forward modifier on location expression, instead of assign.

HISTORY.md

@@ -5,7 +5,8 @@ History of SixtyPical
 ----
 
 *   Can `call` and `goto` routines that are defined further down in the source code.
-*   `assign`, a form of `copy` that can copy (to a vector) a routine that is defined further down.
+*   The `forward` modifier can also be used to indicate that the symbol being copied
+    in a `copy` to a vector is a routine that is defined further down in the source.
 
 0.9
 ---

src/sixtypical/parser.py

@@ -64,14 +64,13 @@ class Parser(object):
                 if not isinstance(self.symbols[name].model.type, ExecutableType):
                     raise SyntaxError('Illegal call of non-executable "%s"' % name)
                 instr.location = self.symbols[name].model
-            if instr.opcode in ('assign',):
+            if instr.opcode in ('copy',) and isinstance(instr.src, basestring):
                 name = instr.src
                 if name not in self.symbols:
                     raise SyntaxError('Undefined routine "%s"' % name)
                 if not isinstance(self.symbols[name].model.type, ExecutableType):
-                    raise SyntaxError('Illegal assign of non-executable "%s"' % name)
+                    raise SyntaxError('Illegal copy of non-executable "%s"' % name)
                 instr.src = self.symbols[name].model
-                instr.opcode = 'copy'
 
         return Program(defns=defns, routines=routines)
 
@@ -205,7 +204,9 @@ class Parser(object):
             return loc
 
     def indlocexpr(self):
-        if self.scanner.consume('['):
+        if self.scanner.consume('forward'):
+            return self.label()
+        elif self.scanner.consume('['):
             loc = self.locexpr()
             self.scanner.expect(']')
             self.scanner.expect('+')
@@ -293,13 +294,6 @@ class Parser(object):
             src = self.indlocexpr()
             self.scanner.expect(',')
             dest = self.indlocexpr()
-            return Instr(opcode=opcode, dest=dest, src=src)
-        elif self.scanner.token == 'assign':
-            opcode = self.scanner.token
-            self.scanner.scan()
-            src = self.label()
-            self.scanner.expect(',')
-            dest = self.indlocexpr()
             instr = Instr(opcode=opcode, dest=dest, src=src)
             self.backpatch_instrs.append(instr)
             return instr

tests/SixtyPical Syntax.md

@@ -356,20 +356,25 @@ A vector can name itself in its inputs, outputs, and trashes.
     | }
     = ok
 
-A routine can be copied into a vector before the routine appears in the program.
-*However*, in order to do this currently, one needs to use the special opcode
-form `assign`, which is equivalent to `copy` except that the routine need not
-have already appeared in the program.
+A routine can be copied into a vector before the routine appears in the program,
+*however*, it must be marked as such with the keyword `forward`.
 
-    | vector cinv
-    |   inputs cinv, a
-    |   outputs cinv, x
-    |   trashes a, x, z, n
-    |   @ 788
-    | 
+    | vector cinv   inputs cinv, a   outputs cinv, x   trashes a, x, z, n @ 788
     | routine main {
     |     with interrupts off {
-    |         assign foo, cinv
+    |         copy foo, cinv
+    |     }
+    |     call cinv
+    | }
+    | routine foo {
+    |     ld a, 0
+    | }
+    ? SyntaxError: Undefined symbol
+
+    | vector cinv   inputs cinv, a   outputs cinv, x   trashes a, x, z, n @ 788
+    | routine main {
+    |     with interrupts off {
+    |         copy forward foo, cinv
     |     }
     |     call cinv
     | }