transform: shortcut range

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

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index cf84e4c..bd63c0f 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -857,6 +857,9 @@ redef class AForExpr
        var method_key: nullable CallSite
        var method_finish: nullable CallSite
 
+       var method_lt: nullable CallSite
+       var method_successor: nullable CallSite
+
        private fun do_type_iterator(v: TypeVisitor, mtype: MType)
        do
                if mtype isa MNullType then
@@ -957,6 +960,19 @@ redef class AForExpr
                        end
                        self.method_key = keydef
                end
+
+               if self.variables.length == 1 and n_expr isa ARangeExpr then
+                       var variable = variables.first
+                       var vtype = variable.declared_type.as(not null)
+
+                       if n_expr isa AOrangeExpr then
+                               self.method_lt = v.get_method(self, vtype, "<", false)
+                       else
+                               self.method_lt = v.get_method(self, vtype, "<=", false)
+                       end
+
+                       self.method_successor = v.get_method(self, vtype, "successor", false)
+               end
        end
 
        redef fun accept_typing(v)

diff --git a/src/transform.nit b/src/transform.nit
index 50ea215..2a4a230 100644 (file)
--- a/src/transform.nit
+++ b/src/transform.nit
@@ -180,6 +180,41 @@ redef class AForExpr
 
                var nexpr = n_expr
 
+               # Shortcut on explicit range
+               # Avoid the instantiation of the range and the iterator
+               if self.variables.length == 1 and nexpr isa ARangeExpr then
+                       var variable = variables.first
+                       nblock.add v.builder.make_var_assign(variable, nexpr.n_expr)
+                       var to = nexpr.n_expr2
+                       nblock.add to
+
+                       var nloop = v.builder.make_loop
+                       nloop.break_mark = escapemark
+                       nblock.add nloop
+
+                       var is_ok = v.builder.make_call(v.builder.make_var_read(variable, variable.declared_type.as(not null)), method_lt.as(not null), [to.make_var_read])
+
+                       var nif = v.builder.make_if(is_ok, null)
+                       nloop.add nif
+
+                       var nthen = nif.n_then
+                       var ndo = v.builder.make_do
+                       ndo.break_mark = escapemark.continue_mark
+                       nthen.add ndo
+
+                       ndo.add self.n_block.as(not null)
+
+                       var one = v.builder.make_int(1)
+                       var succ = v.builder.make_call(v.builder.make_var_read(variable, variable.declared_type.as(not null)), method_successor.as(not null), [one])
+                       nthen.add v.builder.make_var_assign(variable, succ)
+
+                       var nbreak = v.builder.make_break(escapemark)
+                       nif.n_else.add nbreak
+
+                       replace_with(nblock)
+                       return
+               end
+
                nblock.add nexpr
 
                var iter = v.builder.make_call(nexpr.make_var_read, method_iterator.as(not null), null)