1 files changed, 295 insertions, 0 deletions
diff --git a/line-range.c b/line-range.c
new file mode 100644
index 000000000000..9b50583dc051
--- /dev/null
+++ b/line-range.c
@@ -0,0 +1,295 @@
+#include "git-compat-util.h"
+#include "line-range.h"
+#include "xdiff-interface.h"
+#include "strbuf.h"
+#include "userdiff.h"
+
+/*
+ * Parse one item in the -L option
+ *
+ * 'begin' is applicable only to relative range anchors. Absolute anchors
+ * ignore this value.
+ *
+ * When parsing "-L A,B", parse_loc() is called once for A and once for B.
+ *
+ * When parsing A, 'begin' must be a negative number, the absolute value of
+ * which is the line at which relative start-of-range anchors should be
+ * based. Beginning of file is represented by -1.
+ *
+ * When parsing B, 'begin' must be the positive line number immediately
+ * following the line computed for 'A'.
+ */
+static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
+			     void *data, long lines, long begin, long *ret)
+{
+	char *term;
+	const char *line;
+	long num;
+	int reg_error;
+	regex_t regexp;
+	regmatch_t match[1];
+
+	/* Allow "-L <something>,+20" to mean starting at <something>
+	 * for 20 lines, or "-L <something>,-5" for 5 lines ending at
+	 * <something>.
+	 */
+	if (1 <= begin && (spec[0] == '+' || spec[0] == '-')) {
+		num = strtol(spec + 1, &term, 10);
+		if (term != spec + 1) {
+			if (!ret)
+				return term;
+			if (num == 0)
+				die("-L invalid empty range");
+			if (spec[0] == '-')
+				num = 0 - num;
+			if (0 < num)
+				*ret = begin + num - 2;
+			else if (!num)
+				*ret = begin;
+			else
+				*ret = begin + num > 0 ? begin + num : 1;
+			return term;
+		}
+		return spec;
+	}
+	num = strtol(spec, &term, 10);
+	if (term != spec) {
+		if (ret) {
+			if (num <= 0)
+				die("-L invalid line number: %ld", num);
+			*ret = num;
+		}
+		return term;
+	}
+
+	if (begin < 0) {
+		if (spec[0] != '^')
+			begin = -begin;
+		else {
+			begin = 1;
+			spec++;
+		}
+	}
+
+	if (spec[0] != '/')
+		return spec;
+
+	/* it could be a regexp of form /.../ */
+	for (term = (char *) spec + 1; *term && *term != '/'; term++) {
+		if (*term == '\\')
+			term++;
+	}
+	if (*term != '/')
+		return spec;
+
+	/* in the scan-only case we are not interested in the regex */
+	if (!ret)
+		return term+1;
+
+	/* try [spec+1 .. term-1] as regexp */
+	*term = 0;
+	begin--; /* input is in human terms */
+	line = nth_line(data, begin);
+
+	if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&
+	    !(reg_error = regexec(&regexp, line, 1, match, 0))) {
+		const char *cp = line + match[0].rm_so;
+		const char *nline;
+
+		while (begin++ < lines) {
+			nline = nth_line(data, begin);
+			if (line <= cp && cp < nline)
+				break;
+			line = nline;
+		}
+		*ret = begin;
+		regfree(&regexp);
+		*term++ = '/';
+		return term;
+	}
+	else {
+		char errbuf[1024];
+		regerror(reg_error, &regexp, errbuf, 1024);
+		die("-L parameter '%s' starting at line %ld: %s",
+		    spec + 1, begin + 1, errbuf);
+	}
+}
+
+static int match_funcname(xdemitconf_t *xecfg, const char *bol, const char *eol)
+{
+	if (xecfg) {
+		char buf[1];
+		return xecfg->find_func(bol, eol - bol, buf, 1,
+					xecfg->find_func_priv) >= 0;
+	}
+
+	if (bol == eol)
+		return 0;
+	if (isalpha(*bol) || *bol == '_' || *bol == '$')
+		return 1;
+	return 0;
+}
+
+static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char *start,
+						 regex_t *regexp)
+{
+	int reg_error;
+	regmatch_t match[1];
+	while (1) {
+		const char *bol, *eol;
+		reg_error = regexec(regexp, start, 1, match, 0);
+		if (reg_error == REG_NOMATCH)
+			return NULL;
+		else if (reg_error) {
+			char errbuf[1024];
+			regerror(reg_error, regexp, errbuf, 1024);
+			die("-L parameter: regexec() failed: %s", errbuf);
+		}
+		/* determine extent of line matched */
+		bol = start+match[0].rm_so;
+		eol = start+match[0].rm_eo;
+		while (bol > start && *bol != '\n')
+			bol--;
+		if (*bol == '\n')
+			bol++;
+		while (*eol && *eol != '\n')
+			eol++;
+		if (*eol == '\n')
+			eol++;
+		/* is it a funcname line? */
+		if (match_funcname(xecfg, (char*) bol, (char*) eol))
+			return bol;
+		start = eol;
+	}
+}
+
+static const char *parse_range_funcname(
+	const char *arg, nth_line_fn_t nth_line_cb,
+	void *cb_data, long lines, long anchor, long *begin, long *end,
+	const char *path, struct index_state *istate)
+{
+	char *pattern;
+	const char *term;
+	struct userdiff_driver *drv;
+	xdemitconf_t *xecfg = NULL;
+	const char *start;
+	const char *p;
+	int reg_error;
+	regex_t regexp;
+
+	if (*arg == '^') {
+		anchor = 1;
+		arg++;
+	}
+
+	assert(*arg == ':');
+	term = arg+1;
+	while (*term && *term != ':') {
+		if (*term == '\\' && *(term+1))
+			term++;
+		term++;
+	}
+	if (term == arg+1)
+		return NULL;
+	if (!begin) /* skip_range_arg case */
+		return term;
+
+	pattern = xstrndup(arg+1, term-(arg+1));
+
+	anchor--; /* input is in human terms */
+	start = nth_line_cb(cb_data, anchor);
+
+	drv = userdiff_find_by_path(istate, path);
+	if (drv && drv->funcname.pattern) {
+		const struct userdiff_funcname *pe = &drv->funcname;
+		xecfg = xcalloc(1, sizeof(*xecfg));
+		xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);
+	}
+
+	reg_error = regcomp(&regexp, pattern, REG_NEWLINE);
+	if (reg_error) {
+		char errbuf[1024];
+		regerror(reg_error, &regexp, errbuf, 1024);
+		die("-L parameter '%s': %s", pattern, errbuf);
+	}
+
+	p = find_funcname_matching_regexp(xecfg, (char*) start, &regexp);
+	if (!p)
+		die("-L parameter '%s' starting at line %ld: no match",
+		    pattern, anchor + 1);
+	*begin = 0;
+	while (p > nth_line_cb(cb_data, *begin))
+		(*begin)++;
+
+	if (*begin >= lines)
+		die("-L parameter '%s' matches at EOF", pattern);
+
+	*end = *begin+1;
+	while (*end < lines) {
+		const char *bol = nth_line_cb(cb_data, *end);
+		const char *eol = nth_line_cb(cb_data, *end+1);
+		if (match_funcname(xecfg, bol, eol))
+			break;
+		(*end)++;
+	}
+
+	regfree(&regexp);
+	free(xecfg);
+	free(pattern);
+
+	/* compensate for 1-based numbering */
+	(*begin)++;
+
+	return term;
+}
+
+int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,
+		    void *cb_data, long lines, long anchor,
+		    long *begin, long *end,
+		    const char *path, struct index_state *istate)
+{
+	*begin = *end = 0;
+
+	if (anchor < 1)
+		anchor = 1;
+	if (anchor > lines)
+		anchor = lines + 1;
+
+	if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':')) {
+		arg = parse_range_funcname(arg, nth_line_cb, cb_data,
+					   lines, anchor, begin, end,
+					   path, istate);
+		if (!arg || *arg)
+			return -1;
+		return 0;
+	}
+
+	arg = parse_loc(arg, nth_line_cb, cb_data, lines, -anchor, begin);
+
+	if (*arg == ',')
+		arg = parse_loc(arg + 1, nth_line_cb, cb_data, lines, *begin + 1, end);
+
+	if (*arg)
+		return -1;
+
+	if (*begin && *end && *end < *begin) {
+		SWAP(*end, *begin);
+	}
+
+	return 0;
+}
+
+const char *skip_range_arg(const char *arg, struct index_state *istate)
+{
+	if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':'))
+		return parse_range_funcname(arg, NULL, NULL,
+					    0, 0, NULL, NULL,
+					    NULL, istate);
+
+	arg = parse_loc(arg, NULL, NULL, 0, -1, NULL);
+
+	if (*arg == ',')
+		arg = parse_loc(arg+1, NULL, NULL, 0, 0, NULL);
+
+	return arg;
+}