EnvironmentVariables: Simplify and annotate

3 files changed, 51 insertions, 46 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 96d2f4610..9f7f45de7 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -1223,10 +1223,10 @@ class Backend:
     def get_run_target_env(self, target: build.RunTarget) -> build.EnvironmentVariables:
         env = target.env if target.env else build.EnvironmentVariables()
         introspect_cmd = join_args(self.environment.get_build_command() + ['introspect'])
-        env.add_var(env.set, 'MESON_SOURCE_ROOT', [self.environment.get_source_dir()], {})
-        env.add_var(env.set, 'MESON_BUILD_ROOT', [self.environment.get_build_dir()], {})
-        env.add_var(env.set, 'MESON_SUBDIR', [target.subdir], {})
-        env.add_var(env.set, 'MESONINTROSPECT', [introspect_cmd], {})
+        env.set('MESON_SOURCE_ROOT', [self.environment.get_source_dir()])
+        env.set('MESON_BUILD_ROOT', [self.environment.get_build_dir()])
+        env.set('MESON_SUBDIR', [target.subdir])
+        env.set('MESONINTROSPECT', [introspect_cmd])
         return env
 
     def run_postconf_scripts(self) -> None:
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 620f40f93..e3fad3d6f 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -402,41 +402,36 @@ class EnvironmentVariables:
         repr_str = "<{0}: {1}>"
         return repr_str.format(self.__class__.__name__, self.envvars)
 
-    def add_var(self, method, name, args, kwargs):
-        self.varnames.add(name)
-        self.envvars.append((method, name, args, kwargs))
-
-    def has_name(self, name):
+    def has_name(self, name: str) -> bool:
         return name in self.varnames
 
-    def get_value(self, values, kwargs):
-        separator = kwargs.get('separator', os.pathsep)
+    def set(self, name: str, values: T.List[str], separator: str = os.pathsep) -> None:
+        self.varnames.add(name)
+        self.envvars.append((self._set, name, values, separator))
 
-        value = ''
-        for var in values:
-            value += separator + var
-        return separator, value.strip(separator)
+    def append(self, name: str, values: T.List[str], separator: str = os.pathsep) -> None:
+        self.varnames.add(name)
+        self.envvars.append((self._append, name, values, separator))
 
-    def set(self, env, name, values, kwargs):
-        return self.get_value(values, kwargs)[1]
+    def prepend(self, name: str, values: T.List[str], separator: str = os.pathsep) -> None:
+        self.varnames.add(name)
+        self.envvars.append((self._prepend, name, values, separator))
 
-    def append(self, env, name, values, kwargs):
-        sep, value = self.get_value(values, kwargs)
-        if name in env:
-            return env[name] + sep + value
-        return value
+    def _set(self, env: T.Dict[str, str], name: str, values: T.List[str], separator: str) -> str:
+        return separator.join(values)
 
-    def prepend(self, env, name, values, kwargs):
-        sep, value = self.get_value(values, kwargs)
-        if name in env:
-            return value + sep + env[name]
+    def _append(self, env: T.Dict[str, str], name: str, values: T.List[str], separator: str) -> str:
+        curr = env.get(name)
+        return separator.join(values if curr is None else [curr] + values)
 
-        return value
+    def _prepend(self, env: T.Dict[str, str], name: str, values: T.List[str], separator: str) -> str:
+        curr = env.get(name)
+        return separator.join(values if curr is None else values + [curr])
 
     def get_env(self, full_env: T.Dict[str, str]) -> T.Dict[str, str]:
         env = full_env.copy()
-        for method, name, values, kwargs in self.envvars:
-            env[name] = method(full_env, name, values, kwargs)
+        for method, name, values, separator in self.envvars:
+            env[name] = method(full_env, name, values, separator)
         return env
 
 class Target:
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index e563f36f0..84d5e5cd5 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -269,40 +269,50 @@ class EnvironmentVariablesHolder(MutableInterpreterObject, ObjectHolder[build.En
         elif initial_values:
             raise AssertionError('Unsupported EnvironmentVariablesHolder initial_values')
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         repr_str = "<{0}: {1}>"
         return repr_str.format(self.__class__.__name__, self.held_object.envvars)
 
-    def add_var(self, method, args, kwargs):
-        if not isinstance(kwargs.get("separator", ""), str):
+    def unpack_separator(self, kwargs: T.Dict[str, T.Any]) -> str:
+        separator = kwargs.get('separator', os.pathsep)
+        if not isinstance(separator, str):
             raise InterpreterException("EnvironmentVariablesHolder methods 'separator'"
                                        " argument needs to be a string.")
-        if len(args) < 2:
-            raise InterpreterException("EnvironmentVariablesHolder methods require at least"
-                                       "2 arguments, first is the name of the variable and"
-                                       " following one are values")
+        return separator
+
+    def warn_if_has_name(self, name: str) -> None:
         # Warn when someone tries to use append() or prepend() on an env var
         # which already has an operation set on it. People seem to think that
         # multiple append/prepend operations stack, but they don't.
-        if method != self.held_object.set and self.held_object.has_name(args[0]):
-            mlog.warning('Overriding previous value of environment variable {!r} with a new one'
-                         .format(args[0]), location=self.current_node)
-        self.held_object.add_var(method, args[0], args[1:], kwargs)
+        if self.held_object.has_name(name):
+            mlog.warning(f'Overriding previous value of environment variable {name!r} with a new one',
+                         location=self.current_node)
 
     @stringArgs
     @permittedKwargs({'separator'})
-    def set_method(self, args, kwargs):
-        self.add_var(self.held_object.set, args, kwargs)
+    @typed_pos_args('environment.set', str, varargs=str, min_varargs=1)
+    def set_method(self, args: T.Tuple[str, T.List[str]], kwargs: T.Dict[str, T.Any]) -> None:
+        name, values = args
+        separator = self.unpack_separator(kwargs)
+        self.held_object.set(name, values, separator)
 
     @stringArgs
     @permittedKwargs({'separator'})
-    def append_method(self, args, kwargs):
-        self.add_var(self.held_object.append, args, kwargs)
+    @typed_pos_args('environment.append', str, varargs=str, min_varargs=1)
+    def append_method(self, args: T.Tuple[str, T.List[str]], kwargs: T.Dict[str, T.Any]) -> None:
+        name, values = args
+        separator = self.unpack_separator(kwargs)
+        self.warn_if_has_name(name)
+        self.held_object.append(name, values, separator)
 
     @stringArgs
     @permittedKwargs({'separator'})
-    def prepend_method(self, args, kwargs):
-        self.add_var(self.held_object.prepend, args, kwargs)
+    @typed_pos_args('environment.prepend', str, varargs=str, min_varargs=1)
+    def prepend_method(self, args: T.Tuple[str, T.List[str]], kwargs: T.Dict[str, T.Any]) -> None:
+        name, values = args
+        separator = self.unpack_separator(kwargs)
+        self.warn_if_has_name(name)
+        self.held_object.prepend(name, values, separator)
 
 
 class ConfigurationDataHolder(MutableInterpreterObject, ObjectHolder[build.ConfigurationData]):