Added an utils file with basic implementation of some statement list classes.

src/utils.py

+import re
+
+class Statement:
+    def __init__(self, stype, name, *args):
+        self.stype = stype
+        self.name = name
+        self.args = args
+
+    def __getitem__(self, n):
+        """Get an argument."""
+        return self.args[n]
+
+    def jump_target(self, arg):
+        """Get the use[S] of this statement."""
+        if self.name in ['beq', 'bne', 'blez', 'bgtz', 'bltz', 'bgez', \
+                         'bct', 'bcf']:
+            return self[1]
+        else:
+            raise Exception('"%s" command has no jump target' % self.name)
+
+    def is_command(self):
+        """Check if the statement is a command."""
+        return self.stype == 'command'
+
+    def is_jump(self):
+        """Check if the statement is a jump."""
+        return self.is_command() and re.match('j|jal|jr|jalr', self.name)
+
+    def is_shift(self):
+        """Check if the statement is a shift operation."""
+        return self.is_command() and re.match('s(ll|la|rl|ra)', self.name
+
+    def is_load(self):
+        """Check if the statement is a load instruction."""
+        return self.is_command() and self.name in ['lw', 'dlw', 'l.s', 'l.d']
+
+    def is_arith(self):
+        """Check if the statement is an arithmetic operation."""
+        return self.is_command() \
+               and re.match('(add|sub|mult|div|abs|neg)(u|\.d)?', self.name)
+
+    def get_def(self):
+        """Get the def[S] of this statement."""
+        if not self.is_command():
+            return []
+
+        if self.is_load() or self.is_arith():
+            return [self[0]]
+
+        if self.arith():
+            return [self[0]]
+
+    def get_use(self, arg):
+        """Get the use[S] of this statement."""
+        return []
+
+    def defines(self, var):
+        """Check if a variable is defined by this statement."""
+        return var in self.get_def()
+
+    def uses(self, var):
+        """Check if a variable is used by this statement."""
+        return var in self.get_use()
+
+class StatementList:
+    def __init__(self, statement_list):
+        self.statement_list = statement_list
+        self.pointer = 0
+
+    def __getitem__(self, n):
+        return self.statement_list[n]
+
+    def __iter__(self):
+        return iter(self.statement_list)
+
+    def __len__(self):
+        return len(self.statement_list)
+
+    def get_range(self, start, end):
+        return self.statement_list[start:end]
+
+    def replace(self, start, end, replacement):
+        before = self.statement_list[:start]
+        after = self.statement_list[end:]
+        self.statement_list = before + replacement + after
+
+    def move_pointer(self, steps=1):
+        self.pointer += steps
+
+    def liveness(self, stype):
+        """Check if the statement is of a given type."""
+        return self.stype == stype
+
+
+while not block.end():
+    if (...):
+        i = block.current()
+        block.replace(i, i + 3, [nieuwe statements])
+        block.move_pointer(3)
+    else:
+        block.move_pointer(1)