UCW::CGI: Documented the changes

[libucw.git] / ucw / fastbuf.h

diff --git a/ucw/fastbuf.h b/ucw/fastbuf.h
index 4e3199d8bf567973ffc04a4de2f134c908f89eec..4f0d99d3190be67c6fad8ae22e4e11a46760167d 100644 (file)
--- a/ucw/fastbuf.h
+++ b/ucw/fastbuf.h
@@ -129,7 +129,6 @@
  * for how it works.
  **/
 struct fastbuf {
-  byte is_fastbuf[0];                          /* Dummy field for checking of type casts */
   byte *bptr, *bstop;                          /* State of the buffer */
   byte *buffer, *bufend;                       /* Start and end of the buffer */
   char *name;                                  /* File name (used for error messages) */
@@ -445,7 +444,6 @@ struct fb_atomic {
   byte *expected_max_bptr;
   uns slack_size;
 };
-#define FB_ATOMIC(f) ((struct fb_atomic *)(f)->is_fastbuf)
 
 /**
  * Open an atomic fastbuf.
@@ -475,6 +473,53 @@ static inline void fbatomic_commit(struct fastbuf *b)
     fbatomic_internal_write(b);
 }
 
+/***
+ * === Fastbufs atop other fastbufs [[fbmulti]]
+ *
+ * Imagine some code which does massive string processing. It takes an input
+ * buffer, writes a part of it into an output buffer, then some other string
+ * and then the remaining part of the input buffer. Or anything else where you
+ * copy all the data at each stage of the complicated process.
+ *
+ * This backend takes multiple fastbufs and concatenates them formally into
+ * one. You may then read them consecutively as they were one fastbuf at all.
+ *
+ * This backend is read-only.
+ *
+ * This backend is seekable iff all of the supplied fastbufs are seekable.
+ *
+ * You aren't allowed to do anything with the underlying buffers while these
+ * are connected into fbmulti.
+ *
+ * The fbmulti is inited by @fbmulti_create(). It returns an empty fbmulti.
+ * Then you call @fbmulti_append() for each fbmulti.
+ *
+ * If @bclose() is called on fbmulti, all the underlying buffers get closed
+ * recursively.
+ *
+ * If you want to keep an underlying fastbuf open after @bclose, just remove it
+ * by @fbmulti_remove where the second parameter is a pointer to the removed
+ * fastbuf. If you pass NULL, all the underlying fastbufs are removed.
+ *
+ * After @fbmulti_remove, the state of the fbmulti is undefined. The only allowed
+ * operation is either another @fbmulti_remove or @bclose on the fbmulti.
+ ***/
+
+/**
+ * Create an empty fbmulti
+ **/
+struct fastbuf *fbmulti_create(void);
+
+/**
+ * Append a fb to fbmulti
+ **/
+void fbmulti_append(struct fastbuf *f, struct fastbuf *fb);
+
+/**
+ * Remove a fb from fbmulti
+ **/
+void fbmulti_remove(struct fastbuf *f, struct fastbuf *fb);
+
 /*** === Configuring stream parameters [[bconfig]] ***/
 
 enum bconfig_type {                    /** Parameters that could be configured. **/