Support numeric symbol names in \(parentheses)

For example, \(_NARG) will get the last argument

src/asm/lexer.c

@@ -724,6 +724,8 @@ static bool isMacroChar(char c)
 static int peek(void);
 static void shiftChar(void);
 static uint32_t readNumber(int radix, uint32_t baseValue);
+static bool startsIdentifier(int c);
+static bool continuesIdentifier(int c);
 
 static uint32_t readParentheticMacroArgNum(void)
 {
@@ -736,15 +738,42 @@ static uint32_t readParentheticMacroArgNum(void)
 
 	uint32_t num = 0;
 	int c = peek();
-	bool hasDigit = c >= '0' && c <= '9';
+	bool empty = false;
 
-	if (hasDigit)
+	if (c >= '0' && c <= '9') {
 		num = readNumber(10, 0);
+	} else if (startsIdentifier(c)) {
+		char symName[MAXSYMLEN + 1];
+		size_t i = 0;
+
+		for (; continuesIdentifier(c); c = peek()) {
+			if (i < sizeof(symName))
+				symName[i++] = c;
+			shiftChar();
+		}
+
+		if (i == sizeof(symName)) {
+			warning(WARNING_LONG_STR, "Symbol name too long\n");
+			i--;
+		}
+		symName[i] = '\0';
+
+		struct Symbol const *sym = sym_FindScopedSymbol(symName);
+
+		if (!sym)
+			fatalerror("Parenthetic symbol \"%s\" does not exist\n", symName);
+		else if (!sym_IsNumeric(sym))
+			fatalerror("Parenthetic symbol \"%s\" is not numeric\n", symName);
+
+		num = sym_GetConstantSymValue(sym);
+	} else {
+		empty = true;
+	}
 
 	c = peek();
 	if (c != ')')
 		fatalerror("Invalid character in parenthetic macro argument %s\n", printChar(c));
-	else if (!hasDigit)
+	else if (empty)
 		fatalerror("Empty parenthetic macro argument\n");
 	else if (num == 0)
 		fatalerror("Invalid parenthetic macro argument '\\(0)'\n");

src/asm/rgbasm.5

@@ -1569,7 +1569,10 @@ does not need to be escaped because string literals also work as usual inside ma
 Since there are only nine digits, you can only access the first nine macro arguments like this.
 To use the rest, you need to put the multi-digit argument number in parentheses, like
 .Ql \[rs](10) .
-This parenthetic syntax only supports decimal numbers.
+This parenthetic syntax supports decimal numbers and numeric symbol names.
+For example,
+.Ql \[rs](_NARG)
+will get the last argument.
 .Pp
 Other macro arguments and symbol interpolations will be expanded inside the parentheses.
 For example, if
@@ -1580,10 +1583,12 @@ then
 .Ql \[rs](\[rs]1)
 will expand to
 .Ql \[rs](13) .
-And if
-.Ql x = 42 ,
+Or if
+.Ql v10 = 42
+and
+.Ql x = 10 ,
 then
-.Ql \[rs]({d:x})
+.Ql \[rs](v{d:x})
 will expand to
 .Ql \[rs](42) .
 .Pp

test/asm/invalid-macro-arg-symbol.asm

@@ -0,0 +1 @@
+\(foo)

test/asm/invalid-macro-arg-symbol.err

@@ -0,0 +1,2 @@
+FATAL: invalid-macro-arg-symbol.asm(1):
+    Parenthetic symbol "foo" does not exist

test/asm/parenthetic-macro-args.asm

@@ -12,6 +12,8 @@ MACRO mac
 	println \(2__) + \(1_2) + \(\1)
 x = 2
 	println \({d:x}) + \(1_{d:x}) + \(\(\(13)))
+y equs "NARG"
+	println \(x) + \(1_{d:x}_) + \(\(\(_{y})))
 ENDM
 
 	mac 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 1

test/asm/parenthetic-macro-args.out

@@ -4,3 +4,4 @@ next = C
 last = D
 $F0
 $F0
+$F0