Implement libfonts_decode_font_description

Signed-off-by: Mattias Andrée <maandree@kth.se>

2 files changed, 217 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 53e9215..978519e 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,7 @@ LIB_NAME = fonts
 
 OBJ =\
 	libfonts_calculate_subpixel_order.o\
+	libfonts_decode_font_description.o\
 	libfonts_encode_font_description.o\
 	libfonts_get_output_dpi.o
 
diff --git a/libfonts_decode_font_description.c b/libfonts_decode_font_description.c
new file mode 100644
index 0000000..329d338
--- /dev/null
+++ b/libfonts_decode_font_description.c
@@ -0,0 +1,216 @@
+/* See LICENSE file for copyright and license details. */
+#include "libfonts.h"
+#include <ctype.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LIST_FIELDS_EXCEPT_FINAL(X)\
+	X(foundry)\
+	X(family_name)\
+	X(weight_name)\
+	X(slant)\
+	X(setwidth_name)\
+	X(add_style_name)\
+	X(pixel_size)\
+	X(point_size)\
+	X(resolution_x)\
+	X(resolution_y)\
+	X(spacing)\
+	X(average_width)\
+	X(charset_registry)
+
+struct range {
+	uint32_t first;
+	uint32_t last;
+};
+
+static int
+parse_hexadecimal(const char *s, const char **endp, uint32_t *valuep)
+{
+	uint64_t r = 0;
+	if (!isxdigit(*s))
+		return -1;
+	for (;; s++) {
+		if (isdigit(*s))
+			r = (r * 16) | (*s & 15);
+		else if (isxdigit(*s))
+			r = (r * 16) | ((*s & 15) + 9);
+		else
+			break;
+		if (r > INT32_MAX)
+			return -1;
+	}
+	*endp = s;
+	*valuep = (uint32_t)r;
+	return 0;
+}
+
+static int
+parse_decimal(const char *s, const char **endp, uint32_t *valuep)
+{
+	uint64_t r = 0;
+	if (!isdigit(*s))
+		return -1;
+	for (; isdigit(*s); s++) {
+		r = r * 10 + (*s & 15);
+		if (r > INT32_MAX)
+			return -1;
+	}
+	*endp = s;
+	*valuep = (uint32_t)r;
+	return 0;
+}
+
+static int
+parse_number(const char *s, const char **endp, uint32_t *valuep)
+{
+	if (s[0] == '0' && s[1] == 'x')
+		return parse_hexadecimal(&s[2], endp, valuep);
+	else
+		return parse_decimal(&s[0], endp, valuep);
+}
+
+static int
+cmprange(const void *av, const void *bv)
+{
+	const struct range *a = av, *b = bv;
+	return a->first < b->first ? -1 : a->first > b->first;
+}
+
+static int
+fix_charset_subset(char *out, const char *in)
+{
+	struct range ranges[128], saved;
+	size_t i, n = 0;
+	const char *s;
+	uint32_t t;
+
+	for (s = in; *s; s++) {
+		if (*s == ' ')
+			continue;
+		if (parse_number(s, &s, &ranges[0].first))
+			return -1;
+		if (*s == '_') {
+			if (parse_number(&s[1], &s, &ranges[0].last))
+				return -1;
+			if (ranges[0].first > ranges[0].last) {
+				t = ranges[0].first;
+				ranges[0].first = ranges[0].last;
+				ranges[0].last = t;
+			}
+		} else {
+			ranges[0].last = ranges[0].first;
+		}
+		if (*s && *s != ' ')
+			return -1;
+	}
+
+	if (!n) {
+		*out = '\0';
+		return 0;
+	}
+
+	qsort(ranges, n, sizeof(*ranges), cmprange);
+	saved = ranges[0];
+	for (i = 1; i < n; i++) {
+		if (ranges[i].first <= saved.last) {
+			saved.last = ranges[i].last;
+		} else {
+			if (saved.first == saved.last)
+				out += sprintf(out, "%"PRId32" ", saved.first);
+			else
+				out += sprintf(out, "%"PRId32"-%"PRId32" ", saved.first, saved.last);
+			saved = ranges[i];
+		}
+	}
+	if (saved.first == saved.last)
+		out += sprintf(out, "%"PRId32" ", saved.first);
+	else
+		out += sprintf(out, "%"PRId32"-%"PRId32" ", saved.first, saved.last);
+
+	out[-1] = '\0';
+	return 0;
+}
+
+int
+libfonts_decode_font_description(struct libfonts_font_description *desc, const char *in)
+{
+	char subset[256];
+	const char *s = in;
+	char *buf, *ss = subset;
+	int have_subset = 0;
+	int in_subset = 0;
+
+	if (strlen(in) > 255) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(desc, 0, sizeof(*desc));
+	buf = desc->_buf;
+
+	if (*s == '+') {
+		desc->xlfd_version = buf;
+		for (s++; *s && *s != '-'; s++)
+			*buf++ = *s == '~' ? '-' : *s;
+		*buf++ = '\0';
+	}
+
+#define X(F)\
+	if (*s != '-')\
+		goto private;\
+	desc->F = buf;\
+	for (s++; *s && *s != '-'; s++)\
+		*buf++ = *s == '~' ? '-' : *s;\
+	*buf++ = '\0';
+	LIST_FIELDS_EXCEPT_FINAL(X)
+#undef X
+
+	if (*s != '-')
+		goto private;
+	desc->charset_encoding = buf;
+	for (s++; *s && *s != '-'; s++) {
+		if (in_subset) {
+			if (*s == ']')
+				in_subset = 0;
+			else
+				*ss++ = *s == '~' ? '-' : *s;
+		} else {
+			if (*s == '[') {
+				in_subset = 1;
+				if (have_subset)
+					*ss++ = ' ';
+				else
+					have_subset = 1;
+			} else {
+				*buf++ = *s == '~' ? '-' : *s;
+			}
+		}
+	}
+	*buf++ = '\0';
+	if (in_subset)
+		goto private;
+	if (have_subset) {
+		*ss = '\0';
+		desc->charset_subset = buf;
+		if (fix_charset_subset(buf, subset))
+			goto private;
+	}
+
+	if (*s == '-') {
+		desc->unrecognised_fields = buf;
+		stpcpy(buf, &s[1]);
+	}
+
+	return 0;
+
+private:
+	memset(desc, 0, sizeof(*desc));
+	stpcpy(desc->_buf, in);
+	desc->private_font_name = desc->_buf;
+	return 0;
+}