tvl-depot/third_party/git/graph.h
Vincent Ambo f4609b896f merge(3p/git): Merge git subtree at v2.29.2
This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb
2020-11-21 19:45:56 +01:00

260 lines
8.6 KiB
C

#ifndef GRAPH_H
#define GRAPH_H
#include "diff.h"
/**
* The graph API is used to draw a text-based representation of the commit
* history. The API generates the graph in a line-by-line fashion.
*
* Calling sequence
* ----------------
*
* - Create a `struct git_graph` by calling `graph_init()`. When using the
* revision walking API, this is done automatically by `setup_revisions()` if
* the '--graph' option is supplied.
*
* - Use the revision walking API to walk through a group of contiguous commits.
* The `get_revision()` function automatically calls `graph_update()` each time
* it is invoked.
*
* - For each commit, call `graph_next_line()` repeatedly, until
* `graph_is_commit_finished()` returns non-zero. Each call to
* `graph_next_line()` will output a single line of the graph. The resulting
* lines will not contain any newlines. `graph_next_line()` returns 1 if the
* resulting line contains the current commit, or 0 if this is merely a line
* needed to adjust the graph before or after the current commit. This return
* value can be used to determine where to print the commit summary information
* alongside the graph output.
*
* Limitations
* -----------
* - Check the graph_update() function for its limitations.
*
* - The graph API does not currently support reverse commit ordering. In
* order to implement reverse ordering, the graphing API needs an
* (efficient) mechanism to find the children of a commit.
*
* Sample usage
* ------------
*
* ------------
* struct commit *commit;
* struct git_graph *graph = graph_init(opts);
*
* while ((commit = get_revision(opts)) != NULL) {
* while (!graph_is_commit_finished(graph))
* {
* struct strbuf sb;
* int is_commit_line;
*
* strbuf_init(&sb, 0);
* is_commit_line = graph_next_line(graph, &sb);
* fputs(sb.buf, stdout);
*
* if (is_commit_line)
* log_tree_commit(opts, commit);
* else
* putchar(opts->diffopt.line_termination);
* }
* }
* ------------
* Sample output
* -------------
*
* The following is an example of the output from the graph API. This output does
* not include any commit summary information--callers are responsible for
* outputting that information, if desired.
* ------------
* *
* *
* *
* |\
* * |
* | | *
* | \ \
* | \ \
* *-. \ \
* |\ \ \ \
* | | * | |
* | | | | | *
* | | | | | *
* | | | | | *
* | | | | | |\
* | | | | | | *
* | * | | | | |
* | | | | | * \
* | | | | | |\ |
* | | | | * | | |
* | | | | * | | |
* * | | | | | | |
* | |/ / / / / /
* |/| / / / / /
* * | | | | | |
* |/ / / / / /
* * | | | | |
* | | | | | *
* | | | | |/
* | | | | *
* ------------
*
*/
/* A graph is a pointer to this opaque structure */
struct git_graph;
/*
* Called to setup global display of line_prefix diff option.
*
* Passed a diff_options structure which indicates the line_prefix and the
* file to output the prefix to. This is sort of a hack used so that the
* line_prefix will be honored by all flows which also honor "--graph"
* regardless of whether a graph has actually been setup. The normal graph
* flow will honor the exact diff_options passed, but a NULL graph will cause
* display of a line_prefix to stdout.
*/
void graph_setup_line_prefix(struct diff_options *diffopt);
/*
* Set up a custom scheme for column colors.
*
* The default column color scheme inserts ANSI color escapes to colorize
* the graph. The various color escapes are stored in an array of strings
* where each entry corresponds to a color, except for the last entry,
* which denotes the escape for resetting the color back to the default.
* When generating the graph, strings from this array are inserted before
* and after the various column characters.
*
* This function allows you to enable a custom array of color escapes.
* The 'colors_max' argument is the index of the last "reset" entry.
*
* This functions must be called BEFORE graph_init() is called.
*
* NOTE: This function isn't used in Git outside graph.c but it is used
* by CGit (http://git.zx2c4.com/cgit/) to use HTML for colors.
*/
void graph_set_column_colors(const char **colors, unsigned short colors_max);
/*
* Create a new struct git_graph.
*/
struct git_graph *graph_init(struct rev_info *opt);
/*
* Update a git_graph with a new commit.
* This will cause the graph to begin outputting lines for the new commit
* the next time graph_next_line() is called.
*
* If graph_update() is called before graph_is_commit_finished() returns 1,
* the next call to graph_next_line() will output an ellipsis ("...")
* to indicate that a portion of the graph is missing.
*
* Limitations:
* -----------
*
* - `graph_update()` must be called with commits in topological order. It should
* not be called on a commit if it has already been invoked with an ancestor of
* that commit, or the graph output will be incorrect.
*
* - `graph_update()` must be called on a contiguous group of commits. If
* `graph_update()` is called on a particular commit, it should later be called
* on all parents of that commit. Parents must not be skipped, or the graph
* output will appear incorrect.
*
* - `graph_update()` may be used on a pruned set of commits only if the parent list
* has been rewritten so as to include only ancestors from the pruned set.
*/
void graph_update(struct git_graph *graph, struct commit *commit);
/*
* Determine if a graph has finished outputting lines for the current
* commit.
*
* Returns 1 if graph_next_line() needs to be called again before
* graph_update() should be called. Returns 0 if no more lines are needed
* for this commit. If 0 is returned, graph_next_line() may still be
* called without calling graph_update(), and it will merely output
* appropriate "vertical padding" in the graph.
*
* If `graph_update()` is called before all lines for the current commit have
* been printed, the next call to `graph_next_line()` will output an ellipsis,
* to indicate that a portion of the graph was omitted.
*/
int graph_is_commit_finished(struct git_graph const *graph);
/*
* Output the next line for a graph.
* This formats the next graph line into the specified strbuf. It is not
* terminated with a newline.
*
* Returns 1 if the line includes the current commit, and 0 otherwise.
* graph_next_line() will return 1 exactly once for each time
* graph_update() is called.
*
* NOTE: This function isn't used in Git outside graph.c but it is used
* by CGit (http://git.zx2c4.com/cgit/) to wrap HTML around graph lines.
*/
int graph_next_line(struct git_graph *graph, struct strbuf *sb);
/*
* Return current width of the graph in on-screen characters.
*/
int graph_width(struct git_graph *graph);
/*
* graph_show_*: helper functions for printing to stdout
*/
/*
* If the graph is non-NULL, print the history graph to stdout,
* up to and including the line containing this commit.
* Does not print a terminating newline on the last line.
*/
void graph_show_commit(struct git_graph *graph);
/*
* If the graph is non-NULL, print one line of the history graph to stdout.
* Does not print a terminating newline on the last line.
*/
void graph_show_oneline(struct git_graph *graph);
/*
* If the graph is non-NULL, print one line of vertical graph padding to
* stdout. Does not print a terminating newline on the last line.
*/
void graph_show_padding(struct git_graph *graph);
/*
* If the graph is non-NULL, print the rest of the history graph for this
* commit to stdout. Does not print a terminating newline on the last line.
* Returns 1 if output was printed, and 0 if no output was necessary.
*/
int graph_show_remainder(struct git_graph *graph);
/*
* Print a commit message strbuf and the remainder of the graph to stdout.
*
* This is similar to graph_show_strbuf(), but it always prints the
* remainder of the graph.
*
* It is better than directly calling `graph_show_strbuf()` followed by
* `graph_show_remainder()` since it properly handles buffers that do not end in
* a terminating newline.
*
* If the strbuf ends with a newline, the output printed by
* graph_show_commit_msg() will end with a newline. If the strbuf is
* missing a terminating newline (including if it is empty), the output
* printed by graph_show_commit_msg() will also be missing a terminating
* newline.
*
* Note that unlike some other graph display functions, you must pass the file
* handle directly. It is assumed that this is the same file handle as the
* file specified by the graph diff options. This is necessary so that
* graph_show_commit_msg can be called even with a NULL graph.
*/
void graph_show_commit_msg(struct git_graph *graph,
FILE *file,
struct strbuf const *sb);
#endif /* GRAPH_H */