Add Fish support for environments

conan/tools/env/environment.py

@@ -508,12 +508,52 @@ def save_sh(self, file_location, generate_deactivate=True):
         content = f'script_folder="{os.path.abspath(filepath)}"\n' + content
         save(file_location, content)
 
+    def save_fish(self, file_location, generate_deactivate=True):
+        filepath, filename = os.path.split(file_location)
+        deactivate_file = os.path.join(filepath, "deactivate_{}".format(filename))
+        values = self._values.keys()
+        if len(values) == 0:
+            # Empty environment, nothing to restore (Easier to handle in Fish)
+            deactivate = ("""echo "echo Nothing to restore" > {deactivate_file}"""
+                          .format(deactivate_file=deactivate_file))
+        else:
+            deactivate = textwrap.dedent("""\
+               echo "echo Restoring environment" > "{deactivate_file}"
+               for v in {vars}
+                   set is_defined "true"
+                   set value (printenv $v); or set is_defined ""
+                   if test -n "$value" -o -n "$is_defined"
+                       echo set -gx "$v" "$value" >> "{deactivate_file}"
+                   else
+                       echo set -ge "$v" >> "{deactivate_file}"
+                   end
+               end
+               """.format(deactivate_file=deactivate_file, vars=" ".join(self._values.keys())))
+        capture = textwrap.dedent("""\
+              {deactivate}
+              """).format(deactivate=deactivate if generate_deactivate else "")
+        result = [capture]
+        for varname, varvalues in self._values.items():
+            value = varvalues.get_str("${name}", self._subsystem, pathsep=self._pathsep)
+            value = value.replace('"', '\\"')
+            if value:
+                result.append('set -gx {} "{}"'.format(varname, value))
+            else:
+                result.append('set -ge {}'.format(varname))
+
+        content = "\n".join(result)
+        content = relativize_generated_file(content, self._conanfile, "$script_folder")
+        content = f'set script_folder "{os.path.abspath(filepath)}"\n' + content
+        save(file_location, content)
+
     def save_script(self, filename):
         """
         Saves a script file (bat, sh, ps1) with a launcher to set the environment.
         If the conf "tools.env.virtualenv:powershell" is set to True it will generate powershell
         launchers if Windows.
 
+        If the conf "tools.env.virtualenv:fish" is set to True it will generate fish launchers.
+
         :param filename: Name of the file to generate. If the extension is provided, it will generate
                          the launcher script for that extension, otherwise the format will be deduced
                          checking if we are running inside Windows (checking also the subsystem) or not.
@@ -522,18 +562,27 @@ def save_script(self, filename):
         if ext:
             is_bat = ext == ".bat"
             is_ps1 = ext == ".ps1"
+            is_fish = ext == ".fish"
         else:  # Need to deduce it automatically
             is_bat = self._subsystem == WINDOWS
             is_ps1 = self._conanfile.conf.get("tools.env.virtualenv:powershell", check_type=bool)
-            if is_ps1:
+            is_fish = self._conanfile.conf.get("tools.env.virtualenv:fish", check_type=bool)
+            if is_fish:
+                filename = filename + ".fish"
+                is_bat = False
+                is_ps1 = False
+            elif is_ps1:
                 filename = filename + ".ps1"
                 is_bat = False
+                is_fish = False
             else:
                 filename = filename + (".bat" if is_bat else ".sh")
 
         path = os.path.join(self._conanfile.generators_folder, filename)
         if is_bat:
             self.save_bat(path)
+        elif is_fish:
+            self.save_fish(path)
         elif is_ps1:
             self.save_ps1(path)
         else:

conans/model/conf.py

@@ -104,6 +104,7 @@
     "tools.apple:enable_arc": "(boolean) Enable/Disable ARC Apple Clang flags",
     "tools.apple:enable_visibility": "(boolean) Enable/Disable Visibility Apple Clang flags",
     "tools.env.virtualenv:powershell": "If it is set to True it will generate powershell launchers if os=Windows",
+    "tools.env.virtualenv:fish": "If it is set to True it will generate fish launchers",
     # Compilers/Flags configurations
     "tools.build:compiler_executables": "Defines a Python dict-like with the compilers path to be used. Allowed keys {'c', 'cpp', 'cuda', 'objc', 'objcxx', 'rc', 'fortran', 'asm', 'hip', 'ispc'}",
     "tools.build:cxxflags": "List of extra CXX flags used by different toolchains like CMakeToolchain, AutotoolsToolchain and MesonToolchain",