New function 'luaL_addgsub'

Added a new function 'luaL_addgsub', similar to 'luaL_gsub' but that
adds its result directly to a preexisting buffer, avoiding the creation
of one extra intermediate string. Also added two simple macros,
'luaL_bufflen' and 'luaL_buffaddr', to query the current length
and the contents address of a buffer.

3 files changed, 58 insertions, 13 deletions

diff --git a/lauxlib.c b/lauxlib.c
index e9c02d36..dfe501a7 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -951,18 +951,24 @@ LUALIB_API void luaL_requiref (lua_State *L, const char *modname,
 }
 
 
-LUALIB_API const char *luaL_gsub (lua_State *L, const char *s, const char *p,
-                                                               const char *r) {
+LUALIB_API void luaL_addgsub (luaL_Buffer *b, const char *s,
+                                     const char *p, const char *r) {
   const char *wild;
   size_t l = strlen(p);
-  luaL_Buffer b;
-  luaL_buffinit(L, &b);
   while ((wild = strstr(s, p)) != NULL) {
-    luaL_addlstring(&b, s, wild - s);  /* push prefix */
-    luaL_addstring(&b, r);  /* push replacement in place of pattern */
+    luaL_addlstring(b, s, wild - s);  /* push prefix */
+    luaL_addstring(b, r);  /* push replacement in place of pattern */
     s = wild + l;  /* continue after 'p' */
   }
-  luaL_addstring(&b, s);  /* push last suffix */
+  luaL_addstring(b, s);  /* push last suffix */
+}
+
+
+LUALIB_API const char *luaL_gsub (lua_State *L, const char *s,
+                                  const char *p, const char *r) {
+  luaL_Buffer b;
+  luaL_buffinit(L, &b);
+  luaL_addgsub(&b, s, p, r);
   luaL_pushresult(&b);
   return lua_tostring(L, -1);
 }
diff --git a/lauxlib.h b/lauxlib.h
index e5d378ae..f68f6af1 100644
--- a/lauxlib.h
+++ b/lauxlib.h
@@ -19,6 +19,8 @@
 #define LUA_GNAME       "_G"
 
 
+typedef struct luaL_Buffer luaL_Buffer;
+
 
 /* extra error code for 'luaL_loadfilex' */
 #define LUA_ERRFILE     (LUA_ERRERR+1)
@@ -99,8 +101,10 @@ LUALIB_API lua_State *(luaL_newstate) (void);
 
 LUALIB_API lua_Integer (luaL_len) (lua_State *L, int idx);
 
-LUALIB_API const char *(luaL_gsub) (lua_State *L, const char *s, const char *p,
-                                                  const char *r);
+LUALIB_API void luaL_addgsub (luaL_Buffer *b, const char *s,
+                                     const char *p, const char *r);
+LUALIB_API const char *(luaL_gsub) (lua_State *L, const char *s,
+                                    const char *p, const char *r);
 
 LUALIB_API void (luaL_setfuncs) (lua_State *L, const luaL_Reg *l, int nup);
 
@@ -155,7 +159,7 @@ LUALIB_API void (luaL_requiref) (lua_State *L, const char *modname,
 ** =======================================================
 */
 
-typedef struct luaL_Buffer {
+struct luaL_Buffer {
   char *b;  /* buffer address */
   size_t size;  /* buffer size */
   size_t n;  /* number of characters in buffer */
@@ -164,7 +168,11 @@ typedef struct luaL_Buffer {
     LUAI_MAXALIGN;  /* ensure maximum alignment for buffer */
     char b[LUAL_BUFFERSIZE];  /* initial buffer */
   } init;
-} luaL_Buffer;
+};
+
+
+#define luaL_bufflen(bf)        ((bf)->n)
+#define luaL_buffaddr(bf)       ((bf)->b)
 
 
 #define luaL_addchar(B,c) \
diff --git a/manual/manual.of b/manual/manual.of
index 24ac45ae..5f265708 100644
--- a/manual/manual.of
+++ b/manual/manual.of
@@ -591,7 +591,7 @@ controls how long the collector waits before starting a new cycle.
 The collector starts a new cycle when the use of memory
 hits @M{n%} of the use after the previous collection.
 Larger values make the collector less aggressive.
-Values less than 100 mean the collector will not wait to
+Values equal to or less than 100 mean the collector will not wait to
 start a new cycle.
 A value of 200 means that the collector waits for the total memory in use
 to double before starting a new cycle.
@@ -4928,6 +4928,18 @@ Adds the byte @id{c} to the buffer @id{B}
 
 }
 
+@APIEntry{
+const void luaL_addgsub (luaL_Buffer *B, const char *s,
+                         const char *p, const char *r);|
+@apii{0,0,m}
+
+Adds a copy of the string @id{s} to the buffer @id{B},
+replacing any occurrence of the string @id{p}
+with the string @id{r}.
+@seeC{luaL_Buffer}.
+
+}
+
 @APIEntry{void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);|
 @apii{?,?,m}
 
@@ -5070,6 +5082,15 @@ plus the final string on its top.
 
 }
 
+@APIEntry{char *luaL_buffaddr (luaL_Buffer *B);|
+@apii{0,0,-}
+
+Returns the address of the current contents of buffer @id{B}.
+Note that any addition to the buffer may invalidate this address.
+@seeC{luaL_Buffer}.
+
+}
+
 @APIEntry{void luaL_buffinit (lua_State *L, luaL_Buffer *B);|
 @apii{0,0,-}
 
@@ -5080,6 +5101,14 @@ the buffer must be declared as a variable
 
 }
 
+@APIEntry{size_t luaL_bufflen (luaL_Buffer *B);|
+@apii{0,0,-}
+
+Returns the length of the current contents of buffer @id{B}.
+@seeC{luaL_Buffer}.
+
+}
+
 @APIEntry{char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);|
 @apii{?,?,m}
 
@@ -5935,6 +5964,7 @@ This option can be followed by three numbers:
 the garbage-collector pause,
 the step multiplier,
 and the step size.
+A zero means to not change that value.
 }
 
 @item{@St{generational}|
@@ -5942,6 +5972,7 @@ Change the collector mode to generational.
 This option can be followed by two numbers:
 the garbage-collector minor multiplier
 and the major multiplier.
+A zero means to not change that value.
 }
 
 @item{@St{isrunning}|
@@ -6552,7 +6583,7 @@ the value of the environment variable @defid{LUA_PATH_5_4} or
 the environment variable @defid{LUA_PATH} or
 with a default path defined in @id{luaconf.h},
 if those environment variables are not defined.
-Any @St{;;} in the value of the environment variable
+A @St{;;} in the value of the environment variable
 is replaced by the default path.
 
 }