From 8b995e50612149fbd85c6af010173a0367c21f64 Mon Sep 17 00:00:00 2001
From: Ferdinand Majerech <kiithsacmp@gmail.com>
Date: Tue, 25 Oct 2011 00:16:43 +0200
Subject: [PATCH] Fixed a bug in FastCharSearch. Reader buffer is now manually
 allocated, decreasing GC workload even further.

---
 dyaml/fastcharsearch.d | 18 ++++++------------
 dyaml/reader.d         | 40 +++++++++++++++++++++++++++++++---------
 dyaml/scanner.d        |  2 +-
 3 files changed, 38 insertions(+), 22 deletions(-)

diff --git a/dyaml/fastcharsearch.d b/dyaml/fastcharsearch.d
index 3c45cc2..d992d80 100644
--- a/dyaml/fastcharsearch.d
+++ b/dyaml/fastcharsearch.d
@@ -81,22 +81,16 @@ string searchCode(dstring chars, uint tableSize)()
 
     if(tableSize)
     {
-        code ~= specialChars.length 
-                ?
-                "    if(c < " ~ tableSizeStr ~ ")\n"
+        code ~= "    if(c < " ~ tableSizeStr ~ ")\n"
                 "    {\n"
                 "        return cast(bool)table_[c];\n"
-                "    }\n"
-                :
-                "    return cast(bool)table_[c];\n";
-    }
-    if(specialChars.length)
-    {
-        code ~= "    return " ~ specialCharsCode() ~ ";\n";
+                "    }\n";
     }
 
-    code ~= "    assert(false);\n"
-            "}\n";
+    code ~= specialChars.length 
+            ? "    return " ~ specialCharsCode() ~ ";\n"
+            : "    return false";
+    code ~= "}\n";
 
     return code;
 }
diff --git a/dyaml/reader.d b/dyaml/reader.d
index 8e4e1a2..43bf0e3 100644
--- a/dyaml/reader.d
+++ b/dyaml/reader.d
@@ -40,6 +40,8 @@ final class Reader
     private:
         ///Input stream.
         EndianStream stream_;
+        ///Allocated space for buffer_.
+        dchar[] bufferAllocated_;
         ///Buffer of currently loaded characters.
         dchar[] buffer_;
         ///Current position within buffer. Only data after this position can be read.
@@ -123,13 +125,15 @@ final class Reader
                 default: assert(false, "Unknown UTF BOM");
             }
             available_ = stream_.available;
+
+            bufferReserve(256);
         }
 
         ///Destroy the Reader.
         ~this()
         {
-            clear(buffer_);
-            buffer_ = null;
+            core.stdc.stdlib.free(bufferAllocated_.ptr);
+            buffer_ = bufferAllocated_ = null;
         }
 
         /**
@@ -158,6 +162,9 @@ final class Reader
         /**
          * Get specified number of characters starting at current position.
          *
+         * Note: This gets only a "view" into the internal buffer,
+         *       which WILL get invalidated after other Reader calls.
+         *
          * Params: length = Number of characters to get.
          *
          * Returns: Characters starting at current position.
@@ -172,7 +179,7 @@ final class Reader
             const end = min(buffer_.length, bufferOffset_ + length);
             //need to duplicate as we change buffer content with C functions
             //and could end up with returned string referencing changed data
-            return cast(dstring)buffer_[bufferOffset_ .. end].dup;
+            return cast(dstring)buffer_[bufferOffset_ .. end];
         }
 
         /**
@@ -202,9 +209,9 @@ final class Reader
          */
         dstring get(in size_t length)
         {
-            dstring result = prefix(length);
+            auto result = prefix(length).dup;
             forward(length);
-            return result;
+            return cast(dstring)result;
         }
 
         /**
@@ -273,7 +280,7 @@ final class Reader
                 size_t bufferLength = buffer_.length - bufferOffset_;
                 memmove(buffer_.ptr, buffer_.ptr + bufferOffset_,
                         bufferLength * dchar.sizeof);
-                buffer_.length = bufferLength;
+                buffer_ = buffer_[0 .. bufferLength];
                 bufferOffset_ = 0;
             }
 
@@ -286,7 +293,9 @@ final class Reader
                 {
                     if(buffer_.length == 0 || buffer_[$ - 1] != '\0')
                     {
-                        buffer_ ~= '\0';
+                        bufferReserve(buffer_.length + 1);
+                        buffer_ = bufferAllocated_[0 .. buffer_.length + 1];
+                        buffer_[$ - 1] = '\0';
                     }
                     break;
                 }
@@ -380,10 +389,12 @@ final class Reader
             const oldPosition = stream_.position;
 
             //Preallocating memory to limit GC reallocations.
-            buffer_.length = buffer_.length + chars;
+
+            bufferReserve(buffer_.length + chars);
+            buffer_ = bufferAllocated_[0 .. buffer_.length + chars];
             scope(exit)
             {
-                buffer_.length = buffer_.length - chars;
+                buffer_ = buffer_[0 .. $ - chars];
                 enforce(printable(buffer_[oldLength .. $]), 
                         new ReaderException("Special unicode characters are not allowed"));
             }
@@ -436,6 +447,17 @@ final class Reader
                      encoding_ == Encoding.UTF_32));
         }
 
+        ///Ensure there is space for at least capacity characters in bufferAllocated_.
+        void bufferReserve(in size_t capacity)
+        {
+            if(bufferAllocated_.length >= capacity){return;}
+
+            auto newPtr = core.stdc.stdlib.realloc(bufferAllocated_.ptr,  
+                                                   capacity * dchar.sizeof);
+            bufferAllocated_ = (cast(dchar*)newPtr)[0 .. capacity];
+            buffer_ = bufferAllocated_[0 .. buffer_.length];
+        }
+
     unittest
     {
         writeln("D:YAML reader endian unittest");
diff --git a/dyaml/scanner.d b/dyaml/scanner.d
index c9d34e3..69a0226 100644
--- a/dyaml/scanner.d
+++ b/dyaml/scanner.d
@@ -1363,7 +1363,7 @@ final class Scanner
             {
                 //Instead of checking indentation, we check for document separators.
                 const prefix = reader_.prefix(3);
-                if((prefix == "---" || prefix == "...") && 
+                if((prefix == "---"d || prefix == "..."d) && 
                    " \t\0\n\r\u0085\u2028\u2029"d.canFind(reader_.peek(3)))
                 {
                     throw new Error("While scanning a quoted scalar", startMark,