parser: implement octal and hex literals v1 PROPOSED

Cormac Stephenson: 1
 parser: implement octal and hex literals

 2 files changed, 54 insertions(+), 7 deletions(-)

[RFC PATCH] parser: implement octal and hex literals Export this patch

---

I'm not sure whether returning 0 in the case that none of the base
prefixes match is appropriate. If it's not, what's the better way to
handle that error?

 parser/arithm.c | 58 +++++++++++++++++++++++++++++++++++++++++++------
 test/arithm.sh  |  3 +++
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/parser/arithm.c b/parser/arithm.c
index cfd49e2..85c0602 100644
--- a/parser/arithm.c
+++ b/parser/arithm.c
@@ -53,18 +53,62 @@ static bool parse_str(struct mrsh_parser *parser, const char *str) {
 	return true;
 }
 
+static bool isoctal(char c)
+{
+	return (unsigned)c - '0' < 8;
+}
+
 static size_t peek_literal(struct mrsh_parser *parser) {
+	enum { DEC, OCT, HEX } base = DEC;
 	size_t i = 0;
-	while (true) {
-		parser_peek(parser, NULL, i + 1);
 
-		char c = parser->buf.data[i];
-		// TODO: 0x, 0b prefixes
-		if (!isdigit(c)) {
-			break;
+	parser_peek(parser, NULL, i + 1);
+	char c = parser->buf.data[i];
+	if (c == '0') {
+		parser_peek(parser, NULL, i + 2);
+		c = parser->buf.data[i + 1];
+		if (isoctal(c)) {
+			base = OCT;
+			i += 1;
+		} else if (c == 'x' || c == 'X') {
+			base = HEX;
+			i += 2;
+		} else {
+			return 0;
 		}
+	}
 
-		++i;
+	switch (base) {
+	case DEC:
+		while (true) {
+			parser_peek(parser, NULL, i + 1);
+			char c = parser->buf.data[i];
+			if (!isdigit(c)) {
+				break;
+			}
+			++i;
+		}
+		break;
+	case OCT:
+		while (true) {
+			parser_peek(parser, NULL, i + 1);
+			c = parser->buf.data[i];
+			if (!isoctal(c)) {
+				break;
+			}
+			++i;
+		}
+		break;
+	case HEX:
+		while (true) {
+			parser_peek(parser, NULL, i + 1);
+			c = parser->buf.data[i];
+			if (!isxdigit(c)) {
+				break;
+			}
+			++i;
+		}
+		break;
 	}
 
 	return i;
diff --git a/test/arithm.sh b/test/arithm.sh
index 7cc9df5..1a0abb0 100644
--- a/test/arithm.sh
+++ b/test/arithm.sh
@@ -44,6 +44,9 @@ echo "\$a+2 =" $(($a+2))
 
 # Assignments
 a=0
+echo "(a=042) =" $((a=042)) "->" $a
+echo "(a=0x42af) =" $((a=0x42af)) "->" $a
+echo "(a=0X42AF) =" $((a=0X42AF)) "->" $a
 echo "(a=42) =" $((a=42)) "->" $a
 echo "(a+=1) =" $((a+=1)) "->" $a
 echo "(a-=4) =" $((a-=4)) "->" $a
-- 
2.35.1