nitcc: generate a faster DFA::trans sequence of `if`

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

diff --git a/contrib/nitcc/src/autom.nit b/contrib/nitcc/src/autom.nit
index 5b545b8..84df722 100644 (file)
--- a/contrib/nitcc/src/autom.nit
+++ b/contrib/nitcc/src/autom.nit
@@ -750,6 +750,13 @@ private class DFAGenerator
                                end
 
                                # Generate a sequence of `if` for the dispatch
+                               if haslast != null then
+                                       # Special case: handle up-bound first if not an error
+                                       add("\t\tif c > {last} then return dfastate_{names[haslast]}\n")
+                                       # previous become the new last case
+                                       haslast = dispatch[last]
+                                       dispatch.keys.remove(last)
+                               end
                                for c, next in dispatch do
                                        if next == null then
                                                add("\t\tif c <= {c} then return null\n")

diff --git a/lib/json/json_lexer.nit b/lib/json/json_lexer.nit
index 4a54598..8ec28ff 100644 (file)
--- a/lib/json/json_lexer.nit
+++ b/lib/json/json_lexer.nit
@@ -97,11 +97,11 @@ private class DFAState2
        super DFAState
        redef fun trans(char) do
                var c = char.code_point
+               if c > 92 then return dfastate_2
                if c <= 33 then return dfastate_2
                if c <= 34 then return dfastate_29
                if c <= 91 then return dfastate_2
-               if c <= 92 then return dfastate_30
-               return dfastate_2
+               return dfastate_30
        end
 end
 private class DFAState3