refactor logic for parsing dependency variables into type_checking module

We will momentarily use this to implement typed_kwargs, but not for all
usage sites.

2 files changed, 41 insertions, 12 deletions

diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 5cadf52..07afdce 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -77,6 +77,8 @@ from .type_checking import (
     REQUIRED_KW,
     NoneType,
     in_set_validator,
+    variables_validator,
+    variables_convertor,
     env_convertor_with_method
 )
 from . import primitives as P_OBJ
@@ -633,23 +635,19 @@ class Interpreter(InterpreterBase, HoldableObject):
             if dict_new and variables:
                 FeatureNew.single_use(f'{argname} as dictionary', '0.56.0', self.subproject, location=self.current_node)
         else:
-            varlist = mesonlib.stringlistify(variables)
+            variables = mesonlib.stringlistify(variables)
             if list_new:
                 FeatureNew.single_use(f'{argname} as list of strings', '0.56.0', self.subproject, location=self.current_node)
-            variables = {}
-            for v in varlist:
-                try:
-                    (key, value) = v.split('=', 1)
-                except ValueError:
-                    raise InterpreterException(f'Variable {v!r} must have a value separated by equals sign.')
-                variables[key.strip()] = value.strip()
+
+        invalid_msg = variables_validator(variables)
+        if invalid_msg is not None:
+            raise InterpreterException(invalid_msg)
+
+        variables = variables_convertor(variables)
         for k, v in variables.items():
-            if not k or not v:
-                raise InterpreterException('Empty variable name or value')
-            if any(c.isspace() for c in k):
-                raise InterpreterException(f'Invalid whitespace in variable name "{k}"')
             if not isinstance(v, str):
                 raise InterpreterException('variables values must be strings.')
+
         return variables
 
     @FeatureNewKwargs('declare_dependency', '0.46.0', ['link_whole'])
diff --git a/mesonbuild/interpreter/type_checking.py b/mesonbuild/interpreter/type_checking.py
index ec23f36..864153c 100644
--- a/mesonbuild/interpreter/type_checking.py
+++ b/mesonbuild/interpreter/type_checking.py
@@ -107,6 +107,37 @@ def _lower_strlist(input: T.List[str]) -> T.List[str]:
     return [i.lower() for i in input]
 
 
+def variables_validator(contents: T.Union[T.List[str], T.Dict[str, str]]) -> T.Optional[str]:
+    if isinstance(contents, dict):
+        variables = contents
+    else:
+        variables = {}
+        for v in contents:
+            try:
+                key, val = v.split('=', 1)
+            except ValueError:
+                return f'variable {v!r} must have a value separated by equals sign.'
+            variables[key.strip()] = val.strip()
+    for k, v in variables.items():
+        if not k:
+            return 'empty variable name'
+        if not v:
+            return 'empty variable value'
+        if any(c.isspace() for c in k):
+            return f'invalid whitespace in variable name {k!r}'
+    return None
+
+
+def variables_convertor(contents: T.Union[T.List[str], T.Dict[str, str]]) -> T.Dict[str, str]:
+    if isinstance(contents, dict):
+        return contents
+    variables = {}
+    for v in contents:
+        key, val = v.split('=', 1)
+        variables[key.strip()] = val.strip()
+    return variables
+
+
 NATIVE_KW = KwargInfo(
     'native', bool,
     default=False,