X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=ref.cc;h=8ed747ddaa59b0c992442e56abfe4a3275d5b2ac;hb=5b346a4689ac2c8458e30fd8752abd6e2f207c56;hp=b5c02d605ae4c3ad6f2274c0e98010912b466a37;hpb=fafef931da9ed8e7b64b250749166c588bb79743;p=cumulus.git

diff --git a/ref.cc b/ref.cc
index b5c02d6..8ed747d 100644
--- a/ref.cc
+++ b/ref.cc
@@ -29,12 +29,21 @@ string generate_uuid()
 }
 
 ObjectReference::ObjectReference()
-    : segment(""), object("")
+    : type(REF_NULL), segment(""), object("")
 {
+    clear_checksum();
+    clear_range();
+}
+
+ObjectReference::ObjectReference(RefType t)
+    : type(t), segment(""), object("")
+{
+    clear_checksum();
+    clear_range();
 }
 
 ObjectReference::ObjectReference(const std::string& segment, int sequence)
-    : segment(segment)
+    : type(REF_NORMAL), segment(segment)
 {
     char seq_buf[64];
     sprintf(seq_buf, "%08x", sequence);
@@ -46,7 +55,7 @@ ObjectReference::ObjectReference(const std::string& segment, int sequence)
 
 ObjectReference::ObjectReference(const std::string& segment,
                                  const std::string& sequence)
-    : segment(segment), object(sequence)
+    : type(REF_NORMAL), segment(segment), object(sequence)
 {
     clear_checksum();
     clear_range();
@@ -54,14 +63,26 @@ ObjectReference::ObjectReference(const std::string& segment,
 
 string ObjectReference::to_string() const
 {
-    string result = segment + "/" + object;
+    if (type == REF_NULL)
+        return "null";
+
+    string result;
+    if (type == REF_ZERO) {
+        result = "zero";
+    } else if (type == REF_NORMAL) {
+        result = segment + "/" + object;
 
-    if (checksum_valid)
-        result += "(" + checksum + ")";
+        if (checksum_valid)
+            result += "(" + checksum + ")";
+    }
 
     if (range_valid) {
         char buf[64];
-        sprintf(buf, "[%zu+%zu]", range_start, range_length);
+        if (range_start == 0) {
+            sprintf(buf, "[%zu]", range_length);
+        } else {
+            sprintf(buf, "[%zu+%zu]", range_start, range_length);
+        }
         result += buf;
     }
 
@@ -71,26 +92,38 @@ string ObjectReference::to_string() const
 /* Parse a string object reference and return a pointer to a new
  * ObjectReference.  The caller is responsible for freeing the object.  NULL is
  * returned if there is an error in the syntax. */
-ObjectReference *ObjectReference::parse(const std::string& str)
+ObjectReference ObjectReference::parse(const std::string& str)
 {
     const char *s = str.c_str();
     const char *t;
+    ObjectReference::RefType type = ObjectReference::REF_NORMAL;
+
+    // Special case: explicit zero objects
+    if (strncmp(s, "zero", 4) == 0) {
+        type = ObjectReference::REF_ZERO;
+        s += 4;
+    }
 
     // Segment
     t = s;
-    while ((*t >= '0' && *t <= '9') || (*t >= 'a' && *t <= 'f') || (*t == '-'))
-        t++;
-    if (*t != '/')
-        return NULL;
+    if (type == ObjectReference::REF_NORMAL) {
+        while ((*t >= '0' && *t <= '9') || (*t >= 'a' && *t <= 'f')
+               || (*t == '-'))
+            t++;
+        if (*t != '/')
+            return ObjectReference();
+    }
     string segment(s, t - s);
 
     // Object sequence number
-    t++;
-    s = t;
-    while ((*t >= '0' && *t <= '9') || (*t >= 'a' && *t <= 'f'))
+    if (type == ObjectReference::REF_NORMAL) {
         t++;
-    if (*t != '\0' && *t != '(' && *t != '[')
-        return NULL;
+        s = t;
+        while ((*t >= '0' && *t <= '9') || (*t >= 'a' && *t <= 'f'))
+            t++;
+        if (*t != '\0' && *t != '(' && *t != '[')
+            return ObjectReference();
+    }
     string object(s, t - s);
 
     // Checksum
@@ -101,44 +134,95 @@ ObjectReference *ObjectReference::parse(const std::string& str)
         while (*t != ')' && *t != '\0')
             t++;
         if (*t != ')')
-            return NULL;
+            return ObjectReference();
         checksum = string(s, t - s);
         t++;
     }
 
     // Range
     bool have_range = false;
-    int64_t range1, range2;
+    int64_t range1 = 0, range2 = 0;
     if (*t == '[') {
         t++;
         s = t;
         while (*t >= '0' && *t <= '9')
             t++;
-        if (*t != '+')
-            return NULL;
 
-        string val(s, t - s);
-        range1 = atoll(val.c_str());
+        // Abbreviated-length only range?
+        if (*t == ']') {
+            string val(s, t - s);
+            range2 = atoll(val.c_str());
+        } else {
+            if (*t != '+')
+                return ObjectReference();
+
+            string val(s, t - s);
+            range1 = atoll(val.c_str());
 
-        t++;
-        s = t;
-        while (*t >= '0' && *t <= '9')
             t++;
-        if (*t != ']')
-            return NULL;
+            s = t;
+            while (*t >= '0' && *t <= '9')
+                t++;
+            if (*t != ']')
+                return ObjectReference();
 
-        val = string(s, t - s);
-        range2 = atoll(val.c_str());
+            val = string(s, t - s);
+            range2 = atoll(val.c_str());
+        }
 
         have_range = true;
     }
 
-    ObjectReference *ref = new ObjectReference(segment, object);
+    ObjectReference ref;
+    switch (type) {
+    case ObjectReference::REF_ZERO:
+        ref = ObjectReference(ObjectReference::REF_ZERO);
+        break;
+    case ObjectReference::REF_NORMAL:
+        ref = ObjectReference(segment, object);
+        break;
+    default:
+        return ObjectReference();
+    }
+
     if (checksum.size() > 0)
-        ref->set_checksum(checksum);
+        ref.set_checksum(checksum);
 
     if (have_range)
-        ref->set_range(range1, range2);
+        ref.set_range(range1, range2);
 
     return ref;
 }
+
+/* Attempt to merge a new object reference into the current one.  Returns a
+ * boolean indicating success; if successful this reference is modified so that
+ * it refers to the range of bytes originally covered by this reference plus
+ * the reference passed in.  Merging only succeeds if both references refer to
+ * the same object and the byte ranges are contiguous. */
+bool ObjectReference::merge(ObjectReference ref)
+{
+    // Exception: We can always merge into a null object
+    if (is_null()) {
+        *this = ref;
+        return true;
+    }
+
+    if (segment != ref.segment)
+        return false;
+    if (object != ref.object)
+        return false;
+
+    // TODO: Allow the case where only one checksum was filled in
+    if (checksum_valid != ref.checksum_valid || checksum != ref.checksum)
+        return false;
+
+    if (!range_valid || !ref.range_valid)
+        return false;
+
+    if (range_start + range_length == ref.range_start) {
+        range_length += ref.range_length;
+        return true;
+    } else {
+        return false;
+    }
+}