builtin-grep: make pieces of it available as library.

This makes three functions and associated option structures from
builtin-grep available from other parts of the system.

 * options to drive built-in grep engine is stored in struct
   grep_opt;

 * pattern strings and extended grep expressions are added to
   struct grep_opt with append_grep_pattern();

 * when finished calling append_grep_pattern(), call
   compile_grep_patterns() to prepare for execution;

 * call grep_buffer() to find matches in the in-core buffer.

This also adds an internal option "status_only" to grep_opt,
which suppresses any output from grep_buffer().  Callers of the
function as library can use it to check if there is a match
without producing any output.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 71 insertions, 0 deletions

diff --git a/grep.h b/grep.h
new file mode 100644
index 0000000..80122b0
--- /dev/null
+++ b/grep.h
@@ -0,0 +1,71 @@
+#ifndef GREP_H
+#define GREP_H
+
+enum grep_pat_token {
+	GREP_PATTERN,
+	GREP_AND,
+	GREP_OPEN_PAREN,
+	GREP_CLOSE_PAREN,
+	GREP_NOT,
+	GREP_OR,
+};
+
+struct grep_pat {
+	struct grep_pat *next;
+	const char *origin;
+	int no;
+	enum grep_pat_token token;
+	const char *pattern;
+	regex_t regexp;
+};
+
+enum grep_expr_node {
+	GREP_NODE_ATOM,
+	GREP_NODE_NOT,
+	GREP_NODE_AND,
+	GREP_NODE_OR,
+};
+
+struct grep_expr {
+	enum grep_expr_node node;
+	union {
+		struct grep_pat *atom;
+		struct grep_expr *unary;
+		struct {
+			struct grep_expr *left;
+			struct grep_expr *right;
+		} binary;
+	} u;
+};
+
+struct grep_opt {
+	struct grep_pat *pattern_list;
+	struct grep_pat **pattern_tail;
+	struct grep_expr *pattern_expression;
+	int prefix_length;
+	regex_t regexp;
+	unsigned linenum:1;
+	unsigned invert:1;
+	unsigned status_only:1;
+	unsigned name_only:1;
+	unsigned unmatch_name_only:1;
+	unsigned count:1;
+	unsigned word_regexp:1;
+	unsigned fixed:1;
+#define GREP_BINARY_DEFAULT	0
+#define GREP_BINARY_NOMATCH	1
+#define GREP_BINARY_TEXT	2
+	unsigned binary:2;
+	unsigned extended:1;
+	unsigned relative:1;
+	unsigned pathname:1;
+	int regflags;
+	unsigned pre_context;
+	unsigned post_context;
+};
+
+extern void append_grep_pattern(struct grep_opt *opt, const char *pat, const char *origin, int no, enum grep_pat_token t);
+extern void compile_grep_patterns(struct grep_opt *opt);
+extern int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsigned long size);
+
+#endif