Merge pull request #2592 from libgit2/cmn/describe

Implement git-describe

4 files changed, 166 insertions, 0 deletions

diff --git a/include/git2.h b/include/git2.h
index d84353955..baa7fcaf8 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -19,6 +19,7 @@
 #include "git2/commit.h"
 #include "git2/common.h"
 #include "git2/config.h"
+#include "git2/describe.h"
 #include "git2/diff.h"
 #include "git2/errors.h"
 #include "git2/filter.h"
diff --git a/include/git2/common.h b/include/git2/common.h
index 32237efed..ceb27205a 100644
--- a/include/git2/common.h
+++ b/include/git2/common.h
@@ -83,6 +83,8 @@ GIT_BEGIN_DECL
  */
 #define GIT_OID_HEX_ZERO "0000000000000000000000000000000000000000"
 
+#define FLAG_BITS 27
+
 /**
  * Return the version of the libgit2 library
  * being currently used.
diff --git a/include/git2/describe.h b/include/git2/describe.h
new file mode 100644
index 000000000..66b88c4fa
--- /dev/null
+++ b/include/git2/describe.h
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_describe_h__
+#define INCLUDE_git_describe_h__
+
+#include "common.h"
+#include "types.h"
+#include "buffer.h"
+
+/**
+ * @file git2/describe.h
+ * @brief Git describing routines
+ * @defgroup git_describe Git describing routines
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Reference lookup strategy
+ *
+ * These behave like the --tags and --all optios to git-describe,
+ * namely they say to look for any reference in either refs/tags/ or
+ * refs/ respectively.
+ */
+typedef enum {
+	GIT_DESCRIBE_DEFAULT,
+	GIT_DESCRIBE_TAGS,
+	GIT_DESCRIBE_ALL,
+} git_describe_strategy_t;
+
+/**
+ * Describe options structure
+ *
+ * Initialize with `GIT_DESCRIBE_OPTIONS_INIT` macro to correctly set
+ * the `version` field.  E.g.
+ *
+ *		git_describe_options opts = GIT_DESCRIBE_OPTIONS_INIT;
+ */
+typedef struct git_describe_options {
+	unsigned int version;
+
+	unsigned int max_candidates_tags; /** default: 10 */
+	unsigned int describe_strategy; /** default: GIT_DESCRIBE_DEFAULT */
+	const char *pattern;
+	/**
+	 * When calculating the distance from the matching tag or
+	 * reference, only walk down the first-parent ancestry.
+	 */
+	int only_follow_first_parent;
+	/**
+	 * If no matching tag or reference is found, the describe
+	 * operation would normally fail. If this option is set, it
+	 * will instead fall back to showing the full id of the
+	 * commit.
+	 */
+	int show_commit_oid_as_fallback;
+} git_describe_options;
+
+#define GIT_DESCRIBE_DEFAULT_MAX_CANDIDATES_TAGS 10
+#define GIT_DESCRIBE_DEFAULT_ABBREVIATED_SIZE 7
+
+#define GIT_DESCRIBE_OPTIONS_VERSION 1
+#define GIT_DESCRIBE_OPTIONS_INIT { \
+	GIT_DESCRIBE_OPTIONS_VERSION, \
+	GIT_DESCRIBE_DEFAULT_MAX_CANDIDATES_TAGS, \
+}
+
+GIT_EXTERN(int) git_describe_init_options(git_describe_options *opts, unsigned int version);
+
+/**
+ * Options for formatting the describe string
+ */
+typedef struct {
+	unsigned int version;
+
+	/**
+	 * Size of the abbreviated commit id to use. This value is the
+	 * lower bound for the length of the abbreviated string. The
+	 * default is 7.
+	 */
+	unsigned int abbreviated_size;
+
+	/**
+	 * Set to use the long format even when a shorter name could be used.
+	 */
+	int always_use_long_format;
+
+	/**
+	 * If the workdir is dirty and this is set, this string will
+	 * be appended to the description string.
+	 */
+	char *dirty_suffix;
+} git_describe_format_options;
+
+#define GIT_DESCRIBE_FORMAT_OPTIONS_VERSION 1
+#define GIT_DESCRIBE_FORMAT_OPTIONS_INIT { \
+		GIT_DESCRIBE_FORMAT_OPTIONS_VERSION,   \
+		GIT_DESCRIBE_DEFAULT_ABBREVIATED_SIZE, \
+ }
+
+GIT_EXTERN(int) git_describe_init_format_options(git_describe_format_options *opts, unsigned int version);
+
+typedef struct git_describe_result git_describe_result;
+
+/**
+ * Describe a commit
+ *
+ * Perform the describe operation on the given committish object.
+ *
+ * @param result pointer to store the result. You must free this once
+ * you're done with it.
+ * @param committish a committish to describe
+ * @param opts the lookup options
+ */
+GIT_EXTERN(int) git_describe_commit(
+	git_describe_result **result,
+	git_object *committish,
+	git_describe_options *opts);
+
+/**
+ * Describe a commit
+ *
+ * Perform the describe operation on the current commit and the
+ * worktree. After peforming describe on HEAD, a status is run and the
+ * description is considered to be dirty if there are.
+ *
+ * @param result pointer to store the result. You must free this once
+ * you're done with it.
+ * @param repo the repository in which to perform the describe
+ * @param opts the lookup options
+ */
+GIT_EXTERN(int) git_describe_workdir(
+	git_describe_result **out,
+	git_repository *repo,
+	git_describe_options *opts);
+
+/**
+ * Print the describe result to a buffer
+ *
+ * @param result the result from `git_describe_commit()` or
+ * `git_describe_workdir()`.
+ * @param opt the formatting options
+ */
+GIT_EXTERN(int) git_describe_format(
+	git_buf *out,
+	const git_describe_result *result,
+	const git_describe_format_options *opts);
+
+/**
+ * Free the describe result.
+ */
+GIT_EXTERN(void) git_describe_result_free(git_describe_result *result);
+
+/** @} */
+GIT_END_DECL
+
+#endif
diff --git a/include/git2/errors.h b/include/git2/errors.h
index 2ba9924f5..1e3ed3acb 100644
--- a/include/git2/errors.h
+++ b/include/git2/errors.h
@@ -89,6 +89,7 @@ typedef enum {
 	GITERR_REVERT,
 	GITERR_CALLBACK,
 	GITERR_CHERRYPICK,
+	GITERR_DESCRIBE,
 } git_error_t;
 
 /**