optimize variable assignments

Except for set_variable(), the variable name is certainly an identifier because it
comes from the parser; thus, the check is unnecessary.  Move the regular expression
match to func_set_variable().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 6 insertions, 3 deletions

diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 4933ba65a..4a878e54d 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -3520,6 +3520,8 @@ class Interpreter(InterpreterBase, HoldableObject):
     @noSecondLevelHolderResolving
     def func_set_variable(self, node: mparser.BaseNode, args: T.Tuple[str, object], kwargs: 'TYPE_kwargs') -> None:
         varname, value = args
+        if mparser.IDENT_RE.fullmatch(varname) is None:
+            raise InvalidCode('Invalid variable name: ' + varname)
         self.set_variable(varname, value, holderify=True)
 
     @typed_pos_args('get_variable', (str, Disabler), optargs=[object])
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index 5f9df4cb5..5849e9ca9 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -655,8 +655,6 @@ class InterpreterBase:
                 raise mesonlib.MesonBugException(f'set_variable in InterpreterBase called with a non InterpreterObject {variable} of type {type(variable).__name__}')
         if not isinstance(varname, str):
             raise InvalidCode('First argument to set_variable must be a string.')
-        if re.match('[_a-zA-Z][_0-9a-zA-Z]*$', varname) is None:
-            raise InvalidCode('Invalid variable name: ' + varname)
         if varname in self.builtin:
             raise InvalidCode(f'Tried to overwrite internal variable "{varname}"')
         self.variables[varname] = variable
diff --git a/mesonbuild/mparser.py b/mesonbuild/mparser.py
index 4f4345546..0ffaceb7c 100644
--- a/mesonbuild/mparser.py
+++ b/mesonbuild/mparser.py
@@ -94,6 +94,9 @@ class Token(T.Generic[TV_TokenTypes]):
             return self.tid == other.tid
         return NotImplemented
 
+
+IDENT_RE = re.compile('[_a-zA-Z][_0-9a-zA-Z]*')
+
 class Lexer:
     def __init__(self, code: str):
         if code.startswith(codecs.BOM_UTF8.decode('utf-8')):
@@ -113,7 +116,7 @@ class Lexer:
             ('whitespace', re.compile(r'[ \t]+')),
             ('multiline_fstring', re.compile(r"f'''(.|\n)*?'''", re.M)),
             ('fstring', re.compile(r"f'([^'\\]|(\\.))*'")),
-            ('id', re.compile('[_a-zA-Z][_0-9a-zA-Z]*')),
+            ('id', IDENT_RE),
             ('number', re.compile(r'0[bB][01]+|0[oO][0-7]+|0[xX][0-9a-fA-F]+|0|[1-9]\d*')),
             ('eol_cont', re.compile(r'\\[ \t]*(#.*)?\n')),
             ('eol', re.compile(r'\n')),