[PATCH] Add a topological sort procedure to commit.c
[gitweb.git] / commit.c
index 911f6435a74b93f6d25c6852d1814fa8dbaf626e..0bbfa2ab31917e2a7584b0267c04f3324fad28d9 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1,25 +1,75 @@
+#include <ctype.h>
+#include "tag.h"
 #include "commit.h"
 #include "cache.h"
-#include <string.h>
-#include <limits.h>
+
+struct sort_node
+{
+       /*
+         * the number of children of the associated commit
+         * that also occur in the list being sorted.
+         */
+       unsigned int indegree;
+
+       /*
+         * reference to original list item that we will re-use
+         * on output.
+         */
+       struct commit_list * list_item;
+
+};
 
 const char *commit_type = "commit";
 
-struct commit *lookup_commit(unsigned char *sha1)
+enum cmit_fmt get_commit_format(const char *arg)
+{
+       if (!*arg)
+               return CMIT_FMT_DEFAULT;
+       if (!strcmp(arg, "=raw"))
+               return CMIT_FMT_RAW;
+       if (!strcmp(arg, "=medium"))
+               return CMIT_FMT_MEDIUM;
+       if (!strcmp(arg, "=short"))
+               return CMIT_FMT_SHORT;
+       if (!strcmp(arg, "=full"))
+               return CMIT_FMT_FULL;
+       die("invalid --pretty format");
+}
+
+static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
+{
+       if (obj->type != commit_type) {
+               error("Object %s is a %s, not a commit", 
+                     sha1_to_hex(sha1), obj->type);
+               return NULL;
+       }
+       return (struct commit *) obj;
+}
+
+struct commit *lookup_commit_reference(const unsigned char *sha1)
+{
+       struct object *obj = parse_object(sha1);
+
+       if (!obj)
+               return NULL;
+       if (obj->type == tag_type)
+               obj = ((struct tag *)obj)->tagged;
+       return check_commit(obj, sha1);
+}
+
+struct commit *lookup_commit(const unsigned char *sha1)
 {
        struct object *obj = lookup_object(sha1);
        if (!obj) {
-               struct commit *ret = malloc(sizeof(struct commit));
+               struct commit *ret = xmalloc(sizeof(struct commit));
                memset(ret, 0, sizeof(struct commit));
                created_object(sha1, &ret->object);
+               ret->object.type = commit_type;
                return ret;
        }
-       if (obj->parsed && obj->type != commit_type) {
-               error("Object %s is a %s, not a commit", 
-                     sha1_to_hex(sha1), obj->type);
-               return NULL;
-       }
-       return (struct commit *) obj;
+       if (!obj->type)
+               obj->type = commit_type;
+       return check_commit(obj, sha1);
 }
 
 static unsigned long parse_commit_date(const char *buf)
@@ -40,45 +90,68 @@ static unsigned long parse_commit_date(const char *buf)
        return date;
 }
 
-int parse_commit(struct commit *item)
+int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 {
-       char type[20];
-       void * buffer, *bufptr;
-       unsigned long size;
+       void *bufptr = buffer;
        unsigned char parent[20];
+       struct commit_list **pptr;
+
        if (item->object.parsed)
                return 0;
        item->object.parsed = 1;
-       buffer = bufptr = read_sha1_file(item->object.sha1, type, &size);
-       if (!buffer)
-               return error("Could not read %s",
-                            sha1_to_hex(item->object.sha1));
-       if (strcmp(type, commit_type))
-               return error("Object %s not a commit",
-                            sha1_to_hex(item->object.sha1));
-       item->object.type = commit_type;
        get_sha1_hex(bufptr + 5, parent);
        item->tree = lookup_tree(parent);
-       add_ref(&item->object, &item->tree->object);
+       if (item->tree)
+               add_ref(&item->object, &item->tree->object);
        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
+       pptr = &item->parents;
        while (!memcmp(bufptr, "parent ", 7) &&
               !get_sha1_hex(bufptr + 7, parent)) {
                struct commit *new_parent = lookup_commit(parent);
-               commit_list_insert(new_parent, &item->parents);
-               add_ref(&item->object, &new_parent->object);
+               if (new_parent) {
+                       pptr = &commit_list_insert(new_parent, pptr)->next;
+                       add_ref(&item->object, &new_parent->object);
+               }
                bufptr += 48;
        }
        item->date = parse_commit_date(bufptr);
-       free(buffer);
        return 0;
 }
 
-void commit_list_insert(struct commit *item, struct commit_list **list_p)
+int parse_commit(struct commit *item)
+{
+       char type[20];
+       void *buffer;
+       unsigned long size;
+       int ret;
+
+       if (item->object.parsed)
+               return 0;
+       buffer = read_sha1_file(item->object.sha1, type, &size);
+       if (!buffer)
+               return error("Could not read %s",
+                            sha1_to_hex(item->object.sha1));
+       if (strcmp(type, commit_type)) {
+               free(buffer);
+               return error("Object %s not a commit",
+                            sha1_to_hex(item->object.sha1));
+       }
+       ret = parse_commit_buffer(item, buffer, size);
+       if (!ret) {
+               item->buffer = buffer;
+               return 0;
+       }
+       free(buffer);
+       return ret;
+}
+
+struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 {
-       struct commit_list *new_list = malloc(sizeof(struct commit_list));
+       struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
        new_list->item = item;
        new_list->next = *list_p;
        *list_p = new_list;
+       return new_list;
 }
 
 void free_commit_list(struct commit_list *list)
@@ -90,7 +163,7 @@ void free_commit_list(struct commit_list *list)
        }
 }
 
-static void insert_by_date(struct commit_list **list, struct commit *item)
+struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 {
        struct commit_list **pp = list;
        struct commit_list *p;
@@ -100,7 +173,7 @@ static void insert_by_date(struct commit_list **list, struct commit *item)
                }
                pp = &p->next;
        }
-       commit_list_insert(item, pp);
+       return commit_list_insert(item, pp);
 }
 
        
@@ -108,13 +181,14 @@ void sort_by_date(struct commit_list **list)
 {
        struct commit_list *ret = NULL;
        while (*list) {
-               insert_by_date(&ret, (*list)->item);
+               insert_by_date((*list)->item, &ret);
                *list = (*list)->next;
        }
        *list = ret;
 }
 
-struct commit *pop_most_recent_commit(struct commit_list **list)
+struct commit *pop_most_recent_commit(struct commit_list **list,
+                                     unsigned int mark)
 {
        struct commit *ret = (*list)->item;
        struct commit_list *parents = ret->parents;
@@ -124,9 +198,258 @@ struct commit *pop_most_recent_commit(struct commit_list **list)
        free(old);
 
        while (parents) {
-               parse_commit(parents->item);
-               insert_by_date(list, parents->item);
+               struct commit *commit = parents->item;
+               parse_commit(commit);
+               if (!(commit->object.flags & mark)) {
+                       commit->object.flags |= mark;
+                       insert_by_date(commit, list);
+               }
                parents = parents->next;
        }
        return ret;
 }
+
+/*
+ * Generic support for pretty-printing the header
+ */
+static int get_one_line(const char *msg, unsigned long len)
+{
+       int ret = 0;
+
+       while (len--) {
+               char c = *msg++;
+               ret++;
+               if (c == '\n')
+                       break;
+               if (!c)
+                       return 0;
+       }
+       return ret;
+}
+
+static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
+{
+       char *date;
+       unsigned int namelen;
+       unsigned long time;
+       int tz, ret;
+
+       date = strchr(line, '>');
+       if (!date)
+               return 0;
+       namelen = ++date - line;
+       time = strtoul(date, &date, 10);
+       tz = strtol(date, NULL, 10);
+
+       ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
+       if (fmt == CMIT_FMT_MEDIUM)
+               ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
+       return ret;
+}
+
+static int is_empty_line(const char *line, int len)
+{
+       while (len && isspace(line[len-1]))
+               len--;
+       return !len;
+}
+
+static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
+{
+       int offset = 0;
+       switch (parents) {
+       case 1:
+               break;
+       case 2:
+               /* Go back to the previous line: 40 characters of previous parent, and one '\n' */
+               offset = sprintf(buf, "Merge: %.40s\n", line-41);
+               /* Fallthrough */
+       default:
+               /* Replace the previous '\n' with a space */
+               buf[offset-1] = ' ';
+               offset += sprintf(buf + offset, "%.40s\n", line+7);
+       }
+       return offset;
+}
+
+unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
+{
+       int hdr = 1, body = 0;
+       unsigned long offset = 0;
+       int parents = 0;
+
+       for (;;) {
+               const char *line = msg;
+               int linelen = get_one_line(msg, len);
+
+               if (!linelen)
+                       break;
+
+               /*
+                * We want some slop for indentation and a possible
+                * final "...". Thus the "+ 20".
+                */
+               if (offset + linelen + 20 > space) {
+                       memcpy(buf + offset, "    ...\n", 8);
+                       offset += 8;
+                       break;
+               }
+
+               msg += linelen;
+               len -= linelen;
+               if (hdr) {
+                       if (linelen == 1) {
+                               hdr = 0;
+                               buf[offset++] = '\n';
+                               continue;
+                       }
+                       if (fmt == CMIT_FMT_RAW) {
+                               memcpy(buf + offset, line, linelen);
+                               offset += linelen;
+                               continue;
+                       }
+                       if (!memcmp(line, "parent ", 7)) {
+                               if (linelen != 48)
+                                       die("bad parent line in commit");
+                               offset += add_parent_info(fmt, buf + offset, line, ++parents);
+                       }
+                       if (!memcmp(line, "author ", 7))
+                               offset += add_user_info("Author", fmt, buf + offset, line + 7);
+                       if (fmt == CMIT_FMT_FULL) {
+                               if (!memcmp(line, "committer ", 10))
+                                       offset += add_user_info("Commit", fmt, buf + offset, line + 10);
+                       }
+                       continue;
+               }
+
+               if (is_empty_line(line, linelen)) {
+                       if (!body)
+                               continue;
+                       if (fmt == CMIT_FMT_SHORT)
+                               break;
+               } else {
+                       body = 1;
+               }
+               memset(buf + offset, ' ', 4);
+               memcpy(buf + offset + 4, line, linelen);
+               offset += linelen + 4;
+       }
+       /* Make sure there is an EOLN */
+       if (buf[offset - 1] != '\n')
+               buf[offset++] = '\n';
+       buf[offset] = '\0';
+       return offset;
+}
+
+struct commit *pop_commit(struct commit_list **stack)
+{
+       struct commit_list *top = *stack;
+       struct commit *item = top ? top->item : NULL;
+
+       if (top) {
+               *stack = top->next;
+               free(top);
+       }
+       return item;
+}
+
+int count_parents(struct commit * commit)
+{
+        int count = 0;
+        struct commit_list * parents = commit->parents;
+        for (count=0;parents; parents=parents->next,count++)
+          ;
+        return count;
+}
+
+/*
+ * Performs an in-place topological sort on the list supplied.
+ */
+void sort_in_topological_order(struct commit_list ** list)
+{
+       struct commit_list * next = *list;
+       struct commit_list * work = NULL;
+       struct commit_list ** pptr = list;
+       struct sort_node * nodes;
+       struct sort_node * next_nodes;
+       int count = 0;
+
+       /* determine the size of the list */
+       while (next) {
+               next = next->next;
+               count++;
+       }
+       /* allocate an array to help sort the list */
+       nodes = xcalloc(count, sizeof(*nodes));
+       /* link the list to the array */
+       next_nodes = nodes;
+       next=*list;
+       while (next) {
+               next_nodes->list_item = next;
+               next->item->object.util = next_nodes;
+               next_nodes++;
+               next = next->next;
+       }
+       /* update the indegree */
+       next=*list;
+       while (next) {
+               struct commit_list * parents = next->item->parents;
+               while (parents) {
+                       struct commit * parent=parents->item;
+                       struct sort_node * pn = (struct sort_node *)parent->object.util;
+                       
+                       if (pn)
+                               pn->indegree++;
+                       parents=parents->next;
+               }
+               next=next->next;
+       }
+       /* 
+         * find the tips
+         *
+         * tips are nodes not reachable from any other node in the list 
+         * 
+         * the tips serve as a starting set for the work queue.
+         */
+       next=*list;
+       while (next) {
+               struct sort_node * node = (struct sort_node *)next->item->object.util;
+
+               if (node->indegree == 0) {
+                       commit_list_insert(next->item, &work);
+               }
+               next=next->next;
+       }
+       /* process the list in topological order */
+       while (work) {
+               struct commit * work_item = pop_commit(&work);
+               struct sort_node * work_node = (struct sort_node *)work_item->object.util;
+               struct commit_list * parents = work_item->parents;
+
+               while (parents) {
+                       struct commit * parent=parents->item;
+                       struct sort_node * pn = (struct sort_node *)parent->object.util;
+                       
+                       if (pn) {
+                               /* 
+                                * parents are only enqueued for emission 
+                                 * when all their children have been emitted thereby
+                                 * guaranteeing topological order.
+                                 */
+                               pn->indegree--;
+                               if (!pn->indegree) 
+                                       commit_list_insert(parent, &work);
+                       }
+                       parents=parents->next;
+               }
+               /*
+                 * work_item is a commit all of whose children
+                 * have already been emitted. we can emit it now.
+                 */
+               *pptr = work_node->list_item;
+               pptr = &(*pptr)->next;
+               *pptr = NULL;
+               work_item->object.util = NULL;
+       }
+       free(nodes);
+}