfolder(self):
     def _build_subfolder(self):
         return "build_subfolder"
 
-    def validate(self):
-        if self.options.char_type == "wchar_t" and self.settings.os != "Windows":
+    def _validate(self, option: str, value: str, os: Union[str, Tuple[str]]):
+        """
+        Validate that the given `option` has the required `value` for the given `os`
+        If not raises a ConanInvalidConfiguration error
+
+        :param option: the name of the option to validate
+        :param value: the value that the `option` should have
+        :param os: either a single string or a tuple of strings containing the
+                   OS(es) that `value` is valid on
+        """
+        if ((isinstance(os, str) and self.settings.os != os) or \
+            (isinstance(os, tuple) and self.settings.os not in os)) \
+             and getattr(self.options, option) == value:
             raise ConanInvalidConfiguration(
-                "Option 'char_type=wchar_t' is only supported in Windows"
+                f"Option '{option}={value}' is only supported on {os}"
             )
 
+    def validate(self):
+        self._validate("char_type", "wchar_t", "Windows")
+        self._validate("network_accessor", "winsock", "Windows")
+        self._validate("network_accessor", "cfurl", "Macos")
+        self._validate("network_accessor", "socket", ("Linux", "Macos"))
+        self._validate("network_accessor", "curl", ("Linux", "Macos"))
+        self._validate("transcoder", "macosunicodeconverter", "Macos")
+        self._validate("transcoder", "windows", "Windows")
+        self._validate("mutex_manager", "posix", ("Linux", "Macos"))
+        self._validate("mutex_manager", "windows", "Windows")
+
+    def requirements(self):
+        if "icu" in (self.options.transcoder, self.options.message_loader):
+            self.requires("icu/69.1")
+
     def config_options(self):
+        self.options.shared = False
+        self.options.fPIC = True
+        self.options.char_type = "uint16_t"
+        self.options.message_loader = "inmemory"
+
         if self.settings.os == "Windows":
             del self.options.fPIC
+            self.options.network_accessor = "winsock"
+            self.options.transcoder = "windows"
+            self.options.mutex_manager = "windows"
+        elif self.settings.os == "Macos":
+            self.options.network_accessor = "cfurl"
+            self.options.transcoder = "macosunicodeconverter"
+            self.options.mutex_manager = "posix"
+        elif self.settings.os == "Linux":
+            self.options.network_accessor = "socket"
+            self.options.transcoder = "gnuiconv"
+            self.options.mutex_manager = "posix"
 
     def configure(self):
         if self.settings.os not in ("Windows", "Macos", "Linux"):
@@ -58,27 +105,13 @@ def _configure_cmake(self):
             return self._cmake
         self._cmake = CMake(self)
         # https://xerces.apache.org/xerces-c/build-3.html
-        self._cmake.definitions["network-accessor"] = {
-            "Windows": "winsock",
-            "Macos": "cfurl",
-            "Linux": "socket",
-        }.get(str(self.settings.os))
-        self._cmake.definitions["transcoder"] = {
-            "Windows": "windows",
-            "Macos": "macosunicodeconverter",
-            "Linux": "gnuiconv",
-        }.get(str(self.settings.os))
+        self._cmake.definitions["network-accessor"] = self.options.network_accessor
+        self._cmake.definitions["transcoder"] = self.options.transcoder
         self._cmake.definitions["message-loader"] = "inmemory"
-
         self._cmake.definitions["xmlch-type"] = self.options.char_type
-
-        self._cmake.definitions["mutex-manager"] = {
-            "Windows": "windows",
-            "Macos": "posix",
-            "Linux": "posix",
-        }.get(str(self.settings.os))
+        self._cmake.definitions["mutex-manager"] = self.options.mutex_manager
         # avoid picking up system dependency
-        self._cmake.definitions["CMAKE_DISABLE_FIND_PACKAGE_CURL"] = True
+        self._cmake.definitions["CMAKE_DISABLE_FIND_PACKAGE_CURL"] = self.options.network_accessor != "curl"
         self._cmake.definitions["CMAKE_DISABLE_FIND_PACKAGE_ICU"] = True
         self._cmake.configure(build_folder=self._build_subfolder)
         return self._cmake
@@ -103,5 +136,7 @@ def package_info(self):
             self.cpp_info.frameworks = ["CoreFoundation", "CoreServices"]
         elif self.settings.os == "Linux":
             self.cpp_info.system_libs.append("pthread")
+        if self.options.network_accessor == "curl":
+            self.cpp_info.system_libs.append("curl")
         self.cpp_info.names["cmake_find_package"] = "XercesC"
         self.cpp_info.names["cmake_find_package_multi"] = "XercesC"