niti: introduce `read_variable` and `write_variable`

So the internal map is no more acceded directly, thus opening the door to
a more efficient implementation.

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/interpreter/naive_interpreter.nit b/src/interpreter/naive_interpreter.nit
index 5b79f0c..6c65469 100644 (file)
--- a/src/interpreter/naive_interpreter.nit
+++ b/src/interpreter/naive_interpreter.nit
@@ -293,6 +293,20 @@ private class NaiveInterpreter
                end
        end
 
+       # Retrieve the value of the variable in the current frame
+       fun read_variable(v: Variable): Instance
+       do
+               var f = frames.first
+               return f.map[v]
+       end
+
+       # Assign the value of the variable in the current frame
+       fun write_variable(v: Variable, value: Instance)
+       do
+               var f = frames.first
+               f.map[v] = value
+       end
+
        # Store known method, used to trace methods as thez are reached
        var discover_call_trace: Set[MMethodDef] = new HashSet[MMethodDef]
 
@@ -599,9 +613,9 @@ private class Frame
        # The executed property.
        # A Method in case of a call, an attribute in case of a default initialization.
        var mpropdef: MPropDef
-       # Arguments of the method (the first is te receiver
+       # Arguments of the method (the first is the receiver)
        var arguments: Array[Instance]
-       # Mapping betwen a variable an the current value
+       # Mapping between a variable and the current value
        var map: Map[Variable, Instance] = new HashMap[Variable, Instance]
 end
 
@@ -649,14 +663,14 @@ redef class AMethPropdef
 
        private fun call_commons(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance], f: Frame): nullable Instance
        do
+               v.frames.unshift(f)
+
                for i in [0..mpropdef.msignature.arity[ do
                        var variable = self.n_signature.n_params[i].variable
                        assert variable != null
-                       f.map[variable] = arguments[i+1]
+                       v.write_variable(variable, arguments[i+1])
                end
 
-               v.frames.unshift(f)
-
                if mpropdef.is_abstract then
                        v.fatal("Abstract method `{mpropdef.mproperty.name}` called on `{arguments.first.mtype}`")
                        abort
@@ -1158,7 +1172,7 @@ redef class AVardeclExpr
                if ne != null then
                        var i = v.expr(ne)
                        if i == null then return
-                       v.frame.map[self.variable.as(not null)] = i
+                       v.write_variable(self.variable.as(not null), i)
                end
        end
 end
@@ -1166,7 +1180,7 @@ end
 redef class AVarExpr
        redef fun expr(v)
        do
-               return v.frame.map[self.variable.as(not null)]
+               return v.read_variable(self.variable.as(not null))
        end
 end
 
@@ -1175,7 +1189,7 @@ redef class AVarAssignExpr
        do
                var i = v.expr(self.n_value)
                if i == null then return null
-               v.frame.map[self.variable.as(not null)] = i
+               v.write_variable(self.variable.as(not null), i)
                return i
        end
 end
@@ -1183,12 +1197,13 @@ end
 redef class AVarReassignExpr
        redef fun stmt(v)
        do
-               var vari = v.frame.map[self.variable.as(not null)]
+               var variable = self.variable.as(not null)
+               var vari = v.read_variable(variable)
                var value = v.expr(self.n_value)
                if value == null then return
                var res = v.callsite(reassign_callsite, [vari, value])
                assert res != null
-               v.frame.map[self.variable.as(not null)] = res
+               v.write_variable(variable, res)
        end
 end
 
@@ -1334,12 +1349,12 @@ redef class AForExpr
                        if self.variables.length == 1 then
                                var item = v.callsite(method_item, [iter]).as(not null)
                                #self.debug("item {item}")
-                               v.frame.map[self.variables.first] = item
+                               v.write_variable(self.variables.first, item)
                        else if self.variables.length == 2 then
                                var key = v.callsite(method_key, [iter]).as(not null)
-                               v.frame.map[self.variables[0]] = key
+                               v.write_variable(self.variables[0], key)
                                var item = v.callsite(method_item, [iter]).as(not null)
-                               v.frame.map[self.variables[1]] = item
+                               v.write_variable(self.variables[1], item)
                        else
                                abort
                        end