syntax: if_false_variable_ctx

Allow casts to be propagated in 'else' branches

Example:
  if not a isa B then
    a.only_b_can_do # Static error
  else
    a.only_b_can_do # OK since current static type of a is B here
  end

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

diff --git a/src/syntax/typing.nit b/src/syntax/typing.nit
index 679b88e..f9d5eba 100644 (file)
--- a/src/syntax/typing.nit
+++ b/src/syntax/typing.nit
@@ -65,9 +65,14 @@ special AbsSyntaxVisitor
        private meth use_if_true_variable_ctx(e: PExpr)
        do
                var ctx = e.if_true_variable_ctx
-               if ctx != null then
-                       variable_ctx = ctx
-               end
+               if ctx != null then variable_ctx = ctx
+       end
+
+       # Make the if_false_variable_ctx of the expression effective
+       private meth use_if_false_variable_ctx(e: PExpr)
+       do
+               var ctx = e.if_false_variable_ctx
+               if ctx != null then variable_ctx = ctx
        end
 
        # Number of nested once
@@ -303,6 +308,9 @@ redef class PExpr
 
        # The variable type information if current boolean expression is true
        readable private attr _if_true_variable_ctx: VariableContext
+
+       # The variable type information if current boolean expression is false
+       readable private attr _if_false_variable_ctx: VariableContext
 end
 
 redef class AVardeclExpr
@@ -420,24 +428,31 @@ redef class AIfExpr
                v.visit(n_expr)
                v.check_conform_expr(n_expr, v.type_bool)
 
+               # Prepare 'then' context
                v.use_if_true_variable_ctx(n_expr)
-               v.variable_ctx = v.variable_ctx.sub(n_then)
 
-               v.visit(n_then)
+               # Process the 'then'
+               if n_then != null then
+                       v.variable_ctx = v.variable_ctx.sub(n_then)
+                       v.visit(n_then)
+               end
 
-               if n_else == null then
-                       # Restore variable ctx since the 'then' block is optional
-                       v.variable_ctx = old_var_ctx
-               else
-                       # Remember what appened in the 'then'
-                       var then_var_ctx = v.variable_ctx
-                       # Reset to process the 'else'
-                       v.variable_ctx = old_var_ctx.sub(n_else)
+               # Remember what appened in the 'then'
+               var then_var_ctx = v.variable_ctx
+
+               # Prepare 'else' context
+               v.variable_ctx = old_var_ctx
+               v.use_if_false_variable_ctx(n_expr)
+
+               # Process the 'else'
+               if n_else != null then
+                       v.variable_ctx = v.variable_ctx.sub(n_else)
                        v.visit(n_else)
-                       # Merge then and else in the old control_flow
-                       old_var_ctx.merge2(then_var_ctx, v.variable_ctx)
-                       v.variable_ctx = old_var_ctx
                end
+
+               # Merge 'then' and 'else' contexts
+               old_var_ctx.merge2(then_var_ctx, v.variable_ctx)
+               v.variable_ctx = old_var_ctx
                _is_typed = true
        end
 end
@@ -635,6 +650,7 @@ redef class AIfexprExpr
                v.use_if_true_variable_ctx(n_expr)
                v.visit(n_then)
                v.variable_ctx = old_var_ctx
+               v.use_if_false_variable_ctx(n_expr)
                v.visit(n_else)
 
                v.check_conform_expr(n_expr, v.type_bool)
@@ -655,6 +671,20 @@ end
 redef class AOrExpr
        redef meth after_typing(v)
        do
+               var old_var_ctx = v.variable_ctx
+
+               v.visit(n_expr)
+               v.use_if_false_variable_ctx(n_expr)
+
+               v.visit(n_expr2)
+               if n_expr2.if_false_variable_ctx != null then 
+                       _if_false_variable_ctx = n_expr2.if_false_variable_ctx
+               else
+                       _if_false_variable_ctx = v.variable_ctx
+               end
+
+               v.variable_ctx = old_var_ctx
+
                v.check_conform_expr(n_expr, v.type_bool)
                v.check_conform_expr(n_expr2, v.type_bool)
                _stype = v.type_bool
@@ -690,6 +720,11 @@ redef class ANotExpr
        redef meth after_typing(v)
        do
                v.check_conform_expr(n_expr, v.type_bool)
+
+               # Invert if_true/if_false information
+               _if_false_variable_ctx = n_expr._if_true_variable_ctx
+               _if_true_variable_ctx = n_expr._if_false_variable_ctx
+
                _stype = v.type_bool
                _is_typed = true
        end

diff --git a/tests/base_isa_cast3.nit b/tests/base_isa_cast3.nit
new file mode 100644 (file)
index 0000000..e4c6f62
--- /dev/null
+++ b/tests/base_isa_cast3.nit
@@ -0,0 +1,60 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Copyright 2009 Jean Privat <jean@pryen.org>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import kernel
+
+class A
+       init do end
+end
+
+class B
+special A
+       meth foo(i: Int) do i.output
+       init do end
+end
+
+var a: A = new B
+
+if a isa B then
+       a.foo(1)
+else
+       #alt1#a.foo(-1)
+end
+#alt2#a.foo(-2)
+
+if not a isa B then
+       #alt3#a.foo(-3)
+else
+       a.foo(2)
+end
+#alt4#a.foo(-4)
+
+if a isa B and false then
+       a.foo(3)
+else
+       #alt5#a.foo(-5)
+end
+#alt6#a.foo(-6)
+
+if not a isa B or true then
+       #alt7#a.foo(-7)
+else
+       a.foo(3)
+end
+#alt8#a.foo(-8)
+
+
+

diff --git a/tests/sav/base_isa_cast3.sav b/tests/sav/base_isa_cast3.sav
new file mode 100644 (file)
index 0000000..1191247
--- /dev/null
+++ b/tests/sav/base_isa_cast3.sav
@@ -0,0 +1,2 @@
+1
+2

diff --git a/tests/sav/base_isa_cast3_alt1.sav b/tests/sav/base_isa_cast3_alt1.sav
new file mode 100644 (file)
index 0000000..26dcf6f
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt1.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt1.nit:34,2--9: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt2.sav b/tests/sav/base_isa_cast3_alt2.sav
new file mode 100644 (file)
index 0000000..b3e455f
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt2.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt2.nit:36,1--8: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt3.sav b/tests/sav/base_isa_cast3_alt3.sav
new file mode 100644 (file)
index 0000000..ea93124
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt3.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt3.nit:39,2--9: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt4.sav b/tests/sav/base_isa_cast3_alt4.sav
new file mode 100644 (file)
index 0000000..dcb1bf6
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt4.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt4.nit:43,1--8: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt5.sav b/tests/sav/base_isa_cast3_alt5.sav
new file mode 100644 (file)
index 0000000..d524248
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt5.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt5.nit:48,2--9: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt6.sav b/tests/sav/base_isa_cast3_alt6.sav
new file mode 100644 (file)
index 0000000..3c9fc0f
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt6.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt6.nit:50,1--8: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt7.sav b/tests/sav/base_isa_cast3_alt7.sav
new file mode 100644 (file)
index 0000000..a301a75
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt7.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt7.nit:53,2--9: Error: Method 'foo' doesn't exists in A.

diff --git a/tests/sav/base_isa_cast3_alt8.sav b/tests/sav/base_isa_cast3_alt8.sav
new file mode 100644 (file)
index 0000000..6fc6d23
--- /dev/null
+++ b/tests/sav/base_isa_cast3_alt8.sav
@@ -0,0 +1 @@
+alt/base_isa_cast3_alt8.nit:57,1--8: Error: Method 'foo' doesn't exists in A.