Add breakpoint support and user conveniences to IEx

Author: josevalim

lib/elixir/lib/macro/env.ex

@@ -44,8 +44,9 @@ defmodule Macro.Env do
 
     * `export_vars` - a list keeping all variables to be exported in a
       construct (may be `nil`)
-    * `match_vars` - a list of variables defined in a given match (is
-      `nil` when not inside a match)
+    * `match_vars` - controls how "new" variables are handled. Inside a
+      match it is a list with all variables in a match. Outside of a match
+      is either `:warn` or `:apply`
     * `prematch_vars` - a list of variables defined before a match (is
       `nil` when not inside a match)
 
@@ -66,7 +67,7 @@ defmodule Macro.Env do
   @type local :: atom | nil
 
   @opaque export_vars :: vars | nil
-  @opaque match_vars :: vars | nil
+  @opaque match_vars :: vars | :warn | :apply
   @opaque prematch_vars :: vars | nil
 
   @type t :: %{__struct__: __MODULE__,
@@ -103,7 +104,7 @@ defmodule Macro.Env do
       vars: [],
       lexical_tracker: nil,
       export_vars: nil,
-      match_vars: nil,
+      match_vars: :warn,
       prematch_vars: nil}
   end
 

lib/elixir/src/elixir.erl

@@ -183,8 +183,14 @@ env_for_eval(Env, Opts) ->
     false -> nil
   end,
 
+  FA = case lists:keyfind(function, 1, Opts) of
+    {function, {Function, Arity}} when is_atom(Function), is_integer(Arity) -> {Function, Arity};
+    {function, nil} -> nil;
+    false -> nil
+  end,
+
   Env#{
-    file := File, module := Module,
+    file := File, module := Module, function := FA,
     macros := Macros, functions := Functions,
     requires := Requires, aliases := Aliases, line := Line
   }.

lib/elixir/src/elixir_clauses.erl

@@ -9,13 +9,13 @@
 
 match(Fun, Expr, #{context := match} = E) ->
   Fun(Expr, E);
-match(Fun, Expr, #{context := Context, match_vars := nil, prematch_vars := nil, vars := Vars} = E) ->
+match(Fun, Expr, #{context := Context, match_vars := Match, prematch_vars := nil, vars := Vars} = E) ->
   {EExpr, EE} = Fun(Expr, E#{context := match, match_vars := [], prematch_vars := Vars}),
-  {EExpr, EE#{context := Context, match_vars := nil, prematch_vars := nil}}.
+  {EExpr, EE#{context := Context, match_vars := Match, prematch_vars := nil}}.
 
-def({Meta, Args, Guards, Body}, E) ->
+def({Meta, Args, Guards, Body}, #{match_vars := Match} = E) ->
   {EArgs, EA}   = elixir_expand:expand(Args, E#{context := match, match_vars := []}),
-  {EGuards, EG} = guard(Guards, EA#{context := guard, match_vars := nil}),
+  {EGuards, EG} = guard(Guards, EA#{context := guard, match_vars := Match}),
   {EBody, _}    = elixir_expand:expand(Body, EG#{context := ?key(E, context)}),
   {Meta, EArgs, EGuards, EBody}.
 

lib/elixir/src/elixir_env.erl

@@ -19,8 +19,8 @@ new() ->
     lexical_tracker => nil,                %% holds the lexical tracker PID
     vars => [],                            %% a set of defined variables
     export_vars => nil,                    %% a set of variables to be exported in some constructs
-    match_vars => nil,                     %% a set of variables defined in the current match
-    prematch_vars => nil}.                 %% a set of variables defined before the current match
+    prematch_vars => nil,                  %% a set of variables defined before the current match
+    match_vars => warn}.                   %% handling of new variables
 
 linify({Line, Env}) ->
   Env#{line := Line};

lib/elixir/src/elixir_erl_try.erl

@@ -28,14 +28,14 @@ each_clause({'catch', Meta, Raw, Expr}, S) ->
 
 each_clause({rescue, Meta, [{in, _, [Left, Right]}], Expr}, S) ->
   {TempName, _, CS} = elixir_erl_var:build('_', S),
-  TempVar = {TempName, Meta, nil},
+  TempVar = {TempName, Meta, 'Elixir'},
   {Parts, Safe, FS} = rescue_guards(Meta, TempVar, Right, CS),
   Body = rescue_clause_body(Left, Expr, Safe, TempVar, Meta),
   build_rescue(Meta, Parts, Body, FS);
 
 each_clause({rescue, Meta, [{VarName, _, Context} = Left], Expr}, S) when is_atom(VarName), is_atom(Context) ->
   {TempName, _, CS} = elixir_erl_var:build('_', S),
-  TempVar = {TempName, Meta, nil},
+  TempVar = {TempName, Meta, 'Elixir'},
   Body = rescue_clause_body(Left, Expr, false, TempVar, Meta),
   build_rescue(Meta, [{TempVar, []}], Body, CS).
 
@@ -76,7 +76,7 @@ rescue_guards(Meta, Var, Aliases, S) ->
       [] -> {[], S};
       _  ->
         {VarName, _, CS} = elixir_erl_var:build('_', S),
-        StructVar = {VarName, Meta, nil},
+        StructVar = {VarName, Meta, 'Elixir'},
         Map = {'%{}', Meta, [{'__struct__', StructVar}, {'__exception__', true}]},
         Match = {'=', Meta, [Map, Var]},
         Guards = [{erl(Meta, '=='), Meta, [StructVar, Mod]} || Mod <- Elixir],

lib/elixir/src/elixir_expand.erl

@@ -360,10 +360,15 @@ expand({Name, Meta, Kind} = Var, #{vars := Vars} = E) when is_atom(Name), is_ato
         {var, true} ->
           form_error(Meta, ?key(E, file), ?MODULE, {undefined_var, Name, Kind});
         _ ->
-          Message =
-            io_lib:format("variable \"~ts\" does not exist and is being expanded to \"~ts()\","
-              " please use parentheses to remove the ambiguity or change the variable name", [Name, Name]),
-          elixir_errors:warn(?line(Meta), ?key(E, file), Message),
+          case ?key(E, match_vars) of
+            warn ->
+              Message =
+                io_lib:format("variable \"~ts\" does not exist and is being expanded to \"~ts()\","
+                  " please use parentheses to remove the ambiguity or change the variable name", [Name, Name]),
+              elixir_errors:warn(?line(Meta), ?key(E, file), Message);
+            apply ->
+              ok
+          end,
           expand({Name, Meta, []}, E)
       end
   end;