Some sort of elif implementation.

interpreter.py

@@ -793,6 +793,7 @@ class Interpreter():
         if node is None:
             return
         if not isinstance(node, nodes.CodeBlock):
+            print(node)
             e = InvalidCode('Tried to execute a non-codeblock. Possibly a bug in the parser.')
             e.lineno = node.lineno()
             raise e
@@ -1196,22 +1197,44 @@ class Interpreter():
         return obj.method_call(method_name, args, kwargs)
     
     def evaluate_if(self, node):
-        result = self.evaluate_statement(node.get_clause())
+        result = self.evaluate_statement(node.clause)
         cond = None
         if isinstance(result, nodes.BoolExpression) or \
            isinstance(result, nodes.BoolStatement):
             cond = result.get_value()
         if isinstance(result, bool):
             cond = result
-        
         if cond is not None:
             if cond:
-                self.evaluate_codeblock(node.get_trueblock())
+                self.evaluate_codeblock(node.trueblock)
             else:
-                self.evaluate_codeblock(node.get_falseblock())
+                block = node.falseblock
+                if isinstance(block, nodes.ElifStatement):
+                    self.evaluate_elif(block)
+                else:
+                    self.evaluate_codeblock(block)
         else:
             raise InvalidCode('If clause does not evaluate to true or false.')
-    
+
+    def evaluate_elif(self, node):
+        result = self.evaluate_statement(node.clause)
+        cond = None
+        if isinstance(result, nodes.BoolExpression) or \
+           isinstance(result, nodes.BoolStatement):
+            cond = result.get_value()
+        if isinstance(result, bool):
+            cond = result
+        if cond is not None:
+            if cond:
+                self.evaluate_codeblock(node.trueblock)
+            else:
+                block = node.elseblock
+                if isinstance(block, nodes.ElifStatement):
+                    self.evaluate_elif(block)
+                self.evaluate_codeblock(block)
+        else:
+            raise InvalidCode('Elif clause does not evaluate to true or false.')
+
     def is_elementary_type(self, v):
         if isinstance(v, int) or isinstance(v, str) or isinstance(v, bool):
             return True

meson.py

@@ -129,6 +129,7 @@ if __name__ == '__main__':
         else:
             this_file = resolved 
     app = MesonApp(dir1, dir2, this_file, options)
+    app.generate()
     try:
         app.generate()
     except Exception as e:

mparser.py

@@ -26,6 +26,7 @@ reserved = {'true' : 'TRUE',
             'false' : 'FALSE',
             'if' : 'IF',
             'endif' : 'ENDIF',
+            'elif' : 'ELIF',
             'else' : 'ELSE',
             'and' : 'AND',
             'or' : 'OR',
@@ -205,6 +206,10 @@ def p_statement_not(t):
     'statement : NOT statement'
     t[0] = nodes.NotStatement(t[2])
 
+def p_statement_elif(t):
+    'elseblock : ELIF statement EOL codeblock elseblock'
+    t[0] = nodes.ElifStatement(t[2], t[4], t[5], t.lineno(1))
+
 def p_empty_else(t):
     'elseblock : '
     return None

nodes.py

@@ -106,6 +106,13 @@ class IfStatement(Statement):
         self.trueblock = trueblock
         self.falseblock = falseblock
 
+class ElifStatement(Statement):
+    def __init__(self, clause, trueblock, elseblock, lineno):
+        Statement.__init__(self, lineno)
+        self.clause = clause
+        self.trueblock = trueblock
+        self.elseblock = elseblock
+
     def get_clause(self):
         return self.clause