Begin introducing shortcut syntax for nested saves.

src/sixtypical/analyzer.py

@@ -771,17 +771,21 @@ class Analyzer(object):
         context.set_writeable(instr.dest)
 
     def analyze_save(self, instr, context):
-        if len(instr.locations) != 1:
-            raise NotImplementedError("Only 1 location in save is supported right now")
-        location = instr.locations[0]
-        self.assert_type(TYPE_BYTE, location)
+        batons = []
+        for location in instr.locations:
+            self.assert_type(TYPE_BYTE, location)
+            baton = context.extract(location)
+            batons.append(baton)
 
-        baton = context.extract(location)
         self.analyze_block(instr.block, context)
         if context.encountered_gotos():
             raise IllegalJumpError(instr, instr)
-        context.re_introduce(baton)
 
+        for location in reversed(instr.locations):
+            baton = batons.pop()
+            context.re_introduce(baton)
+
+        # FIXME check if A needs to be the outer thing that is saved, I think it does.
         if location == REG_A:
             pass
         else:

tests/SixtyPical Analysis.md

@@ -2107,6 +2107,20 @@ first in a nested series of `save`s.
     | }
     = ok
 
+There is a shortcut syntax for a nested series of `save`s.
+
+    | routine main
+    |   inputs a
+    |   outputs a
+    |   trashes z, n
+    | {
+    |     save a, x {
+    |         ld a, 0
+    |         ld x, 1
+    |     }
+    | }
+    = ok
+
 Not just registers, but also user-defined locations can be saved.
 
     | byte foo

tests/SixtyPical Compilation.md

@@ -601,6 +601,28 @@ Compiling `save`.
     = $0816   PLA
     = $0817   RTS
 
+Compiling `save` with shortcut syntax.
+
+    | routine main
+    |   inputs a
+    |   outputs a
+    |   trashes z, n
+    | {
+    |     save a, x {
+    |         ld a, 0
+    |         ld x, 1
+    |     }
+    | }
+    = $080D   PHA
+    = $080E   TXA
+    = $080F   PHA
+    = $0810   LDA #$00
+    = $0812   LDX #$01
+    = $0814   PLA
+    = $0815   TAX
+    = $0816   PLA
+    = $0817   RTS
+
 Compiling `save` on a user-defined location.
 
     | byte foo