From 0b0c4df3dc7b94c139c5305ea0991a34f0c43238 Mon Sep 17 00:00:00 2001
From: Jed Barber <jjbarber@y7mail.com>
Date: Thu, 21 Jan 2021 20:01:23 +1100
Subject: Lexer combinator Needs_More case fixed

---
 src/packrat-lexers.adb | 35 ++++++++++++++++++-----------------
 src/packrat-lexers.ads |  8 ++++++++
 2 files changed, 26 insertions(+), 17 deletions(-)

(limited to 'src')

diff --git a/src/packrat-lexers.adb b/src/packrat-lexers.adb
index b09b6eb..341b87f 100644
--- a/src/packrat-lexers.adb
+++ b/src/packrat-lexers.adb
@@ -417,7 +417,7 @@ package body Packrat.Lexers is
         Position : Positive := Start;
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         end if;
         for C of Params loop
             if Position > Input'Last then
@@ -441,7 +441,7 @@ package body Packrat.Lexers is
         Position : Positive := Start;
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         end if;
         for I in Integer range 1 .. Number loop
             if Position > Input'Last then
@@ -467,7 +467,7 @@ package body Packrat.Lexers is
         Counter  : Natural := 0;
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         end if;
         loop
             exit when Position > Input'Last;
@@ -503,7 +503,7 @@ package body Packrat.Lexers is
         Counter  : Natural := 0;
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         end if;
         loop
             exit when Position > Input'Last;
@@ -541,7 +541,7 @@ package body Packrat.Lexers is
         return Combinator_Result is
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         elsif Test (Input (Start)) then
             return (Start, Success);
         else
@@ -556,7 +556,7 @@ package body Packrat.Lexers is
         return Combinator_Result is
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         elsif Test (Change (Input (Start))) then
             return (Start, Success);
         else
@@ -571,7 +571,7 @@ package body Packrat.Lexers is
         return Combinator_Result is
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         elsif Input (Start) = Item then
             return (Start, Success);
         else
@@ -586,7 +586,7 @@ package body Packrat.Lexers is
         return Combinator_Result is
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         elsif Change (Input (Start)) = Item then
             return (Start, Success);
         else
@@ -603,13 +603,10 @@ package body Packrat.Lexers is
         Current_Offset : Natural := 0;
     begin
         if Items'Length = 0 then
-            return (0, Success);
+            return Empty_Success;
+        elsif Start > Input'Last then
+            return Empty_Needs_More;
         end if;
-
-        if Input'Last - Start + 1 <= 0 then
-            return Empty_Fail;
-        end if;
-
         while Input (Start + Current_Offset) = Items (Items'First + Current_Offset) loop
             if Items'First + Current_Offset = Items'Last then
                 return (Start + Current_Offset, Success);
@@ -632,7 +629,7 @@ package body Packrat.Lexers is
         return Combinator_Result is
     begin
         if Start > Input'Last then
-            return Empty_Fail;
+            return Empty_Needs_More;
         elsif Start + Number - 1 > Input'Last then
             return (Input'Last, Needs_More);
         else
@@ -649,7 +646,9 @@ package body Packrat.Lexers is
         Finish : Positive := Start;
         Status : Result_Status;
     begin
-        if Start > Input'Last or else not Test (Input (Start)) then
+        if Start > Input'Last then
+            return Empty_Needs_More;
+        elsif not Test (Input (Start)) then
             return Empty_Fail;
         end if;
         while Finish <= Input'Last and then Test (Input (Finish)) loop
@@ -672,7 +671,9 @@ package body Packrat.Lexers is
         Finish : Positive := Start;
         Status : Result_Status;
     begin
-        if Start > Input'Last or else Test (Input (Start)) then
+        if Start > Input'Last then
+            return Empty_Needs_More;
+        elsif Test (Input (Start)) then
             return Empty_Fail;
         end if;
         while Finish <= Input'Last and then not Test (Input (Finish)) loop
diff --git a/src/packrat-lexers.ads b/src/packrat-lexers.ads
index 4b6bbc9..c303feb 100644
--- a/src/packrat-lexers.ads
+++ b/src/packrat-lexers.ads
@@ -305,6 +305,14 @@ private
        (Finish => 0,
         Status => Failure);
 
+    Empty_Needs_More : constant Combinator_Result :=
+       (Finish => 0,
+        Status => Needs_More);
+
+    Empty_Success : constant Combinator_Result :=
+       (Finish => 0,
+        Status => Success);
+
 
 
 
-- 
cgit