[PATCH 03/10] graph: move doc to graph.h and graph.c

From

Heba Waly via GitGitGadget <gitgitgadget@gmail.com>

Date

Oct 29, 2019, 10:00 UTC

Message-ID

<dabfe5e60baee8fa4c5ff72a832348125fa410b6.1572343246.git.gitgitgadget@gmail.com>

In-Reply-To

<pull.434.git.1572343246.gitgitgadget@gmail.com>

From: Heba Waly <heba.waly@gmail.com>

Signed-off-by: Heba Waly <heba.waly@gmail.com>
---
 Documentation/technical/api-history-graph.txt | 173 ------------------
 graph.c                                       |   1 +
 graph.h                                       | 121 ++++++++++++
 3 files changed, 122 insertions(+), 173 deletions(-)
 delete mode 100644 Documentation/technical/api-history-graph.txt

diff --git a/Documentation/technical/api-history-graph.txt b/Documentation/technical/api-history-graph.txt
deleted file mode 100644
index d0d1707c8c..0000000000
--- a/Documentation/technical/api-history-graph.txt
+++ /dev/null
@@ -1,173 +0,0 @@
-history graph API
-=================
-
-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.
-
-Functions
----------
-
-Core functions:
-
-* `graph_init()` creates a new `struct git_graph`
-
-* `graph_update()` moves the graph to a new commit.
-
-* `graph_next_line()` outputs the next line of the graph into a strbuf.  It
-  does not add a terminating newline.
-
-* `graph_padding_line()` outputs a line of vertical padding in the graph.  It
-  is similar to `graph_next_line()`, but is guaranteed to never print the line
-  containing the current commit.  Where `graph_next_line()` would print the
-  commit line next, `graph_padding_line()` prints a line that simply extends
-  all branch lines downwards one row, leaving their positions unchanged.
-
-* `graph_is_commit_finished()` determines if the graph has output all lines
-  necessary for the current commit.  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.
-
-The following utility functions are wrappers around `graph_next_line()` and
-`graph_is_commit_finished()`.  They always print the output to stdout.
-They can all be called with a NULL graph argument, in which case no graph
-output will be printed.
-
-* `graph_show_commit()` calls `graph_next_line()` and
-  `graph_is_commit_finished()` until one of them return non-zero.  This prints
-  all graph lines up to, and including, the line containing this commit.
-  Output is printed to stdout.  The last line printed does not contain a
-  terminating newline.
-
-* `graph_show_oneline()` calls `graph_next_line()` and prints the result to
-  stdout.  The line printed does not contain a terminating newline.
-
-* `graph_show_padding()` calls `graph_padding_line()` and prints the result to
-  stdout.  The line printed does not contain a terminating newline.
-
-* `graph_show_remainder()` calls `graph_next_line()` until
-  `graph_is_commit_finished()` returns non-zero.  Output is printed to stdout.
-  The last line printed does not contain a terminating newline.  Returns 1 if
-  output was printed, and 0 if no output was necessary.
-
-* `graph_show_strbuf()` prints the specified strbuf to stdout, prefixing all
-  lines but the first with a graph line.  The caller is responsible for
-  ensuring graph output for the first line has already been printed to stdout.
-  (This can be done with `graph_show_commit()` or `graph_show_oneline()`.)  If
-  a NULL graph is supplied, the strbuf is printed as-is.
-
-* `graph_show_commit_msg()` is similar to `graph_show_strbuf()`, but it also
-  prints the remainder of the graph, if more lines are needed after the strbuf
-  ends.  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.  The output printed by `graph_show_commit_msg()` will
-  end in a newline if and only if the strbuf ends in a newline.
-
-Data structure
---------------
-`struct git_graph` is an opaque data type used to store the current graph
-state.
-
-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
------------
-
-* `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.
-
-* 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.
-
-------------
-*
-*
-*
-|\
-* |
-| | *
-| \ \
-|  \ \
-*-. \ \
-|\ \ \ \
-| | * | |
-| | | | | *
-| | | | | *
-| | | | | *
-| | | | | |\
-| | | | | | *
-| * | | | | |
-| | | | | *  \
-| | | | | |\  |
-| | | | * | | |
-| | | | * | | |
-* | | | | | | |
-| |/ / / / / /
-|/| / / / / /
-* | | | | | |
-|/ / / / / /
-* | | | | |
-| | | | | *
-| | | | |/
-| | | | *
-------------
diff --git a/graph.c b/graph.c
index f53135485f..eab3af1dc7 100644
--- a/graph.c
+++ b/graph.c
@@ -34,6 +34,7 @@ static void graph_padding_line(struct git_graph *graph, struct strbuf *sb);
  * 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_strbuf can be called even with a NULL graph.
+ * If a NULL graph is supplied, the strbuf is printed as-is.
  */
 static void graph_show_strbuf(struct git_graph *graph,
 			      FILE *file,
diff --git a/graph.h b/graph.h
index af623390b6..8313e293c7 100644
--- a/graph.h
+++ b/graph.h
@@ -2,6 +2,103 @@
 #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;
 
@@ -50,6 +147,21 @@ struct git_graph *graph_init(struct rev_info *opt);
  * 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);
 
@@ -62,6 +174,10 @@ void graph_update(struct git_graph *graph, struct commit *commit);
  * 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);
 
@@ -112,6 +228,7 @@ 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);
 
@@ -121,6 +238,10 @@ int graph_show_remainder(struct git_graph *graph);
  * 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

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