[core/vm] Simplify _Callable.Call() signature (#1719)

This will help us produce better errors in the future.

core/code.py

@@ -11,9 +11,10 @@
 from core.error import e_die
 from core import state
 from core import vm
+from frontend import typed_args
 from mycpp.mylib import log
 
-from typing import List, Dict, cast, TYPE_CHECKING
+from typing import List, cast, TYPE_CHECKING
 if TYPE_CHECKING:
     from _devbuild.gen.syntax_asdl import command, loc_t
     from _devbuild.gen.runtime_asdl import Proc
@@ -33,8 +34,9 @@ def __init__(self, name, node, mem, cmd_ev):
         self.cmd_ev = cmd_ev
         self.mem = mem
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
+        pos_args = args.RestPos()
         num_args = len(pos_args)
         num_params = len(self.node.pos_params)
 
@@ -53,6 +55,8 @@ def Call(self, pos_args, named_args):
                 "%s() expects %d arguments but %d were given" %
                 (self.name, num_params, num_args), blame_loc)
 
+        named_args = args.RestNamed()
+        args.Done()
         num_args = len(named_args)
         num_params = len(self.node.named_params)
         if num_args != num_params:

core/vm.py

@@ -8,10 +8,11 @@
 from core import pyos
 from mycpp.mylib import log
 
-from typing import Dict, List, Any, TYPE_CHECKING
+from typing import List, Any, TYPE_CHECKING
 if TYPE_CHECKING:
     from _devbuild.gen.runtime_asdl import cmd_value, RedirValue, value_t
     from _devbuild.gen.syntax_asdl import (command, command_t, CommandSub)
+    from frontend import typed_args
     from osh import sh_expr_eval
     from osh.sh_expr_eval import ArithEvaluator
     from osh.sh_expr_eval import BoolEvaluator
@@ -259,8 +260,8 @@ def __init__(self):
         """Empty constructor for mycpp."""
         pass
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
         raise NotImplementedError()
 
 

frontend/typed_args.py

@@ -125,6 +125,10 @@ def PosValue(self):
         # type: () -> value_t
         return self._GetNextPos()
 
+    def NumPos(self):
+        # type: () -> int
+        return len(self.pos_args)
+
     def RestPos(self):
         # type: () -> List[value_t]
         ret = self.pos_args

library/func_eggex.py

@@ -23,13 +23,12 @@ def __init__(self, mem):
         vm._Callable.__init__(self)
         self.mem = mem
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
-        r = typed_args.Reader(pos_args, named_args)
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
         arg = 0
-        if len(pos_args):
-            arg = r.PosInt()
-            r.Done()
+        if args.NumPos():
+            arg = args.PosInt()
+            args.Done()
 
         # TODO: Support strings
         s = self.mem.GetMatch(arg)
@@ -50,8 +49,8 @@ def __init__(self, mem):
         vm._Callable.__init__(self)
         self.mem = mem
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
         raise NotImplementedError('_start')
 
 
@@ -63,8 +62,8 @@ def __init__(self, mem):
         vm._Callable.__init__(self)
         self.mem = mem
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
         raise NotImplementedError('_end')
 
 

library/func_hay.py

@@ -67,12 +67,11 @@ def _Call(self, path):
         # Wrap in expr.Block?
         return value.Block(node)
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
 
-        r = typed_args.Reader(pos_args, named_args)
-        string = r.PosStr()
-        r.Done()
+        string = args.PosStr()
+        args.Done()
         return self._Call(string)
 
 
@@ -98,12 +97,11 @@ def _Call(self, cmd):
         # Note: we should discourage the unvalidated top namespace for files?  It
         # needs more validation.
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
 
-        r = typed_args.Reader(pos_args, named_args)
-        cmd = r.PosCommand()
-        r.Done()
+        cmd = args.PosCommand()
+        args.Done()
         return value.Dict(self._Call(cmd))
 
 
@@ -123,9 +121,11 @@ def _Call(self, block):
         # type: (value_t) -> value_t
         return block
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
-        return self._Call(pos_args[0])
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
+        val = args.PosValue()
+        args.Done()
+        return self._Call(val)
 
 
 class HayFunc(vm._Callable):
@@ -139,8 +139,8 @@ def _Call(self):
         # type: () -> Dict[str, value_t]
         return self.hay_state.HayRegister()
 
-    def Call(self, pos_args, named_args):
-        # type: (List[value_t], Dict[str, value_t]) -> value_t
+    def Call(self, args):
+        # type: (typed_args.Reader) -> value_t
 
         # TODO: check args
         return value.Dict(self._Call())