parser: guard loops in ComputeProdLocationVisitor

Most of the time, _need arrays are empty.
So, add 'if' to do the work only if there is work to do.

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

diff --git a/src/parser/parser.nit b/src/parser/parser.nit
index 7e931d7..c2ede2b 100644 (file)
--- a/src/parser/parser.nit
+++ b/src/parser/parser.nit
@@ -947,20 +947,24 @@ private class ComputeProdLocationVisitor
                        _last_location = loc
 
                        # Add a first token to productions that need one
-                       for no in _need_first_prods do
-                               no._first_location = loc
+                       if not _need_first_prods.is_empty then
+                               for no in _need_first_prods do
+                                       no._first_location = loc
+                               end
+                               _need_first_prods.clear
                        end
-                       _need_first_prods.clear
 
                        # Find location for already visited epsilon production that need one
-                       for no in _need_after_epsilons do
-                               # Epsilon production that is in the middle of a non-epsilon production
-                               # The epsilon production has both a token before and after it
-                               var endl = loc
-                               var startl = no._last_location
-                               no.location = new Location(endl.file, startl.line_end, endl.line_start, startl.column_end, endl.column_start)
+                       if not _need_after_epsilons.is_empty then
+                               for no in _need_after_epsilons do
+                                       # Epsilon production that is in the middle of a non-epsilon production
+                                       # The epsilon production has both a token before and after it
+                                       var endl = loc
+                                       var startl = no._last_location
+                                       no.location = new Location(endl.file, startl.line_end, endl.line_start, startl.column_end, endl.column_start)
+                               end
+                               _need_after_epsilons.clear
                        end
-                       _need_after_epsilons.clear
                else
                        assert n isa Prod
                        _need_first_prods.add(n)
@@ -979,19 +983,23 @@ private class ComputeProdLocationVisitor
 
                                n.location = new Location(startl.file, startl.line_start, endl.line_end, startl.column_start, endl.column_end)
 
-                               for no in _need_before_epsilons do
-                                       # Epsilon production that starts the current non-epsilon production
-                                       #var startl = n.location
-                                       no.location = new Location(startl.file, startl.line_start, startl.line_start, startl.column_start, startl.column_start)
+                               if not _need_before_epsilons.is_empty then
+                                       var loc = new Location(startl.file, startl.line_start, startl.line_start, startl.column_start, startl.column_start)
+                                       for no in _need_before_epsilons do
+                                               # Epsilon production that starts the current non-epsilon production
+                                               no.location = loc
+                                       end
+                                       _need_before_epsilons.clear
                                end
-                               _need_before_epsilons.clear
 
-                               for no in _need_after_epsilons do
-                                       # Epsilon production that finishes the current non-epsilon production
-                                       #var endl = n.location
-                                       no.location = new Location(endl.file, endl.line_end, endl.line_end, endl.column_end, endl.column_end)
+                               if not _need_after_epsilons.is_empty then
+                                       var loc = new Location(endl.file, endl.line_end, endl.line_end, endl.column_end, endl.column_end)
+                                       for no in _need_after_epsilons do
+                                               # Epsilon production that finishes the current non-epsilon production
+                                               no.location = loc
+                                       end
+                                       _need_after_epsilons.clear
                                end
-                               _need_after_epsilons.clear
                        else
                                # No first token means epsilon production (or "throw all my tokens" production)
                                # So, it must be located it later

diff --git a/src/parser/xss/parser.xss b/src/parser/xss/parser.xss
index 3a8cc06..45d4590 100644 (file)
--- a/src/parser/xss/parser.xss
+++ b/src/parser/xss/parser.xss
@@ -206,20 +206,24 @@ private class ComputeProdLocationVisitor
                        _last_location = loc
 
                        # Add a first token to productions that need one
-                       for no in _need_first_prods do
-                               no._first_location = loc
+                       if not _need_first_prods.is_empty then
+                               for no in _need_first_prods do
+                                       no._first_location = loc
+                               end
+                               _need_first_prods.clear
                        end
-                       _need_first_prods.clear
 
                        # Find location for already visited epsilon production that need one
-                       for no in _need_after_epsilons do
-                               # Epsilon production that is in the middle of a non-epsilon production
-                               # The epsilon production has both a token before and after it
-                               var endl = loc
-                               var startl = no._last_location
-                               no.location = new Location(endl.file, startl.line_end, endl.line_start, startl.column_end, endl.column_start)
+                       if not _need_after_epsilons.is_empty then
+                               for no in _need_after_epsilons do
+                                       # Epsilon production that is in the middle of a non-epsilon production
+                                       # The epsilon production has both a token before and after it
+                                       var endl = loc
+                                       var startl = no._last_location
+                                       no.location = new Location(endl.file, startl.line_end, endl.line_start, startl.column_end, endl.column_start)
+                               end
+                               _need_after_epsilons.clear
                        end
-                       _need_after_epsilons.clear
                else
                        assert n isa Prod
                        _need_first_prods.add(n)
@@ -238,19 +242,23 @@ private class ComputeProdLocationVisitor
 
                                n.location = new Location(startl.file, startl.line_start, endl.line_end, startl.column_start, endl.column_end)
 
-                               for no in _need_before_epsilons do
-                                       # Epsilon production that starts the current non-epsilon production
-                                       #var startl = n.location
-                                       no.location = new Location(startl.file, startl.line_start, startl.line_start, startl.column_start, startl.column_start)
+                               if not _need_before_epsilons.is_empty then
+                                       var loc = new Location(startl.file, startl.line_start, startl.line_start, startl.column_start, startl.column_start)
+                                       for no in _need_before_epsilons do
+                                               # Epsilon production that starts the current non-epsilon production
+                                               no.location = loc
+                                       end
+                                       _need_before_epsilons.clear
                                end
-                               _need_before_epsilons.clear
 
-                               for no in _need_after_epsilons do
-                                       # Epsilon production that finishes the current non-epsilon production
-                                       #var endl = n.location
-                                       no.location = new Location(endl.file, endl.line_end, endl.line_end, endl.column_end, endl.column_end)
+                               if not _need_after_epsilons.is_empty then
+                                       var loc = new Location(endl.file, endl.line_end, endl.line_end, endl.column_end, endl.column_end)
+                                       for no in _need_after_epsilons do
+                                               # Epsilon production that finishes the current non-epsilon production
+                                               no.location = loc
+                                       end
+                                       _need_after_epsilons.clear
                                end
-                               _need_after_epsilons.clear
                        else
                                # No first token means epsilon production (or "throw all my tokens" production)
                                # So, it must be located it later