diff --git a/interpreter/NassiShneidermann.py b/interpreter/NassiShneidermann.py
index d3d6882..fc21424 100644
--- a/interpreter/NassiShneidermann.py
+++ b/interpreter/NassiShneidermann.py
@@ -40,9 +40,8 @@ class NassiShneidermanDiagram:
         cti.NSD_save(filename)
 
     def load_from_file(self, filepath:str):
-        src_code = itp.load_src(filepath)
-        global_scope = itp.get_instructions_in_scope(src_code)[0]
-        self.add_instructions_from_scope(global_scope)
+        instructions = itp.load_instructions(filepath)
+        self.add_instructions_from_scope(instructions)
 
     def add_instructions_from_scope(self, scope: List[Iinstruction]):
         for inst in scope:
diff --git a/interpreter/interpret_source.py b/interpreter/interpret_source.py
index e64e0a7..dadc40a 100644
--- a/interpreter/interpret_source.py
+++ b/interpreter/interpret_source.py
@@ -1,17 +1,12 @@
 import logging
 from os import remove
 import re
-from typing import List, Text, Tuple
+from typing import Callable, List, Tuple
 
 from draw.Iinstruction import *
 
-COMMENT_REGEX = r"""^//|^#|^COMMENT|^--"""
-REMOVE_KEYWORDS = [' ', "public", "private", "void"]
-
-WHILE_TAG = "solange " #german for 'while'. Change this depending on your language
-
-REPLACE = dict((re.escape(k), '') for k in REMOVE_KEYWORDS)
-remove_pattern = re.compile("|".join(REPLACE.keys()))
+class InterpreterError(Exception):
+    pass
 
 class JavaSyntaxError(Exception):
     pass
@@ -19,6 +14,14 @@ class JavaSyntaxError(Exception):
 class ScopeNotFoundException(Exception):
     pass
 
+COMMENT_REGEX = r"""^//|^#|^COMMENT|^--"""
+REMOVE_KEYWORDS = [' ', "public", "private", "void", ';']
+
+WHILE_TAG = "solange " #german for 'while'. Change this depending on your language
+
+REPLACE = dict((re.escape(k), '') for k in REMOVE_KEYWORDS)
+remove_pattern = re.compile("|".join(REPLACE.keys()))
+
 def replace_all_tags(org: str):
     return remove_pattern.sub(lambda m: REPLACE[re.escape(m.group(0))], org)
 
@@ -43,80 +46,126 @@ def load_src(filepath: str) -> List[str]:
     
     return lines
 
+def check_src(src: List[str], line_index: int, tag: str) -> bool:
+    if line_index >= len(src):
+        return False
+    return src[line_index].__contains__(tag)
+
+def check_line_start(src: List[str], line_index: int, tag: str) -> bool:
+    if line_index >= len(src):
+        return False
+    return src[line_index].startswith(tag)
+
 def get_next_occurence_of(src: List[str], start_idx:int, tag:str) -> int:
+    """Returns the index of the next occurence of tag in src from start_idx"""
     i = start_idx
     while i < len(src):
-        if src[i].__contains__(tag):
-            return i
+        if check_src(src, i, tag):
+            break
         i += 1
+    return i
 
-def get_scope_start_offset(src: List[str], start_idx: int) -> int:
-    i = get_next_occurence_of(src, start_idx, '{')
-    if i != len(src):
-        return i + 1
+def get_scope_start_offset(src: List[str], i: int) -> int:
+    if check_src(src, i, "{"):
+        return 1
+    elif check_src(src, i+1, "{"):
+        return 2
     raise ScopeNotFoundException("Unable to find scope start. Is the program ill-formed?")
 
+def handle_while(line: str, src: List[str], i: int) -> Tuple[Iinstruction, int]:
+    bracket_idx = line.rindex(')') # throws if while contruct is illformed
+
+    instruction_txt = line[6:bracket_idx]
+    brace_offset = get_scope_start_offset(src, i)
+    child_instructions, i = get_instructions_in_scope(src, i+brace_offset)
+    return while_instruction_front((WHILE_TAG + instruction_txt), child_instructions), i
+
+def handle_else(src: List[str], i: int) -> Tuple[List[Iinstruction], int]:
+    brace_offset = get_scope_start_offset(src, i)
+    return get_instructions_in_scope(src, i+brace_offset)
+
+def handle_if(line: str, src: List[str], i: int) -> Tuple[Iinstruction, int]:
+    bracket_idx = line.rindex(')') # throws if the contruct is illformed
+    instruction_txt = line[3:bracket_idx]
+
+    brace_offset = get_scope_start_offset(src, i)
+    true_instructions, i = get_instructions_in_scope(src, i+brace_offset)
+
+    false_instructions = None
+
+    #check for else statements
+    if check_line_start(src, i, "}else"):
+        logging.debug("found else construct in line: %i", i+1)
+        false_instructions, i = handle_else(src, i)
+    
+    elif check_line_start(src, i+1, "else"):
+        logging.debug("found else construct in line: %i", i+2)
+        false_instructions, i = handle_else(src, i+1)
+    
+    return if_instruction(instruction_txt, true_instructions, false_instructions), i
+
+def handle_do_while(line: str, src: List[str], i: int) -> Tuple[Iinstruction, int]:
+    brace_offset = get_scope_start_offset(src, i)
+    child_instructions, i = get_instructions_in_scope(src, i+brace_offset)
+
+    instruction_txt = None
+    if check_line_start(src, i, "}while("):
+        end_line = src[i]
+        bracket_index = end_line.rindex(')') #throws if contruct id ill-formed
+        instruction_txt = end_line[7:bracket_index]
+    elif check_line_start(src, i+1, "while("):
+        i += 1 #make sure we return the correct value for i
+        end_line = src[i]
+        bracket_index = end_line.rindex(')')
+        instruction_txt = end_line[6:bracket_index]
+    else:
+        raise JavaSyntaxError("Ill-formed do-while construct!")
+
+    return while_instruction_back(instruction_txt, child_instructions), i
+
+def handle_instruction(line: str, src: List[str], i: int) -> Tuple[Iinstruction, int]:
+    if line.startswith("while("):
+        logging.debug("Found while construct in line: %i", i+1)
+        return handle_while(line, src, i)
+    
+    elif line.startswith("if("):
+        logging.debug("Found if construct in line: %i", i+1)
+        return handle_if(line, src, i)
+
+    elif line.startswith("do"):
+        logging.debug("Found do-while construct in line: %i", i+1)
+        return handle_do_while(line, src, i)
+    
+    else:
+        logging.debug("found generic instruction in line %i", i+1)
+        return generic_instruction(line), i
 
 def get_instructions_in_scope(src: List[str], start_idx: int = 0) -> Tuple[List[Iinstruction], int]:
     outer_scope: List[Iinstruction] = []
     i = start_idx
     while i < len(src):
+
         line = src[i]
         try:
-            if line.__contains__('}'): #We exited this scope, return it
-                return outer_scope, i
+            if check_src(src, i, "}"): #We exited this scope, return it
+                break
+
+            instruction, i = handle_instruction(line, src, i)
+            outer_scope.append(instruction)
             
-            if line.startswith("while("):
-                logging.debug("Found while construct in line: %i", i+1)
-
-                bracket_idx = line.rindex(')') # throws if while contruct is illformed
-
-                instruction_txt = line[6:bracket_idx]
-                brace_offset = get_scope_start_offset(src, i)
-                child_instructions, i = get_instructions_in_scope(src, i+brace_offset)
-
-                outer_scope.append(while_instruction_front((WHILE_TAG + instruction_txt), child_instructions))
-            
-            elif line.startswith("if("):
-                logging.debug("Found if construct in line: %i", i+1)
-
-                bracket_idx = line.rindex(')') # throws if the contruct is illformed
-
-                instruction_txt = line[3:bracket_idx]
-                brace_offset = get_scope_start_offset(src, i)
-                true_instructions, i = get_instructions_in_scope(src, i+brace_offset)
-
-                false_instructions = None
-                #if there is an else statement, check it
-                if src[i].__contains__("else"):
-                    logging.debug("found else construct in line: %i", i+1)
-                    brace_offset = get_scope_start_offset(src, i)
-                    false_instructions, i = get_instructions_in_scope(src, i+brace_offset)
-                elif src[i+1].__contains__("else"):
-                    logging.debug("found else construct in line: %i", i+2)
-                    brace_offset = get_scope_start_offset(src, i+1)
-                    false_instructions, i = get_instructions_in_scope(src, i+1+brace_offset)
-
-                
-                outer_scope.append(if_instruction(instruction_txt, true_instructions, false_instructions))
-
-            elif line.startswith("do"):
-                logging.debug("Found start of do-while construct in line: %i", i+1)
-
-                brace_offset = get_scope_start_offset(src, i)
-                child_instructions, i = get_instructions_in_scope(src, i+brace_offset)
-
-                end_line = src[i]
-                bracket_idx = end_line.rindex(");")
-                instruction_txt = end_line[7: bracket_idx]
-
-                outer_scope.append(while_instruction_back((WHILE_TAG + instruction_txt), child_instructions))
-            
-            else:
-                logging.debug("Found generic instruction in line: %i", i+1)
-                outer_scope.append(generic_instruction(line))
+        except Exception as e:
+            logging.error("Encountered error in line %i: %s", i+1, str(e))
+            raise
         except:
-            logging.error("Encountered error in line: %i", i+1)
-            raise # rethrow
+            logging.fatal("Encountered unexpected error in line: %i", i+1)
+            raise
         i += 1
-    return outer_scope, 0
\ No newline at end of file
+    
+    return outer_scope, i
+
+def load_instructions(filepath: str) -> List[Iinstruction]:
+    src = load_src(filepath)
+    instructions, i = get_instructions_in_scope(src)
+    if i != len(src):
+        raise InterpreterError("Unknown error during source interpretation! Unsupported language constructs or ill-formed?")
+    return instructions
\ No newline at end of file
diff --git a/res/input/input.java b/res/input/input.java
index e4c4f8a..ee6e2ac 100644
--- a/res/input/input.java
+++ b/res/input/input.java
@@ -1,138 +1,74 @@
-// // fahre1();
-// // fahre2();
-// // while(shouldNiet())
-
-
-// // {
-// //     niet4();
-// //     niet5();
-// //     if(if6)
-// //     {
-// //         niet7();
-// //         niet8();
-// //     } else
-// //     {
-// //         niet10();
-// //         niet11();
-// //     }
-// //     niet13();
-// // }
-// // niet15();
-// // niet16();
-
-// // do{
-// //     niet21();
-// //     niet22();
-// // }while(bool23);
-
-// //the following code was heavily distorted in order to test the interpreter. Sorry to everyone who has to read this
-
-// void
-
-// private void
-
-
-
-// drehe("links");
-// while(huegelVorhanden("rechts"))
-// {
-//                     gesteinSammeln();
-//     fahre();
-
-
-
-
-
-// }
-// drehe("rechts");
-    
-    
-    
-    
-//     gesteinSammeln();
-
-
-
-// fahre();
-
-
-//                     while(huegelVorhanden("rechts"))
-// {
-//                     gesteinSammeln();
-//     fahre();
-// }
-// drehe("rechts");
-
-        
-            
-                
-                
-                    
-                    
-//                         gesteinSammeln();
-// fahre();
-
-
-
-
-
-//                 while(huegelVorhanden("rechts"))
-// {
-//     gesteinSammeln();
-//     if(!huegelVorhanden("vorne"))
-                
-                
-                
-//                         {
-
-
-
-
-
-
-//         fahre();
-//     }     
-//     else 
-
-
-//     {
-//         fahre();
-//     }
-// }
-
-
-
-
-
-
-
-
-//                         drehe("rechts");
-
-// do
-
-
-
-
-// {
-//                     insideDoWhile();
-//     insideDoWhile();
-    
-    
-//     insideDoWhile();
-
-
-
-//     insideDoWhile();
-// }
-// while(               !huegelVorhanden(    "vorne"     )      )       ;
-
-if(bool) {
+beforeIf();
+if(if_condition1) {
     true_case;
     true_case;
-} 
+}
+afterIf();
+beforeIf();
+if(if_condition2)
+{
+    true_case;
+    true_case;
+}
+afterIf();
+beforeIf();
+if(if_else_condition1) {
+    true_case;
+    true_case;
+} else {
+    false_case;
+    false_case;
+}
+afterIf();
+beforeIf();
+if(if_else_condition2) {
+    true_case;
+    true_case;
+}
+else {
+    false_case;
+    false_case;
+}
+afterIf();
+beforeIf();
+if(if_else_condition3) {
+    true_case;
+    true_case;
+}
 else
 {
     false_case;
     false_case;
-}
\ No newline at end of file
+}
+afterIf();
+beforeWhile();
+while(while_condition1) {
+    insideWhile;
+    insideWhile;
+}
+beforeWhile();
+while(while_condition2)
+{
+    insideWhile;
+    insideWhile;
+}
+beforeDoWhile();
+do{
+    insideDoWhile;
+    insideDoWhile;
+}while(do_while_condition1);
+beforeDoWhile();
+do
+{
+    insideDoWhile;
+    insideDoWhile;
+}while(do_while_condition2);
+beforeDoWhile();
+do
+{
+    insideDoWhile;
+    insideDoWhile;
+}
+while(do_while_condition3)
+
+//since the interpreter ignores all empty lines and spaces, any changes in tabs *should* not have any effect
\ No newline at end of file