Implement __SCOPE__

__SCOPE__ expands to the currently scoped label.
It is empty if inside the main scope.

Fixes gbdev#775

src/asm/rgbasm.5

@@ -1258,6 +1258,7 @@ The following symbols are defined by the assembler:
 .It Dv _NARG Ta Ic EQU Ta Number of arguments passed to macro, updated by Ic SHIFT
 .It Dv __LINE__ Ta Ic EQU Ta The current line number
 .It Dv __FILE__ Ta Ic EQUS Ta The current filename
+.It Dv __SCOPE__ Ta Ic EQU Ta The current scoped label (empty if none is scoped)
 .It Dv __DATE__ Ta Ic EQUS Ta Today's date
 .It Dv __TIME__ Ta Ic EQUS Ta The current time
 .It Dv __ISO_8601_LOCAL__ Ta Ic EQUS Ta ISO 8601 timestamp (local)

src/asm/symbol.c

@@ -90,7 +90,7 @@ static int32_t Callback__LINE__(void)
 	return lexer_GetLineNo();
 }
 
-static char const *Callback__FILE__(void)
+static const char *Callback__FILE__(void)
 {
 	/*
 	 * FIXME: this is dangerous, and here's why this is CURRENTLY okay. It's still bad, fix it.
@@ -129,6 +129,22 @@ static char const *Callback__FILE__(void)
 	return buf;
 }
 
+static const char *Callback__SCOPE__(void)
+{
+	static char buf[MAXSYMLEN + 1];
+
+	if (!labelScope) {
+		// __SCOPE__ is empty inside the main scope (no global label)
+		buf[0] = '\0';
+	} else {
+		// labelScope is a valid label, so it will fit within MAXSYMLEN characters
+		assert(strlen(labelScope) < sizeof(buf));
+		strcpy(buf, labelScope);
+	}
+
+	return buf;
+}
+
 static int32_t CallbackPC(void)
 {
 	struct Section const *section = sect_GetSymbolSection();
@@ -717,6 +733,7 @@ void sym_Init(time_t now)
 	struct Symbol *_NARGSymbol = createBuiltinSymbol("_NARG");
 	struct Symbol *__LINE__Symbol = createBuiltinSymbol("__LINE__");
 	struct Symbol *__FILE__Symbol = createBuiltinSymbol("__FILE__");
+	struct Symbol *__SCOPE__Symbol = createBuiltinSymbol("__SCOPE__");
 
 	PCSymbol->type = SYM_LABEL;
 	PCSymbol->section = NULL;
@@ -727,6 +744,8 @@ void sym_Init(time_t now)
 	__LINE__Symbol->numCallback = Callback__LINE__;
 	__FILE__Symbol->type = SYM_EQUS;
 	__FILE__Symbol->strCallback = Callback__FILE__;
+	__SCOPE__Symbol->type = SYM_EQUS;
+	__SCOPE__Symbol->strCallback = Callback__SCOPE__;
 	sym_AddSet("_RS", 0)->isBuiltin = true;
 
 	sym_AddEqu("__RGBDS_MAJOR__", PACKAGE_VERSION_MAJOR)->isBuiltin = true;

test/asm/scope-noscope.asm

@@ -0,0 +1 @@
+	PRINTLN "inside {__SCOPE__}"

test/asm/scope-noscope.out

@@ -0,0 +1 @@
+inside 

test/asm/scope.asm

@@ -0,0 +1,28 @@
+SECTION "test", ROM0
+
+	assert !STRLEN("{__SCOPE__}")
+
+SomeFunction:
+	println __FILE__, ":{d:__LINE__}:{__SCOPE__}: 2 + 2 = ", 2+2
+
+verify: MACRO
+	assert !STRCMP("{__SCOPE__}", "\1")
+	assert __SCOPE__ == \1
+ENDM
+
+Alpha:
+	verify Alpha
+.local
+	verify Alpha
+
+Beta::
+.local::
+	verify Beta
+
+S EQUS """
+Gamma:
+	verify Gamma
+"""
+	S
+	PURGE S
+	verify Gamma

test/asm/scope.out

@@ -0,0 +1 @@
+scope.asm:6:SomeFunction: 2 + 2 = $4